-. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.1 2006/02/01 11:01:02 ph10 Exp $
-.
. /////////////////////////////////////////////////////////////////////////////
. This is the primary source of the Exim Manual. It is an xfpt document that is
. converted into DocBook XML for subsequent conversion into printing and online
. formats. The markup used herein is "standard" xfpt markup, with some extras.
. The markup is summarized in a file called Markup.txt.
+.
+. WARNING: When you use the .new macro, make sure it appears *before* any
+. adjacent index items; otherwise you get an empty "paragraph" which causes
+. unwanted vertical space.
. /////////////////////////////////////////////////////////////////////////////
.include stdflags
.include stdmacs
+
+. /////////////////////////////////////////////////////////////////////////////
+. This outputs the standard DocBook boilerplate.
+. /////////////////////////////////////////////////////////////////////////////
+
.docbook
+
+. /////////////////////////////////////////////////////////////////////////////
+. These lines are processing instructions for the Simple DocBook Processor that
+. Philip Hazel has developed as a less cumbersome way of making PostScript and
+. PDFs than using xmlto and fop. They will be ignored by all other XML
+. processors.
+. /////////////////////////////////////////////////////////////////////////////
+
+.literal xml
+<?sdop
+ foot_right_recto="&chaptertitle; (&chapternumber;)"
+ foot_right_verso="&chaptertitle; (&chapternumber;)"
+ toc_chapter_blanks="yes,yes"
+ table_warn_overflow="overprint"
+?>
+.literal off
+
+. /////////////////////////////////////////////////////////////////////////////
+. This generate the outermost <book> element that wraps then entire document.
+. /////////////////////////////////////////////////////////////////////////////
+
.book
. /////////////////////////////////////////////////////////////////////////////
. the <bookinfo> element must also be updated for each new edition.
. /////////////////////////////////////////////////////////////////////////////
+.set previousversion "4.80"
+.set version "4.80"
+
.set ACL "access control lists (ACLs)"
-.set previousversion "4.50"
-.set version "4.60"
+.set I " "
. /////////////////////////////////////////////////////////////////////////////
.flag &!? "</emphasis>‡<emphasis>"
. --- A macro for an Exim option definition heading, generating a one-line
-. --- table with four columns.
+. --- table with four columns. For cases when the option name is given with
+. --- a space, so that it can be split, a fifth argument is used for the
+. --- index entry.
.macro option
-.oindex "$1"
-.itable all 0 0 4 8* left 5* center 5* center 6* right
+.arg 5
+.oindex "&%$5%&"
+.endarg
+.arg -5
+.oindex "&%$1%&"
+.endarg
+.itable all 0 0 4 8* left 6* center 6* center 6* right
.row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&"
.endtable
.endmacro
. --- is suitable for the many tables at the start of the main options chapter;
. --- the small number of other 2-column tables override it.
-.macro table2 190pt 300pt
+.macro table2 196pt 254pt
.itable none 0 0 2 $1 left $2 left
.endmacro
-. --- Macros for the concept and option index entries
+. --- A macro that generates .row, but puts &I; at the start of the first
+. --- argument, thus indenting it. Assume a minimum of two arguments, and
+. --- allow up to four arguments, which is as many as we'll ever need.
+
+.macro irow
+.arg 4
+.row "&I;$1" "$2" "$3" "$4"
+.endarg
+.arg -4
+.arg 3
+.row "&I;$1" "$2" "$3"
+.endarg
+.arg -3
+.row "&I;$1" "$2"
+.endarg
+.endarg
+.endmacro
+
+. --- Macros for option, variable, and concept index entries. For a "range"
+. --- style of entry, use .scindex for the start and .ecindex for the end. The
+. --- first argument of .scindex and the only argument of .ecindex must be the
+. --- ID that ties them together.
.macro cindex
&<indexterm role="concept">&
&</indexterm>&
.endmacro
+.macro scindex
+&<indexterm role="concept" id="$1" class="startofrange">&
+&<primary>&$2&</primary>&
+.arg 3
+&<secondary>&$3&</secondary>&
+.endarg
+&</indexterm>&
+.endmacro
+
+.macro ecindex
+&<indexterm role="concept" startref="$1" class="endofrange"/>&
+.endmacro
+
.macro oindex
&<indexterm role="option">&
&<primary>&$1&</primary>&
&</indexterm>&
.endmacro
+.macro vindex
+&<indexterm role="variable">&
+&<primary>&$1&</primary>&
+.arg 2
+&<secondary>&$2&</secondary>&
+.endarg
+&</indexterm>&
+.endmacro
+
.macro index
-.echo "** Don't use .index; use .cindex or .oindex"
+.echo "** Don't use .index; use .cindex or .oindex or .vindex"
.endmacro
. ////////////////////////////////////////////////////////////////////////////
<bookinfo>
<title>Specification of the Exim Mail Transfer Agent</title>
<titleabbrev>The Exim MTA</titleabbrev>
-<date>05 January 2006</date>
-<author><firstname>Philip</firstname><surname>Hazel</surname></author>
-<authorinitials>PH</authorinitials>
-<affiliation><orgname>University of Cambridge Computing Service</orgname></affiliation>
-<address>New Museums Site, Pembroke Street, Cambridge CB2 3QH, England</address>
+<date>17 May 2012</date>
+<author><firstname>Exim</firstname><surname>Maintainers</surname></author>
+<authorinitials>EM</authorinitials>
<revhistory><revision>
- <revnumber>4.60-1</revnumber>
- <date>30 January 2006</date>
- <authorinitials>PH</authorinitials>
+ <revnumber>4.80</revnumber>
+ <date>17 May 2012</date>
+ <authorinitials>EM</authorinitials>
</revision></revhistory>
-<copyright><year>2006</year><holder>University of Cambridge</holder></copyright>
+<copyright><year>2012</year><holder>University of Cambridge</holder></copyright>
</bookinfo>
.literal off
. at the top level, so we have to put the .chapter directive first.
. /////////////////////////////////////////////////////////////////////////////
-.chapter "Introduction"
+.chapter "Introduction" "CHID1"
.literal xml
-<indexterm role="concept">
+<indexterm role="variable">
<primary>$1, $2, etc.</primary>
<see><emphasis>numerical variables</emphasis></see>
</indexterm>
</indexterm>
<indexterm role="concept">
<primary>maximum</primary>
- <see><emphasis>limit</emphasis></see>
+ <seealso><emphasis>limit</emphasis></seealso>
</indexterm>
<indexterm role="concept">
<primary>monitor</primary>
contributors.
-.section "Exim documentation"
+.section "Exim documentation" "SECID1"
+. Keep this example change bar when updating the documentation!
+
.new
.cindex "documentation"
This edition of the Exim specification applies to version &version; of Exim.
.cindex "books about Exim"
An &"easier"& discussion of Exim which provides more in-depth explanatory,
introductory, and tutorial material can be found in a book entitled &'The Exim
-SMTP Mail Server'&, published by UIT Cambridge
+SMTP Mail Server'& (second edition, 2007), published by UIT Cambridge
(&url(http://www.uit.co.uk/exim-book/)).
This book also contains a chapter that gives a general introduction to SMTP and
with the latest release of Exim. (Note that the earlier book about Exim,
published by O'Reilly, covers Exim 3, and many things have changed in Exim 4.)
-.new
.cindex "Debian" "information sources"
If you are using a Debian distribution of Exim, you will find information about
Debian-specific features in the file
-.display
-&_/usr/share/doc/exim4-base/README.Debian_&
-.endd
+&_/usr/share/doc/exim4-base/README.Debian_&.
The command &(man update-exim.conf)& is another source of Debian-specific
information.
-.wen
.cindex "&_doc/NewStuff_&"
.cindex "&_doc/ChangeLog_&"
.row &_exim.8_& "a man page of Exim's command line options"
.row &_experimental.txt_& "documentation of experimental features"
.row &_filter.txt_& "specification of the filter language"
-.row &_pcrepattern.txt_& "specification of PCRE regular expressions"
-.row &_pcretest.txt_& "specification of the PCRE testing program"
.row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3"
.row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4"
.endtable
-.section "FTP and web sites"
+.section "FTP and web sites" "SECID2"
.cindex "web site"
.cindex "FTP site"
The primary site for Exim source distributions is currently the University of
.cindex "wiki"
.cindex "FAQ"
As well as Exim distribution tar files, the Exim web site contains a number of
-differently formatted versions of the documentation, including the FAQ in both
-text and HTML formats. The HTML version comes with a keyword-in-context index.
-A recent addition to the online information is the Exim wiki
-(&url(http://www.exim.org/eximwiki/)). We hope that this will make it easier
-for Exim users to contribute examples, tips, and know-how for the benefit of
-others.
+differently formatted versions of the documentation. A recent addition to the
+online information is the Exim wiki (&url(http://wiki.exim.org)),
+which contains what used to be a separate FAQ, as well as various other
+examples, tips, and know-how that have been contributed by Exim users.
+
+.cindex Bugzilla
+An Exim Bugzilla exists at &url(http://bugs.exim.org). You can use
+this to report bugs, and also to add items to the wish list. Please search
+first to check that you are not duplicating a previous entry.
-.section "Mailing lists"
+.section "Mailing lists" "SECID3"
.cindex "mailing lists" "for Exim users"
-The following are the three main Exim mailing lists:
+The following Exim mailing lists exist:
.table2 140pt
-.row &'exim-users@exim.org'& "general discussion list"
-.row &'exim-dev@exim.org'& "discussion of bugs, enhancements, etc."
-.row &'exim-announce@exim.org'& "moderated, low volume announcements list"
+.row &'exim-announce@exim.org'& "Moderated, low volume announcements list"
+.row &'exim-users@exim.org'& "General discussion list"
+.row &'exim-dev@exim.org'& "Discussion of bugs, enhancements, etc."
+.row &'exim-cvs@exim.org'& "Automated commit messages from the VCS"
.endtable
You can subscribe to these lists, change your existing subscriptions, and view
or search the archives via the mailing lists link on the Exim home page.
.cindex "Debian" "mailing list for"
-&new("If you are using a Debian distribution of Exim, you may wish to subscribe
-to the Debian-specific mailing list
-&'pkg-exim4-users@lists.alioth.debian.org'&.")
-.wen
+If you are using a Debian distribution of Exim, you may wish to subscribe to
+the Debian-specific mailing list &'pkg-exim4-users@lists.alioth.debian.org'&
+via this web page:
+.display
+&url(http://lists.alioth.debian.org/mailman/listinfo/pkg-exim4-users)
+.endd
+Please ask Debian-specific questions on this list and not on the general Exim
+lists.
-.section "Exim training"
+.section "Exim training" "SECID4"
.cindex "training courses"
-From time to time (approximately annually at the time of writing), training
-courses are run by the author of Exim in Cambridge, UK. Details of any
-forthcoming courses can be found on the web site
-&url(http://www-tus.csx.cam.ac.uk/courses/exim/).
-
+Training courses in Cambridge (UK) used to be run annually by the author of
+Exim, before he retired. At the time of writing, there are no plans to run
+further Exim courses in Cambridge. However, if that changes, relevant
+information will be posted at &url(http://www-tus.csx.cam.ac.uk/courses/exim/).
-.section "Bug reports"
+.section "Bug reports" "SECID5"
.cindex "bug reports"
.cindex "reporting bugs"
-Reports of obvious bugs should be emailed to &'bugs@exim.org'&. However, if you
-are unsure whether some behaviour is a bug or not, the best thing to do is to
-post a message to the &'exim-dev'& mailing list and have it discussed.
+Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported
+via the Bugzilla (&url(http://bugs.exim.org)). However, if you are unsure
+whether some behaviour is a bug or not, the best thing to do is to post a
+message to the &'exim-dev'& mailing list and have it discussed.
.cindex "distribution" "signing details"
.cindex "distribution" "public key"
.cindex "public key for signed distribution"
-The distributions are currently signed with Philip Hazel's GPG key. The
+The distributions are currently signed with Nigel Metheringham's GPG key. The
corresponding public key is available from a number of keyservers, and there is
-also a copy in the file &_Public-Key_&. The signatures for the tar bundles are
+also a copy in the file &_nigel-pubkey.asc_&. The signatures for the tar bundles are
in:
.display
-&_exim-n.nn.tar.gz.sig_&
-&_exim-n.nn.tar.bz2.sig_&
+&_exim-n.nn.tar.gz.asc_&
+&_exim-n.nn.tar.bz2.asc_&
.endd
For each released version, the log of changes is made separately available in a
separate file in the directory &_ChangeLogs_& so that it is possible to
.endd
These tar files contain only the &_doc_& directory, not the complete
distribution, and are also available in &_.bz2_& as well as &_.gz_& forms.
-.cindex "FAQ"
-The FAQ is available for downloading in two different formats in these files:
-.display
-&_exim4/FAQ.txt.gz_&
-&_exim4/FAQ.html.tar.gz_&
-.endd
-The first of these is a single ASCII file that can be searched with a text
-editor. The second is a directory of HTML files, normally accessed by starting
-at &_index.html_&. The HTML version of the FAQ (which is also included in the
-HTML documentation tarbundle) includes a keyword-in-context index, which is
-often the most convenient way of finding your way around.
-
-
-.section "Wish list"
-.cindex "wish list"
-A wish list is maintained, containing ideas for new features that have been
-submitted. From time to time the file is exported to the ftp site into the file
-&_exim4/WishList_&. Items are removed from the list if they get implemented.
-
-.section "Contributed material"
-.cindex "contributed material"
-At the ftp site, there is a directory called &_Contrib_& that contains
-miscellaneous files contributed to the Exim community by Exim users. There is
-also a collection of contributed configuration examples in
-&_exim4/config.samples.tar.gz_&. These samples are referenced from the FAQ.
-
-
-
-.section "Limitations"
+.section "Limitations" "SECID6"
.ilist
.cindex "limitations of Exim"
.cindex "bang paths" "not handled by Exim"
.endlist
-.section "Run time configuration"
+.section "Run time configuration" "SECID7"
Exim's run time configuration is held in a single text file that is divided
into a number of sections. The entries in this file consist of keywords and
values, in the style of Smail 3 configuration files. A default configuration
distribution, and is described in chapter &<<CHAPdefconfil>>& below.
-.section "Calling interface"
+.section "Calling interface" "SECID8"
.cindex "Sendmail compatibility" "command line interface"
Like many MTAs, Exim has adopted the Sendmail command line interface so that it
can be a straight replacement for &_/usr/lib/sendmail_& or
-.section "Terminology"
+.section "Terminology" "SECID9"
.cindex "terminology definitions"
.cindex "body of message" "definition of"
The &'body'& of a message is the actual data that the sender wants to transmit.
host's name. It is &'not'& used in that sense here, where it normally refers to
the part of an email address following the @ sign.
-.cindex "envelope" "definition of"
+.cindex "envelope, definition of"
.cindex "sender" "definition of"
A message in transit has an associated &'envelope'&, as well as a header and a
body. The envelope contains a sender address (to which bounce messages should
envelope. An MTA uses these addresses for delivery, and for returning bounce
messages, not the addresses that appear in the header lines.
-.cindex "message header" "definition of"
+.cindex "message" "header, definition of"
.cindex "header section" "definition of"
The &'header'& of a message is the first part of a message's text, consisting
of a number of lines, each of which has a name such as &'From:'&, &'To:'&,
@ sign is called the &'domain'& or &'mail domain'&.
.cindex "local delivery" "definition of"
-.cindex "remote delivery" "definition of"
+.cindex "remote delivery, definition of"
The terms &'local delivery'& and &'remote delivery'& are used to distinguish
delivery to a file or a pipe on the local host from delivery by SMTP over
TCP/IP to another host. As far as Exim is concerned, all hosts other than the
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "Incorporated code"
+.chapter "Incorporated code" "CHID2"
.cindex "incorporated code"
.cindex "regular expressions" "library"
.cindex "PCRE"
A number of pieces of external code are included in the Exim distribution.
.ilist
-Regular expressions are supported in the main Exim program and in the Exim
-monitor using the freely-distributable PCRE library, copyright ©
-University of Cambridge. The source is distributed in the directory
-&_src/pcre_&. However, this is a cut-down version of PCRE. If you want to use
-the PCRE library in other programs, you should obtain and install the full
-version from &*ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre*&.
-.next
-.cindex "cdb" "acknowledgement"
+Regular expressions are supported in the main Exim program and in the
+Exim monitor using the freely-distributable PCRE library, copyright
+© University of Cambridge. The source to PCRE is no longer shipped with
+Exim, so you will need to use the version of PCRE shipped with your system,
+or obtain and install the full version of the library from
+&url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre).
+.next
+.cindex "cdb" "acknowledgment"
Support for the cdb (Constant DataBase) lookup method is provided by code
contributed by Nigel Metheringham of (at the time he contributed it) Planet
Online Ltd. The implementation is completely contained within the code of Exim.
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
-
This code implements Dan Bernstein's Constant DataBase (cdb) spec. Information,
the spec and sample code for cdb can be obtained from
-&url(http://www.pobox.com/~djb/cdb.html). This implementation borrows some
-code from Dan Bernstein's implementation (which has no license restrictions
-applied to it).
+&url(http://www.pobox.com/~djb/cdb.html). This implementation borrows
+some code from Dan Bernstein's implementation (which has no license
+restrictions applied to it).
.endblockquote
.next
.cindex "SPA authentication"
.endblockquote
.next
-.cindex "Exim monitor" "acknowledgement"
+.cindex "Exim monitor" "acknowledgment"
.cindex "X-windows"
.cindex "Athena"
The Exim Monitor program, which is an X-Window application, includes
.next
Many people have contributed code fragments, some large, some small, that were
not covered by any specific licence requirements. It is assumed that the
-contributors are happy to see their code incoporated into Exim under the GPL.
+contributors are happy to see their code incorporated into Exim under the GPL.
.endlist
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "How Exim receives and delivers mail" "" &&&
+.chapter "How Exim receives and delivers mail" "CHID11" &&&
"Receiving and delivering mail"
-.section "Overall philosophy"
+.section "Overall philosophy" "SECID10"
.cindex "design philosophy"
Exim is designed to work efficiently on systems that are permanently connected
to the Internet and are handling a general mix of mail. In such circumstances,
has been down, and it also maintains per-host retry information.
-.section "Policy control"
+.section "Policy control" "SECID11"
.cindex "policy control" "overview"
Policy controls are now an important feature of MTAs that are connected to the
Internet. Perhaps their most important job is to stop MTAs being abused as
which can then use it to decide what to do with the message.
.next
When a message has been received, either from a remote host or from the local
-host, but before the final acknowledgement has been sent, a locally supplied C
+host, but before the final acknowledgment has been sent, a locally supplied C
function called &[local_scan()]& can be run to inspect the message and decide
whether to accept it or not (see chapter &<<CHAPlocalscan>>&). If the message
is accepted, the list of recipients can be modified by the function.
-.section "User filters"
+.section "User filters" "SECID12"
.cindex "filter" "introduction"
.cindex "Sieve filter"
In a conventional Exim configuration, users are able to run private filters by
.next
There are two different possibilities for the final two characters:
.olist
-.cindex "&%localhost_number%&"
+.oindex "&%localhost_number%&"
If &%localhost_number%& is not set, this value is the fractional part of the
time of reception, normally in units of 1/2000 of a second, but for systems
that must use base 36 instead of base 62 (because of case-insensitive file
will already have ticked while the message was being received.
-.section "Receiving mail"
+.section "Receiving mail" "SECID13"
.cindex "receiving mail"
.cindex "message" "reception"
The only way Exim can receive mail from another host is using SMTP over
.endlist
-.cindex "message sender" "constructed by Exim"
+.cindex "message sender, constructed by Exim"
.cindex "sender" "constructed by Exim"
In the three cases that do not involve TCP/IP, the sender address is
constructed from the login name of the user that called Exim and a default
-.section "Handling an incoming message"
+.section "Handling an incoming message" "SECID14"
.cindex "spool directory" "files that hold a message"
.cindex "file" "how a message is held"
When Exim accepts a message, it writes two files in its spool directory. The
.cindex "spool directory" "&_input_& sub-directory"
By default all these message files are held in a single directory called
&_input_& inside the general Exim spool directory. Some operating systems do
-not perform very well if the number of files in a directory gets very large; to
+not perform very well if the number of files in a directory gets large; to
improve performance in such cases, the &%split_spool_directory%& option can be
used. This causes Exim to split up the input files into 62 sub-directories
-whose names are single letters or digits.
+whose names are single letters or digits. When this is done, the queue is
+processed one sub-directory at a time instead of all at once, which can improve
+overall performance even when there are not enough files in each directory to
+affect file system performance.
The envelope information consists of the address of the message's sender and
the addresses of the recipients. This information is entirely separate from
-.section "Life of a message"
+.section "Life of a message" "SECID15"
.cindex "message" "life of"
.cindex "message" "frozen"
A message remains in the spool directory until it is completely delivered to
addition, an administrator can force a delivery error, causing a bounce message
to be sent.
-.new
-.cindex "&%timeout_frozen_after%&"
-.cindex "&%ignore_bounce_errors_after%&"
+.oindex "&%timeout_frozen_after%&"
+.oindex "&%ignore_bounce_errors_after%&"
There are options called &%ignore_bounce_errors_after%& and
&%timeout_frozen_after%&, which discard frozen messages after a certain time.
The first applies only to frozen bounces, the second to any frozen messages.
-.wen
.cindex "message" "log file for"
.cindex "log" "file for each message"
-.section "Processing an address for verification"
+.section "Processing an address for verification" "SECID16"
.cindex "router" "for verification"
.cindex "verifying address" "overview"
As well as being used to decide how to deliver to an address, Exim's routers
&'accept'&: The router accepts the address, and either assigns it to a
transport, or generates one or more &"child"& addresses. Processing the
original address ceases,
-.cindex "&%unseen%& option"
+.oindex "&%unseen%&"
unless the &%unseen%& option is set on the router. This option
can be used to set up multiple deliveries with different routing (for example,
for keeping archive copies of messages). When &%unseen%& is set, the address is
facility for this purpose.
-.section "Duplicate addresses"
-.new
+.section "Duplicate addresses" "SECID17"
.cindex "case of local parts"
-.cindex "address duplicate" "discarding"
+.cindex "address duplicate, discarding"
+.cindex "duplicate addresses"
Once routing is complete, Exim scans the addresses that are assigned to local
and remote transports, and discards any duplicates that it finds. During this
-check, local parts are treated as case-sensitive.
-.wen
+check, local parts are treated as case-sensitive. This happens only when
+actually delivering a message; when testing routers with &%-bt%&, all the
+routed addresses are shown.
+
.section "Router preconditions" "SECTrouprecon"
-.cindex "router preconditions" "order of processing"
+.cindex "router" "preconditions, order of processing"
.cindex "preconditions" "order of processing"
The preconditions that are tested for each router are listed below, in the
order in which they are tested. The individual configuration options are
If the &%domains%& option is set, the domain of the address must be in the set
of domains that it defines.
.next
-.cindex "&$local_part_prefix$&"
-.cindex "&$local_part$&"
-.cindex "&$local_part_suffix$&"
+.vindex "&$local_part_prefix$&"
+.vindex "&$local_part$&"
+.vindex "&$local_part_suffix$&"
If the &%local_parts%& option is set, the local part of the address must be in
the set of local parts that it defines. If &%local_part_prefix%& or
&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
that uses the variables &$local_part$&, &$local_part_prefix$&, and
&$local_part_suffix$& as necessary.
.next
-.cindex "&$local_user_uid$&"
-.cindex "&$local_user_gid$&"
-.cindex "&$home$&"
+.vindex "&$local_user_uid$&"
+.vindex "&$local_user_gid$&"
+.vindex "&$home$&"
If the &%check_local_user%& option is set, the local part must be the name of
an account on the local host. If this check succeeds, the uid and gid of the
local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
-.section "Delivery in detail"
+.section "Delivery in detail" "SECID18"
.cindex "delivery" "in detail"
When a message is to be delivered, the sequence of events is as follows:
-.section "Retry mechanism"
+.section "Retry mechanism" "SECID19"
.cindex "delivery" "retry mechanism"
.cindex "retry" "description of mechanism"
.cindex "queue runner"
-.section "Temporary delivery failure"
+.section "Temporary delivery failure" "SECID20"
.cindex "delivery" "temporary failure"
There are many reasons why a message may not be immediately deliverable to a
particular address. Failure to connect to a remote machine (because it, or the
waiting for it by the time it recovers, and sending them in a single SMTP
connection is clearly beneficial. Whenever a delivery to a remote host is
deferred,
-
.cindex "hints database"
Exim makes a note in its hints database, and whenever a successful
SMTP delivery has happened, it looks to see if any other messages are waiting
-
-.section "Permanent delivery failure"
+.section "Permanent delivery failure" "SECID21"
.cindex "delivery" "permanent failure"
.cindex "bounce message" "when generated"
When a message cannot be delivered to some or all of its intended recipients, a
-.section "Failures to deliver bounce messages"
+.section "Failures to deliver bounce messages" "SECID22"
.cindex "bounce message" "failure to deliver"
If a bounce message (either locally generated or received from a remote host)
itself suffers a permanent delivery failure, the message is left on the queue,
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "Building and installing Exim"
-.cindex "building Exim"
+.chapter "Building and installing Exim" "CHID3"
+.scindex IIDbuex "building Exim"
-.section "Unpacking"
-Exim is distributed as a gzipped or bzipped tar file which, when upacked,
+.section "Unpacking" "SECID23"
+Exim is distributed as a gzipped or bzipped tar file which, when unpacked,
creates a directory with the name of the current release (for example,
&_exim-&version;_&) into which the following files are placed:
.table2 140pt
-.row &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
-.row &_CHANGES_& "contains a reference to where changes are documented"
-.row &_LICENCE_& "the GNU General Public Licence"
-.row &_Makefile_& "top-level make file"
-.row &_NOTICE_& "conditions for the use of Exim"
-.row &_README_& "list of files, directories and simple build &&&
- instructions"
+.irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
+.irow &_CHANGES_& "contains a reference to where changes are &&&
+ documented"
+.irow &_LICENCE_& "the GNU General Public Licence"
+.irow &_Makefile_& "top-level make file"
+.irow &_NOTICE_& "conditions for the use of Exim"
+.irow &_README_& "list of files, directories and simple build &&&
+ instructions"
.endtable
Other files whose names begin with &_README_& may also be present. The
following subdirectories are created:
.table2 140pt
-.row &_Local_& "an empty directory for local configuration files"
-.row &_OS_& "OS-specific files"
-.row &_doc_& "documentation files"
-.row &_exim_monitor_& "source files for the Exim monitor"
-.row &_scripts_& "scripts used in the build process"
-.row &_src_& "remaining source files"
-.row &_util_& "independent utilities"
+.irow &_Local_& "an empty directory for local configuration files"
+.irow &_OS_& "OS-specific files"
+.irow &_doc_& "documentation files"
+.irow &_exim_monitor_& "source files for the Exim monitor"
+.irow &_scripts_& "scripts used in the build process"
+.irow &_src_& "remaining source files"
+.irow &_util_& "independent utilities"
.endtable
The main utility programs are contained in the &_src_& directory, and are built
that may be useful to some sites.
-.section "Multiple machine architectures and operating systems"
+.section "Multiple machine architectures and operating systems" "SECID24"
.cindex "building Exim" "multiple OS/architectures"
The building process for Exim is arranged to make it easy to build binaries for
a number of different architectures and operating systems from the same set of
overridden if necessary.
+.section "PCRE library" "SECTpcre"
+.cindex "PCRE library"
+Exim no longer has an embedded PCRE library as the vast majority of
+modern systems include PCRE as a system library, although you may need
+to install the PCRE or PCRE development package for your operating
+system. If your system has a normal PCRE installation the Exim build
+process will need no further configuration. If the library or the
+headers are in an unusual location you will need to either set the PCRE_LIBS
+and INCLUDE directives appropriately,
+or set PCRE_CONFIG=yes to use the installed &(pcre-config)& command.
+If your operating system has no
+PCRE support then you will need to obtain and build the current PCRE
+from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/).
+More information on PCRE is available at &url(http://www.pcre.org/).
+
.section "DBM libraries" "SECTdb"
.cindex "DBM libraries" "discussion of"
.cindex "hints database" "DBM files used for"
different operating systems often have different ones installed.
.cindex "Solaris" "DBM library for"
-.cindex "IRIX" "DBM library for"
-.cindex "BSD" "DBM library for"
-.cindex "Linux" "DBM library for"
+.cindex "IRIX, DBM library for"
+.cindex "BSD, DBM library for"
+.cindex "Linux, DBM library for"
If you are using Solaris, IRIX, one of the modern BSD systems, or a modern
Linux distribution, the DBM configuration should happen automatically, and you
may be able to ignore this section. Otherwise, you may have to learn more than
versions of Unix seem to vary in what they contain as standard. In particular,
some early versions of Linux have no default DBM library, and different
distributors have chosen to bundle different libraries with their packaged
-versions. However, the more recent releases seem to have standardised on the
+versions. However, the more recent releases seem to have standardized on the
Berkeley DB library.
Different DBM libraries have different conventions for naming the files they
-.section "Pre-building configuration"
+.section "Pre-building configuration" "SECID25"
.cindex "building Exim" "pre-building configuration"
.cindex "configuration for building Exim"
.cindex "&_Local/Makefile_&"
.cindex "&_Local/eximon.conf_&"
-.cindex "_exim_monitor/EDITME_"
+.cindex "&_exim_monitor/EDITME_&"
If you are going to build the Exim monitor, a similar configuration process is
required. The file &_exim_monitor/EDITME_& must be edited appropriately for
your installation and saved under the name &_Local/eximon.conf_&. If you are
-.section "Support for iconv()"
+.section "Support for iconv()" "SECID26"
.cindex "&[iconv()]& support"
.cindex "RFC 2047"
The contents of header lines in messages may be encoded according to the rules
TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
TLS_INCLUDE=-I/usr/local/openssl/include/
.endd
+.cindex "pkg-config" "OpenSSL"
+If you have &'pkg-config'& available, then instead you can just use:
+.code
+SUPPORT_TLS=yes
+USE_OPENSSL_PC=openssl
+.endd
.cindex "USE_GNUTLS"
If GnuTLS is installed, you should set
.code
TLS_LIBS=-L/usr/gnu/lib -lgnutls -ltasn1 -lgcrypt
TLS_INCLUDE=-I/usr/gnu/include
.endd
+.cindex "pkg-config" "GnuTLS"
+If you have &'pkg-config'& available, then instead you can just use:
+.code
+SUPPORT_TLS=yes
+USE_GNUTLS=yes
+USE_GNUTLS_PC=gnutls
+.endd
+
You do not need to set TLS_INCLUDE if the relevant directory is already
specified in INCLUDE. Details of how to configure Exim to make use of TLS are
given in chapter &<<CHAPTLS>>&.
-.section "Use of tcpwrappers"
-.cindex "tcpwrappers" "building Exim to support"
+.section "Use of tcpwrappers" "SECID27"
+
+.cindex "tcpwrappers, building Exim to support"
.cindex "USE_TCP_WRAPPERS"
+.cindex "TCP_WRAPPERS_DAEMON_NAME"
+.cindex "tcp_wrappers_daemon_name"
Exim can be linked with the &'tcpwrappers'& library in order to check incoming
SMTP calls using the &'tcpwrappers'& control files. This may be a convenient
alternative to Exim's own checking facilities for installations that are
CFLAGS=-O -I/usr/local/include
EXTRALIBS_EXIM=-L/usr/local/lib -lwrap
.endd
-in &_Local/Makefile_&. The name to use in the &'tcpwrappers'& control files is
-&"exim"&. For example, the line
+in &_Local/Makefile_&. The daemon name to use in the &'tcpwrappers'& control
+files is &"exim"&. For example, the line
.code
exim : LOCAL 192.168.1. .friendly.domain.example
.endd
in your &_/etc/hosts.allow_& file allows connections from the local host, from
the subnet 192.168.1.0/24, and from all hosts in &'friendly.domain.example'&.
-All other connections are denied. Consult the &'tcpwrappers'& documentation for
+All other connections are denied. The daemon name used by &'tcpwrappers'&
+can be changed at build time by setting TCP_WRAPPERS_DAEMON_NAME in
+in &_Local/Makefile_&, or by setting tcp_wrappers_daemon_name in the
+configure file. Consult the &'tcpwrappers'& documentation for
further details.
-
-.section "Including support for IPv6"
+.section "Including support for IPv6" "SECID28"
.cindex "IPv6" "including support for"
Exim contains code for use on systems that have IPv6 support. Setting
&`HAVE_IPV6=YES`& in &_Local/Makefile_& causes the IPv6 code to be included;
library files.
Two different types of DNS record for handling IPv6 addresses have been
-defined. AAAA records (analagous to A records for IPv4) are in use, and are
+defined. AAAA records (analogous to A records for IPv4) are in use, and are
currently seen as the mainstream. Another record type called A6 was proposed
as better than AAAA because it had more flexibility. However, it was felt to be
over-complex, and its status was reduced to &"experimental"&. It is not known
-.section "The building process"
+.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
+.cindex "lookup modules"
+.cindex "dynamic modules"
+.cindex ".so building"
+On some platforms, Exim supports not compiling all lookup types directly into
+the main binary, instead putting some into external modules which can be loaded
+on demand.
+This permits packagers to build Exim with support for lookups with extensive
+library dependencies without requiring all users to install all of those
+dependencies.
+Most, but not all, lookup types can be built this way.
+
+Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
+installed; Exim will only load modules from that directory, as a security
+measure. You will need to set &`CFLAGS_DYNAMIC`& if not already defined
+for your OS; see &_OS/Makefile-Linux_& for an example.
+Some other requirements for adjusting &`EXTRALIBS`& may also be necessary,
+see &_src/EDITME_& for details.
+
+Then, for each module to be loaded dynamically, define the relevant
+&`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes".
+For example, this will build in lsearch but load sqlite and mysql support
+on demand:
+.code
+LOOKUP_LSEARCH=yes
+LOOKUP_SQLITE=2
+LOOKUP_MYSQL=2
+.endd
+
+
+.section "The building process" "SECID29"
.cindex "build directory"
Once &_Local/Makefile_& (and &_Local/eximon.conf_&, if required) have been
created, run &'make'& at the top level. It determines the architecture and
-.section 'Output from &"make"&'
-.new
+.section 'Output from &"make"&' "SECID283"
The output produced by the &'make'& process for compile lines is often very
unreadable, because these lines can be very long. For this reason, the normal
output is suppressed by default, and instead output similar to that which
.endd
The value of FULLECHO defaults to &"@"&, the flag character that suppresses
command reflection in &'make'&. When you ask for the full output, it is
-given in addition to the the short output.
-.wen
+given in addition to the short output.
.section "Overriding build-time options for Exim" "SECToverride"
-.cindex "build-time options" "overriding"
+.cindex "build-time options, overriding"
The main make file that is created at the beginning of the building process
consists of the concatenation of a number of files which set configuration
values, followed by a fixed set of &'make'& instructions. If a value is set
binary, attempts to configure Exim to use it cause run time configuration
errors.
+.cindex "pkg-config" "lookups"
+.cindex "pkg-config" "authenticators"
+Many systems now use a tool called &'pkg-config'& to encapsulate information
+about how to compile against a library; Exim has some initial support for
+being able to use pkg-config for lookups and authenticators. For any given
+makefile variable which starts &`LOOKUP_`& or &`AUTH_`&, you can add a new
+variable with the &`_PC`& suffix in the name and assign as the value the
+name of the package to be queried. The results of querying via the
+&'pkg-config'& command will be added to the appropriate Makefile variables
+with &`+=`& directives, so your version of &'make'& will need to support that
+syntax. For instance:
+.code
+LOOKUP_SQLITE=yes
+LOOKUP_SQLITE_PC=sqlite3
+AUTH_GSASL=yes
+AUTH_GSASL_PC=libgsasl
+AUTH_HEIMDAL_GSSAPI=yes
+AUTH_HEIMDAL_GSSAPI_PC=heimdal-gssapi
+.endd
+
.cindex "Perl" "including support for"
Exim can be linked with an embedded Perl interpreter, allowing Perl
subroutines to be called during string expansion. To enable this facility,
must be defined in &_Local/Makefile_&. Details of this facility are given in
chapter &<<CHAPperl>>&.
-.cindex "X11 libraries" "location of"
+.cindex "X11 libraries, location of"
The location of the X11 libraries is something that varies a lot between
operating systems, and there may be different versions of X11 to cope
with. Exim itself makes no use of X11, but if you are compiling the Exim
&_Local/Makefile_& or &_Local/eximon.conf_&) before rebuilding.
-.section "OS-specific header files"
+.section "OS-specific header files" "SECID30"
.cindex "&_os.h_&"
.cindex "building Exim" "OS-specific C header files"
The &_OS_& directory contains a number of files with names of the form
-.section "Overriding build-time options for the monitor"
-.cindex "building Eximon" "overriding default options"
+.section "Overriding build-time options for the monitor" "SECID31"
+.cindex "building Eximon"
A similar process is used for overriding things when building the Exim monitor,
where the files that are involved are
.display
variables of the same name, preceded by EXIMON_. For example, setting
EXIMON_LOG_DEPTH in the environment overrides the value of
LOG_DEPTH at run time.
+.ecindex IIDbuex
-
-
-.section "Installing Exim binaries and scripts"
+.section "Installing Exim binaries and scripts" "SECID32"
.cindex "installing Exim"
.cindex "BIN_DIRECTORY"
The command &`make install`& runs the &(exim_install)& script with no
.cindex "installing Exim" "what is not installed"
Running &'make install'& does not copy the Exim 4 conversion script
-&'convert4r4'&, or the &'pcretest'& test program. You will probably run the
-first of these only once (if you are upgrading from Exim 3), and the second
-isn't really part of Exim. None of the documentation files in the &_doc_&
+&'convert4r4'&. You will probably run this only once if you are
+upgrading from Exim 3. None of the documentation files in the &_doc_&
directory are copied, except for the info files when you have set
INFO_DIRECTORY, as described in section &<<SECTinsinfdoc>>& below.
-.section "Setting up the spool directory"
+.section "Setting up the spool directory" "SECID33"
.cindex "spool directory" "creating"
When it starts up, Exim tries to create its spool directory if it does not
exist. The Exim uid and gid are used for the owner and group of the spool
-.section "Testing"
+.section "Testing" "SECID34"
.cindex "testing" "installation"
Having installed Exim, you can check that the run time configuration file is
syntactically valid by running the following command, which assumes that the
production version.
-.section "Replacing another MTA with Exim"
+.section "Replacing another MTA with Exim" "SECID35"
.cindex "replacing another MTA"
Building and installing Exim for the first time does not of itself put it in
general use. The name by which the system's MTA is called by mail user agents
privilege and executable status from the old MTA. It is then necessary to stop
and restart the mailer daemon, if one is running.
-.cindex "FreeBSD" "MTA indirection"
+.cindex "FreeBSD, MTA indirection"
.cindex "&_/etc/mail/mailer.conf_&"
Some operating systems have introduced alternative ways of switching MTAs. For
example, if you are running FreeBSD, you need to edit the file
-.section "Upgrading Exim"
+.section "Upgrading Exim" "SECID36"
.cindex "upgrading Exim"
If you are already running Exim on your host, building and installing a new
version automatically makes it available to MUAs, or any other programs that
-.section "Stopping the Exim daemon on Solaris"
+.section "Stopping the Exim daemon on Solaris" "SECID37"
.cindex "Solaris" "stopping Exim on"
The standard command for stopping the mailer daemon on Solaris is
.code
. ////////////////////////////////////////////////////////////////////////////
.chapter "The Exim command line" "CHAPcommandline"
-.cindex "command line" "options"
-.cindex "options" "command line"
+.scindex IIDclo1 "command line" "options"
+.scindex IIDclo2 "options" "command line"
Exim's command line takes the standard Unix form of a sequence of options,
each starting with a hyphen character, followed by a number of arguments. The
options are compatible with the main options of Sendmail, and there are also
The form of the arguments depends on which options are set.
-.section "Setting options by program name"
+.section "Setting options by program name" "SECID38"
.cindex "&'mailq'&"
If Exim is called under the name &'mailq'&, it behaves as if the option &%-bp%&
were present before any other options.
&%exim_group%& options. These do not necessarily have to use the name &"exim"&.
.ilist
-.cindex "trusted user" "definition of"
+.cindex "trusted users" "definition of"
.cindex "user" "trusted definition of"
The trusted users are root, the Exim user, any user listed in the
&%trusted_users%& configuration option, and any user whose current group or any
-.section "Command line options"
-The command options are described in alphabetical order below.
+.section "Command line options" "SECID39"
+Exim's command line options are described in alphabetical order below. If none
+of the options that specifies a specific action (such as starting the daemon or
+a queue runner, or testing an address, or receiving a message in a specific
+format, or listing the queue) are present, and there is at least one argument
+on the command line, &%-bm%& (accept a local message on the standard input,
+with the arguments specifying the recipients) is assumed. Otherwise, Exim
+outputs a brief message about itself and exits.
. ////////////////////////////////////////////////////////////////////////////
. Insert a stylized XML comment here, to identify the start of the command line
The same output is generated if the Exim binary is called with no options and
no arguments.
+.vitem &%--version%&
+.oindex "&%--version%&"
+This option is an alias for &%-bV%& and causes version information to be
+displayed.
+
.vitem &%-B%&<&'type'&>
.oindex "&%-B%&"
.cindex "8-bit characters"
.vitem &%-bd%&
.oindex "&%-bd%&"
.cindex "daemon"
-.cindex "SMTP listener"
+.cindex "SMTP" "listener"
.cindex "queue runner"
This option runs Exim as a daemon, awaiting incoming SMTP connections. Usually
the &%-bd%& option is combined with the &%-q%&<&'time'&> option, to specify
The SIGHUP signal
.cindex "SIGHUP"
-can be used to cause the daemon to re-exec itself. This should be done whenever
-Exim's configuration file, or any file that is incorporated into it by means of
-the &%.include%& facility, is changed, and also whenever a new version of Exim
-is installed. It is not necessary to do this when other files that are
+.cindex "daemon" "restarting"
+can be used to cause the daemon to re-execute itself. This should be done
+whenever Exim's configuration file, or any file that is incorporated into it by
+means of the &%.include%& facility, is changed, and also whenever a new version
+of Exim is installed. It is not necessary to do this when other files that are
referenced from the configuration (for example, alias files) are changed,
because these are reread each time they are used.
Run Exim in expansion testing mode. Exim discards its root privilege, to
prevent ordinary users from using this mode to read otherwise inaccessible
files. If no arguments are given, Exim runs interactively, prompting for lines
-of data. &new("Otherwise, it processes each argument in turn.")
+of data. Otherwise, it processes each argument in turn.
If Exim was built with USE_READLINE=yes in &_Local/Makefile_&, it tries
to load the &%libreadline%& library dynamically whenever the &%-be%& option is
continuation lines is ignored. Each argument or data line is passed through the
string expansion mechanism, and the result is output. Variable values from the
configuration file (for example, &$qualify_domain$&) are available, but no
-message-specific values (such as &$domain$&) are set, because no message is
-being processed.
+message-specific values (such as &$sender_domain$&) are set, because no message
+is being processed (but see &%-bem%& and &%-Mset%&).
-.new
&*Note*&: If you use this mechanism to test lookups, and you change the data
files or databases you are using, you must exit and restart Exim before trying
the same lookup again. Otherwise, because each Exim process caches the results
of lookups, you will just get the same result as before.
-.wen
+
+.vitem &%-bem%&&~<&'filename'&>
+.oindex "&%-bem%&"
+.cindex "testing" "string expansion"
+.cindex "expansion" "testing"
+This option operates like &%-be%& except that it must be followed by the name
+of a file. For example:
+.code
+exim -bem /tmp/testmessage
+.endd
+The file is read as a message (as if receiving a locally-submitted non-SMTP
+message) before any of the test expansions are done. Thus, message-specific
+variables such as &$message_size$& and &$header_from:$& are available. However,
+no &'Received:'& header is added to the message. If the &%-t%& option is set,
+recipients are read from the headers in the normal way, and are shown in the
+&$recipients$& variable. Note that recipients cannot be given on the command
+line, because further arguments are taken as strings to expand (just like
+&%-be%&).
.vitem &%-bF%&&~<&'filename'&>
.oindex "&%-bF%&"
When testing a filter file,
.cindex "&""From""& line"
.cindex "envelope sender"
-.cindex "&%-f%& option" "for filter testing"
+.oindex "&%-f%&" "for filter testing"
the envelope sender can be set by the &%-f%& option,
or by a &"From&~"& line at the start of the test message. Various parameters
that would normally be taken from the envelope recipient address of the message
.vitem &%-bfd%&&~<&'domain'&>
.oindex "&%-bfd%&"
-.cindex "&$qualify_domain$&"
+.vindex "&$qualify_domain$&"
This sets the domain of the recipient address when a filter file is being
tested by means of the &%-bf%& option. The default is the value of
&$qualify_domain$&.
&*Warning 1*&:
.cindex "RFC 1413"
-You cannot test features of the configuration that rely on
-ident (RFC 1413) callouts. These cannot be done when testing using
-&%-bh%& because there is no incoming SMTP connection.
+You can test features of the configuration that rely on ident (RFC 1413)
+information by using the &%-oMt%& option. However, Exim cannot actually perform
+an ident callout when testing using &%-bh%& because there is no incoming SMTP
+connection.
&*Warning 2*&: Address verification callouts (see section &<<SECTcallver>>&)
are also skipped when testing using &%-bh%&. If you want these callouts to
Messages supplied during the testing session are discarded, and nothing is
written to any of the real log files. There may be pauses when DNS (and other)
lookups are taking place, and of course these may time out. The &%-oMi%& option
-can be used to specify a specific IP interface and port if this is important.
+can be used to specify a specific IP interface and port if this is important,
+and &%-oMaa%& and &%-oMai%& can be used to set parameters as if the SMTP
+session were authenticated.
The &'exim_checkaccess'& utility is a &"packaged"& version of &%-bh%& whose
output just states whether a given recipient address from a given host is
acceptable or not. See section &<<SECTcheckaccess>>&.
+Features such as authentication and encryption, where the client input is not
+plain text, cannot easily be tested with &%-bh%&. Instead, you should use a
+specialized SMTP test program such as
+&url(http://jetmore.org/john/code/#swaks,swaks).
+
.vitem &%-bhc%&&~<&'IP&~address'&>
.oindex "&%-bhc%&"
This option operates in the same way as &%-bh%&, except that address
if this is required. If the &%bi_command%& option is not set, calling Exim with
&%-bi%& is a no-op.
+.new
+. // Keep :help first, then the rest in alphabetical order
+.vitem &%-bI:help%&
+.oindex "&%-bI:help%&"
+.cindex "querying exim information"
+We shall provide various options starting &`-bI:`& for querying Exim for
+information. The output of many of these will be intended for machine
+consumption. This one is not. The &%-bI:help%& option asks Exim for a
+synopsis of supported options beginning &`-bI:`&. Use of any of these
+options shall cause Exim to exit after producing the requested output.
+
+.vitem &%-bI:dscp%&
+.oindex "&%-bI:dscp%&"
+.cindex "DSCP" "values"
+This option causes Exim to emit an alphabetically sorted list of all
+recognised DSCP names.
+
+.vitem &%-bI:sieve%&
+.oindex "&%-bI:sieve%&"
+.cindex "Sieve filter" "capabilities"
+This option causes Exim to emit an alphabetically sorted list of all supported
+Sieve protocol extensions on stdout, one per line. This is anticipated to be
+useful for ManageSieve (RFC 5804) implementations, in providing that protocol's
+&`SIEVE`& capability response line. As the precise list may depend upon
+compile-time build options, which this option will adapt to, this is the only
+way to guarantee a correct response.
+.wen
+
.vitem &%-bm%&
.oindex "&%-bm%&"
.cindex "local message reception"
matching against the regular expression defined by the &%uucp_from_pattern%&
option, which can be changed if necessary.
-The
-.cindex "&%-f%& option" "overriding &""From""& line"
-specified sender is treated as if it were given as the argument to the
+.oindex "&%-f%&" "overriding &""From""& line"
+The specified sender is treated as if it were given as the argument to the
&%-f%& option, but if a &%-f%& option is also present, its argument is used in
preference to the address taken from the message. The caller of Exim must be a
trusted user for the sender of a message to be set in this way.
+.vitem &%-bmalware%&&~<&'filename'&>
+.oindex "&%-bmalware%&"
+.cindex "testing", "malware"
+.cindex "malware scan test"
+This debugging option causes Exim to scan the given file,
+using the malware scanning framework. The option of &%av_scanner%& influences
+this option, so if &%av_scanner%&'s value is dependent upon an expansion then
+the expansion should have defaults which apply to this invocation. ACLs are
+not invoked, so if &%av_scanner%& references an ACL variable then that variable
+will never be populated and &%-bmalware%& will fail.
+
+Exim will have changed working directory before resolving the filename, so
+using fully qualified pathnames is advisable. Exim will be running as the Exim
+user when it tries to open the file, rather than as the invoking user.
+This option requires admin privileges.
+
+The &%-bmalware%& option will not be extended to be more generally useful,
+there are better tools for file-scanning. This option exists to help
+administrators verify their Exim and AV scanner configuration.
+
.vitem &%-bnq%&
.oindex "&%-bnq%&"
-.cindex "address qualification" "suppressing"
+.cindex "address qualification, suppressing"
By default, Exim automatically qualifies unqualified addresses (those
without domains) that appear in messages that are submitted locally (that
is, not over TCP/IP). This qualification applies both to addresses in
.code
exim -bP qualify_domain hold_domains
.endd
+.cindex "hiding configuration option values"
+.cindex "configuration options" "hiding value of"
+.cindex "options" "hiding value of"
However, any option setting that is preceded by the word &"hide"& in the
configuration file is not shown in full, except to an admin user. For other
users, the output is as in this example:
If a list of configuration files was supplied, the value that is output here
is the name of the file that was actually used.
+.new
+.cindex "options" "hiding name of"
+If the &%-n%& flag is given, then for most modes of &%-bP%& operation the
+name will not be output.
+.wen
+
.cindex "daemon" "process id (pid)"
.cindex "pid (process id)" "of daemon"
If &%log_file_path%& or &%pid_file_path%& are given, the names of the
.cindex "options" "router &-- extracting"
.cindex "options" "transport &-- extracting"
+.cindex "options" "authenticator &-- extracting"
If one of the words &%router%&, &%transport%&, or &%authenticator%& is given,
followed by the name of an appropriate driver instance, the option settings for
that driver are output. For example:
settings can be obtained by using &%routers%&, &%transports%&, or
&%authenticators%&.
+.cindex "options" "macro &-- extracting"
+If invoked by an admin user, then &%macro%&, &%macro_list%& and &%macros%&
+are available, similarly to the drivers. Because macros are sometimes used
+for storing passwords, this option is restricted.
+The output format is one item per line.
.vitem &%-bp%&
.oindex "&%-bp%&"
.endd
See chapter &<<CHAPretry>>& for a description of Exim's retry rules. The first
argument, which is required, can be a complete address in the form
-&'local_part@domain'&, or it can be just a domain name. The second argument is
-an optional second domain name; if no retry rule is found for the first
-argument, the second is tried. This ties in with Exim's behaviour when looking
-for retry rules for remote hosts &-- if no rule is found that matches the host,
-one that matches the mail domain is sought. The final argument is the name of a
-specific delivery error, as used in setting up retry rules, for example
-&"quota_3d"&.
+&'local_part@domain'&, or it can be just a domain name. If the second argument
+contains a dot, it is interpreted as an optional second domain name; if no
+retry rule is found for the first argument, the second is tried. This ties in
+with Exim's behaviour when looking for retry rules for remote hosts &-- if no
+rule is found that matches the host, one that matches the mail domain is
+sought. Finally, an argument that is the name of a specific delivery error, as
+used in setting up retry rules, can be given. For example:
+.code
+exim -brt haydn.comp.mus.example quota_3d
+Retry rule: *@haydn.comp.mus.example quota_3d F,1h,15m
+.endd
.vitem &%-brw%&
.oindex "&%-brw%&"
.cindex "testing" "addresses"
.cindex "address" "testing"
This option runs Exim in address testing mode, in which each argument is taken
-as an address to be tested for deliverability. The results are written to the
-standard output. If a test fails, and the caller is not an admin user, no
-details of the failure are output, because these might contain sensitive
-information such as usernames and passwords for database lookups.
+as a recipient address to be tested for deliverability. The results are
+written to the standard output. If a test fails, and the caller is not an admin
+user, no details of the failure are output, because these might contain
+sensitive information such as usernames and passwords for database lookups.
If no arguments are given, Exim runs in an interactive manner, prompting with a
right angle bracket for addresses to be tested.
genuine routing tests if your first router passes everything to a scanner
program.
-The
.cindex "return code" "for &%-bt%&"
-return code is 2 if any address failed outright; it is 1 if no address
+The return code is 2 if any address failed outright; it is 1 if no address
failed outright but at least one could not be resolved for some reason. Return
code 0 is given only when all addresses succeed.
+.cindex "duplicate addresses"
+&*Note*&: When actually delivering a message, Exim removes duplicate recipient
+addresses after routing is complete, so that only one delivery takes place.
+This does not happen when testing with &%-bt%&; the full results of routing are
+always shown.
+
&*Warning*&: &%-bt%& can only do relatively simple testing. If any of the
routers in the configuration makes any tests on the sender address of a
message,
-.cindex "&%-f%& option" "for address testing"
+.oindex "&%-f%&" "for address testing"
you can use the &%-f%& option to set an appropriate sender when running
&%-bt%& tests. Without it, the sender is assumed to be the calling user at the
default qualifying domain. However, if you have set up (for example) routers
.vitem &%-bV%&
.oindex "&%-bV%&"
-.cindex "version number of Exim" "verifying"
+.cindex "version number of Exim"
This option causes Exim to write the current version number, compilation
number, and compilation date of the &'exim'& binary to the standard output.
-It also lists the DBM library this is being used, the optional modules (such as
+It also lists the DBM library that is being used, the optional modules (such as
specific lookup types), the drivers that are included in the binary, and the
name of the run time configuration file that is in use.
.cindex "verifying address" "using &%-bv%&"
.cindex "address" "verification"
This option runs Exim in address verification mode, in which each argument is
-taken as an address to be verified. During normal operation, verification
+taken as a recipient address to be verified by the routers. (This does
+not involve any verification callouts). During normal operation, verification
happens mostly as a consequence processing a &%verify%& condition in an ACL
-(see chapter &<<CHAPACL>>&). If you want to test an entire ACL, see the &%-bh%&
-option.
+(see chapter &<<CHAPACL>>&). If you want to test an entire ACL, possibly
+including callouts, see the &%-bh%& and &%-bhc%& options.
If verification fails, and the caller is not an admin user, no details of the
failure are output, because these might contain sensitive information such as
If the &%-v%& option is not set, the output consists of a single line for each
address, stating whether it was verified or not, and giving a reason in the
-latter case. Otherwise, more details are given of how the address has been
-handled, and in the case of address redirection, all the generated addresses
-are also considered. Without &%-v%&, generating more than one address by
-redirection causes verification to end successfully.
+latter case. Without &%-v%&, generating more than one address by redirection
+causes verification to end successfully, without considering the generated
+addresses. However, if just one address is generated, processing continues,
+and the generated address must verify successfully for the overall verification
+to succeed.
+
+When &%-v%& is set, more details are given of how the address has been handled,
+and in the case of address redirection, all the generated addresses are also
+considered. Verification may succeed for some and fail for others.
The
.cindex "return code" "for &%-bv%&"
than a recipient address. This affects any rewriting and qualification that
might happen.
+.vitem &%-bw%&
+.oindex "&%-bw%&"
+.cindex "daemon"
+.cindex "inetd"
+.cindex "inetd" "wait mode"
+This option runs Exim as a daemon, awaiting incoming SMTP connections,
+similarly to the &%-bd%& option. All port specifications on the command-line
+and in the configuration file are ignored. Queue-running may not be specified.
+
+In this mode, Exim expects to be passed a socket as fd 0 (stdin) which is
+listening for connections. This permits the system to start up and have
+inetd (or equivalent) listen on the SMTP ports, starting an Exim daemon for
+each port only when the first connection is received.
+
+If the option is given as &%-bw%&<&'time'&> then the time is a timeout, after
+which the daemon will exit, which should cause inetd to listen once more.
+
.vitem &%-C%&&~<&'filelist'&>
.oindex "&%-C%&"
.cindex "configuration file" "alternate"
file that exists is used. Failure to open an existing file stops Exim from
proceeding any further along the list, and an error is generated.
-When this option is used by a caller other than root or the Exim user, and the
-list is different from the compiled-in list, Exim gives up its root privilege
-immediately, and runs with the real and effective uid and gid set to those of
-the caller. However, if ALT_CONFIG_ROOT_ONLY is defined in
-&_Local/Makefile_&, root privilege is retained for &%-C%& only if the caller of
-Exim is root.
-
-That is, the Exim user is no longer privileged in this regard. This build-time
-option is not set by default in the Exim source distribution tarbundle.
-However, if you are using a &"packaged"& version of Exim (source or binary),
-the packagers might have enabled it.
-
-Setting ALT_CONFIG_ROOT_ONLY locks out the possibility of testing a
-configuration using &%-C%& right through message reception and delivery, even
-if the caller is root. The reception works, but by that time, Exim is running
-as the Exim user, so when it re-executes to regain privilege for the delivery,
-the use of &%-C%& causes privilege to be lost. However, root can test reception
-and delivery using two separate commands (one to put a message on the queue,
-using &%-odq%&, and another to do the delivery, using &%-M%&).
+When this option is used by a caller other than root, and the list is different
+from the compiled-in list, Exim gives up its root privilege immediately, and
+runs with the real and effective uid and gid set to those of the caller.
+However, if a TRUSTED_CONFIG_LIST file is defined in &_Local/Makefile_&, that
+file contains a list of full pathnames, one per line, for configuration files
+which are trusted. Root privilege is retained for any configuration file so
+listed, as long as the caller is the Exim user (or the user specified in the
+CONFIGURE_OWNER option, if any), and as long as the configuration file is
+not writeable by inappropriate users or groups.
+
+Leaving TRUSTED_CONFIG_LIST unset precludes the possibility of testing a
+configuration using &%-C%& right through message reception and delivery,
+even if the caller is root. The reception works, but by that time, Exim is
+running as the Exim user, so when it re-executes to regain privilege for the
+delivery, the use of &%-C%& causes privilege to be lost. However, root can
+test reception and delivery using two separate commands (one to put a message
+on the queue, using &%-odq%&, and another to do the delivery, using &%-M%&).
If ALT_CONFIG_PREFIX is defined &_in Local/Makefile_&, it specifies a
prefix string with which any file named in a &%-C%& command line option
require privilege. No check is made on the owner or group of the files
specified by this option.
+
.vitem &%-D%&<&'macro'&>=<&'value'&>
.oindex "&%-D%&"
.cindex "macro" "setting on command line"
If DISABLE_D_OPTION is defined in &_Local/Makefile_&, the use of &%-D%& is
completely disabled, and its use causes an immediate error exit.
+If WHITELIST_D_MACROS is defined in &_Local/Makefile_& then it should be a
+colon-separated list of macros which are considered safe and, if &%-D%& only
+supplies macros from this list, and the values are acceptable, then Exim will
+not give up root privilege if the caller is root, the Exim run-time user, or
+the CONFIGURE_OWNER, if set. This is a transition mechanism and is expected
+to be removed in the future. Acceptable values for the macros satisfy the
+regexp: &`^[A-Za-z0-9_/.-]*$`&
+
The entire option (including equals sign if present) must all be within one
command line item. &%-D%& can be used to set the value of a macro to the empty
string, in which case the equals sign is optional. These two commands are
.endd
&%-D%& may be repeated up to 10 times on a command line.
+
.vitem &%-d%&<&'debug&~options'&>
.oindex "&%-d%&"
.cindex "debugging" "list of selectors"
This option causes debugging information to be written to the standard
error stream. It is restricted to admin users because debugging output may show
database queries that contain password information. Also, the details of users'
-filter files should be protected. When &%-d%& is used, &%-v%& is assumed. If
-&%-d%& is given on its own, a lot of standard debugging data is output. This
-can be reduced, or increased to include some more rarely needed information, by
-directly following &%-d%& with a string made up of names preceded by plus or
-minus characters. These add or remove sets of debugging data, respectively. For
-example, &%-d+filter%& adds filter debugging, whereas &%-d-all+filter%& selects
-only filter debugging. Note that no spaces are allowed in the debug setting.
-The available debugging categories are:
+filter files should be protected. If a non-admin user uses &%-d%&, Exim
+writes an error message to the standard error stream and exits with a non-zero
+return code.
+
+When &%-d%& is used, &%-v%& is assumed. If &%-d%& is given on its own, a lot of
+standard debugging data is output. This can be reduced, or increased to include
+some more rarely needed information, by directly following &%-d%& with a string
+made up of names preceded by plus or minus characters. These add or remove sets
+of debugging data, respectively. For example, &%-d+filter%& adds filter
+debugging, whereas &%-d-all+filter%& selects only filter debugging. Note that
+no spaces are allowed in the debug setting. The available debugging categories
+are:
.display
&`acl `& ACL interpretation
&`auth `& authenticators
&`verify `& address verification logic
&`all `& almost all of the above (see below), and also &%-v%&
.endd
-.new
The &`all`& option excludes &`memory`& when used as &`+all`&, but includes it
for &`-all`&. The reason for this is that &`+all`& is something that people
tend to use when generating debug output for Exim maintainers. If &`+memory`&
is included, an awful lot of output that is very rarely of interest is
generated, so it now has to be explicitly requested. However, &`-all`& does
turn everything off.
-.wen
-.cindex "resolver" "debugging output"
-.cindex "DNS resolver" "debugging output"
+.cindex "resolver, debugging output"
+.cindex "DNS resolver, debugging output"
The &`resolver`& option produces output only if the DNS resolver was compiled
with DEBUG enabled. This is not the case in some operating systems. Also,
unfortunately, debugging output from the DNS resolver is written to stdout
.oindex "&%-f%&"
.cindex "sender" "address"
.cindex "address" "sender"
-.cindex "trusted user"
+.cindex "trusted users"
.cindex "envelope sender"
.cindex "user" "trusted"
This option sets the address of the envelope sender of a locally-generated
.vitem &%-i%&
.oindex "&%-i%&"
.cindex "Solaris" "&'mail'& command"
-.cindex "dot in incoming" "non-SMTP message"
+.cindex "dot" "in incoming non-SMTP message"
This option, which has the same effect as &%-oi%&, specifies that a dot on a
line by itself should not terminate an incoming, non-SMTP message. I can find
no documentation for this option in Solaris 2.4 Sendmail, but the &'mailx'&
which can be set false to relax this restriction (and also the same requirement
for the &%-q%&, &%-R%&, and &%-S%& options).
-.new
The deliveries happen synchronously, that is, the original Exim process does
not terminate until all the delivery attempts have finished. No output is
produced unless there is a serious error. If you want to see what is happening,
use the &%-v%& option as well, or inspect Exim's main log.
-.wen
.vitem &%-Mar%&&~<&'message&~id'&>&~<&'address'&>&~<&'address'&>&~...
.oindex "&%-Mar%&"
active (in the middle of a delivery attempt), it is not altered. This option
can be used only by an admin user.
-.vitem "&*-MC*&&~<&'transport'&>&~<&'hostname'&>&~<&'sequence&~number'&>&&&
+.vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&~<&'sequence&~number'&>&&&
&~<&'message&~id'&>"
.oindex "&%-MC%&"
.cindex "SMTP" "passed connection"
only by an admin user or by the user who originally caused the message to be
placed on the queue.
+.vitem &%-Mset%&&~<&'message&~id'&>
+.oindex "&%-Mset%&
+.cindex "testing" "string expansion"
+.cindex "expansion" "testing"
+This option is useful only in conjunction with &%-be%& (that is, when testing
+string expansions). Exim loads the given message from its spool before doing
+the test expansions, thus setting message-specific variables such as
+&$message_size$& and the header variables. The &$recipients$& variable is made
+available. This feature is provided to make it easier to test expansions that
+make use of these variables. However, this option can be used only by an admin
+user. See also &%-bem%&.
+
.vitem &%-Mt%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
.oindex "&%-Mt%&"
.cindex "thawing messages"
This option causes the contents of the message body (-D) spool file to be
written to the standard output. This option can be used only by an admin user.
+.vitem &%-Mvc%&&~<&'message&~id'&>
+.oindex "&%-Mvc%&"
+.cindex "message" "listing in RFC 2822 format"
+.cindex "listing" "message in RFC 2822 format"
+This option causes a copy of the complete message (header lines plus body) to
+be written to the standard output in RFC 2822 format. This option can be used
+only by an admin user.
+
.vitem &%-Mvh%&&~<&'message&~id'&>
.oindex "&%-Mvh%&"
.cindex "listing" "message headers"
.vitem &%-n%&
.oindex "&%-n%&"
-.cindex "Sendmail compatibility" "&%-n%& option ignored"
-This option is interpreted by Sendmail to mean &"no aliasing"&. It is ignored
-by Exim.
+This option is interpreted by Sendmail to mean &"no aliasing"&.
+For normal modes of operation, it is ignored by Exim.
+When combined with &%-bP%& it suppresses the name of an option from being output.
.vitem &%-O%&&~<&'data'&>
.oindex "&%-O%&"
.vitem &%-oi%&
.oindex "&%-oi%&"
-.cindex "dot in incoming" "non-SMTP message"
+.cindex "dot" "in incoming non-SMTP message"
This option, which has the same effect as &%-i%&, specifies that a dot on a
line by itself should not terminate an incoming, non-SMTP message. Otherwise, a
single dot does terminate, though Exim does no special processing for other
.vitem &%-oMa%&&~<&'host&~address'&>
.oindex "&%-oMa%&"
-.cindex "sender host address" "specifying for local message"
+.cindex "sender" "host address, specifying for local message"
A number of options starting with &%-oM%& can be used to set values associated
with remote hosts on locally-submitted messages (that is, messages not received
over TCP/IP). These options can be used by any caller in conjunction with the
exim -bs -oMa [10.9.8.7]:1234
.endd
The IP address is placed in the &$sender_host_address$& variable, and the
-port, if present, in &$sender_host_port$&.
+port, if present, in &$sender_host_port$&. If both &%-oMa%& and &%-bh%&
+are present on the command line, the sender host IP address is taken from
+whichever one is last.
.vitem &%-oMaa%&&~<&'name'&>
.oindex "&%-oMaa%&"
-.cindex "authentication name" "specifying for local message"
+.cindex "authentication" "name, specifying for local message"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMaa%&
option sets the value of &$sender_host_authenticated$& (the authenticator
name). See chapter &<<CHAPSMTPAUTH>>& for a discussion of SMTP authentication.
+This option can be used with &%-bh%& and &%-bs%& to set up an
+authenticated SMTP session without actually using the SMTP AUTH command.
.vitem &%-oMai%&&~<&'string'&>
.oindex "&%-oMai%&"
-.cindex "authentication id" "specifying for local message"
+.cindex "authentication" "id, specifying for local message"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMai%&
option sets the value of &$authenticated_id$& (the id that was authenticated).
-This overrides the default value (the caller's login id) for messages from
-local sources. See chapter &<<CHAPSMTPAUTH>>& for a discussion of authenticated
-ids.
+This overrides the default value (the caller's login id, except with &%-bh%&,
+where there is no default) for messages from local sources. See chapter
+&<<CHAPSMTPAUTH>>& for a discussion of authenticated ids.
.vitem &%-oMas%&&~<&'address'&>
.oindex "&%-oMas%&"
-.cindex "authentication sender" "specifying for local message"
+.cindex "authentication" "sender, specifying for local message"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMas%&
option sets the authenticated sender value in &$authenticated_sender$&. It
overrides the sender address that is created from the caller's login id for
-messages from local sources. See chapter &<<CHAPSMTPAUTH>>& for a discussion of
-authenticated senders.
+messages from local sources, except when &%-bh%& is used, when there is no
+default. For both &%-bh%& and &%-bs%&, an authenticated sender that is
+specified on a MAIL command overrides this value. See chapter
+&<<CHAPSMTPAUTH>>& for a discussion of authenticated senders.
.vitem &%-oMi%&&~<&'interface&~address'&>
.oindex "&%-oMi%&"
-.cindex "interface address" "specifying for local message"
+.cindex "interface" "address, specifying for local message"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMi%&
option sets the IP interface address value. A port number may be included,
using the same syntax as for &%-oMa%&. The interface address is placed in
-&$interface_address$& and the port number, if present, in &$interface_port$&.
+&$received_ip_address$& and the port number, if present, in &$received_port$&.
.vitem &%-oMr%&&~<&'protocol&~name'&>
.oindex "&%-oMr%&"
-.cindex "protocol" "incoming &-- specifying for local message"
-.cindex "&$received_protocol$&"
+.cindex "protocol, specifying for local message"
+.vindex "&$received_protocol$&"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMr%&
option sets the received protocol value that is stored in
-&$received_protocol$&. However, this applies only when &%-bs%& is not used. For
-interactive SMTP input (&%-bs%&), the protocol is always &"local-"& followed by
-one of the standard SMTP protocol names (see the description of
-&$received_protocol$& in section &<<SECTexpvar>>&). For &%-bS%& (batch SMTP)
-however, the protocol can be set by &%-oMr%&.
+&$received_protocol$&. However, it does not apply (and is ignored) when &%-bh%&
+or &%-bs%& is used. For &%-bh%&, the protocol is forced to one of the standard
+SMTP protocol names (see the description of &$received_protocol$& in section
+&<<SECTexpvar>>&). For &%-bs%&, the protocol is always &"local-"& followed by
+one of those same names. For &%-bS%& (batched SMTP) however, the protocol can
+be set by &%-oMr%&.
.vitem &%-oMs%&&~<&'host&~name'&>
.oindex "&%-oMs%&"
-.cindex "sender host name" "specifying for local message"
+.cindex "sender" "host name, specifying for local message"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMs%&
option sets the sender host name in &$sender_host_name$&. When this option is
present, Exim does not attempt to look up a host name from an IP address; it
.vitem &%-oMt%&&~<&'ident&~string'&>
.oindex "&%-oMt%&"
-.cindex "sender ident string" "specifying for local message"
+.cindex "sender" "ident string, specifying for local message"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMt%&
option sets the sender ident value in &$sender_ident$&. The default setting for
-local callers is the login id of the calling process.
+local callers is the login id of the calling process, except when &%-bh%& is
+used, when there is no default.
.vitem &%-om%&
.oindex "&%-om%&"
.vitem &%-os%&&~<&'time'&>
.oindex "&%-os%&"
.cindex "timeout" "for SMTP input"
-.cindex "SMTP timeout" "input"
+.cindex "SMTP" "input timeout"
This option sets a timeout value for incoming SMTP messages. The timeout
applies to each SMTP command and block of data. The value can also be set by
the &%smtp_receive_timeout%& option; it defaults to 5 minutes. The format used
way. If the <&'rsflags'&> start with &'r'&, <&'string'&> is interpreted as a
regular expression; otherwise it is a literal string.
-Once a message is selected, all its addresses are processed. For the first
-selected message, Exim overrides any retry information and forces a delivery
-attempt for each undelivered address. This means that if delivery of any
-address in the first message is successful, any existing retry information is
-deleted, and so delivery attempts for that address in subsequently selected
-messages (which are processed without forcing) will run. However, if delivery
-of any address does not succeed, the retry information is updated, and in
-subsequently selected messages, the failing address will be skipped.
+If you want to do periodic queue runs for messages with specific recipients,
+you can combine &%-R%& with &%-q%& and a time value. For example:
+.code
+exim -q25m -R @special.domain.example
+.endd
+This example does a queue run for messages with recipients in the given domain
+every 25 minutes. Any additional flags that are specified with &%-q%& are
+applied to each queue run.
+
+Once a message is selected for delivery by this mechanism, all its addresses
+are processed. For the first selected message, Exim overrides any retry
+information and forces a delivery attempt for each undelivered address. This
+means that if delivery of any address in the first message is successful, any
+existing retry information is deleted, and so delivery attempts for that
+address in subsequently selected messages (which are processed without forcing)
+will run. However, if delivery of any address does not succeed, the retry
+information is updated, and in subsequently selected messages, the failing
+address will be skipped.
.cindex "frozen messages" "forcing delivery"
If the <&'rsflags'&> contain &'f'& or &'ff'&, the delivery forcing applies to
&"queue times"& so that various warning/retry features can be tested.
.vitem &%-t%&
-.new
.oindex "&%-t%&"
.cindex "recipient" "extracting from header lines"
.cindex "&'Bcc:'& header line"
from the &'To:'&, &'Cc:'&, and &'Bcc:'& header lines in the message instead of
from the command arguments. The addresses are extracted before any rewriting
takes place and the &'Bcc:'& header line, if present, is then removed.
-.wen
.cindex "Sendmail compatibility" "&%-t%& option"
If the command has any arguments, they specify addresses to which the message
once, it is common for the original set of &%Resent-%& headers to be renamed as
&%X-Resent-%& when a new set is added. This removes any possible ambiguity.
-.vitem &*-ti*&
+.vitem &%-ti%&
.oindex "&%-ti%&"
This option is exactly equivalent to &%-t%& &%-i%&. It is provided for
compatibility with Sendmail.
-.vitem &*-tls-on-connect*&
+.vitem &%-tls-on-connect%&
.oindex "&%-tls-on-connect%&"
.cindex "TLS" "use without STARTTLS"
.cindex "TLS" "automatic start"
&<<CHAPTLS>>& for further details.
-.vitem &*-U*&
+.vitem &%-U%&
.oindex "&%-U%&"
.cindex "Sendmail compatibility" "&%-U%& option ignored"
Sendmail uses this option for &"initial message submission"&, and its
syntactically invalid messages rather than fixing them when this flag is not
set. Exim ignores this option.
-.vitem &*-v*&
+.vitem &%-v%&
.oindex "&%-v%&"
This option causes Exim to write information to the standard error stream,
describing what it is doing. In particular, it shows the log lines for
selectors are shown with each log line. If none are shown, the logging is
unconditional.
-.vitem &*-x*&
+.vitem &%-x%&
.oindex "&%-x%&"
AIX uses &%-x%& for a private purpose (&"mail from a local mail program has
National Language Support extended characters in the body of the mail item"&).
this option.
.endlist
+.ecindex IIDclo1
+.ecindex IIDclo2
+
+
. ////////////////////////////////////////////////////////////////////////////
. Insert a stylized DocBook comment here, to identify the end of the command
. line options. This is for the benefit of the Perl script that automatically
.cindex "configuration file" "ownership"
.cindex "ownership" "configuration file"
The run time configuration file must be owned by root or by the user that is
-specified at compile time by the EXIM_USER option, or by the user that is
specified at compile time by the CONFIGURE_OWNER option (if set). The
-configuration file must not be world-writeable or group-writeable, unless its
-group is the one specified at compile time by the EXIM_GROUP option or by the
+configuration file must not be world-writeable, or group-writeable unless its
+group is the root group or the one specified at compile time by the
CONFIGURE_GROUP option.
&*Warning*&: In a conventional configuration, where the Exim binary is setuid
to root, anybody who is able to edit the run time configuration file has an
-easy way to run commands as root. If you make your mail administrators members
-of the Exim group, but do not trust them with root, make sure that the run time
-configuration is not group writeable.
+easy way to run commands as root. If you specify a user or group in the
+CONFIGURE_OWNER or CONFIGURE_GROUP options, then that user and/or any users
+who are members of that group will trivially be able to obtain root privileges.
+
+Up to Exim version 4.72, the run time configuration file was also permitted to
+be writeable by the Exim user and/or group. That has been changed in Exim 4.73
+since it offered a simple privilege escalation for any attacker who managed to
+compromise the Exim user account.
A default configuration file, which will work correctly in simple situations,
is provided in the file &_src/configure.default_&. If CONFIGURE_FILE
-.section "Using a different configuration file"
+.section "Using a different configuration file" "SECID40"
.cindex "configuration file" "alternate"
A one-off alternate configuration can be specified by the &%-C%& command line
option, which may specify a single file or a list of files. However, when
-&%-C%& is used, Exim gives up its root privilege, unless called by root or the
-Exim user (or unless the argument for &%-C%& is identical to the built-in value
-from CONFIGURE_FILE). &%-C%& is useful mainly for checking the syntax of
-configuration files before installing them. No owner or group checks are done
-on a configuration file specified by &%-C%&.
-
-The privileged use of &%-C%& by the Exim user can be locked out by setting
-ALT_CONFIG_ROOT_ONLY in &_Local/Makefile_& when building Exim. However,
-if you do this, you also lock out the possibility of testing a
-configuration using &%-C%& right through message reception and delivery, even
-if the caller is root. The reception works, but by that time, Exim is running
-as the Exim user, so when it re-execs to regain privilege for the delivery, the
-use of &%-C%& causes privilege to be lost. However, root can test reception and
-delivery using two separate commands (one to put a message on the queue, using
-&%-odq%&, and another to do the delivery, using &%-M%&).
+&%-C%& is used, Exim gives up its root privilege, unless called by root (or
+unless the argument for &%-C%& is identical to the built-in value from
+CONFIGURE_FILE), or is listed in the TRUSTED_CONFIG_LIST file and the caller
+is the Exim user or the user specified in the CONFIGURE_OWNER setting. &%-C%&
+is useful mainly for checking the syntax of configuration files before
+installing them. No owner or group checks are done on a configuration file
+specified by &%-C%&, if root privilege has been dropped.
+
+Even the Exim user is not trusted to specify an arbitrary configuration file
+with the &%-C%& option to be used with root privileges, unless that file is
+listed in the TRUSTED_CONFIG_LIST file. This locks out the possibility of
+testing a configuration using &%-C%& right through message reception and
+delivery, even if the caller is root. The reception works, but by that time,
+Exim is running as the Exim user, so when it re-execs to regain privilege for
+the delivery, the use of &%-C%& causes privilege to be lost. However, root
+can test reception and delivery using two separate commands (one to put a
+message on the queue, using &%-odq%&, and another to do the delivery, using
+&%-M%&).
If ALT_CONFIG_PREFIX is defined &_in Local/Makefile_&, it specifies a
prefix string with which any file named in a &%-C%& command line option must
If DISABLE_D_OPTION is defined in &_Local/Makefile_&, the use of &%-D%& is
completely disabled, and its use causes an immediate error exit.
+The WHITELIST_D_MACROS option in &_Local/Makefile_& permits the binary builder
+to declare certain macro names trusted, such that root privilege will not
+necessarily be discarded.
+WHITELIST_D_MACROS defines a colon-separated list of macros which are
+considered safe and, if &%-D%& only supplies macros from this list, and the
+values are acceptable, then Exim will not give up root privilege if the caller
+is root, the Exim run-time user, or the CONFIGURE_OWNER, if set. This is a
+transition mechanism and is expected to be removed in the future. Acceptable
+values for the macros satisfy the regexp: &`^[A-Za-z0-9_/.-]*$`&
+
Some sites may wish to use the same Exim binary on different machines that
share a file system, but to use different configuration files on each machine.
If CONFIGURE_FILE_USE_NODE is defined in &_Local/Makefile_&, Exim first
optional parts are:
.ilist
-&'ACL'&: Access control lists for controlling incoming SMTP mail.
+&'ACL'&: Access control lists for controlling incoming SMTP mail (see chapter
+&<<CHAPACL>>&).
.next
.cindex "AUTH" "configuration"
&'authenticators'&: Configuration settings for the authenticator drivers. These
are concerned with the SMTP AUTH command (see chapter &<<CHAPSMTPAUTH>>&).
.next
&'routers'&: Configuration settings for the router drivers. Routers process
-addresses and determine how the message is to be delivered.
+addresses and determine how the message is to be delivered (see chapters
+&<<CHAProutergeneric>>&&--&<<CHAPredirect>>&).
.next
&'transports'&: Configuration settings for the transport drivers. Transports
-define mechanisms for copying messages to destinations.
+define mechanisms for copying messages to destinations (see chapters
+&<<CHAPtransportgeneric>>&&--&<<CHAPsmtptrans>>&).
.next
-&'retry'&: Retry rules, for use when a message cannot be immediately delivered.
+&'retry'&: Retry rules, for use when a message cannot be delivered immediately.
+If there is no retry section, or if it is empty (that is, no retry rules are
+defined), Exim will not retry deliveries. In this situation, temporary errors
+are treated the same as permanent errors. Retry rules are discussed in chapter
+&<<CHAPretry>>&.
.next
&'rewrite'&: Global address rewriting rules, for use when a message arrives and
-when new addresses are generated during delivery.
+when new addresses are generated during delivery. Rewriting is discussed in
+chapter &<<CHAPrewrite>>&.
.next
&'local_scan'&: Private options for the &[local_scan()]& function. If you
want to use this feature, you must set
.code
LOCAL_SCAN_HAS_OPTIONS=yes
.endd
-in &_Local/Makefile_& before building Exim. Full details of the
-&[local_scan()]& facility are given in chapter &<<CHAPlocalscan>>&.
+in &_Local/Makefile_& before building Exim. Details of the &[local_scan()]&
+facility are given in chapter &<<CHAPlocalscan>>&.
.endlist
.cindex "configuration file" "leading white space in"
-.section "File inclusions in the configuration file"
+.section "File inclusions in the configuration file" "SECID41"
.cindex "inclusions in configuration file"
.cindex "configuration file" "including other files"
-.cindex ".include in configuration file"
-.cindex ".include_if_exists in configuration file"
+.cindex "&`.include`& in configuration file"
+.cindex "&`.include_if_exists`& in configuration file"
You can include other files inside Exim's run time configuration file by
using this syntax:
.display
.endd
on a line by itself. Double quotes round the file name are optional. If you use
the first form, a configuration error occurs if the file does not exist; the
-second form does nothing for non-existent files.
+second form does nothing for non-existent files. In all cases, an absolute file
+name is required.
Includes may be nested to any depth, but remember that Exim reads its
configuration file often, so it is a good idea to keep them to a minimum.
.include /some/file
.endd
Include processing happens after macro processing (see below). Its effect is to
-process the lines of the file as if they occurred inline where the inclusion
-appears.
+process the lines of the included file as if they occurred inline where the
+inclusion appears.
space removed. Quotes are not removed. The replacement text can never end with
a backslash character, but this doesn't seem to be a serious limitation.
-.new
Macros may also be defined between router, transport, authenticator, or ACL
definitions. They may not, however, be defined within an individual driver or
ACL, or in the &%local_scan%&, retry, or rewrite sections of the configuration.
-.wen
-.section "Macro substitution"
+.section "Macro substitution" "SECID42"
Once a macro is defined, all subsequent lines in the file (and any included
files) are scanned for the macro name; if there are several macros, the line is
scanned for each in turn, in the order in which the macros are defined. The
comment line or a &`.include`& line.
-.new
-.section "Redefining macros"
+.section "Redefining macros" "SECID43"
Once defined, the value of a macro can be redefined later in the configuration
(or in an included file). Redefinition is specified by using &'=='& instead of
&'='&. For example:
.endd
This can be helpful in situations where the configuration file is built
from a number of other files.
-.wen
-.section "Overriding macro values"
+.section "Overriding macro values" "SECID44"
The values set for macros in the configuration file can be overridden by the
&%-D%& command line option, but Exim gives up its root privilege when &%-D%& is
used, unless called by root or the Exim user. A definition on the command line
-.section "Example of macro usage"
+.section "Example of macro usage" "SECID45"
As an example of macro usage, consider a configuration where aliases are looked
up in a MySQL database. It helps to keep the file less cluttered if long
strings such as SQL statements are defined separately as macros, for example:
.code
ALIAS_QUERY = select mailbox from user where \
- login=${quote_mysql:$local_part};
+ login='${quote_mysql:$local_part}';
.endd
This can then be used in a &(redirect)& router setting like this:
.code
section &<<SECTnamedlists>>&.
-.section "Conditional skips in the configuration file"
+.section "Conditional skips in the configuration file" "SECID46"
.cindex "configuration file" "conditional skips"
-.cindex ".ifdef"
+.cindex "&`.ifdef`&"
You can use the directives &`.ifdef`&, &`.ifndef`&, &`.elifdef`&,
&`.elifndef`&, &`.else`&, and &`.endif`& to dynamically include or exclude
portions of the configuration file. The processing happens whenever the file is
.code
qualify_domain = mydomain.example.com
.endd
+.cindex "hiding configuration option values"
+.cindex "configuration options" "hiding value of"
+.cindex "options" "hiding value of"
Some option settings may contain sensitive data, for example, passwords for
accessing databases. To stop non-admin users from using the &%-bP%& command
line option to read these values, you can precede the option settings with the
that are found in option settings.
-.section "Boolean options"
+.section "Boolean options" "SECID47"
.cindex "format" "boolean"
.cindex "boolean configuration values"
.oindex "&%no_%&&'xxx'&"
-.section "Integer values"
+.section "Integer values" "SECID48"
.cindex "integer configuration values"
.cindex "format" "integer"
-If an integer data item starts with the characters &"0x"&, the remainder of it
-is interpreted as a hexadecimal number. Otherwise, it is treated as octal if it
-starts with the digit 0, and decimal if not. If an integer value is followed by
-the letter K, it is multiplied by 1024; if it is followed by the letter M, it
-is multiplied by 1024x1024.
-
-When the values of integer option settings are output, values which are an
-exact multiple of 1024 or 1024x1024 are
-sometimes, but not always,
-printed using the letters K and M. The printing style is independent of the
-actual input format that was used.
+If an option's type is given as &"integer"&, the value can be given in decimal,
+hexadecimal, or octal. If it starts with a digit greater than zero, a decimal
+number is assumed. Otherwise, it is treated as an octal number unless it starts
+with the characters &"0x"&, in which case the remainder is interpreted as a
+hexadecimal number.
+
+If an integer value is followed by the letter K, it is multiplied by 1024; if
+it is followed by the letter M, it is multiplied by 1024x1024. When the values
+of integer option settings are output, values which are an exact multiple of
+1024 or 1024x1024 are sometimes, but not always, printed using the letters K
+and M. The printing style is independent of the actual input format that was
+used.
-.section "Octal integer values"
+.section "Octal integer values" "SECID49"
.cindex "integer format"
.cindex "format" "octal integer"
-The value of an option specified as an octal integer is always interpreted in
-octal, whether or not it starts with the digit zero. Such options are always
-output in octal.
-
+If an option's type is given as &"octal integer"&, its value is always
+interpreted as an octal number, whether or not it starts with the digit zero.
+Such options are always output in octal.
-.section "Fixed point number values"
+.section "Fixed point numbers" "SECID50"
.cindex "fixed point configuration values"
.cindex "format" "fixed point"
-A fixed point number consists of a decimal integer, optionally followed by a
-decimal point and up to three further digits.
+If an option's type is given as &"fixed-point"&, its value must be a decimal
+integer, optionally followed by a decimal point and up to three further digits.
-.section "Time interval values" "SECTtimeformat"
+.section "Time intervals" "SECTtimeformat"
.cindex "time interval" "specifying in configuration"
.cindex "format" "time interval"
A time interval is specified as a sequence of numbers, each followed by one of
the following letters, with no intervening white space:
-.table2 50pt
-.row &~&%s%& seconds
-.row &~&%m%& minutes
-.row &~&%h%& hours
-.row &~&%d%& days
-.row &~&%w%& weeks
+.table2 30pt
+.irow &%s%& seconds
+.irow &%m%& minutes
+.irow &%h%& hours
+.irow &%d%& days
+.irow &%w%& weeks
.endtable
For example, &"3h50m"& specifies 3 hours and 50 minutes. The values of time
.section "String values" "SECTstrings"
.cindex "string" "format of configuration values"
.cindex "format" "string"
-If a string data item does not start with a double-quote character, it is taken
-as consisting of the remainder of the line plus any continuation lines,
-starting at the first character after any leading white space, with trailing
-white space removed, and with no interpretation of the characters in the
-string. Because Exim removes comment lines (those beginning with #) at an early
-stage, they can appear in the middle of a multi-line string. The following
-settings are therefore equivalent:
+If an option's type is specified as &"string"&, the value can be specified with
+or without double-quotes. If it does not start with a double-quote, the value
+consists of the remainder of the line plus any continuation lines, starting at
+the first character after any leading white space, with trailing white space
+removed, and with no interpretation of the characters in the string. Because
+Exim removes comment lines (those beginning with #) at an early stage, they can
+appear in the middle of a multi-line string. The following two settings are
+therefore equivalent:
.code
trusted_users = uucp:mail
-
trusted_users = uucp:\
# This comment line is ignored
mail
continuation are interpreted as escape characters, as follows:
.table2 100pt
-.row &~&`\\`& "single backslash"
-.row &~&`\n`& "newline"
-.row &~&`\r`& "carriage return"
-.row &~&`\t`& "tab"
-.row "&~&`\`&<&'octal digits'&>" "up to 3 octal digits specify one character"
-.row "&~&`\x`&<&'hex digits'&>" "up to 2 hexadecimal digits specify one &&&
+.irow &`\\`& "single backslash"
+.irow &`\n`& "newline"
+.irow &`\r`& "carriage return"
+.irow &`\t`& "tab"
+.irow "&`\`&<&'octal digits'&>" "up to 3 octal digits specify one character"
+.irow "&`\x`&<&'hex digits'&>" "up to 2 hexadecimal digits specify one &&&
character"
.endtable
and examples that apparently quote unnecessarily.
-.section "Expanded strings"
-.cindex "string expansion" "definition of"
+.section "Expanded strings" "SECID51"
.cindex "expansion" "definition of"
Some strings in the configuration file are subjected to &'string expansion'&,
by which means various parts of the string may be changed according to the
within a quoted configuration string.
-.section "User and group names"
+.section "User and group names" "SECID52"
.cindex "user name" "format of"
.cindex "format" "user name"
-.cindex "group" "name format"
+.cindex "groups" "name format"
.cindex "format" "group name"
User and group names are specified as strings, using the syntax described
above, but the strings are interpreted specially. A user or group name must
.section "List construction" "SECTlistconstruct"
.cindex "list" "syntax of in configuration"
.cindex "format" "list item in configuration"
-.cindex "string list" "definition"
+.cindex "string" "list, definition of"
The data for some configuration options is a list of items, with colon as the
default separator. Many of these options are shown with type &"string list"& in
the descriptions later in this document. Others are listed as &"domain list"&,
.endd
contains two IP addresses, the IPv4 address 127.0.0.1 and the IPv6 address ::1.
-.new
&*Note*&: Although leading and trailing white space is ignored in individual
list items, it is not ignored when parsing the list. The space after the first
colon in the example above is necessary. If it were not there, the list would
be interpreted as the two items 127.0.0.1:: and 1.
-.wen
+.section "Changing list separators" "SECID53"
.cindex "list separator" "changing"
.cindex "IPv6" "addresses in lists"
Doubling colons in IPv6 addresses is an unwelcome chore, so a mechanism was
&%log_file_path%&. It is recommended that the use of non-colon separators be
confined to circumstances where they really are needed.
+.cindex "list separator" "newline as"
+.cindex "newline" "as list separator"
+It is also possible to use newline and other control characters (those with
+code values less than 32, plus DEL) as separators in lists. Such separators
+must be provided literally at the time the list is processed. For options that
+are string-expanded, you can write the separator using a normal escape
+sequence. This will be processed by the expander before the string is
+interpreted as a list. For example, if a newline-separated list of domains is
+generated by a lookup, you can process it directly by a line such as this:
+.code
+domains = <\n ${lookup mysql{.....}}
+.endd
+This avoids having to change the list separator in such data. You are unlikely
+to want to use a control character as a separator in an option that is not
+expanded, because the value is literal text. However, it can be done by giving
+the value in quotes. For example:
+.code
+local_interfaces = "<\n 127.0.0.1 \n ::1"
+.endd
+Unlike printing character separators, which can be included in list items by
+doubling, it is not possible to include a control character as data when it is
+set as the separator. Two such characters in succession are interpreted as
+enclosing an empty list item.
+
.section "Empty items in lists" "SECTempitelis"
. ////////////////////////////////////////////////////////////////////////////
.chapter "The default configuration file" "CHAPdefconfil"
-.cindex "configuration file" "default &""walk through""&"
+.scindex IIDconfiwal "configuration file" "default &""walk through""&"
.cindex "default" "configuration file &""walk through""&"
The default configuration file supplied with Exim as &_src/configure.default_&
is sufficient for a host with simple mail requirements. As an introduction to
-.section "Main configuration settings"
+.section "Main configuration settings" "SECTdefconfmain"
The main (global) configuration option settings must always come first in the
file. The first thing you'll see in the file, after some initial comments, is
the line
acl_smtp_rcpt = acl_check_rcpt
acl_smtp_data = acl_check_data
.endd
-.new
These options specify &'Access Control Lists'& (ACLs) that are to be used
during an incoming SMTP session for every recipient of a message (every RCPT
command), and after the contents of the message have been received,
content-scanning extension. The first specifies the interface to the virus
scanner, and the second specifies the interface to SpamAssassin. Further
details are given in chapter &<<CHAPexiscan>>&.
-.wen
+
+Three more commented-out option settings follow:
+.code
+# tls_advertise_hosts = *
+# tls_certificate = /etc/ssl/exim.crt
+# tls_privatekey = /etc/ssl/exim.pem
+.endd
+These are example settings that can be used when Exim is compiled with
+support for TLS (aka SSL) as described in section &<<SECTinctlsssl>>&. The
+first one specifies the list of clients that are allowed to use TLS when
+connecting to this server; in this case the wildcard means all clients. The
+other options specify where Exim should find its TLS certificate and private
+key, which together prove the server's identity to any clients that connect.
+More details are given in chapter &<<CHAPTLS>>&.
+
+Another two commented-out option settings follow:
+.code
+# daemon_smtp_ports = 25 : 465 : 587
+# tls_on_connect_ports = 465
+.endd
+.cindex "port" "465 and 587"
+.cindex "port" "for message submission"
+.cindex "message" "submission, ports for"
+.cindex "ssmtp protocol"
+.cindex "smtps protocol"
+.cindex "SMTP" "ssmtp protocol"
+.cindex "SMTP" "smtps protocol"
+These options provide better support for roaming users who wish to use this
+server for message submission. They are not much use unless you have turned on
+TLS (as described in the previous paragraph) and authentication (about which
+more in section &<<SECTdefconfauth>>&). The usual SMTP port 25 is often blocked
+on end-user networks, so RFC 4409 specifies that message submission should use
+port 587 instead. However some software (notably Microsoft Outlook) cannot be
+configured to use port 587 correctly, so these settings also enable the
+non-standard &"smtps"& (aka &"ssmtp"&) port 465 (see section
+&<<SECTsupobssmt>>&).
Two more commented-out options settings follow:
.code
1413 (hence their names):
.code
rfc1413_hosts = *
-rfc1413_query_timeout = 30s
+rfc1413_query_timeout = 5s
.endd
These settings cause Exim to make ident callbacks for all incoming SMTP calls.
You can limit the hosts to which these calls are made, or change the timeout
-.section "ACL configuration"
+.section "ACL configuration" "SECID54"
.cindex "default" "ACLs"
.cindex "&ACL;" "default configuration"
In the default configuration, the ACL section follows the main configuration.
accept hosts = +relay_from_hosts
control = submission
.endd
-.new
This statement accepts the address if the message is coming from one of the
hosts that are defined as being allowed to relay through this host. Recipient
verification is omitted here, because in many cases the clients are dumb MUAs
This statement accepts the address if the client host has authenticated itself.
Submission mode is again specified, on the grounds that such messages are most
likely to come from MUAs. The default configuration does not define any
-authenticators, which means that no client can in fact authenticate. You will
-need to add authenticator definitions if you want to make use of this ACL
-statement.
-.wen
+authenticators, though it does include some nearly complete commented-out
+examples described in &<<SECTdefconfauth>>&. This means that no client can in
+fact authenticate until you complete the authenticator definitions.
+.code
+require message = relay not permitted
+ domains = +local_domains : +relay_domains
+.endd
+This statement rejects the address if its domain is neither a local domain nor
+one of the domains for which this host is a relay.
+.code
+require verify = recipient
+.endd
+This statement requires the recipient address to be verified; if verification
+fails, the address is rejected.
.code
# deny message = rejected because $sender_host_address \
# is in a black list at $dnslist_domain\n\
# $dnslist_text
# dnslists = black.list.example
#
-# warn message = X-Warning: $sender_host_address is \
-# in a black list at $dnslist_domain
+# warn dnslists = black.list.example
+# add_header = X-Warning: $sender_host_address is in \
+# a black list at $dnslist_domain
# log_message = found in $dnslist_domain
-# dnslists = black.list.example
.endd
These commented-out lines are examples of how you could configure Exim to check
sending hosts against a DNS black list. The first statement rejects messages
-from blacklisted hosts, whereas the second merely inserts a warning header
+from blacklisted hosts, whereas the second just inserts a warning header
line.
.code
-accept domains = +local_domains
- endpass
- verify = recipient
-.endd
-This statement accepts the incoming recipient address if its domain is one of
-the local domains, but only if the address can be verified. Verification of
-local addresses normally checks both the local part and the domain. The
-&%endpass%& line needs some explanation: if the condition above &%endpass%&
-fails, that is, if the address is not in a local domain, control is passed to
-the next ACL statement. However, if the condition below &%endpass%& fails, that
-is, if a recipient in a local domain cannot be verified, access is denied and
-the recipient is rejected.
-.code
-accept domains = +relay_to_domains
- endpass
- verify = recipient
+# require verify = csa
.endd
-This statement accepts the incoming recipient address if its domain is one of
-the domains for which this host is a relay, but again, only if the address can
-be verified.
+This commented-out line is an example of how you could turn on client SMTP
+authorization (CSA) checking. Such checks do DNS lookups for special SRV
+records.
.code
-deny message = relay not permitted
+accept
.endd
-The final statement denies access, giving a specific error message. Reaching
-the end of the ACL also causes access to be denied, but with the generic
-message &"administrative prohibition"&.
+The final statement in the first ACL unconditionally accepts any recipient
+address that has successfully passed all the previous tests.
.code
acl_check_data:
.endd
-.new
This line marks the start of the second ACL, and names it. Most of the contents
of this ACL are commented out:
.code
accept
.endd
This final line in the DATA ACL accepts the message unconditionally.
-.wen
-.section "Router configuration"
+.section "Router configuration" "SECID55"
.cindex "default" "routers"
.cindex "routers" "default"
The router configuration comes next in the default configuration, introduced
pipe_transport = address_pipe
reply_transport = address_reply
.endd
-.new
This is the most complicated router in the default configuration. It is another
redirection router, but this time it is looking for forwarding data set up by
individual users. The &%check_local_user%& setting specifies a check that the
# local_part_suffix = +* : -*
# local_part_suffix_optional
.endd
-.cindex "&$local_part_suffix$&"
+.vindex "&$local_part_suffix$&"
show how you can specify the recognition of local part suffixes. If the first
is uncommented, a suffix beginning with either a plus or a minus sign, followed
by any sequence of characters, is removed from the local part and placed in the
variable &$local_part_suffix$&. The second suffix option specifies that the
presence of a suffix in the local part is optional. When a suffix is present,
the check for a local login uses the local part with the suffix removed.
-.wen
When a local user account is found, the file called &_.forward_& in the user's
home directory is consulted. If it does not exist, or is empty, the router
# local_part_suffix_optional
transport = local_delivery
.endd
-.new
The final router sets up delivery into local mailboxes, provided that the local
part is the name of a local login, by accepting the address and assigning it to
the &(local_delivery)& transport. Otherwise, we have reached the end of the
routers, so the address is bounced. The commented suffix settings fulfil the
same purpose as they do for the &(userforward)& router.
-.wen
-.section "Transport configuration"
+.section "Transport configuration" "SECID56"
.cindex "default" "transports"
.cindex "transports" "default"
Transports define mechanisms for actually delivering messages. They operate
-.section "Default retry rule"
+.section "Default retry rule" "SECID57"
.cindex "retry" "default rule"
.cindex "default" "retry rule"
The retry section of the configuration file contains rules which affect the way
1.5 until 16 hours have passed, then every 6 hours up to 4 days. If an address
is not delivered after 4 days of temporary failure, it is bounced.
+If the retry section is removed from the configuration, or is empty (that is,
+if no retry rules are defined), Exim will not retry deliveries. This turns
+temporary errors into permanent errors.
-.section "Rewriting configuration"
+.section "Rewriting configuration" "SECID58"
The rewriting section of the configuration, introduced by
.code
begin rewrite
-.section "Authenticators configuration"
+.section "Authenticators configuration" "SECTdefconfauth"
.cindex "AUTH" "configuration"
The authenticators section of the configuration, introduced by
.code
begin authenticators
.endd
-defines mechanisms for the use of the SMTP AUTH command. No authenticators
-are specified in the default configuration file.
+defines mechanisms for the use of the SMTP AUTH command. The default
+configuration file contains two commented-out example authenticators
+which support plaintext username/password authentication using the
+standard PLAIN mechanism and the traditional but non-standard LOGIN
+mechanism, with Exim acting as the server. PLAIN and LOGIN are enough
+to support most MUA software.
+
+The example PLAIN authenticator looks like this:
+.code
+#PLAIN:
+# driver = plaintext
+# server_set_id = $auth2
+# server_prompts = :
+# server_condition = Authentication is not yet configured
+# server_advertise_condition = ${if def:tls_cipher }
+.endd
+And the example LOGIN authenticator looks like this:
+.code
+#LOGIN:
+# driver = plaintext
+# server_set_id = $auth1
+# server_prompts = <| Username: | Password:
+# server_condition = Authentication is not yet configured
+# server_advertise_condition = ${if def:tls_cipher }
+.endd
+
+The &%server_set_id%& option makes Exim remember the authenticated username
+in &$authenticated_id$&, which can be used later in ACLs or routers. The
+&%server_prompts%& option configures the &(plaintext)& authenticator so
+that it implements the details of the specific authentication mechanism,
+i.e. PLAIN or LOGIN. The &%server_advertise_condition%& setting controls
+when Exim offers authentication to clients; in the examples, this is only
+when TLS or SSL has been started, so to enable the authenticators you also
+need to add support for TLS as described in section &<<SECTdefconfmain>>&.
+
+The &%server_condition%& setting defines how to verify that the username and
+password are correct. In the examples it just produces an error message.
+To make the authenticators work, you can use a string expansion
+expression like one of the examples in chapter &<<CHAPplaintext>>&.
+
+Beware that the sequence of the parameters to PLAIN and LOGIN differ; the
+usercode and password are in different positions.
+Chapter &<<CHAPplaintext>>& covers both.
+
+.ecindex IIDconfiwal
O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)).
The documentation for the syntax and semantics of the regular expressions that
-are supported by PCRE is included in plain text in the file
-&_doc/pcrepattern.txt_& in the Exim distribution, and also in the HTML
-tarbundle of Exim documentation. It describes in detail the features of the
-regular expressions that PCRE supports, so no further description is included
-here. The PCRE functions are called from Exim using the default option settings
-(that is, with no PCRE options set), except that the PCRE_CASELESS option is
-set when the matching is required to be case-insensitive.
+are supported by PCRE is included in the PCRE distribution, and no further
+description is included here. The PCRE functions are called from Exim using
+the default option settings (that is, with no PCRE options set), except that
+the PCRE_CASELESS option is set when the matching is required to be
+case-insensitive.
In most cases, when a regular expression is required in an Exim configuration,
it has to start with a circumflex, in order to distinguish it from plain text
-.section "Testing regular expressions"
-.cindex "testing" "regular expressions"
-.cindex "regular expressions" "testing"
-.cindex "&'pcretest'&"
-A program called &'pcretest'& forms part of the PCRE distribution and is built
-with PCRE during the process of building Exim. It is primarily intended for
-testing PCRE itself, but it can also be used for experimenting with regular
-expressions. After building Exim, the binary can be found in the build
-directory (it is not installed anywhere automatically). There is documentation
-of various options in &_doc/pcretest.txt_&, but for simple testing, none are
-needed. This is the output of a sample run of &'pcretest'&:
-.display
-&` re> `&&*&`/^([@]+)@.+\.(ac|edu)\.(?!kr)[a-z]{2}$/`&*&
-&`data> `&&*&`x@y.ac.uk`&*&
-&` 0: x@y.ac.uk`&
-&` 1: x`&
-&` 2: ac`&
-&`data> `&&*&`x@y.ac.kr`&*&
-&`No match`&
-&`data> `&&*&`x@y.edu.com`&*&
-&`No match`&
-&`data> `&&*&`x@y.edu.co`&*&
-&` 0: x@y.edu.co`&
-&` 1: x`&
-&` 2: edu`&
-.endd
-Input typed by the user is shown in bold face. After the &"re>"& prompt, a
-regular expression enclosed in delimiters is expected. If this compiles without
-error, &"data>"& prompts are given for strings against which the expression is
-matched. An empty data line causes a new regular expression to be read. If the
-match is successful, the captured substring values (that is, what would be in
-the variables &$0$&, &$1$&, &$2$&, etc.) are shown. The above example tests for
-an email address whose domain ends with either &"ac"& or &"edu"& followed by a
-two-character top-level domain that is not &"kr"&. The local part is captured
-in &$1$& and the &"ac"& or &"edu"& in &$2$&.
-
-
-
-
-
-
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
.chapter "File and database lookups" "CHAPfdlookup"
-.cindex "file" "lookup"
-.cindex "database lookups"
+.scindex IIDfidalo1 "file" "lookups"
+.scindex IIDfidalo2 "database" "lookups"
.cindex "lookup" "description of"
Exim can be configured to look up data in files or databases as it processes
messages. Two different kinds of syntax are used:
chapter &<<CHAPdomhosaddlists>>&.
.endlist
-.new
String expansions, lists, and lookups interact with each other in such a way
that there is no order in which to describe any one of them that does not
involve references to the others. Each of these three chapters makes more sense
if you have read the other two first. If you are reading this for the first
time, be aware that some of it will make a lot more sense after you have read
chapters &<<CHAPdomhosaddlists>>& and &<<CHAPexpand>>&.
-.wen
-.section "Examples of different lookup syntax"
+.section "Examples of different lookup syntax" "SECID60"
It is easy to confuse the two different kinds of lookup, especially as the
lists that may contain the second kind are always expanded before being
processed as lists. Therefore, they may also contain lookups of the first kind.
domains = ${lookup{$sender_host_address}lsearch{/some/file}}
domains = lsearch;/some/file
.endd
-.new
The first uses a string expansion, the result of which must be a domain list.
No strings have been specified for a successful or a failing lookup; the
defaults in this case are the looked-up data and an empty string, respectively.
The expansion takes place before the string is processed as a list, and the
file that is searched could contain lines like this:
-.wen
.code
192.168.3.4: domain1:domain2:...
192.168.1.9: domain3:domain4:...
lookup is permitted.
-.section "Lookup types"
+.section "Lookup types" "SECID61"
.cindex "lookup" "types of"
.cindex "single-key lookup" "definition of"
Two different types of data lookup are implemented:
&(cdb)&: The given file is searched as a Constant DataBase file, using the key
string without a terminating binary zero. The cdb format is designed for
indexed files that are read frequently and never updated, except by total
-re-creation. As such, it is particulary suitable for large files containing
+re-creation. As such, it is particularly suitable for large files containing
aliases or other indexed data referenced by an MTA. Information about cdb can
be found in several places:
.display
that the library supports, and can be useful for accessing DBM files created by
other applications. (For earlier DB versions, DB_HASH is always used.)
.next
+.cindex "lookup" "dbmjz"
+.cindex "lookup" "dbm &-- embedded NULs"
+.cindex "sasldb2"
+.cindex "dbmjz lookup type"
+&(dbmjz)&: This is the same as &(dbm)&, except that the lookup key is
+interpreted as an Exim list; the elements of the list are joined together with
+ASCII NUL characters to form the lookup key. An example usage would be to
+authenticate incoming SMTP calls using the passwords from Cyrus SASL's
+&_/etc/sasldb2_& file with the &(gsasl)& authenticator or Exim's own
+&(cram_md5)& authenticator.
+.next
.cindex "lookup" "dbmnz"
.cindex "lookup" "dbm &-- terminating zero"
.cindex "binary zero" "in lookup key"
.cindex "Courier"
.cindex "&_/etc/userdbshadow.dat_&"
-.cindex "dmbnz lookup type"
+.cindex "dbmnz lookup type"
&(dbmnz)&: This is the same as &(dbm)&, except that a terminating binary zero
is not included in the key that is passed to the DBM library. You may need this
if you want to look up data in files that are created by or shared with some
.next
.cindex "lookup" "dsearch"
.cindex "dsearch lookup type"
-&(dsearch)&: The given file must be a directory; this is searched for a file
-whose name is the key. The key may not contain any forward slash characters.
-The result of a successful lookup is the name of the file. An example of how
-this lookup can be used to support virtual domains is given in section
+&(dsearch)&: The given file must be a directory; this is searched for an entry
+whose name is the key by calling the &[lstat()]& function. The key may not
+contain any forward slash characters. If &[lstat()]& succeeds, the result of
+the lookup is the name of the entry, which may be a file, directory,
+symbolic link, or any other kind of directory entry. An example of how this
+lookup can be used to support virtual domains is given in section
&<<SECTvirtualdomains>>&.
.next
.cindex "lookup" "iplsearch"
being interpreted as a key terminator. For example:
.code
1.2.3.4: data for 1.2.3.4
-192.168.0.0/16 data for 192.168.0.0/16
+192.168.0.0/16: data for 192.168.0.0/16
"abcd::cdab": data for abcd::cdab
"abcd:abcd::/32" data for abcd:abcd::/32
.endd
&*Warning 2*&: In a host list, you must always use &(net-iplsearch)& so that
the implicit key is the host's IP address rather than its name (see section
&<<SECThoslispatsikey>>&).
-
.next
.cindex "linear search"
.cindex "lookup" "lsearch"
.cindex "lsearch lookup type"
+.cindex "case sensitivity" "in lsearch lookup"
&(lsearch)&: The given file is a text file that is searched linearly for a
line beginning with the search key, terminated by a colon or white space or the
-end of the line. The first occurrence that is found in the file is used. White
-space between the key and the colon is permitted. The remainder of the line,
-with leading and trailing white space removed, is the data. This can be
+end of the line. The search is case-insensitive; that is, upper and lower case
+letters are treated as the same. The first occurrence of the key that is found
+in the file is used.
+
+White space between the key and the colon is permitted. The remainder of the
+line, with leading and trailing white space removed, is the data. This can be
continued onto subsequent lines by starting them with any amount of white
space, but only a single space character is included in the data at such a
junction. If the data begins with a colon, the key must be terminated by a
that for &(wildlsearch)&, each key in the file is string-expanded before being
used, whereas for &(nwildlsearch)&, no expansion takes place.
-Like &(lsearch)&, the testing is done case-insensitively. The following forms
-of wildcard are recognized:
+.cindex "case sensitivity" "in (n)wildlsearch lookup"
+Like &(lsearch)&, the testing is done case-insensitively. However, keys in the
+file that are regular expressions can be made case-sensitive by the use of
+&`(-i)`& within the pattern. The following forms of wildcard are recognized:
. ==== As this is a nested list, any displays it contains must be indented
. ==== as otherwise they are too far to the left.
.code
^\d+\.a\.b data for <digits>.a.b
.endd
+The case-insensitive flag is set at the start of compiling the regular
+expression, but it can be turned off by using &`(-i)`& at an appropriate point.
+For example, to make the entire pattern case-sensitive:
+.code
+ ^(?-i)\d+\.a\.b data for <digits>.a.b
+.endd
+
If the regular expression contains white space or colon characters, you must
either quote it (see &(lsearch)& above), or represent these characters in other
ways. For example, &`\s`& can be used for white space and &`\x3A`& for a
.endlist ilist
-.section "Query-style lookup types"
+.section "Query-style lookup types" "SECID62"
.cindex "lookup" "query-style types"
.cindex "query-style lookup" "list of types"
The supported query-style lookup types are listed below. Further details about
are given in the supplied query. The resulting data is the contents of the
records. See section &<<SECTdnsdb>>&.
.next
-.cindex "Interbase lookup type"
-.cindex "lookup" "Interbase"
-&(ibase)&: This does a lookup in an Interbase database.
+.cindex "InterBase lookup type"
+.cindex "lookup" "InterBase"
+&(ibase)&: This does a lookup in an InterBase database.
.next
.cindex "LDAP" "lookup type"
.cindex "lookup" "LDAP"
PostgreSQL database. See section &<<SECTsql>>&.
.next
-.new
.cindex "sqlite lookup type"
.cindex "lookup" "sqlite"
&(sqlite)&: The format of the query is a file name followed by an SQL statement
that is passed to an SQLite database. See section &<<SECTsqlite>>&.
-.wen
.next
&(testdb)&: This is a lookup type that is used for testing Exim. It is
.next
.cindex "whoson lookup type"
.cindex "lookup" "whoson"
-&(whoson)&: &'Whoson'& (&url(http://whoson.sourceforge.net)) is a proposed
-Internet protocol that allows Internet server programs to check whether a
-particular (dynamically allocated) IP address is currently allocated to a known
-(trusted) user and, optionally, to obtain the identity of the said user. In
-Exim, this can be used to implement &"POP before SMTP"& checking using ACL
-statements such as
+&(whoson)&: &'Whoson'& (&url(http://whoson.sourceforge.net)) is a protocol that
+allows a server to check whether a particular (dynamically allocated) IP
+address is currently allocated to a known (trusted) user and, optionally, to
+obtain the identity of the said user. For SMTP servers, &'Whoson'& was popular
+at one time for &"POP before SMTP"& authentication, but that approach has been
+superseded by SMTP authentication. In Exim, &'Whoson'& can be used to implement
+&"POP before SMTP"& checking using ACL statements such as
.code
require condition = \
${lookup whoson {$sender_host_address}{yes}{no}}
.endd
-.new
The query consists of a single IP address. The value returned is the name of
the authenticated user, which is stored in the variable &$value$&. However, in
this example, the data in &$value$& is not used; the result of the lookup is
one of the fixed strings &"yes"& or &"no"&.
-.wen
.endlist
-.section "Temporary errors in lookups"
+.section "Temporary errors in lookups" "SECID63"
.cindex "lookup" "temporary error in"
Lookup functions can return temporary error codes if the lookup cannot be
completed. For example, an SQL or LDAP database might be unavailable. For this
In this context, a &"default value"& is a value specified by the administrator
that is to be used if a lookup fails.
+&*Note:*& This section applies only to single-key lookups. For query-style
+lookups, the facilities of the query language must be used. An attempt to
+specify a default for a query-style lookup provokes an error.
+
If &"*"& is added to a single-key lookup type (for example, &%lsearch*%&)
and the initial lookup fails, the key &"*"& is looked up in the file to
provide a default value. See also the section on partial matching below.
-.section "Lookup caching"
+.section "Lookup caching" "SECID64"
.cindex "lookup" "caching"
.cindex "caching" "lookup data"
Exim caches all lookup results in order to avoid needless repetition of
-.section "Quoting lookup data"
+.section "Quoting lookup data" "SECID65"
.cindex "lookup" "quoting"
.cindex "quoting" "in lookups"
When data from an incoming message is included in a query-style lookup, there
.code
${lookup dnsdb{mx=a.b.example}{$value}fail}
.endd
-.new
If the lookup succeeds, the result is placed in &$value$&, which in this case
-is used on its own as the result. If the lookup succeeds, the &`fail`& keyword
-causes a &'forced expansion failure'& &-- see section &<<SECTforexpfai>>& for
-an explanation of what this means.
-.wen
+is used on its own as the result. If the lookup does not succeed, the
+&`fail`& keyword causes a &'forced expansion failure'& &-- see section
+&<<SECTforexpfai>>& for an explanation of what this means.
-The supported DNS record types are A, CNAME, MX, NS, PTR, SRV, and TXT, and,
-when Exim is compiled with IPv6 support, AAAA (and A6 if that is also
+The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, and TXT,
+and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is also
configured). If no type is given, TXT is assumed. When the type is PTR,
the data can be an IP address, written as normal; inversion and the addition of
&%in-addr.arpa%& or &%ip6.arpa%& happens automatically. For example:
It is permitted to specify a space as the separator character. Further
white space is ignored.
-.section "Pseudo dnsdb record types"
+.cindex "TXT record" "in &(dnsdb)& lookup"
+.cindex "SPF record" "in &(dnsdb)& lookup"
+For TXT records with multiple items of data, only the first item is returned,
+unless a separator for them is specified using a comma after the separator
+character followed immediately by the TXT record item separator. To concatenate
+items without a separator, use a semicolon instead. For SPF records the
+default behaviour is to concatenate multiple items without using a separator.
+.code
+${lookup dnsdb{>\n,: txt=a.b.example}}
+${lookup dnsdb{>\n; txt=a.b.example}}
+${lookup dnsdb{spf=example.org}}
+.endd
+It is permitted to specify a space as the separator character. Further
+white space is ignored.
+
+.section "Pseudo dnsdb record types" "SECID66"
.cindex "MX record" "in &(dnsdb)& lookup"
By default, both the preference value and the host name are returned for
each MX record, separated by a space. If you want only host names, you can use
In this case, the preference values are omitted, and just the host names are
returned.
-.cindex "name server" "for enclosing domain"
+.cindex "name server for enclosing domain"
Another pseudo-type is ZNS (for &"zone NS"&). It performs a lookup for NS
records on the given domain, but if none are found, it removes the first
component of the domain name, and tries again. This process continues until NS
for the high-level domains such as &%com%& or &%co.uk%& are not going to be on
such a list.
-.new
.cindex "CSA" "in &(dnsdb)& lookup"
A third pseudo-type is CSA (Client SMTP Authorization). This looks up SRV
records according to the CSA rules, which are described in section
has two space-separated fields: an authorization code and a target host name.
The authorization code can be &"Y"& for yes, &"N"& for no, &"X"& for explicit
authorization required but absent, or &"?"& for unknown.
-.wen
-.section "Multiple dnsdb lookups"
+.section "Multiple dnsdb lookups" "SECID67"
In the previous sections, &(dnsdb)& lookups for a single domain are described.
However, you can specify a list of domains or IP addresses in a single
&(dnsdb)& lookup. The list is specified in the normal Exim way, with colon as
.section "More about LDAP" "SECTldap"
-.cindex "LDAP lookup"
+.cindex "LDAP" "lookup, more about"
.cindex "lookup" "LDAP"
.cindex "Solaris" "LDAP"
The original LDAP implementation came from the University of Michigan; this has
secure (encrypted) LDAP connections. The second of these ensures that an
encrypted TLS connection is used.
+With sufficiently modern LDAP libraries, Exim supports forcing TLS over regular
+LDAP connections, rather than the SSL-on-connect &`ldaps`&.
+See the &%ldap_start_tls%& option.
+
-.section "LDAP quoting"
+.section "LDAP quoting" "SECID68"
.cindex "LDAP" "quoting"
Two levels of quoting are required in LDAP queries, the first for LDAP itself
and the second because the LDAP query is represented as a URL. Furthermore,
authentication below.
-.section "LDAP connections"
+.section "LDAP connections" "SECID69"
.cindex "LDAP" "connections"
The connection to an LDAP server may either be over TCP/IP, or, when OpenLDAP
is in use, via a Unix domain socket. The example given above does not specify
failures, and timeouts.
For each server name in the list, a port number can be given. The standard way
-of specifing a host and port is to use a colon separator (RFC 1738). Because
+of specifying a host and port is to use a colon separator (RFC 1738). Because
&%ldap_default_servers%& is a colon-separated list, such colons have to be
doubled. For example
.code
-.section "LDAP authentication and control information"
+.section "LDAP authentication and control information" "SECID70"
.cindex "LDAP" "authentication"
The LDAP URL syntax provides no way of passing authentication and other control
information to the server. To make this possible, the URL in an LDAP query may
&`NETTIME `& set a timeout for a network operation
&`USER `& set the DN, for authenticating the LDAP bind
&`PASS `& set the password, likewise
+&`REFERRALS `& set the referrals parameter
&`SIZE `& set the limit for the number of entries returned
&`TIME `& set the maximum waiting time for a query
.endd
The value of the DEREFERENCE parameter must be one of the words &"never"&,
-&"searching"&, &"finding"&, or &"always"&.
+&"searching"&, &"finding"&, or &"always"&. The value of the REFERRALS parameter
+must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP
+library from trying to follow referrals issued by the LDAP server.
The name CONNECT is an obsolete name for NETTIME, retained for
backwards compatibility. This timeout (specified as a number of seconds) is
-.section "Format of data returned by LDAP"
+.section "Format of data returned by LDAP" "SECID71"
.cindex "LDAP" "returned data formats"
The &(ldapdn)& lookup type returns the Distinguished Name from a single entry
as a sequence of values, for example
.section "SQL lookups" "SECTsql"
-.new
.cindex "SQL lookup types"
-Exim can support lookups in Interbase, MySQL, Oracle, PostgreSQL, and SQLite
+.cindex "MySQL" "lookup type"
+.cindex "PostgreSQL lookup type"
+.cindex "lookup" "MySQL"
+.cindex "lookup" "PostgreSQL"
+.cindex "Oracle" "lookup type"
+.cindex "lookup" "Oracle"
+.cindex "InterBase lookup type"
+.cindex "lookup" "InterBase"
+Exim can support lookups in InterBase, MySQL, Oracle, PostgreSQL, and SQLite
databases. Queries for these databases contain SQL statements, so an example
might be
-.wen
.code
${lookup mysql{select mailbox from users where id='userx'}\
{$value}fail}
with a newline between the data for each row.
-.section "More about MySQL, PostgreSQL, Oracle, and Interbase"
+.section "More about MySQL, PostgreSQL, Oracle, and InterBase" "SECID72"
.cindex "MySQL" "lookup type"
.cindex "PostgreSQL lookup type"
.cindex "lookup" "MySQL"
.cindex "lookup" "PostgreSQL"
.cindex "Oracle" "lookup type"
.cindex "lookup" "Oracle"
-.cindex "Interbase lookup type"
-.cindex "lookup" "Interbase"
-If any MySQL, PostgreSQL, Oracle, or Interbase lookups are used, the
+.cindex "InterBase lookup type"
+.cindex "lookup" "InterBase"
+If any MySQL, PostgreSQL, Oracle, or InterBase lookups are used, the
&%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, or &%ibase_servers%&
option (as appropriate) must be set to a colon-separated list of server
-information. Each item in the list is a slash-separated list of four items:
-host name, database name, user name, and password. In the case of Oracle, the
-host name field is used for the &"service name"&, and the database name field
-is not used and should be empty. For example:
+information.
+(For MySQL and PostgreSQL only, the global option need not be set if all
+queries contain their own server information &-- see section
+&<<SECTspeserque>>&.) Each item in the list is a slash-separated list of four
+items: host name, database name, user name, and password. In the case of
+Oracle, the host name field is used for the &"service name"&, and the database
+name field is not used and should be empty. For example:
.code
hide oracle_servers = oracle.plc.example//userx/abcdwxyz
.endd
.endd
For MySQL and PostgreSQL, a host may be specified as <&'name'&>:<&'port'&> but
because this is a colon-separated list, the colon has to be doubled. For each
-query, these parameter groups are tried in order until a connection and a query
-succeeds.
+query, these parameter groups are tried in order until a connection is made and
+a query is successfully processed. The result of a query may be that no data is
+found, but that is still a successful query. In other words, the list of
+servers provides a backup facility, not a list of different places to look.
The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators
convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b
for MySQL because these escapes are not recognized in contexts where these
characters are not special.
-
-.section "Special MySQL features"
-For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
-causes a connection to the server on the local host by means of a Unix domain
-socket. An alternate socket can be specified in parentheses. The full syntax of
-each item in &%mysql_servers%& is:
+.section "Specifying the server in the query" "SECTspeserque"
+For MySQL and PostgreSQL lookups (but not currently for Oracle and InterBase),
+it is possible to specify a list of servers with an individual query. This is
+done by starting the query with
.display
-<&'hostname'&>::<&'port'&>(<&'socket name'&>)/<&'database'&>/&&&
- <&'user'&>/<&'password'&>
+&`servers=`&&'server1:server2:server3:...'&&`;`&
.endd
-Any of the three sub-parts of the first field can be omitted. For normal use on
-the local host it can be left blank or set to just &"localhost"&.
+Each item in the list may take one of two forms:
+.olist
+If it contains no slashes it is assumed to be just a host name. The appropriate
+global option (&%mysql_servers%& or &%pgsql_servers%&) is searched for a host
+of the same name, and the remaining parameters (database, user, password) are
+taken from there.
+.next
+If it contains any slashes, it is taken as a complete parameter set.
+.endlist
+The list of servers is used in exactly the same way as the global list.
+Once a connection to a server has happened and a query has been
+successfully executed, processing of the lookup ceases.
-No database need be supplied &-- but if it is absent here, it must be given in
+This feature is intended for use in master/slave situations where updates
+are occurring and you want to update the master rather than a slave. If the
+master is in the list as a backup for reading, you might have a global setting
+like this:
+.code
+mysql_servers = slave1/db/name/pw:\
+ slave2/db/name/pw:\
+ master/db/name/pw
+.endd
+In an updating lookup, you could then write:
+.code
+${lookup mysql{servers=master; UPDATE ...} }
+.endd
+That query would then be sent only to the master server. If, on the other hand,
+the master is not to be used for reading, and so is not present in the global
+option, you can still update it by a query of this form:
+.code
+${lookup pgsql{servers=master/db/name/pw; UPDATE ...} }
+.endd
+
+
+.section "Special MySQL features" "SECID73"
+For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
+causes a connection to the server on the local host by means of a Unix domain
+socket. An alternate socket can be specified in parentheses. The full syntax of
+each item in &%mysql_servers%& is:
+.display
+<&'hostname'&>::<&'port'&>(<&'socket name'&>)/<&'database'&>/&&&
+ <&'user'&>/<&'password'&>
+.endd
+Any of the three sub-parts of the first field can be omitted. For normal use on
+the local host it can be left blank or set to just &"localhost"&.
+
+No database need be supplied &-- but if it is absent here, it must be given in
the queries.
If a MySQL query is issued that does not request any data (an insert, update,
is zero because no rows are affected.
-.section "Special PostgreSQL features"
+.section "Special PostgreSQL features" "SECID74"
PostgreSQL lookups can also use Unix domain socket connections to the database.
This is usually faster and costs less CPU time than a TCP/IP connection.
However it can be used only if the mail server runs on the same machine as the
update, or delete command), the result of the lookup is the number of rows
affected.
-.new
.section "More about SQLite" "SECTsqlite"
.cindex "lookup" "SQLite"
-.cindex "SQLite lookup type"
+.cindex "sqlite lookup type"
SQLite is different to the other SQL lookups because a file name is required in
addition to the SQL query. An SQLite database is a single file, and there is no
daemon as in the other SQL databases. The interface to Exim requires the name
waits for the lock to be released. In Exim, the default timeout is set
to 5 seconds, but it can be changed by means of the &%sqlite_lock_timeout%&
option.
-.wen
+.ecindex IIDfidalo1
+.ecindex IIDfidalo2
. ////////////////////////////////////////////////////////////////////////////
.chapter "Domain, host, address, and local part lists" &&&
"CHAPdomhosaddlists" &&&
"Domain, host, and address lists"
-.cindex "list of domains; hosts; etc."
+.scindex IIDdohoadli "lists of domains; hosts; etc."
A number of Exim configuration options contain lists of domains, hosts,
email addresses, or local parts. For example, the &%hold_domains%& option
contains a list of domains whose delivery is currently suspended. These lists
-.section "Expansion of lists"
+.section "Expansion of lists" "SECID75"
.cindex "expansion" "of lists"
Each list is expanded as a single string before it is used. The result of
expansion must be a list, possibly containing empty items, which is split up
-.section "Negated items in lists"
+.section "Negated items in lists" "SECID76"
.cindex "list" "negation"
-.cindex "negation in lists"
+.cindex "negation" "in lists"
Items in a list may be positive or negative. Negative items are indicated by a
leading exclamation mark, which may be followed by optional white space. A list
defines a set of items (domains, etc). When Exim processes one of these lists,
-.section "An lsearch file is not an out-of-line list"
+.section "An lsearch file is not an out-of-line list" "SECID77"
As will be described in the sections that follow, lookups can be used in lists
to provide indexed methods of checking list membership. There has been some
confusion about the way &(lsearch)& lookups work in lists. Because
If you want to use a file to contain wild-card patterns that form part of a
list, just give the file name on its own, without a search type, as described
-in the previous section.
+in the previous section. You could also use the &(wildlsearch)& or
+&(nwildlsearch)&, but there is no advantage in doing this.
-.section "Named lists compared with macros"
+.section "Named lists compared with macros" "SECID78"
.cindex "list" "named compared with macro"
.cindex "macro" "compared with named list"
At first sight, named lists might seem to be no different from macros in the
.endd
-.section "Named list caching"
+.section "Named list caching" "SECID79"
.cindex "list" "caching of named"
.cindex "caching" "named lists"
While processing a message, Exim caches the result of checking a named list if
.ilist
.cindex "primary host name"
.cindex "host name" "matched in domain list"
-.cindex "&%primary_hostname%&"
+.oindex "&%primary_hostname%&"
.cindex "domain list" "matching primary host name"
.cindex "@ in a domain list"
If a pattern consists of a single @ character, it matches the local host name,
.cindex "@[] in a domain list"
.cindex "domain list" "matching local IP interfaces"
.cindex "domain literal"
-If a pattern consists of the string &`@[]`& it matches any local IP interface
-address, enclosed in square brackets, as in an email address that contains a
-domain literal.
+If a pattern consists of the string &`@[]`& it matches an IP address enclosed
+in square brackets (as in an email address that contains a domain literal), but
+only if that IP address is recognized as local for email routing purposes. The
+&%local_interfaces%& and &%extra_local_interfaces%& options can be used to
+control which of a host's several IP addresses are treated as local.
In today's Internet, the use of domain literals is controversial.
.next
.cindex "@mx_any"
.cindex "domain list" "matching MX pointers to local host"
If a pattern consists of the string &`@mx_any`& it matches any domain that
has an MX record pointing to the local host or to any host that is listed in
-.cindex "&%hosts_treat_as_local%&"
+.oindex "&%hosts_treat_as_local%&"
&%hosts_treat_as_local%&. The items &`@mx_primary`& and &`@mx_secondary`&
are similar, except that the first matches only when a primary MX target is the
local host, and the second only when no primary MX target is the local host,
If a pattern starts with a circumflex character, it is treated as a regular
expression, and matched against the domain using a regular expression matching
function. The circumflex is treated as part of the regular expression.
-References to descriptions of the syntax of regular expressions are given in
-chapter &<<CHAPregexp>>&.
+Email domains are case-independent, so this regular expression match is by
+default case-independent, but you can make it case-dependent by starting it
+with &`(?-i)`&. References to descriptions of the syntax of regular expressions
+are given in chapter &<<CHAPregexp>>&.
&*Warning*&: Because domain lists are expanded before being processed, you
must escape any backslash and dollar characters in the regular expression, or
chapter &<<CHAPfdlookup>>&. For example:
.code
hold_domains = mysql;select domain from holdlist \
- where domain = '$domain';
+ where domain = '${quote_mysql:$domain}';
.endd
In most cases, the data that is looked up is not used (so for an SQL query, for
example, it doesn't matter what field you select). Exim is interested only in
involved, to ensure that the right value is being used as the key.
-.section "Special host list patterns"
+.section "Special host list patterns" "SECID80"
.cindex "empty item in hosts list"
.cindex "host list" "empty string in"
If a host list item is the empty string, it matches only when no remote host is
length. A textual string is constructed from the masked value, followed by the
mask, and this is used as the lookup key. For example, if the host's IP address
is 192.168.34.6, the key that is looked up for the above example is
-&"192.168.34.0/24"&. IPv6 addresses are converted to a text value using lower
-case letters and dots as separators instead of the more usual colon, because
-colon is the key terminator in &(lsearch)& files. Full, unabbreviated IPv6
+&"192.168.34.0/24"&.
+
+When an IPv6 address is converted to a string, dots are normally used instead
+of colons, so that keys in &(lsearch)& files need not contain colons (which
+terminate &(lsearch)& keys). This was implemented some time before the ability
+to quote keys was made available in &(lsearch)& files. However, the more
+recently implemented &(iplsearch)& files do require colons in IPv6 keys
+(notated using the quoting facility) so as to distinguish them from IPv4 keys.
+For this reason, when the lookup type is &(iplsearch)&, IPv6 addresses are
+converted using colons and not dots. In all cases, full, unabbreviated IPv6
addresses are always used.
-&*Warning*&: Specifing &%net32-%& (for an IPv4 address) or &%net128-%& (for an
-IPv6 address) is not the same as specifing just &%net-%& without a number. In
+Ideally, it would be nice to tidy up this anomalous situation by changing to
+colons in all cases, given that quoting is now available for &(lsearch)&.
+However, this would be an incompatible change that might break some existing
+configurations.
+
+&*Warning*&: Specifying &%net32-%& (for an IPv4 address) or &%net128-%& (for an
+IPv6 address) is not the same as specifying just &%net-%& without a number. In
the former case the key strings include the mask value, whereas in the latter
case the IP address is used on its own.
By default, in order to find a host name, Exim first does a reverse DNS lookup;
if no name is found in the DNS, the system function (&[gethostbyaddr()]& or
&[getipnodebyaddr()]& if available) is tried. The order in which these lookups
-are done can be changed by setting the &%host_lookup_order%& option.
+are done can be changed by setting the &%host_lookup_order%& option. For
+security, once Exim has found one or more names, it looks up the IP addresses
+for these names and compares them with the IP address that it started with.
+Only those names whose IP addresses match are accepted. Any other names are
+discarded. If no names are left, Exim behaves as if the host name cannot be
+found. In the most common case there is only one name and one IP address.
There are some options that control what happens if a host name cannot be
found. These are described in section &<<SECTbehipnot>>& below.
.cindex "regular expressions" "in host list"
.cindex "host list" "regular expression in"
If the item starts with &"^"& it is taken to be a regular expression which is
-matched against the host name. For example,
+matched against the host name. Host names are case-independent, so this regular
+expression match is by default case-independent, but you can make it
+case-dependent by starting it with &`(?-i)`&. References to descriptions of the
+syntax of regular expressions are given in chapter &<<CHAPregexp>>&. For
+example,
.code
^(a|b)\.c\.d$
.endd
.section "Behaviour when an IP address or name cannot be found" "SECTbehipnot"
-.cindex "host" "lookup failures"
+.cindex "host" "lookup failures, permanent"
While processing a host list, Exim may need to look up an IP address from a
name (see section &<<SECThoslispatip>>&), or it may need to look up a host name
from an IP address (see section &<<SECThoslispatnam>>&). In either case, the
behaviour when it fails to find the information it is seeking is the same.
+&*Note*&: This section applies to permanent lookup failures. It does &'not'&
+apply to temporary DNS errors, whose handling is described in the next section.
+
.cindex "&`+include_unknown`&"
.cindex "&`+ignore_unknown`&"
By default, Exim behaves as if the host does not match the list. This may not
list. The effect of each one lasts until the next, or until the end of the
list.
-&*Note*&: This section applies to permanent lookup failures. It does &'not'&
-apply to temporary DNS errors. They always cause a defer action.
+
+.section "Temporary DNS errors when looking up host information" &&&
+ "SECTtemdnserr"
+.cindex "host" "lookup failures, temporary"
+.cindex "&`+include_defer`&"
+.cindex "&`+ignore_defer`&"
+A temporary DNS lookup failure normally causes a defer action (except when
+&%dns_again_means_nonexist%& converts it into a permanent error). However,
+host lists can include &`+ignore_defer`& and &`+include_defer`&, analagous to
+&`+ignore_unknown`& and &`+include_unknown`&, as described in the previous
+section. These options should be used with care, probably only in non-critical
+host lists such as whitelists.
.section "Host list patterns for single-key lookups by host name" &&&
"SECThoslispatnamsk"
-.cindex "host" "lookup failures"
.cindex "unknown host name"
.cindex "host list" "matching host name"
If a pattern is of the form
.code
dbm;/host/accept/list
.endd
-a single-key lookup is performend, using the host name as its key. If the
+a single-key lookup is performed, using the host name as its key. If the
lookup succeeds, the host matches the item. The actual data that is looked up
is not used.
-.section "Host list patterns for query-style lookups"
+.section "Host list patterns for query-style lookups" "SECID81"
If a pattern is of the form
.display
<&'query-style-search-type'&>;<&'query'&>
detected by a regular expression that matches an empty string,
and by a query-style lookup that succeeds when &$sender_address$& is empty.
-The following kinds of address list pattern can match any address, including
-the empty address that is characteristic of bounce message senders:
+Non-empty items in an address list can be straightforward email addresses. For
+example:
+.code
+senders = jbc@askone.example : hs@anacreon.example
+.endd
+A certain amount of wildcarding is permitted. If a pattern contains an @
+character, but is not a regular expression and does not begin with a
+semicolon-terminated lookup type (described below), the local part of the
+subject address is compared with the local part of the pattern, which may start
+with an asterisk. If the local parts match, the domain is checked in exactly
+the same way as for a pattern in a domain list. For example, the domain can be
+wildcarded, refer to a named list, or be a lookup:
+.code
+deny senders = *@*.spamming.site:\
+ *@+hostile_domains:\
+ bozo@partial-lsearch;/list/of/dodgy/sites:\
+ *@dbm;/bad/domains.db
+.endd
+.cindex "local part" "starting with !"
+.cindex "address list" "local part starting with !"
+If a local part that begins with an exclamation mark is required, it has to be
+specified using a regular expression, because otherwise the exclamation mark is
+treated as a sign of negation, as is standard in lists.
-.ilist
-As explained above, if a pattern item is empty, it matches the empty address
-(and no others).
+If a non-empty pattern that is not a regular expression or a lookup does not
+contain an @ character, it is matched against the domain part of the subject
+address. The only two formats that are recognized this way are a literal
+domain, or a domain pattern that starts with *. In both these cases, the effect
+is the same as if &`*@`& preceded the pattern. For example:
+.code
+deny senders = enemy.domain : *.enemy.domain
+.endd
-.next
+The following kinds of more complicated address list pattern can match any
+address, including the empty address that is characteristic of bounce message
+senders:
+
+.ilist
.cindex "regular expressions" "in address list"
.cindex "address list" "regular expression in"
If (after expansion) a pattern starts with &"^"&, a regular expression match is
as part of the string expansion. The simplest way to do this is to use &`\N`&
to mark that part of the string as non-expandable. For example:
.code
-deny senders = \N^\d{8}.+@spamhaus.example$\N : ...
+deny senders = \N^.*this.*@example\.com$\N : \
+ \N^\d{8}.+@spamhaus.example$\N : ...
.endd
-The &`\N`& sequences are removed by the expansion, so this item does indeed
-start with &"^"& by the time it is being interpreted as an address pattern.
+The &`\N`& sequences are removed by the expansion, so these items do indeed
+start with &"^"& by the time they are being interpreted as address patterns.
.next
.cindex "address list" "lookup for complete address"
The @@<&'lookup'&> style of item can also be used with a query-style
lookup, but in this case, the chaining facility is not available. The lookup
can only return a single list of local parts.
-.next
-If a pattern contains an @ character, but is not a regular expression and does
-not begin with a lookup type as described above, the local part of the subject
-address is compared with the local part of the pattern, which may start with an
-asterisk. If the local parts match, the domain is checked in exactly the same
-way as for a pattern in a domain list. For example, the domain can be
-wildcarded, refer to a named list, or be a lookup:
-.code
-deny senders = *@*.spamming.site:\
- *@+hostile_domains:\
- bozo@partial-lsearch;/list/of/dodgy/sites:\
- *@dbm;/bad/domains.db
-.endd
-.cindex "local part" "starting with !"
-.cindex "address list" "local part starting with !"
-If a local part that begins with an exclamation mark is required, it has to be
-specified using a regular expression, because otherwise the exclamation mark is
-treated as a sign of negation.
-.next
-If a pattern is not one of the above syntax forms, that is, if a
-non-empty pattern that is not a regular expression or a lookup does not contain
-an @ character, it is matched against the domain part of the subject address.
-The only two formats that are recognized this way are a literal domain, or a
-domain pattern that starts with *. In both these cases, the effect is the same
-as if &`*@`& preceded the pattern.
.endlist
&*Warning*&: There is an important difference between the address list items
&`@mx_any`&, &`@mx_primary`&, and &`@mx_secondary`&) are not recognized.
Refer to section &<<SECTdomainlist>>& for details of the other available item
types.
+.ecindex IIDdohoadli
. ////////////////////////////////////////////////////////////////////////////
.chapter "String expansions" "CHAPexpand"
-.cindex "expansion" "of strings"
+.scindex IIDstrexp "expansion" "of strings"
Many strings in Exim's run time configuration are expanded before use. Some of
them are expanded every time they are used; others are expanded only once.
below in section &<<SECTexpansionitems>>& onwards. Backslash is used as an
escape character, as described in the following section.
+Whether a string is expanded depends upon the context. Usually this is solely
+dependent upon the option for which a value is sought; in this documentation,
+options for which string expansion is performed are marked with † after
+the data type. ACL rules always expand strings. A couple of expansion
+conditions do not expand some of the brace-delimited branches, for security
+reasons.
+
.section "Literal text in expanded strings" "SECTlittext"
-.section "Character escape sequences in expanded strings"
+.section "Character escape sequences in expanded strings" "SECID82"
.cindex "expansion" "escape sequences"
A backslash followed by one of the letters &"n"&, &"r"&, or &"t"& in an
expanded string is recognized as an escape sequence for the character newline,
and for other cases such as looked-up strings that are then expanded.
-.section "Testing string expansions"
+.section "Testing string expansions" "SECID83"
.cindex "expansion" "testing"
.cindex "testing" "string expansion"
-.cindex "&%-be%& option"
+.oindex "&%-be%&"
Many expansions can be tested by calling Exim with the &%-be%& option. This
takes the command arguments, or lines from the standard input if there are no
arguments, runs them through the string expansion code, and writes the results
instead runs under the uid and gid it was called with, to prevent users from
using &%-be%& for reading files to which they do not have access.
+.oindex "&%-bem%&"
+If you want to test expansions that include variables whose values are taken
+from a message, there are two other options that can be used. The &%-bem%&
+option is like &%-be%& except that it is followed by a file name. The file is
+read as a message before doing the test expansions. For example:
+.code
+exim -bem /tmp/test.message '$h_subject:'
+.endd
+The &%-Mset%& option is used in conjunction with &%-be%& and is followed by an
+Exim message identifier. For example:
+.code
+exim -be -Mset 1GrA8W-0004WS-LQ '$recipients'
+.endd
+This loads the message from Exim's spool before doing the test expansions, and
+is therefore restricted to admin users.
.section "Forced expansion failure" "SECTforexpfai"
one argument, because it reduces the number of braces and therefore makes the
string easier to understand.
-.new
+.vitem &*$bheader_*&<&'header&~name'&>&*:*&&~or&~&*$bh_*&<&'header&~name'&>&*:*&
+This item inserts &"basic"& header lines. It is described with the &%header%&
+expansion item below.
+
.vitem "&*${dlfunc{*&<&'file'&>&*}{*&<&'function'&>&*}{*&<&'arg'&>&*}&&&
{*&<&'arg'&>&*}...}*&"
-
+.cindex &%dlfunc%&
This expansion dynamically loads and then calls a locally-written C function.
This functionality is available only if Exim is compiled with
.code
When compiling a function that is to be used in this way with gcc,
you need to add &%-shared%& to the gcc command. Also, in the Exim build-time
configuration, you must add &%-export-dynamic%& to EXTRALIBS.
-.wen
.vitem "&*${extract{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&&
{*&<&'string3'&>&*}}*&"
.cindex "expansion" "extracting substrings by key"
+.cindex "&%extract%&" "substrings by key"
The key and <&'string1'&> are first expanded separately. Leading and trailing
white space is removed from the key (but not from any of the strings). The key
must not consist entirely of digits. The expanded <&'string1'&> must be of the
.display
<&'key1'&> = <&'value1'&> <&'key2'&> = <&'value2'&> ...
.endd
-.cindex "&$value$&"
+.vindex "&$value$&"
where the equals signs and spaces (but not both) are optional. If any of the
values contain white space, they must be enclosed in double quotes, and any
values that are enclosed in double quotes are subject to escape processing as
.vitem "&*${extract{*&<&'number'&>&*}{*&<&'separators'&>&*}&&&
{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&"
.cindex "expansion" "extracting substrings by number"
+.cindex "&%extract%&" "substrings by number"
The <&'number'&> argument must consist entirely of decimal digits,
apart from leading and trailing white space, which is ignored.
This is what distinguishes this form of &%extract%& from the previous kind. It
empty (for example, the fifth field above).
+.vitem &*${filter{*&<&'string'&>&*}{*&<&'condition'&>&*}}*&
+.cindex "list" "selecting by condition"
+.cindex "expansion" "selecting from list by condition"
+.vindex "&$item$&"
+After expansion, <&'string'&> is interpreted as a list, colon-separated by
+default, but the separator can be changed in the usual way. For each item
+in this list, its value is place in &$item$&, and then the condition is
+evaluated. If the condition is true, &$item$& is added to the output as an
+item in a new list; if the condition is false, the item is discarded. The
+separator used for the output list is the same as the one used for the
+input, but a separator setting is not included in the output. For example:
+.code
+${filter{a:b:c}{!eq{$item}{b}}
+.endd
+yields &`a:c`&. At the end of the expansion, the value of &$item$& is restored
+to what it was before. See also the &*map*& and &*reduce*& expansion items.
+
+
.vitem &*${hash{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&
.cindex "hash function" "textual"
.cindex "expansion" "textual hash"
.endd
.vitem "&*$header_*&<&'header&~name'&>&*:*&&~or&~&&&
- &*$h_*&<&'header&~name'&>&*:*&"
-See &*$rheader*& below.
-
-.vitem "&*$bheader_*&<&'header&~name'&>&*:*&&~or&~&&&
- &*$bh_*&<&'header&~name'&>&*:*&"
-See &*$rheader*& below.
-
-.vitem "&*$rheader_*&<&'header&~name'&>&*:*&&~or&~&&&
+ &*$h_*&<&'header&~name'&>&*:*&" &&&
+ "&*$bheader_*&<&'header&~name'&>&*:*&&~or&~&&&
+ &*$bh_*&<&'header&~name'&>&*:*&" &&&
+ "&*$rheader_*&<&'header&~name'&>&*:*&&~or&~&&&
&*$rh_*&<&'header&~name'&>&*:*&"
.cindex "expansion" "header insertion"
-.cindex "&$header_$&"
-.cindex "&$bheader_$&"
-.cindex "&$rheader_$&"
+.vindex "&$header_$&"
+.vindex "&$bheader_$&"
+.vindex "&$rheader_$&"
.cindex "header lines" "in expansion strings"
.cindex "header lines" "character sets"
.cindex "header lines" "decoding"
Only header lines that are common to all copies of a message are visible to
this mechanism. These are the original header lines that are received with the
-message, and any that are added by an ACL &%warn%& statement or by a system
+message, and any that are added by an ACL statement or by a system
filter. Header lines that are added to a particular copy of a message by a
router or transport are not accessible.
For incoming SMTP messages, no header lines are visible in ACLs that are obeyed
before the DATA ACL, because the header structure is not set up until the
-message is received. Header lines that are added by &%warn%& statements in a
-RCPT ACL (for example) are saved until the message's incoming header lines
-are available, at which point they are added. When a DATA ACL is running,
-however, header lines added by earlier ACLs are visible.
+message is received. Header lines that are added in a RCPT ACL (for example)
+are saved until the message's incoming header lines are available, at which
+point they are added. When a DATA ACL is running, however, header lines added
+by earlier ACLs are visible.
Upper case and lower case letters are synonymous in header names. If the
following character is white space, the terminating colon may be omitted, but
replaced by an empty string. (See the &%def%& condition in section
&<<SECTexpcond>>& for a means of testing for the existence of a header.)
-If there is more than one header with the same name, they are all
-concatenated to form the substitution string, up to a maximum length of 64K. A
-newline character is inserted between each line. For the &%header%& expansion,
-for those headers that contain lists of addresses, a comma is also inserted at
-the junctions between lines. This does not happen for the &%rheader%&
-expansion.
+If there is more than one header with the same name, they are all concatenated
+to form the substitution string, up to a maximum length of 64K. Unless
+&%rheader%& is being used, leading and trailing white space is removed from
+each header before concatenation, and a completely empty header is ignored. A
+newline character is then inserted between non-empty headers, but there is no
+newline at the very end. For the &%header%& and &%bheader%& expansion, for
+those headers that contain lists of addresses, a comma is also inserted at the
+junctions between headers. This does not happen for the &%rheader%& expansion.
.vitem &*${hmac{*&<&'hashname'&>&*}{*&<&'secret'&>&*}{*&<&'string'&>&*}}*&
.cindex "expansion" "hmac hashing"
+.cindex &%hmac%&
This function uses cryptographic hashing (either MD5 or SHA-1) to convert a
shared secret and some text into a message authentication code, as specified in
RFC 2104. This differs from &`${md5:secret_text...}`& or
.vitem &*${if&~*&<&'condition'&>&*&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&
.cindex "expansion" "conditional"
+.cindex "&%if%&, expansion item"
If <&'condition'&> is true, <&'string1'&> is expanded and replaces the whole
item; otherwise <&'string2'&> is used. The available conditions are described
in section &<<SECTexpcond>>& below. For example:
.vitem &*${length{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&
.cindex "expansion" "string truncation"
+.cindex "&%length%& expansion item"
The &%length%& item is used to extract the initial portion of a string. Both
strings are expanded, and the first one must yield a number, <&'n'&>, say. If
you are using a fixed value for the number, that is, if <&'string1'&> does not
.vitem "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&&
{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&"
.cindex "expansion" "lookup in"
-.cindex "file" "lookup"
+.cindex "file" "lookups"
.cindex "lookup" "in expanded string"
The two forms of lookup item specify data lookups in files and databases, as
discussed in chapter &<<CHAPfdlookup>>&. The first form is used for single-key
in double quotes. The use of data lookups in users' filter files may be locked
out by the system administrator.
-.cindex "&$value$&"
+.vindex "&$value$&"
If the lookup succeeds, <&'string1'&> is expanded and replaces the entire item.
During its expansion, the variable &$value$& contains the data returned by the
lookup. Afterwards it reverts to the value it had previously (at the outer
{$value}fail}
.endd
+
+.vitem &*${map{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&
+.cindex "expansion" "list creation"
+.vindex "&$item$&"
+After expansion, <&'string1'&> is interpreted as a list, colon-separated by
+default, but the separator can be changed in the usual way. For each item
+in this list, its value is place in &$item$&, and then <&'string2'&> is
+expanded and added to the output as an item in a new list. The separator used
+for the output list is the same as the one used for the input, but a separator
+setting is not included in the output. For example:
+.code
+${map{a:b:c}{[$item]}} ${map{<- x-y-z}{($item)}}
+.endd
+expands to &`[a]:[b]:[c] (x)-(y)-(z)`&. At the end of the expansion, the
+value of &$item$& is restored to what it was before. See also the &*filter*&
+and &*reduce*& expansion items.
+
.vitem &*${nhash{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&
.cindex "expansion" "numeric hash"
.cindex "hash function" "numeric"
out the use of this expansion item in filter files.
-.new
.vitem &*${prvs{*&<&'address'&>&*}{*&<&'secret'&>&*}{*&<&'keynumber'&>&*}}*&
-.cindex "prvs" "expansion item"
+.cindex "&%prvs%& expansion item"
The first argument is a complete email address and the second is secret
keystring. The third argument, specifying a key number, is optional. If absent,
it defaults to 0. The result of the expansion is a prvs-signed email address,
to be typically used with the &%return_path%& option on an &(smtp)& transport
as part of a bounce address tag validation (BATV) scheme. For more discussion
and an example, see section &<<SECTverifyPRVS>>&.
-.wen
-.new
.vitem "&*${prvscheck{*&<&'address'&>&*}{*&<&'secret'&>&*}&&&
{*&<&'string'&>&*}}*&"
-.cindex "prvscheck" "expansion item"
+.cindex "&%prvscheck%& expansion item"
This expansion item is the complement of the &%prvs%& item. It is used for
checking prvs-signed addresses. If the expansion of the first argument does not
yield a syntactically valid prvs-signed address, the whole item expands to the
All three variables can be used in the expansion of the third argument.
However, once the expansion is complete, only &$prvscheck_result$& remains set.
For more discussion and an example, see section &<<SECTverifyPRVS>>&.
-.wen
.vitem &*${readfile{*&<&'file&~name'&>&*}{*&<&'eol&~string'&>&*}}*&
.cindex "expansion" "inserting an entire file"
.cindex "file" "inserting into expansion"
+.cindex "&%readfile%& expansion item"
The file name and end-of-line string are first expanded separately. The file is
then read, and its contents replace the entire item. All newline characters in
the file are replaced by the end-of-line string if it is present. Otherwise,
.vitem "&*${readsocket{*&<&'name'&>&*}{*&<&'request'&>&*}&&&
{*&<&'timeout'&>&*}{*&<&'eol&~string'&>&*}{*&<&'fail&~string'&>&*}}*&"
.cindex "expansion" "inserting from a socket"
-.cindex "socket" "use of in expansion"
-This item inserts data that is read from a Unix domain socket into the expanded
-string. The minimal way of using it uses just two arguments:
+.cindex "socket, use of in expansion"
+.cindex "&%readsocket%& expansion item"
+This item inserts data from a Unix domain or Internet socket into the expanded
+string. The minimal way of using it uses just two arguments, as in these
+examples:
.code
${readsocket{/socket/name}{request string}}
+${readsocket{inet:some.host:1234}{request string}}
+.endd
+For a Unix domain socket, the first substring must be the path to the socket.
+For an Internet socket, the first substring must contain &`inet:`& followed by
+a host name or IP address, followed by a colon and a port, which can be a
+number or the name of a TCP port in &_/etc/services_&. An IP address may
+optionally be enclosed in square brackets. This is best for IPv6 addresses. For
+example:
+.code
+${readsocket{inet:[::1]:1234}{request string}}
.endd
-Exim connects to the socket, writes the request string (unless it is an
-empty string) and reads from the socket until an end-of-file is read. A timeout
-of 5 seconds is applied. Additional, optional arguments extend what can be
-done. Firstly, you can vary the timeout. For example:
+Only a single host name may be given, but if looking it up yields more than
+one IP address, they are each tried in turn until a connection is made. For
+both kinds of socket, Exim makes a connection, writes the request string
+(unless it is an empty string) and reads from the socket until an end-of-file
+is read. A timeout of 5 seconds is applied. Additional, optional arguments
+extend what can be done. Firstly, you can vary the timeout. For example:
.code
-${readsocket{/socket/name}{request-string}{3s}}
+${readsocket{/socket/name}{request string}{3s}}
.endd
A fourth argument allows you to change any newlines that are in the data
that is read, in the same way as for &%readfile%& (see above). This example
turns them into spaces:
.code
-${readsocket{/socket/name}{request-string}{3s}{ }}
+${readsocket{inet:127.0.0.1:3294}{request string}{3s}{ }}
.endd
As with all expansions, the substrings are expanded before the processing
happens. Errors in these sub-expansions cause the expansion to fail. In
.next
Failure to connect the socket;
.next
-Failure to write the request-string;
+Failure to write the request string;
.next
Timeout on reading from the socket.
.endlist
you supply a fifth substring, it is expanded and used when any of the above
errors occurs. For example:
.code
-${readsocket{/socket/name}{request-string}{3s}{\n}\
+${readsocket{/socket/name}{request string}{3s}{\n}\
{socket failure}}
.endd
-You can test for the existence of the socket by wrapping this expansion in
-&`${if exists`&, but there is a race condition between that test and the
-actual opening of the socket, so it is safer to use the fifth argument if you
-want to be absolutely sure of avoiding an expansion error for a non-existent
-socket.
+You can test for the existence of a Unix domain socket by wrapping this
+expansion in &`${if exists`&, but there is a race condition between that test
+and the actual opening of the socket, so it is safer to use the fifth argument
+if you want to be absolutely sure of avoiding an expansion error for a
+non-existent Unix domain socket, or a failure to connect to an Internet socket.
The &(redirect)& router has an option called &%forbid_filter_readsocket%& which
locks out the use of this expansion item in filter files.
-.vitem &*$rheader_*&<&'header&~name'&>&*:&~or&~$rh_*&<&'header&~name'&>&*:*&
+
+.vitem &*${reduce{*&<&'string1'&>}{<&'string2'&>&*}{*&<&'string3'&>&*}}*&
+.cindex "expansion" "reducing a list to a scalar"
+.cindex "list" "reducing to a scalar"
+.vindex "&$value$&"
+.vindex "&$item$&"
+This operation reduces a list to a single, scalar string. After expansion,
+<&'string1'&> is interpreted as a list, colon-separated by default, but the
+separator can be changed in the usual way. Then <&'string2'&> is expanded and
+assigned to the &$value$& variable. After this, each item in the <&'string1'&>
+list is assigned to &$item$& in turn, and <&'string3'&> is expanded for each of
+them. The result of that expansion is assigned to &$value$& before the next
+iteration. When the end of the list is reached, the final value of &$value$& is
+added to the expansion output. The &*reduce*& expansion item can be used in a
+number of ways. For example, to add up a list of numbers:
+.code
+${reduce {<, 1,2,3}{0}{${eval:$value+$item}}}
+.endd
+The result of that expansion would be &`6`&. The maximum of a list of numbers
+can be found:
+.code
+${reduce {3:0:9:4:6}{0}{${if >{$item}{$value}{$item}{$value}}}}
+.endd
+At the end of a &*reduce*& expansion, the values of &$item$& and &$value$& are
+restored to what they were before. See also the &*filter*& and &*map*&
+expansion items.
+
+.vitem &*$rheader_*&<&'header&~name'&>&*:*&&~or&~&*$rh_*&<&'header&~name'&>&*:*&
This item inserts &"raw"& header lines. It is described with the &%header%&
expansion item above.
.vitem "&*${run{*&<&'command'&>&*&~*&<&'args'&>&*}{*&<&'string1'&>&*}&&&
{*&<&'string2'&>&*}}*&"
.cindex "expansion" "running a command"
+.cindex "&%run%& expansion item"
The command and its arguments are first expanded separately, and then the
command is run in a separate process, but under the same uid and gid. As in
other command executions from Exim, a shell is not used by default. If you want
a shell, you must explicitly code it.
-.new
+The standard input for the command exists, but is empty. The standard output
+and standard error are set to the same file descriptor.
.cindex "return code" "from &%run%& expansion"
-.cindex "&$value$&"
+.vindex "&$value$&"
If the command succeeds (gives a zero return code) <&'string1'&> is expanded
-and replaces the entire item; during this expansion, the standard output from
-the command is in the variable &$value$&. If the command fails, <&'string2'&>,
-if present, is expanded and used. Once again, during the expansion, the
-standard output from the command is in the variable &$value$&. If <&'string2'&>
-is absent, the result is empty. Alternatively, <&'string2'&> can be the word
-&"fail"& (not in braces) to force expansion failure if the command does not
-succeed. If both strings are omitted, the result is contents of the standard
-output on success, and nothing on failure.
-.wen
-
-.cindex "&$runrc$&"
+and replaces the entire item; during this expansion, the standard output/error
+from the command is in the variable &$value$&. If the command fails,
+<&'string2'&>, if present, is expanded and used. Once again, during the
+expansion, the standard output/error from the command is in the variable
+&$value$&.
+
+If <&'string2'&> is absent, the result is empty. Alternatively, <&'string2'&>
+can be the word &"fail"& (not in braces) to force expansion failure if the
+command does not succeed. If both strings are omitted, the result is contents
+of the standard output/error on success, and nothing on failure.
+
+.vindex "&$runrc$&"
The return code from the command is put in the variable &$runrc$&, and this
remains set afterwards, so in a filter file you can do things like this:
.code
.vitem &*${sg{*&<&'subject'&>&*}{*&<&'regex'&>&*}{*&<&'replacement'&>&*}}*&
.cindex "expansion" "string substitution"
+.cindex "&%sg%& expansion item"
This item works like Perl's substitution operator (s) with the global (/g)
option; hence its name. However, unlike the Perl equivalent, Exim does not
modify the subject string; instead it returns the modified string for insertion
.vitem &*${substr{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&
-.cindex "&%substr%&"
+.cindex "&%substr%& expansion item"
.cindex "substring extraction"
.cindex "expansion" "substring extraction"
The three strings are expanded; the first two must yield numbers. Call them
.vitem "&*${tr{*&<&'subject'&>&*}{*&<&'characters'&>&*}&&&
{*&<&'replacements'&>&*}}*&"
.cindex "expansion" "character translation"
+.cindex "&%tr%& expansion item"
This item does single-character translation on its subject string. The second
argument is a list of characters to be translated in the subject string. Each
matching character is replaced by the corresponding character from the
.vlist
.vitem &*${address:*&<&'string'&>&*}*&
.cindex "expansion" "RFC 2822 address handling"
+.cindex "&%address%& expansion item"
The string is interpreted as an RFC 2822 address, as it might appear in a
header line, and the effective address is extracted from it. If the string does
not parse successfully, the result is empty.
-.new
+.vitem &*${addresses:*&<&'string'&>&*}*&
+.cindex "expansion" "RFC 2822 address handling"
+.cindex "&%addresses%& expansion item"
+The string (after expansion) is interpreted as a list of addresses in RFC
+2822 format, such as can be found in a &'To:'& or &'Cc:'& header line. The
+operative address (&'local-part@domain'&) is extracted from each item, and the
+result of the expansion is a colon-separated list, with appropriate
+doubling of colons should any happen to be present in the email addresses.
+Syntactically invalid RFC2822 address items are omitted from the output.
+
+It is possible to specify a character other than colon for the output
+separator by starting the string with > followed by the new separator
+character. For example:
+.code
+${addresses:>& Chief <ceo@up.stairs>, sec@base.ment (dogsbody)}
+.endd
+expands to &`ceo@up.stairs&&sec@base.ment`&. Compare the &*address*& (singular)
+expansion item, which extracts the working address from a single RFC2822
+address. See the &*filter*&, &*map*&, and &*reduce*& items for ways of
+processing lists.
+
+
.vitem &*${base62:*&<&'digits'&>&*}*&
-.cindex "base62"
+.cindex "&%base62%& expansion item"
.cindex "expansion" "conversion to base 62"
The string must consist entirely of decimal digits. The number is converted to
base 62 and output as a string of six characters, including leading zeros. In
its message identifiers (because those systems do not have case-sensitive file
names), base 36 is used by this operator, despite its name. &*Note*&: Just to
be absolutely clear: this is &'not'& base64 encoding.
-.wen
-.new
.vitem &*${base62d:*&<&'base-62&~digits'&>&*}*&
-.cindex "base62"
+.cindex "&%base62d%& expansion item"
.cindex "expansion" "conversion to base 62"
The string must consist entirely of base-62 digits, or, in operating
environments where Exim uses base 36 instead of base 62 for its message
identifiers, base-36 digits. The number is converted to decimal and output as a
string.
-.wen
.vitem &*${domain:*&<&'string'&>&*}*&
.cindex "domain" "extraction"
.vitem &*${escape:*&<&'string'&>&*}*&
.cindex "expansion" "escaping non-printing characters"
+.cindex "&%escape%& expansion item"
If the string contains any non-printing characters, they are converted to
escape sequences starting with a backslash. Whether characters with the most
significant bit set (so-called &"8-bit characters"&) count as printing or not
.vitem &*${eval:*&<&'string'&>&*}*&&~and&~&*${eval10:*&<&'string'&>&*}*&
.cindex "expansion" "expression evaluation"
.cindex "expansion" "arithmetic expression"
-.new
-These items supports simple arithmetic in expansion strings. The string (after
-expansion) must be a conventional arithmetic expression, but it is limited to
-five basic operators (plus, minus, times, divide, remainder) and parentheses.
-All operations are carried out using integer arithmetic. Plus and minus have a
-lower priority than times, divide, and remainder; operators with the same
-priority are evaluated from left to right.
-.wen
+.cindex "&%eval%& expansion item"
+These items supports simple arithmetic and bitwise logical operations in
+expansion strings. The string (after expansion) must be a conventional
+arithmetic expression, but it is limited to basic arithmetic operators, bitwise
+logical operators, and parentheses. All operations are carried out using
+integer arithmetic. The operator priorities are as follows (the same as in the
+C programming language):
+.table2 70pt 300pt
+.irow &'highest:'& "not (~), negate (-)"
+.irow "" "multiply (*), divide (/), remainder (%)"
+.irow "" "plus (+), minus (-)"
+.irow "" "shift-left (<<), shift-right (>>)"
+.irow "" "and (&&)"
+.irow "" "xor (^)"
+.irow &'lowest:'& "or (|)"
+.endtable
+Binary operators with the same priority are evaluated from left to right. White
+space is permitted before or after operators.
For &%eval%&, numbers may be decimal, octal (starting with &"0"&) or
hexadecimal (starting with &"0x"&). For &%eval10%&, all numbers are taken as
-decimal, even if they start with a leading zero. This can be useful when
-processing numbers extracted from dates or times, which often do have leading
-zeros.
+decimal, even if they start with a leading zero; hexadecimal numbers are not
+permitted. This can be useful when processing numbers extracted from dates or
+times, which often do have leading zeros.
-A number may be followed by &"K"& or &"M"& to multiply it by 1024 or 1024*1024,
+A number may be followed by &"K"&, &"M"& or &"G"& to multiply it by 1024, 1024*1024
+or 1024*1024*1024,
respectively. Negative numbers are supported. The result of the computation is
-a decimal representation of the answer (without &"K"& or &"M"&). For example:
+a decimal representation of the answer (without &"K"&, &"M"& or &"G"&). For example:
-.new
.display
-&`${eval:1+1} `& yields 2
-&`${eval:1+2*3} `& yields 7
-&`${eval:(1+2)*3} `& yields 9
-&`${eval:2+42%5} `& yields 4
+&`${eval:1+1} `& yields 2
+&`${eval:1+2*3} `& yields 7
+&`${eval:(1+2)*3} `& yields 9
+&`${eval:2+42%5} `& yields 4
+&`${eval:0xc&5} `& yields 4
+&`${eval:0xc|5} `& yields 13
+&`${eval:0xc^5} `& yields 9
+&`${eval:0xc>>1} `& yields 6
+&`${eval:0xc<<1} `& yields 24
+&`${eval:~255&0x1234} `& yields 4608
+&`${eval:-(~255&0x1234)} `& yields -4608
.endd
-.wen
As a more realistic example, in an ACL you might have
.code
.cindex "Unicode"
.cindex "UTF-8" "conversion from"
.cindex "expansion" "UTF-8 conversion"
+.cindex "&%from_utf8%& expansion item"
The world is slowly moving towards Unicode, although there are no standards for
email yet. However, other applications (including some databases) are starting
to store data in Unicode, using UTF-8 encoding. This operator converts from a
.vitem &*${hex2b64:*&<&'hexstring'&>&*}*&
.cindex "base64 encoding" "conversion from hex"
.cindex "expansion" "hex to base64"
+.cindex "&%hex2b64%& expansion item"
This operator converts a hex string into one that is base64 encoded. This can
be useful for processing the output of the MD5 and SHA-1 hashing functions.
.cindex "string" "case forcing"
.cindex "lower casing"
.cindex "expansion" "case forcing"
+.cindex "&%lc%& expansion item"
This forces the letters in the string into lower-case, for example:
.code
${lc:$local_part}
.vitem &*${length_*&<&'number'&>&*:*&<&'string'&>&*}*&
.cindex "expansion" "string truncation"
+.cindex "&%length%& expansion item"
The &%length%& operator is a simpler interface to the &%length%& function that
can be used when the parameter is a fixed number (as opposed to a string that
changes when expanded). The effect is the same as
.vitem &*${local_part:*&<&'string'&>&*}*&
.cindex "expansion" "local part extraction"
+.cindex "&%local_part%& expansion item"
The string is interpreted as an RFC 2822 address and the local part is
extracted from it. If the string does not parse successfully, the result is
empty.
.cindex "IP address" "masking"
.cindex "CIDR notation"
.cindex "expansion" "IP address masking"
+.cindex "&%mask%& expansion item"
If the form of the string to be operated on is not an IP address followed by a
slash and an integer (that is, a network address in CIDR notation), the
expansion fails. Otherwise, this operator converts the IP address to binary,
.vitem &*${md5:*&<&'string'&>&*}*&
.cindex "MD5 hash"
.cindex "expansion" "MD5 hash"
+.cindex "&%md5%& expansion item"
The &%md5%& operator computes the MD5 hash value of the string, and returns it
as a 32-digit hexadecimal number, in which any letters are in lower case.
.vitem &*${quote:*&<&'string'&>&*}*&
.cindex "quoting" "in string expansions"
.cindex "expansion" "quoting"
+.cindex "&%quote%& expansion item"
The &%quote%& operator puts its argument into double quotes if it
is an empty string or
contains anything other than letters, digits, underscores, dots, and hyphens.
variable or a message header.
.vitem &*${quote_local_part:*&<&'string'&>&*}*&
+.cindex "&%quote_local_part%& expansion item"
This operator is like &%quote%&, except that it quotes the string only if
required to do so by the rules of RFC 2822 for quoting local parts. For
example, a plus sign would not cause quoting (but it would for &%quote%&).
yields an unchanged string.
-.vitem &*${rxquote:*&<&'string'&>&*}*&
-.cindex "quoting" "in regular expressions"
-.cindex "regular expressions" "quoting"
-The &%rxquote%& operator inserts a backslash before any non-alphanumeric
-characters in its argument. This is useful when substituting the values of
-variables or headers inside regular expressions.
+.vitem &*${randint:*&<&'n'&>&*}*&
+.cindex "random number"
+This operator returns a somewhat random number which is less than the
+supplied number and is at least 0. The quality of this randomness depends
+on how Exim was built; the values are not suitable for keying material.
+If Exim is linked against OpenSSL then RAND_pseudo_bytes() is used.
+If Exim is linked against GnuTLS then gnutls_rnd(GNUTLS_RND_NONCE) is used,
+for versions of GnuTLS with that function.
+Otherwise, the implementation may be arc4random(), random() seeded by
+srandomdev() or srandom(), or a custom implementation even weaker than
+random().
+
+
+.vitem &*${reverse_ip:*&<&'ipaddr'&>&*}*&
+.cindex "expansion" "IP address"
+This operator reverses an IP address; for IPv4 addresses, the result is in
+dotted-quad decimal form, while for IPv6 addreses the result is in
+dotted-nibble hexadecimal form. In both cases, this is the "natural" form
+for DNS. For example,
+.code
+${reverse_ip:192.0.2.4}
+${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
+.endd
+returns
+.code
+4.2.0.192
+3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
+.endd
.vitem &*${rfc2047:*&<&'string'&>&*}*&
.cindex "expansion" "RFC 2047"
.cindex "RFC 2047" "expansion operator"
+.cindex "&%rfc2047%& expansion item"
This operator encodes text according to the rules of RFC 2047. This is an
encoding that is used in header lines to encode non-ASCII characters. It is
assumed that the input string is in the encoding specified by the
characters.
+.vitem &*${rfc2047d:*&<&'string'&>&*}*&
+.cindex "expansion" "RFC 2047"
+.cindex "RFC 2047" "decoding"
+.cindex "&%rfc2047d%& expansion item"
+This operator decodes strings that are encoded as per RFC 2047. Binary zero
+bytes are replaced by question marks. Characters are converted into the
+character set defined by &%headers_charset%&. Overlong RFC 2047 &"words"& are
+not recognized unless &%check_rfc2047_length%& is set false.
+
+&*Note*&: If you use &%$header%&_&'xxx'&&*:*& (or &%$h%&_&'xxx'&&*:*&) to
+access a header line, RFC 2047 decoding is done automatically. You do not need
+to use this operator as well.
+
+
+
+.vitem &*${rxquote:*&<&'string'&>&*}*&
+.cindex "quoting" "in regular expressions"
+.cindex "regular expressions" "quoting"
+.cindex "&%rxquote%& expansion item"
+The &%rxquote%& operator inserts a backslash before any non-alphanumeric
+characters in its argument. This is useful when substituting the values of
+variables or headers inside regular expressions.
+
.vitem &*${sha1:*&<&'string'&>&*}*&
.cindex "SHA-1 hash"
.cindex "expansion" "SHA-1 hashing"
+.cindex "&%sha2%& expansion item"
The &%sha1%& operator computes the SHA-1 hash value of the string, and returns
it as a 40-digit hexadecimal number, in which any letters are in upper case.
.vitem &*${stat:*&<&'string'&>&*}*&
.cindex "expansion" "statting a file"
.cindex "file" "extracting characteristics"
+.cindex "&%stat%& expansion item"
The string, after expansion, must be a file path. A call to the &[stat()]&
function is made for this path. If &[stat()]& fails, an error occurs and the
expansion fails. If it succeeds, the data from the stat replaces the item, as a
&"links"&, &"uid"&, &"gid"&, &"size"&, &"atime"&, &"mtime"&, and &"ctime"&. You
can extract individual fields using the &%extract%& expansion item.
-.new
The use of the &%stat%& expansion in users' filter files can be locked out by
the system administrator. &*Warning*&: The file size may be incorrect on 32-bit
systems for files larger than 2GB.
-.wen
.vitem &*${str2b64:*&<&'string'&>&*}*&
.cindex "expansion" "base64 encoding"
.cindex "base64 encoding" "in string expansion"
+.cindex "&%str2b64%& expansion item"
This operator converts a string into one that is base64 encoded.
.vitem &*${strlen:*&<&'string'&>&*}*&
.cindex "expansion" "string length"
.cindex "string" "length in expansion"
+.cindex "&%strlen%& expansion item"
The item is replace by the length of the expanded string, expressed as a
decimal number. &*Note*&: Do not confuse &%strlen%& with &%length%&.
.vitem &*${substr_*&<&'start'&>&*_*&<&'length'&>&*:*&<&'string'&>&*}*&
-.cindex "&%substr%&"
+.cindex "&%substr%& expansion item"
.cindex "substring extraction"
.cindex "expansion" "substring expansion"
The &%substr%& operator is a simpler interface to the &%substr%& function that
See the description of the general &%substr%& item above for details. The
abbreviation &%s%& can be used when &%substr%& is used as an operator.
+.vitem &*${time_eval:*&<&'string'&>&*}*&
+.cindex "&%time_eval%& expansion item"
+.cindex "time interval" "decoding"
+This item converts an Exim time interval such as &`2d4h5m`& into a number of
+seconds.
+
.vitem &*${time_interval:*&<&'string'&>&*}*&
-.cindex "&%time_interval%&"
+.cindex "&%time_interval%& expansion item"
.cindex "time interval" "formatting"
The argument (after sub-expansion) must be a sequence of decimal digits that
represents an interval of time as a number of seconds. It is converted into a
.cindex "string" "case forcing"
.cindex "upper casing"
.cindex "expansion" "case forcing"
+.cindex "&%uc%& expansion item"
This forces the letters in the string into upper-case.
.endlist
.section "Expansion conditions" "SECTexpcond"
-.cindex "expansion" "conditions"
+.scindex IIDexpcond "expansion" "conditions"
The following conditions are available for testing by the &%${if%& construct
while expanding strings:
.vlist
.vitem &*!*&<&'condition'&>
.cindex "expansion" "negating a condition"
+.cindex "negation" "in expansion condition"
Preceding any condition with an exclamation mark negates the result of the
condition.
two strings must take the form of optionally signed decimal integers,
optionally followed by one of the letters &"K"& or &"M"& (in either upper or
lower case), signifying multiplication by 1024 or 1024*1024, respectively.
+As a special case, the numerical value of an empty string is taken as
+zero.
+
+In all cases, a relative comparator OP is testing if <&'string1'&> OP
+<&'string2'&>; the above example is checking if &$message_size$& is larger than
+10M, not if 10M is larger than &$message_size$&.
+
+
+.vitem &*bool&~{*&<&'string'&>&*}*&
+.cindex "expansion" "boolean parsing"
+.cindex "&%bool%& expansion condition"
+This condition turns a string holding a true or false representation into
+a boolean state. It parses &"true"&, &"false"&, &"yes"& and &"no"&
+(case-insensitively); also positive integer numbers map to true if non-zero,
+false if zero.
+An empty string is treated as false.
+Leading and trailing whitespace is ignored;
+thus a string consisting only of whitespace is false.
+All other string values will result in expansion failure.
+
+When combined with ACL variables, this expansion condition will let you
+make decisions in one place and act on those decisions in another place.
+For example:
+.code
+${if bool{$acl_m_privileged_sender} ...
+.endd
+
+
+.vitem &*bool_lax&~{*&<&'string'&>&*}*&
+.cindex "expansion" "boolean parsing"
+.cindex "&%bool_lax%& expansion condition"
+Like &%bool%&, this condition turns a string into a boolean state. But
+where &%bool%& accepts a strict set of strings, &%bool_lax%& uses the same
+loose definition that the Router &%condition%& option uses. The empty string
+and the values &"false"&, &"no"& and &"0"& map to false, all others map to
+true. Leading and trailing whitespace is ignored.
+
+Note that where &"bool{00}"& is false, &"bool_lax{00}"& is true.
.vitem &*crypteq&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "expansion" "encrypted comparison"
-.cindex "encrypted strings" "comparing"
+.cindex "encrypted strings, comparing"
+.cindex "&%crypteq%& expansion condition"
This condition is included in the Exim binary if it is built to support any
authentication mechanisms (see chapter &<<CHAPSMTPAUTH>>&). Otherwise, it is
necessary to define SUPPORT_CRYPTEQ in &_Local/Makefile_& to get &%crypteq%&
only the first eight characters of the password. However, in modern operating
systems this is no longer true, and in many cases the entire password is used,
whatever its length.
+
.next
.cindex "&[crypt16()]&"
-&%{crypt16}%& calls the &[crypt16()]& function (also known as &[bigcrypt()]&),
-which was orginally created to use up to 16 characters of the password. Again,
-in modern operating systems, more characters may be used.
+&%{crypt16}%& calls the &[crypt16()]& function, which was originally created to
+use up to 16 characters of the password in some operating systems. Again, in
+modern operating systems, more characters may be used.
.endlist
-
-Exim has its own version of &[crypt16()]& (which is just a double call to
-&[crypt()]&). For operating systems that have their own version, setting
+Exim has its own version of &[crypt16()]&, which is just a double call to
+&[crypt()]&. For operating systems that have their own version, setting
HAVE_CRYPT16 in &_Local/Makefile_& when building Exim causes it to use the
operating system version instead of its own. This option is set by default in
the OS-dependent &_Makefile_& for those operating systems that are known to
support &[crypt16()]&.
-If you do not put any curly bracket encryption type in a &%crypteq%&
-comparison, the default is either &`{crypt}`& or &`{crypt16}`&, as determined
-by the setting of DEFAULT_CRYPT in &_Local/Makefile_&. The default default is
-&`{crypt}`&. Whatever the default, you can always use either function by
-specifying it explicitly in curly brackets.
+Some years after Exim's &[crypt16()]& was implemented, a user discovered that
+it was not using the same algorithm as some operating systems' versions. It
+turns out that as well as &[crypt16()]& there is a function called
+&[bigcrypt()]& in some operating systems. This may or may not use the same
+algorithm, and both of them may be different to Exim's built-in &[crypt16()]&.
+
+However, since there is now a move away from the traditional &[crypt()]&
+functions towards using SHA1 and other algorithms, tidying up this area of
+Exim is seen as very low priority.
-Note that if a password is no longer than 8 characters, the results of
-encrypting it with &[crypt()]& and &[crypt16()]& are identical. That means that
-&[crypt16()]& is backwards compatible, as long as nobody feeds it a password
-longer than 8 characters.
+If you do not put a encryption type (in curly brackets) in a &%crypteq%&
+comparison, the default is usually either &`{crypt}`& or &`{crypt16}`&, as
+determined by the setting of DEFAULT_CRYPT in &_Local/Makefile_&. The default
+default is &`{crypt}`&. Whatever the default, you can always use either
+function by specifying it explicitly in curly brackets.
.vitem &*def:*&<&'variable&~name'&>
.cindex "expansion" "checking for empty variable"
+.cindex "&%def%& expansion condition"
The &%def%& condition must be followed by the name of one of the expansion
variables defined in section &<<SECTexpvar>>&. The condition is true if the
variable does not contain the empty string. For example:
&*Note*&: No &%$%& appears before &%header_%& or &%h_%& in the condition, and
the header name must be terminated by a colon if white space does not follow.
-.vitem &*eq&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
-.cindex "string" "comparison"
-.cindex "expansion" "string comparison"
-The two substrings are first expanded. The condition is true if the two
-resulting strings are identical, including the case of letters.
-
-.vitem &*eqi&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.vitem &*eq&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
+ &*eqi&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "string" "comparison"
.cindex "expansion" "string comparison"
+.cindex "&%eq%& expansion condition"
+.cindex "&%eqi%& expansion condition"
The two substrings are first expanded. The condition is true if the two
-resulting strings are identical when compared in a case-independent way.
+resulting strings are identical. For &%eq%& the comparison includes the case of
+letters, whereas for &%eqi%& the comparison is case-independent.
.vitem &*exists&~{*&<&'file&~name'&>&*}*&
.cindex "expansion" "file existence test"
.cindex "file" "existence test"
+.cindex "&%exists%&, expansion condition"
The substring is first expanded and then interpreted as an absolute path. The
condition is true if the named file (or directory) exists. The existence test
is done by calling the &[stat()]& function. The use of the &%exists%& test in
.cindex "delivery" "first"
.cindex "first delivery"
.cindex "expansion" "first delivery test"
+.cindex "&%first_delivery%& expansion condition"
This condition, which has no data, is true during a message's first delivery
attempt. It is false during any subsequent delivery attempts.
-.vitem &*ge&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
-See &*gei*&.
-.vitem &*gei&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.vitem "&*forall{*&<&'a list'&>&*}{*&<&'a condition'&>&*}*&" &&&
+ "&*forany{*&<&'a list'&>&*}{*&<&'a condition'&>&*}*&"
+.cindex "list" "iterative conditions"
+.cindex "expansion" "&*forall*& condition"
+.cindex "expansion" "&*forany*& condition"
+.vindex "&$item$&"
+These conditions iterate over a list. The first argument is expanded to form
+the list. By default, the list separator is a colon, but it can be changed by
+the normal method. The second argument is interpreted as a condition that is to
+be applied to each item in the list in turn. During the interpretation of the
+condition, the current list item is placed in a variable called &$item$&.
+.ilist
+For &*forany*&, interpretation stops if the condition is true for any item, and
+the result of the whole condition is true. If the condition is false for all
+items in the list, the overall condition is false.
+.next
+For &*forall*&, interpretation stops if the condition is false for any item,
+and the result of the whole condition is false. If the condition is true for
+all items in the list, the overall condition is true.
+.endlist
+Note that negation of &*forany*& means that the condition must be false for all
+items for the overall condition to succeed, and negation of &*forall*& means
+that the condition must be false for at least one item. In this example, the
+list separator is changed to a comma:
+.code
+${if forany{<, $recipients}{match{$item}{^user3@}}{yes}{no}}
+.endd
+The value of &$item$& is saved and restored while &*forany*& or &*forall*& is
+being processed, to enable these expansion items to be nested.
+
+
+.vitem &*ge&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
+ &*gei&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "string" "comparison"
.cindex "expansion" "string comparison"
+.cindex "&%ge%& expansion condition"
+.cindex "&%gei%& expansion condition"
The two substrings are first expanded. The condition is true if the first
-string is lexically greater than or equal to the second string: for &%ge%& the
+string is lexically greater than or equal to the second string. For &%ge%& the
comparison includes the case of letters, whereas for &%gei%& the comparison is
case-independent.
-.vitem &*gt&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
-See &*gti*&.
-
-.vitem &*gti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.vitem &*gt&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
+ &*gti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "string" "comparison"
.cindex "expansion" "string comparison"
+.cindex "&%gt%& expansion condition"
+.cindex "&%gti%& expansion condition"
The two substrings are first expanded. The condition is true if the first
-string is lexically greater than the second string: for &%gt%& the comparison
+string is lexically greater than the second string. For &%gt%& the comparison
includes the case of letters, whereas for &%gti%& the comparison is
case-independent.
-.vitem &*isip&~{*&<&'string'&>&*}*&
-See &*isip6*&.
+.vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
+ &*inlisti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.cindex "string" "comparison"
+.cindex "list" "iterative conditions"
+Both strings are expanded; the second string is treated as a list of simple
+strings; if the first string is a member of the second, then the condition
+is true.
-.vitem &*isip4&~{*&<&'string'&>&*}*&
-See &*isip6*&.
+These are simpler to use versions of the more powerful &*forany*& condition.
+Examples, and the &*forany*& equivalents:
+.code
+${if inlist{needle}{foo:needle:bar}}
+ ${if forany{foo:needle:bar}{eq{$item}{needle}}}
+${if inlisti{Needle}{fOo:NeeDLE:bAr}}
+ ${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}}
+.endd
-.vitem &*isip6&~{*&<&'string'&>&*}*&
+.vitem &*isip&~{*&<&'string'&>&*}*& &&&
+ &*isip4&~{*&<&'string'&>&*}*& &&&
+ &*isip6&~{*&<&'string'&>&*}*&
.cindex "IP address" "testing string format"
.cindex "string" "testing for IP address"
+.cindex "&%isip%& expansion condition"
+.cindex "&%isip4%& expansion condition"
+.cindex "&%isip6%& expansion condition"
The substring is first expanded, and then tested to see if it has the form of
an IP address. Both IPv4 and IPv6 addresses are valid for &%isip%&, whereas
-&%isip4%& and &%isip6%& test just for IPv4 or IPv6 addresses, respectively. For
-example, you could use
+&%isip4%& and &%isip6%& test specifically for IPv4 or IPv6 addresses.
+
+For an IPv4 address, the test is for four dot-separated components, each of
+which consists of from one to three digits. For an IPv6 address, up to eight
+colon-separated components are permitted, each containing from one to four
+hexadecimal digits. There may be fewer than eight components if an empty
+component (adjacent colons) is present. Only one empty component is permitted.
+
+&*Note*&: The checks are just on the form of the address; actual numerical
+values are not considered. Thus, for example, 999.999.999.999 passes the IPv4
+check. The main use of these tests is to distinguish between IP addresses and
+host names, or between IPv4 and IPv6 addresses. For example, you could use
.code
${if isip4{$sender_host_address}...
.endd
-to test which version of IP an incoming SMTP connection is using.
-
+to test which IP version an incoming SMTP connection is using.
.vitem &*ldapauth&~{*&<&'ldap&~query'&>&*}*&
.cindex "LDAP" "use for authentication"
.cindex "expansion" "LDAP authentication test"
+.cindex "&%ldapauth%& expansion condition"
This condition supports user authentication using LDAP. See section
&<<SECTldap>>& for details of how to use LDAP in lookups and the syntax of
queries. For this use, the query must contain a user name and password. The
this can be used.
-.vitem &*le&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
-See &*lei*&.
-
-.vitem &*lei&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.vitem &*le&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
+ &*lei&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "string" "comparison"
.cindex "expansion" "string comparison"
+.cindex "&%le%& expansion condition"
+.cindex "&%lei%& expansion condition"
The two substrings are first expanded. The condition is true if the first
-string is lexically less than or equal to the second string: for &%le%& the
+string is lexically less than or equal to the second string. For &%le%& the
comparison includes the case of letters, whereas for &%lei%& the comparison is
case-independent.
-.vitem &*lt&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
-See &*lti*&.
-
-.vitem &*lti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.vitem &*lt&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
+ &*lti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "string" "comparison"
.cindex "expansion" "string comparison"
+.cindex "&%lt%& expansion condition"
+.cindex "&%lti%& expansion condition"
The two substrings are first expanded. The condition is true if the first
-string is lexically less than the second string: for &%lt%& the comparison
+string is lexically less than the second string. For &%lt%& the comparison
includes the case of letters, whereas for &%lti%& the comparison is
case-independent.
.vitem &*match&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "expansion" "regular expression comparison"
.cindex "regular expressions" "match in expanded string"
+.cindex "&%match%& expansion condition"
The two substrings are first expanded. The second is then treated as a regular
expression and applied to the first. Because of the pre-expansion, if the
regular expression contains dollar, or backslash characters, they must be
variables are those of the condition that succeeded.
.vitem &*match_address&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.cindex "&%match_address%& expansion condition"
See &*match_local_part*&.
.vitem &*match_domain&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.cindex "&%match_domain%& expansion condition"
See &*match_local_part*&.
-.new
.vitem &*match_ip&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.cindex "&%match_ip%& expansion condition"
This condition matches an IP address to a list of IP address patterns. It must
be followed by two argument strings. The first (after expansion) must be an IP
-address or an empty string. The second (after expansion) is a restricted host
+address or an empty string. The second (not expanded) is a restricted host
list that can match only an IP address, not a host name. For example:
.code
${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}}
useful for testing for a locally submitted message or one from specific hosts
in a single test such as
. ==== As this is a nested list, any displays it contains must be indented
-. ==== as otherwise they are too far to the left.
+. ==== as otherwise they are too far to the left. This comment applies to
+. ==== the use of xmlto plus fop. There's no problem when formatting with
+. ==== sdop, with or without the extra indent.
.code
${if match_ip{$sender_host_address}{:4.3.2.1:...}{...}{...}}
.endd
.next
The item @[] matches any of the local host's interface addresses.
.next
-Lookups are assumed to be &"net-"& style lookups, even if &`net-`& is not
-specified. Thus, the following are equivalent:
+Single-key lookups are assumed to be like &"net-"& style lookups in host lists,
+even if &`net-`& is not specified. There is never any attempt to turn the IP
+address into a host name. The most common type of linear search for
+&*match_ip*& is likely to be &*iplsearch*&, in which the file can contain CIDR
+masks. For example:
+.code
+ ${if match_ip{$sender_host_address}{iplsearch;/some/file}...
+.endd
+It is of course possible to use other kinds of lookup, and in such a case, you
+do need to specify the &`net-`& prefix if you want to specify a specific
+address mask, for example:
+.code
+ ${if match_ip{$sender_host_address}{net24-dbm;/some/file}...
+.endd
+However, unless you are combining a &%match_ip%& condition with others, it is
+just as easy to use the fact that a lookup is itself a condition, and write:
.code
- ${if match_ip{$sender_host_address}{lsearch;/some/file}...
- ${if match_ip{$sender_host_address}{net-lsearch;/some/file}...
+ ${lookup{${mask:$sender_host_address/24}}dbm{/a/file}...
.endd
-You do need to specify the &`net-`& prefix if you want to specify a
-specific address mask, for example, by using &`net24-`&.
.endlist ilist
+Note that <&'string2'&> is not itself subject to string expansion, unless
+Exim was built with the EXPAND_LISTMATCH_RHS option.
+
Consult section &<<SECThoslispatip>>& for further details of these patterns.
-.wen
.vitem &*match_local_part&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "domain list" "in expansion condition"
.cindex "address list" "in expansion condition"
-.cindex "local part list" "in expansion condition"
+.cindex "local part" "list, in expansion condition"
+.cindex "&%match_local_part%& expansion condition"
This condition, together with &%match_address%& and &%match_domain%&, make it
possible to test domain, address, and local part lists within expansions. Each
condition requires two arguments: an item and a list to match. A trivial
have their local parts matched casefully. Domains are always matched
caselessly.
+Note that <&'string2'&> is not itself subject to string expansion, unless
+Exim was built with the EXPAND_LISTMATCH_RHS option.
+
&*Note*&: Host lists are &'not'& supported in this way. This is because
hosts have two identities: a name and an IP address, and it is not clear
how to specify cleanly how such a test would work. However, IP addresses can be
.cindex "AUTH" "with PAM"
.cindex "Solaris" "PAM support"
.cindex "expansion" "PAM authentication test"
+.cindex "&%pam%& expansion condition"
&'Pluggable Authentication Modules'&
(&url(http://www.kernel.org/pub/linux/libs/pam/)) are a facility that is
available in the latest releases of Solaris and in some GNU/Linux
item can be used to double any existing colons. For example, the configuration
of a LOGIN authenticator might contain this setting:
.code
-server_condition = ${if pam{$1:${sg{$2}{:}{::}}}{yes}{no}}
+server_condition = ${if pam{$auth1:${sg{$auth2}{:}{::}}}}
.endd
For a PLAIN authenticator you could use:
.code
-server_condition = ${if pam{$2:${sg{$3}{:}{::}}}{yes}{no}}
+server_condition = ${if pam{$auth2:${sg{$auth3}{:}{::}}}}
.endd
In some operating systems, PAM authentication can be done only from a process
running as root. Since Exim is running as the Exim user when receiving
.cindex "&'pwcheck'& daemon"
.cindex "Cyrus"
.cindex "expansion" "&'pwcheck'& authentication test"
+.cindex "&%pwcheck%& expansion condition"
This condition supports user authentication using the Cyrus &'pwcheck'& daemon.
This is one way of making it possible for passwords to be checked by a process
that is not running as root. &*Note*&: The use of &'pwcheck'& is now
password, separated by a colon. For example, in a LOGIN authenticator
configuration, you might have this:
.code
-server_condition = ${if pwcheck{$1:$2}{1}{0}}
+server_condition = ${if pwcheck{$auth1:$auth2}}
+.endd
+Again, for a PLAIN authenticator configuration, this would be:
+.code
+server_condition = ${if pwcheck{$auth2:$auth3}}
.endd
.vitem &*queue_running*&
.cindex "queue runner" "detecting when delivering from"
.cindex "expansion" "queue runner test"
+.cindex "&%queue_running%& expansion condition"
This condition, which has no data, is true during delivery attempts that are
initiated by queue runner processes, and false otherwise.
.vitem &*radius&~{*&<&'authentication&~string'&>&*}*&
.cindex "Radius"
.cindex "expansion" "Radius authentication"
+.cindex "&%radius%& expansion condition"
Radius authentication (RFC 2865) is supported in a similar way to PAM. You must
set RADIUS_CONFIG_FILE in &_Local/Makefile_& to specify the location of
the Radius client configuration file in order to build Exim with Radius
support.
-.new
With just that one setting, Exim expects to be linked with the &%radiusclient%&
library, using the original API. If you are using release 0.4.0 or later of
this library, you need to set
.endd
in &_Local/Makefile_& when building Exim. You can also link Exim with the
&%libradius%& library that comes with FreeBSD. To do this, set
-.wen
.code
RADIUS_LIB_TYPE=RADLIB
.endd
Radius client library, which calls the Radius server. The condition is true if
the authentication is successful. For example:
.code
-server_condition = ${if radius{<arguments>}{yes}{no}}
+server_condition = ${if radius{<arguments>}}
.endd
.cindex "&'saslauthd'& daemon"
.cindex "Cyrus"
.cindex "expansion" "&'saslauthd'& authentication test"
+.cindex "&%saslauthd%& expansion condition"
This condition supports user authentication using the Cyrus &'saslauthd'&
daemon. This replaces the older &'pwcheck'& daemon, which is now deprecated.
Using this daemon is one way of making it possible for passwords to be checked
Up to four arguments can be supplied to the &%saslauthd%& condition, but only
two are mandatory. For example:
.code
-server_condition = ${if saslauthd{{$1}{$2}}{1}{0}}
+server_condition = ${if saslauthd{{$auth1}{$auth2}}}
.endd
The service and the realm are optional (which is why the arguments are enclosed
in their own set of braces). For details of the meaning of the service and
-.section "Combining expansion conditions"
+.section "Combining expansion conditions" "SECID84"
.cindex "expansion" "combining conditions"
Several conditions can be tested at once by combining them using the &%and%&
and &%or%& combination conditions. Note that &%and%& and &%or%& are complete
the last one. When a false sub-condition is found, the following ones are
parsed but not evaluated.
.endlist
+.ecindex IIDexpcond
.section "Expansion variables" "SECTexpvar"
-.cindex "expansion variables" "list of"
+.cindex "expansion" "variables, list of"
This section contains an alphabetical list of all the expansion variables. Some
of them are available only when Exim is compiled with specific options such as
support for TLS or the content scanning extension.
.cindex "numerical variables (&$1$& &$2$& etc)"
When a &%match%& expansion condition succeeds, these variables contain the
captured substrings identified by the regular expression during subsequent
-processing of the success string of the containing &%if%& expansion item. They
-may also be set externally by some other matching process which precedes the
-expansion of the string. For example, the commands available in Exim filter
-files include an &%if%& command with its own regular expression matching
-condition.
-
-.vitem "&$acl_c0$& &-- &$acl_c9$&"
-Values can be placed in these variables by the &%set%& modifier in an ACL. The
-values persist throughout the lifetime of an SMTP connection. They can be used
-to pass information between ACLs and different invocations of the same ACL.
-When a message is received, the values of these variables are saved with the
-message, and can be accessed by filters, routers, and transports during
-subsequent delivery.
-
-.vitem "&$acl_m0$& &-- &$acl_m9$&"
+processing of the success string of the containing &%if%& expansion item.
+However, they do not retain their values afterwards; in fact, their previous
+values are restored at the end of processing an &%if%& item. The numerical
+variables may also be set externally by some other matching process which
+precedes the expansion of the string. For example, the commands available in
+Exim filter files include an &%if%& command with its own regular expression
+matching condition.
+
+.vitem "&$acl_c...$&"
Values can be placed in these variables by the &%set%& modifier in an ACL. They
-retain their values while a message is being received, but are reset
-afterwards. They are also reset by MAIL, RSET, EHLO, HELO, and after starting a
-TLS session. When a message is received, the values of these variables are
-saved with the message, and can be accessed by filters, routers, and transports
+can be given any name that starts with &$acl_c$& and is at least six characters
+long, but the sixth character must be either a digit or an underscore. For
+example: &$acl_c5$&, &$acl_c_mycount$&. The values of the &$acl_c...$&
+variables persist throughout the lifetime of an SMTP connection. They can be
+used to pass information between ACLs and between different invocations of the
+same ACL. When a message is received, the values of these variables are saved
+with the message, and can be accessed by filters, routers, and transports
during subsequent delivery.
-.new
+.vitem "&$acl_m...$&"
+These variables are like the &$acl_c...$& variables, except that their values
+are reset after a message has been received. Thus, if several messages are
+received in one SMTP connection, &$acl_m...$& values are not passed on from one
+message to the next, as &$acl_c...$& values are. The &$acl_m...$& variables are
+also reset by MAIL, RSET, EHLO, HELO, and after starting a TLS session. When a
+message is received, the values of these variables are saved with the message,
+and can be accessed by filters, routers, and transports during subsequent
+delivery.
+
.vitem &$acl_verify_message$&
-.cindex "&$acl_verify_message$&"
+.vindex "&$acl_verify_message$&"
After an address verification has failed, this variable contains the failure
message. It retains its value for use in subsequent modifiers. The message can
be preserved by coding like this:
You can use &$acl_verify_message$& during the expansion of the &%message%& or
&%log_message%& modifiers, to include information about the verification
failure.
-.wen
.vitem &$address_data$&
-.cindex "&$address_data$&"
+.vindex "&$address_data$&"
This variable is set by means of the &%address_data%& option in routers. The
value then remains with the address while it is processed by subsequent routers
and eventually a transport. If the transport is handling multiple addresses,
these values for longer, you can save them in ACL variables.
.vitem &$address_file$&
-.cindex "&$address_file$&"
+.vindex "&$address_file$&"
When, as a result of aliasing, forwarding, or filtering, a message is directed
to a specific file, this variable holds the name of the file when the transport
is running. At other times, the variable is empty. For example, using the
/home/r2d2/savemail
.endd
then when the &(address_file)& transport is running, &$address_file$&
-contains &"/home/r2d2/savemail"&.
-
+contains the text string &`/home/r2d2/savemail`&.
.cindex "Sieve filter" "value of &$address_file$&"
For Sieve filters, the value may be &"inbox"& or a relative folder name. It is
then up to the transport configuration to generate an appropriate absolute path
to the relevant file.
.vitem &$address_pipe$&
-.cindex "&$address_pipe$&"
+.vindex "&$address_pipe$&"
When, as a result of aliasing or forwarding, a message is directed to a pipe,
this variable holds the pipe command when the transport is running.
+.vitem "&$auth1$& &-- &$auth3$&"
+.vindex "&$auth1$&, &$auth2$&, etc"
+These variables are used in SMTP authenticators (see chapters
+&<<CHAPplaintext>>&&--&<<CHAPspa>>&). Elsewhere, they are empty.
+
.vitem &$authenticated_id$&
.cindex "authentication" "id"
-.cindex "&$authenticated_id$&"
+.vindex "&$authenticated_id$&"
When a server successfully authenticates a client it may be configured to
preserve some of the authentication information in the variable
&$authenticated_id$& (see chapter &<<CHAPSMTPAUTH>>&). For example, a
user/password authenticator configuration might preserve the user name for use
in the routers. Note that this is not the same information that is saved in
-&$sender_host_authenticated$&. When a message is submitted locally (that is,
-not over a TCP connection), the value of &$authenticated_id$& is the login name
-of the calling process.
+&$sender_host_authenticated$&.
+When a message is submitted locally (that is, not over a TCP connection)
+the value of &$authenticated_id$& is normally the login name of the calling
+process. However, a trusted user can override this by means of the &%-oMai%&
+command line option.
+
+
+
.vitem &$authenticated_sender$&
.cindex "sender" "authenticated"
.cindex "authentication" "sender"
.cindex "AUTH" "on MAIL command"
-.cindex "&$authenticated_sender$&"
+.vindex "&$authenticated_sender$&"
When acting as a server, Exim takes note of the AUTH= parameter on an incoming
SMTP MAIL command if it believes the sender is sufficiently trusted, as
described in section &<<SECTauthparamail>>&. Unless the data is the string
available during delivery in the &$authenticated_sender$& variable. If the
sender is not trusted, Exim accepts the syntax of AUTH=, but ignores the data.
-.cindex "&$qualify_domain$&"
+.vindex "&$qualify_domain$&"
When a message is submitted locally (that is, not over a TCP connection), the
value of &$authenticated_sender$& is an address constructed from the login
-name of the calling process and &$qualify_domain$&.
+name of the calling process and &$qualify_domain$&, except that a trusted user
+can override this by means of the &%-oMas%& command line option.
.vitem &$authentication_failed$&
.cindex "authentication" "failure"
-.cindex "&$authentication_failed$&"
+.vindex "&$authentication_failed$&"
This variable is set to &"1"& in an Exim server if a client issues an AUTH
command that does not succeed. Otherwise it is set to &"0"&. This makes it
possible to distinguish between &"did not try to authenticate"&
negative response to an AUTH command, including (for example) an attempt to use
an undefined mechanism.
+.vitem &$av_failed$&
+.cindex "content scanning" "AV scanner failure"
+This variable is available when Exim is compiled with the content-scanning
+extension. It is set to &"0"& by default, but will be set to &"1"& if any
+problem occurs with the virus scanner (specified by &%av_scanner%&) during
+the ACL malware condition.
+
.vitem &$body_linecount$&
.cindex "message body" "line count"
.cindex "body of message" "line count"
-.cindex "&$body_linecount$&"
+.vindex "&$body_linecount$&"
When a message is being received or delivered, this variable contains the
number of lines in the message's body. See also &$message_linecount$&.
.cindex "message body" "binary zero count"
.cindex "body of message" "binary zero count"
.cindex "binary zero" "in message body"
-.cindex "&$body_zerocount$&"
+.vindex "&$body_zerocount$&"
When a message is being received or delivered, this variable contains the
-number of binary zero bytes in the message's body.
+number of binary zero bytes (ASCII NULs) in the message's body.
.vitem &$bounce_recipient$&
-.cindex "&$bounce_recipient$&"
+.vindex "&$bounce_recipient$&"
This is set to the recipient address of a bounce message while Exim is creating
it. It is useful if a customized bounce message text file is in use (see
chapter &<<CHAPemsgcust>>&).
.vitem &$bounce_return_size_limit$&
-.cindex "&$bounce_return_size_limit$&"
+.vindex "&$bounce_return_size_limit$&"
This contains the value set in the &%bounce_return_size_limit%& option, rounded
up to a multiple of 1000. It is useful when a customized error message text
file is in use (see chapter &<<CHAPemsgcust>>&).
.vitem &$caller_gid$&
.cindex "gid (group id)" "caller"
-.cindex "&$caller_gid$&"
+.vindex "&$caller_gid$&"
The real group id under which the process that called Exim was running. This is
not the same as the group id of the originator of a message (see
&$originator_gid$&). If Exim re-execs itself, this variable in the new
.vitem &$caller_uid$&
.cindex "uid (user id)" "caller"
-.cindex "&$caller_uid$&"
+.vindex "&$caller_uid$&"
The real user id under which the process that called Exim was running. This is
not the same as the user id of the originator of a message (see
&$originator_uid$&). If Exim re-execs itself, this variable in the new
incarnation normally contains the Exim uid.
.vitem &$compile_date$&
-.cindex "&$compile_date$&"
+.vindex "&$compile_date$&"
The date on which the Exim binary was compiled.
.vitem &$compile_number$&
-.cindex "&$compile_number$&"
+.vindex "&$compile_number$&"
The building process for Exim keeps a count of the number
of times it has been compiled. This serves to distinguish different
compilations of the same version of the program.
.vitem &$demime_errorlevel$&
-.cindex "&$demime_errorlevel$&"
+.vindex "&$demime_errorlevel$&"
This variable is available when Exim is compiled with
the content-scanning extension and the obsolete &%demime%& condition. For
details, see section &<<SECTdemimecond>>&.
.vitem &$demime_reason$&
-.cindex "&$demime_reason$&"
+.vindex "&$demime_reason$&"
This variable is available when Exim is compiled with the
content-scanning extension and the obsolete &%demime%& condition. For details,
see section &<<SECTdemimecond>>&.
-
-.vitem &$dnslist_domain$&
+.vitem &$dnslist_domain$& &&&
+ &$dnslist_matched$& &&&
+ &$dnslist_text$& &&&
+ &$dnslist_value$&
+.vindex "&$dnslist_domain$&"
+.vindex "&$dnslist_matched$&"
+.vindex "&$dnslist_text$&"
+.vindex "&$dnslist_value$&"
.cindex "black list (DNS)"
-.cindex "&$dnslist_domain$&"
-When a client host is found to be on a DNS (black) list,
-the list's domain name is put into this variable so that it can be included in
-the rejection message.
-
-.vitem &$dnslist_text$&
-.cindex "&$dnslist_text$&"
-When a client host is found to be on a DNS (black) list, the
-contents of any associated TXT record are placed in this variable.
-
-.vitem &$dnslist_value$&
-.cindex "&$dnslist_value$&"
-When a client host is found to be on a DNS (black) list,
-the IP address from the resource record is placed in this variable.
-If there are multiple records, all the addresses are included, comma-space
-separated.
+When a DNS (black) list lookup succeeds, these variables are set to contain
+the following data from the lookup: the list's domain name, the key that was
+looked up, the contents of any associated TXT record, and the value from the
+main A record. See section &<<SECID204>>& for more details.
.vitem &$domain$&
-.cindex "&$domain$&"
+.vindex "&$domain$&"
When an address is being routed, or delivered on its own, this variable
-contains the domain. Global address rewriting happens when a message is
-received, so the value of &$domain$& during routing and delivery is the value
-after rewriting. &$domain$& is set during user filtering, but not during system
-filtering, because a message may have many recipients and the system filter is
-called just once.
+contains the domain. Uppercase letters in the domain are converted into lower
+case for &$domain$&.
+
+Global address rewriting happens when a message is received, so the value of
+&$domain$& during routing and delivery is the value after rewriting. &$domain$&
+is set during user filtering, but not during system filtering, because a
+message may have many recipients and the system filter is called just once.
When more than one address is being delivered at once (for example, several
RCPT commands in one SMTP delivery), &$domain$& is set only if they all
the default for local transports. For further details of the environment in
which local transports are run, see chapter &<<CHAPenvironment>>&.
-.cindex "&%delay_warning_condition%&"
+.oindex "&%delay_warning_condition%&"
At the end of a delivery, if all deferred addresses have the same domain, it is
set in &$domain$& during the expansion of &%delay_warning_condition%&.
.next
.cindex "ETRN" "value of &$domain$&"
-.cindex "&%smtp_etrn_command%&"
+.oindex "&%smtp_etrn_command%&"
When the &%smtp_etrn_command%& option is being expanded, &$domain$& contains
the complete argument of the ETRN command (see section &<<SECTETRN>>&).
.endlist
.vitem &$domain_data$&
-.cindex "&$domain_data$&"
+.vindex "&$domain_data$&"
When the &%domains%& option on a router matches a domain by
means of a lookup, the data read by the lookup is available during the running
of the router as &$domain_data$&. In addition, if the driver routes the
to nothing.
.vitem &$exim_gid$&
-.cindex "&$exim_gid$&"
+.vindex "&$exim_gid$&"
This variable contains the numerical value of the Exim group id.
.vitem &$exim_path$&
-.cindex "&$exim_path$&"
+.vindex "&$exim_path$&"
This variable contains the path to the Exim binary.
.vitem &$exim_uid$&
-.cindex "&$exim_uid$&"
+.vindex "&$exim_uid$&"
This variable contains the numerical value of the Exim user id.
.vitem &$found_extension$&
-.cindex "&$found_extension$&"
+.vindex "&$found_extension$&"
This variable is available when Exim is compiled with the
content-scanning extension and the obsolete &%demime%& condition. For details,
see section &<<SECTdemimecond>>&.
characters. Note also that braces must &'not'& be used.
.vitem &$home$&
-.cindex "&$home$&"
+.vindex "&$home$&"
When the &%check_local_user%& option is set for a router, the user's home
directory is placed in &$home$& when the check succeeds. In particular, this
means it is set during the running of users' filter files. A router may also
of the environment variable HOME.
.vitem &$host$&
-.cindex "&$host$&"
-When the &(smtp)& transport is expanding its options for encryption using TLS,
-&$host$& contains the name of the host to which it is connected. Likewise, when
-used in the client part of an authenticator configuration (see chapter
-&<<CHAPSMTPAUTH>>&), &$host$& contains the name of the server to which the
-client is connected.
+.vindex "&$host$&"
+If a router assigns an address to a transport (any transport), and passes a
+list of hosts with the address, the value of &$host$& when the transport starts
+to run is the name of the first host on the list. Note that this applies both
+to local and remote transports.
.cindex "transport" "filter"
.cindex "filter" "transport filter"
-When used in a transport filter (see chapter &<<CHAPtransportgeneric>>&)
-&$host$& refers to the host involved in the current connection. When a local
-transport is run as a result of a router that sets up a host list, &$host$&
-contains the name of the first host.
+For the &(smtp)& transport, if there is more than one host, the value of
+&$host$& changes as the transport works its way through the list. In
+particular, when the &(smtp)& transport is expanding its options for encryption
+using TLS, or for specifying a transport filter (see chapter
+&<<CHAPtransportgeneric>>&), &$host$& contains the name of the host to which it
+is connected.
+
+When used in the client part of an authenticator configuration (see chapter
+&<<CHAPSMTPAUTH>>&), &$host$& contains the name of the server to which the
+client is connected.
+
.vitem &$host_address$&
-.cindex "&$host_address$&"
+.vindex "&$host_address$&"
This variable is set to the remote host's IP address whenever &$host$& is set
for a remote connection. It is also set to the IP address that is being checked
when the &%ignore_target_hosts%& option is being processed.
.vitem &$host_data$&
-.cindex "&$host_data$&"
+.vindex "&$host_data$&"
If a &%hosts%& condition in an ACL is satisfied by means of a lookup, the
result of the lookup is made available in the &$host_data$& variable. This
allows you, for example, to do things like this:
message = $host_data
.endd
.vitem &$host_lookup_deferred$&
-.cindex "host name lookup" "failure of"
-.cindex "&$host_lookup_deferred$&"
+.cindex "host name" "lookup, failure of"
+.vindex "&$host_lookup_deferred$&"
This variable normally contains &"0"&, as does &$host_lookup_failed$&. When a
message comes from a remote host and there is an attempt to look up the host's
name from its IP address, and the attempt is not successful, one of these
&"1"&. See also &$sender_host_name$&.
.vitem &$host_lookup_failed$&
-.cindex "&$host_lookup_failed$&"
+.vindex "&$host_lookup_failed$&"
See &$host_lookup_deferred$&.
.vitem &$inode$&
-.cindex "&$inode$&"
+.vindex "&$inode$&"
The only time this variable is set is while expanding the &%directory_file%&
option in the &(appendfile)& transport. The variable contains the inode number
of the temporary file which is about to be renamed. It can be used to construct
a unique name for the file.
-.new
.vitem &$interface_address$&
-.cindex "&$interface_address$&"
-As soon as a server starts processing a TCP/IP connection, this variable is set
-to the address of the local IP interface, and &$interface_port$& is set to the
-port number. These values are therefore available for use in the &"connect"&
-ACL. See also the &%-oMi%& command line option. As well as being used in ACLs,
-these variable could be used, for example, to make the file name for a TLS
-certificate depend on which interface and/or port is being used.
-.wen
+.vindex "&$interface_address$&"
+This is an obsolete name for &$received_ip_address$&.
.vitem &$interface_port$&
-.cindex "&$interface_port$&"
-See &$interface_address$&.
+.vindex "&$interface_port$&"
+This is an obsolete name for &$received_port$&.
+
+.vitem &$item$&
+.vindex "&$item$&"
+This variable is used during the expansion of &*forall*& and &*forany*&
+conditions (see section &<<SECTexpcond>>&), and &*filter*&, &*map*&, and
+&*reduce*& items (see section &<<SECTexpcond>>&). In other circumstances, it is
+empty.
.vitem &$ldap_dn$&
-.cindex "&$ldap_dn$&"
+.vindex "&$ldap_dn$&"
This variable, which is available only when Exim is compiled with LDAP support,
contains the DN from the last entry in the most recently successful LDAP
lookup.
.vitem &$load_average$&
-.cindex "&$load_average$&"
-This variable contains the system load average, multiplied by 1000 to that it
+.vindex "&$load_average$&"
+This variable contains the system load average, multiplied by 1000 so that it
is an integer. For example, if the load average is 0.21, the value of the
variable is 210. The value is recomputed every time the variable is referenced.
.vitem &$local_part$&
-.cindex "&$local_part$&"
+.vindex "&$local_part$&"
When an address is being routed, or delivered on its own, this
variable contains the local part. When a number of addresses are being
delivered together (for example, multiple RCPT commands in an SMTP
because a message may have many recipients and the system filter is called just
once.
-.cindex "&$local_part_prefix$&"
-.cindex "&$local_part_suffix$&"
+.vindex "&$local_part_prefix$&"
+.vindex "&$local_part_suffix$&"
If a local part prefix or suffix has been recognized, it is not included in the
value of &$local_part$& during routing and subsequent delivery. The values of
any prefix or suffix are in &$local_part_prefix$& and
&%caseful_local_part%& option (see chapter &<<CHAProutergeneric>>&).
.vitem &$local_part_data$&
-.cindex "&$local_part_data$&"
+.vindex "&$local_part_data$&"
When the &%local_parts%& option on a router matches a local part by means of a
lookup, the data read by the lookup is available during the running of the
router as &$local_part_data$&. In addition, if the driver routes the address
variable expands to nothing.
.vitem &$local_part_prefix$&
-.cindex "&$local_part_prefix$&"
+.vindex "&$local_part_prefix$&"
When an address is being routed or delivered, and a
specific prefix for the local part was recognized, it is available in this
variable, having been removed from &$local_part$&.
.vitem &$local_part_suffix$&
-.cindex "&$local_part_suffix$&"
+.vindex "&$local_part_suffix$&"
When an address is being routed or delivered, and a
specific suffix for the local part was recognized, it is available in this
variable, having been removed from &$local_part$&.
.vitem &$local_scan_data$&
-.cindex "&$local_scan_data$&"
+.vindex "&$local_scan_data$&"
This variable contains the text returned by the &[local_scan()]& function when
a message is received. See chapter &<<CHAPlocalscan>>& for more details.
.vitem &$local_user_gid$&
-.cindex "&$local_user_gid$&"
+.vindex "&$local_user_gid$&"
See &$local_user_uid$&.
.vitem &$local_user_uid$&
-.cindex "&$local_user_uid$&"
+.vindex "&$local_user_uid$&"
This variable and &$local_user_gid$& are set to the uid and gid after the
&%check_local_user%& router precondition succeeds. This means that their values
are available for the remaining preconditions (&%senders%&, &%require_files%&,
are &`(uid_t)(-1)`& and &`(gid_t)(-1)`&, respectively.
.vitem &$localhost_number$&
-.cindex "&$localhost_number$&"
+.vindex "&$localhost_number$&"
This contains the expanded value of the
&%localhost_number%& option. The expansion happens after the main options have
been read.
.vitem &$log_inodes$&
-.cindex "&$log_inodes$&"
+.vindex "&$log_inodes$&"
The number of free inodes in the disk partition where Exim's
log files are being written. The value is recalculated whenever the variable is
referenced. If the relevant file system does not have the concept of inodes,
the value of is -1. See also the &%check_log_inodes%& option.
.vitem &$log_space$&
-.cindex "&$log_space$&"
+.vindex "&$log_space$&"
The amount of free space (as a number of kilobytes) in the disk
partition where Exim's log files are being written. The value is recalculated
whenever the variable is referenced. If the operating system does not have the
.vitem &$mailstore_basename$&
-.cindex "&$mailstore_basename$&"
+.vindex "&$mailstore_basename$&"
This variable is set only when doing deliveries in &"mailstore"& format in the
&(appendfile)& transport. During the expansion of the &%mailstore_prefix%&,
&%mailstore_suffix%&, &%message_prefix%&, and &%message_suffix%& options, it
variable is empty.
.vitem &$malware_name$&
-.cindex "&$malware_name$&"
+.vindex "&$malware_name$&"
This variable is available when Exim is compiled with the
content-scanning extension. It is set to the name of the virus that was found
when the ACL &%malware%& condition is true (see section &<<SECTscanvirus>>&).
+.vitem &$max_received_linelength$&
+.vindex "&$max_received_linelength$&"
+.cindex "maximum" "line length"
+.cindex "line length" "maximum"
+This variable contains the number of bytes in the longest line that was
+received as part of the message, not counting the line termination
+character(s).
.vitem &$message_age$&
.cindex "message" "age of"
-.cindex "&$message_age$&"
+.vindex "&$message_age$&"
This variable is set at the start of a delivery attempt to contain the number
of seconds since the message was received. It does not change during a single
delivery attempt.
.cindex "body of message" "expansion variable"
.cindex "message body" "in expansion"
.cindex "binary zero" "in message body"
-.cindex "&$message_body$&"
-This variable contains the initial portion of a message's
-body while it is being delivered, and is intended mainly for use in filter
-files. The maximum number of characters of the body that are put into the
-variable is set by the &%message_body_visible%& configuration option; the
-default is 500. Newlines are converted into spaces to make it easier to search
-for phrases that might be split over a line break.
-Binary zeros are also converted into spaces.
+.vindex "&$message_body$&"
+.oindex "&%message_body_visible%&"
+This variable contains the initial portion of a message's body while it is
+being delivered, and is intended mainly for use in filter files. The maximum
+number of characters of the body that are put into the variable is set by the
+&%message_body_visible%& configuration option; the default is 500.
+
+.oindex "&%message_body_newlines%&"
+By default, newlines are converted into spaces in &$message_body$&, to make it
+easier to search for phrases that might be split over a line break. However,
+this can be disabled by setting &%message_body_newlines%& to be true. Binary
+zeros are always converted into spaces.
.vitem &$message_body_end$&
.cindex "body of message" "expansion variable"
.cindex "message body" "in expansion"
-.cindex "&$message_body_end$&"
+.vindex "&$message_body_end$&"
This variable contains the final portion of a message's
body while it is being delivered. The format and maximum size are as for
&$message_body$&.
.vitem &$message_body_size$&
.cindex "body of message" "size"
.cindex "message body" "size"
-.cindex "&$message_body_size$&"
+.vindex "&$message_body_size$&"
When a message is being delivered, this variable contains the size of the body
in bytes. The count starts from the character after the blank line that
separates the body from the header. Newlines are included in the count. See
also &$message_size$&, &$body_linecount$&, and &$body_zerocount$&.
-.new
.vitem &$message_exim_id$&
-.cindex "&$message_exim_id$&"
+.vindex "&$message_exim_id$&"
When a message is being received or delivered, this variable contains the
unique message id that is generated and used by Exim to identify the message.
An id is not created for a message until after its header has been successfully
received. &*Note*&: This is &'not'& the contents of the &'Message-ID:'& header
line; it is the local id that Exim assigns to the message, for example:
&`1BXTIK-0001yO-VA`&.
-.wen
.vitem &$message_headers$&
+.vindex &$message_headers$&
This variable contains a concatenation of all the header lines when a message
is being processed, except for lines added by routers or transports. The header
-lines are separated by newline characters.
+lines are separated by newline characters. Their contents are decoded in the
+same way as a header line that is inserted by &%bheader%&.
+
+.vitem &$message_headers_raw$&
+.vindex &$message_headers_raw$&
+This variable is like &$message_headers$& except that no processing of the
+contents of header lines is done.
.vitem &$message_id$&
-.new
This is an old name for &$message_exim_id$&, which is now deprecated.
-.wen
-.new
.vitem &$message_linecount$&
-.cindex "&$message_linecount$&"
+.vindex "&$message_linecount$&"
This variable contains the total number of lines in the header and body of the
message. Compare &$body_linecount$&, which is the count for the body only.
During the DATA and content-scanning ACLs, &$message_linecount$& contains the
routers, and transports run) the count is increased to include the
&'Received:'& header line that Exim standardly adds, and also any other header
lines that are added by ACLs. The blank line that separates the message header
-from the body is not counted. Here is an example of the use of this variable in
-a DATA ACL:
+from the body is not counted.
+
+As with the special case of &$message_size$&, during the expansion of the
+appendfile transport's maildir_tag option in maildir format, the value of
+&$message_linecount$& is the precise size of the number of newlines in the
+file that has been written (minus one for the blank line between the
+header and the body).
+
+Here is an example of the use of this variable in a DATA ACL:
.code
deny message = Too many lines in message header
condition = \
- ${if <{250}{${eval:$message_linecount - $body_linecount}}}
+ ${if <{250}{${eval:$message_linecount - $body_linecount}}}
.endd
In the MAIL and RCPT ACLs, the value is zero because at that stage the
message has not yet been received.
-.wen
.vitem &$message_size$&
.cindex "size" "of message"
.cindex "message" "size"
-.cindex "&$message_size$&"
+.vindex "&$message_size$&"
When a message is being processed, this variable contains its size in bytes. In
most cases, the size includes those headers that were received with the
message, but not those (such as &'Envelope-to:'&) that are added to individual
&$message_body_size$&, &$body_linecount$&, and &$body_zerocount$&.
.cindex "RCPT" "value of &$message_size$&"
-While running an ACL at the time of an SMTP RCPT command, &$message_size$&
+While running a per message ACL (mail/rcpt/predata), &$message_size$&
contains the size supplied on the MAIL command, or -1 if no size was given. The
value may not, of course, be truthful.
of the &%add%& command in filter files.
.vitem &$original_domain$&
-.cindex "&$domain$&"
-.cindex "&$original_domain$&"
+.vindex "&$domain$&"
+.vindex "&$original_domain$&"
When a top-level address is being processed for delivery, this contains the
same value as &$domain$&. However, if a &"child"& address (for example,
generated by an alias, forward, or filter file) is being processed, this
-variable contains the domain of the original address. This differs from
-&$parent_domain$& only when there is more than one level of aliasing or
-forwarding. When more than one address is being delivered in a single transport
-run, &$original_domain$& is not set.
+variable contains the domain of the original address (lower cased). This
+differs from &$parent_domain$& only when there is more than one level of
+aliasing or forwarding. When more than one address is being delivered in a
+single transport run, &$original_domain$& is not set.
If a new address is created by means of a &%deliver%& command in a system
filter, it is set up with an artificial &"parent"& address. This has the local
part &'system-filter'& and the default qualify domain.
.vitem &$original_local_part$&
-.cindex "&$local_part$&"
-.cindex "&$original_local_part$&"
+.vindex "&$local_part$&"
+.vindex "&$original_local_part$&"
When a top-level address is being processed for delivery, this contains the
same value as &$local_part$&, unless a prefix or suffix was removed from the
local part, because &$original_local_part$& always contains the full local
.vitem &$originator_gid$&
.cindex "gid (group id)" "of originating user"
.cindex "sender" "gid"
-.cindex "&$caller_gid$&"
-.cindex "&$originator_gid$&"
+.vindex "&$caller_gid$&"
+.vindex "&$originator_gid$&"
This variable contains the value of &$caller_gid$& that was set when the
message was received. For messages received via the command line, this is the
gid of the sending user. For messages received by SMTP over TCP/IP, this is
.vitem &$originator_uid$&
.cindex "uid (user id)" "of originating user"
.cindex "sender" "uid"
-.cindex "&$caller_uid$&"
-.cindex "&$originaltor_uid$&"
+.vindex "&$caller_uid$&"
+.vindex "&$originaltor_uid$&"
The value of &$caller_uid$& that was set when the message was received. For
messages received via the command line, this is the uid of the sending user.
For messages received by SMTP over TCP/IP, this is normally the uid of the Exim
user.
.vitem &$parent_domain$&
-.cindex "&$parent_domain$&"
+.vindex "&$parent_domain$&"
This variable is similar to &$original_domain$& (see
above), except that it refers to the immediately preceding parent address.
.vitem &$parent_local_part$&
-.cindex "&$parent_local_part$&"
+.vindex "&$parent_local_part$&"
This variable is similar to &$original_local_part$&
(see above), except that it refers to the immediately preceding parent address.
.vitem &$pid$&
.cindex "pid (process id)" "of current process"
-.cindex "&$pid$&"
+.vindex "&$pid$&"
This variable contains the current process id.
.vitem &$pipe_addresses$&
.cindex "filter" "transport filter"
.cindex "transport" "filter"
-.cindex "&$pipe_addresses$&"
+.vindex "&$pipe_addresses$&"
This is not an expansion variable, but is mentioned here because the string
-&"$pipe_addresses"& is handled specially in the command specification for the
+&`$pipe_addresses`& is handled specially in the command specification for the
&(pipe)& transport (chapter &<<CHAPpipetransport>>&) and in transport filters
(described under &%transport_filter%& in chapter &<<CHAPtransportgeneric>>&).
It cannot be used in general expansion strings, and provokes an &"unknown
variable"& error if encountered.
.vitem &$primary_hostname$&
-.cindex "&$primary_hostname$&"
+.vindex "&$primary_hostname$&"
This variable contains the value set by &%primary_hostname%& in the
configuration file, or read by the &[uname()]& function. If &[uname()]& returns
a single-component name, Exim calls &[gethostbyname()]& (or
qualified host name. See also &$smtp_active_hostname$&.
-.new
.vitem &$prvscheck_address$&
This variable is used in conjunction with the &%prvscheck%& expansion item,
which is described in sections &<<SECTexpansionitems>>& and
This variable is used in conjunction with the &%prvscheck%& expansion item,
which is described in sections &<<SECTexpansionitems>>& and
&<<SECTverifyPRVS>>&.
-.wen
.vitem &$qualify_domain$&
-.cindex "&$qualify_domain$&"
+.vindex "&$qualify_domain$&"
The value set for the &%qualify_domain%& option in the configuration file.
.vitem &$qualify_recipient$&
-.cindex "&$qualify_recipient$&"
+.vindex "&$qualify_recipient$&"
The value set for the &%qualify_recipient%& option in the configuration file,
or if not set, the value of &$qualify_domain$&.
.vitem &$rcpt_count$&
-.cindex "&$rcpt_count$&"
+.vindex "&$rcpt_count$&"
When a message is being received by SMTP, this variable contains the number of
RCPT commands received for the current message. If this variable is used in a
RCPT ACL, its value includes the current command.
.vitem &$rcpt_defer_count$&
-.cindex "&$rcpt_defer_count$&"
+.vindex "&$rcpt_defer_count$&"
+.cindex "4&'xx'& responses" "count of"
When a message is being received by SMTP, this variable contains the number of
RCPT commands in the current message that have previously been rejected with a
temporary (4&'xx'&) response.
.vitem &$rcpt_fail_count$&
-.cindex "&$rcpt_fail_count$&"
+.vindex "&$rcpt_fail_count$&"
When a message is being received by SMTP, this variable contains the number of
RCPT commands in the current message that have previously been rejected with a
permanent (5&'xx'&) response.
.vitem &$received_count$&
-.cindex "&$received_count$&"
+.vindex "&$received_count$&"
This variable contains the number of &'Received:'& header lines in the message,
including the one added by Exim (so its value is always greater than zero). It
is available in the DATA ACL, the non-SMTP ACL, and while routing and
delivering.
.vitem &$received_for$&
-.cindex "&$received_for$&"
+.vindex "&$received_for$&"
If there is only a single recipient address in an incoming message, this
variable contains that address when the &'Received:'& header line is being
built. The value is copied after recipient rewriting has happened, but before
the &[local_scan()]& function is run.
+.vitem &$received_ip_address$&
+.vindex "&$received_ip_address$&"
+As soon as an Exim server starts processing an incoming TCP/IP connection, this
+variable is set to the address of the local IP interface, and &$received_port$&
+is set to the local port number. (The remote IP address and port are in
+&$sender_host_address$& and &$sender_host_port$&.) When testing with &%-bh%&,
+the port value is -1 unless it has been set using the &%-oMi%& command line
+option.
+
+As well as being useful in ACLs (including the &"connect"& ACL), these variable
+could be used, for example, to make the file name for a TLS certificate depend
+on which interface and/or port is being used for the incoming connection. The
+values of &$received_ip_address$& and &$received_port$& are saved with any
+messages that are received, thus making these variables available at delivery
+time.
+
+&*Note:*& There are no equivalent variables for outgoing connections, because
+the values are unknown (unless they are explicitly set by options of the
+&(smtp)& transport).
+
+.vitem &$received_port$&
+.vindex "&$received_port$&"
+See &$received_ip_address$&.
+
.vitem &$received_protocol$&
-.cindex "&$received_protocol$&"
+.vindex "&$received_protocol$&"
When a message is being processed, this variable contains the name of the
protocol by which it was received. Most of the names used by Exim are defined
by RFCs 821, 2821, and 3848. They start with &"smtp"& (the client used HELO) or
messages that are injected locally by trusted callers. This is commonly used to
identify messages that are being re-injected after some kind of scanning.
-.new
.vitem &$received_time$&
-.cindex "&$received_time$&"
+.vindex "&$received_time$&"
This variable contains the date and time when the current message was received,
as a number of seconds since the start of the Unix epoch.
-.wen
.vitem &$recipient_data$&
-.cindex "&$recipient_data$&"
+.vindex "&$recipient_data$&"
This variable is set after an indexing lookup success in an ACL &%recipients%&
condition. It contains the data from the lookup, and the value remains set
until the next &%recipients%& test. Thus, you can do things like this:
expansion that all such lists undergo before being interpreted.
.vitem &$recipient_verify_failure$&
-.cindex "&$recipient_verify_failure$&"
+.vindex "&$recipient_verify_failure$&"
In an ACL, when a recipient verification fails, this variable contains
information about the failure. It is set to one of the following words:
rejections of MAIL and rejections of RCPT.
.vitem &$recipients$&
-.cindex "&$recipients$&"
-This variable contains a list of envelope recipients for a
-message. A comma and a space separate the addresses in the replacement text.
-However, the variable is not generally available, to prevent exposure of Bcc
-recipients in unprivileged users' filter files. You can use &$recipients$& only
-in these two cases:
+.vindex "&$recipients$&"
+This variable contains a list of envelope recipients for a message. A comma and
+a space separate the addresses in the replacement text. However, the variable
+is not generally available, to prevent exposure of Bcc recipients in
+unprivileged users' filter files. You can use &$recipients$& only in these
+cases:
.olist
In a system filter file.
.next
-In the ACLs associated with the DATA command, that is, the ACLs defined by
-&%acl_smtp_predata%& and &%acl_smtp_data%&.
+In the ACLs associated with the DATA command and with non-SMTP messages, that
+is, the ACLs defined by &%acl_smtp_predata%&, &%acl_smtp_data%&,
+&%acl_smtp_mime%&, &%acl_not_smtp_start%&, &%acl_not_smtp%&, and
+&%acl_not_smtp_mime%&.
+.next
+From within a &[local_scan()]& function.
.endlist
.vitem &$recipients_count$&
-.cindex "&$recipients_count$&"
+.vindex "&$recipients_count$&"
When a message is being processed, this variable contains the number of
envelope recipients that came with the message. Duplicates are not excluded
from the count. While a message is being received over SMTP, the number
increases for each accepted recipient. It can be referenced in an ACL.
+
+.vitem &$regex_match_string$&
+.vindex "&$regex_match_string$&"
+This variable is set to contain the matching regular expression after a
+&%regex%& ACL condition has matched (see section &<<SECTscanregex>>&).
+
+
.vitem &$reply_address$&
-.cindex "&$reply_address$&"
+.vindex "&$reply_address$&"
When a message is being processed, this variable contains the contents of the
&'Reply-To:'& header line if one exists and it is not empty, or otherwise the
-contents of the &'From:'& header line.
+contents of the &'From:'& header line. Apart from the removal of leading
+white space, the value is not processed in any way. In particular, no RFC 2047
+decoding or character code translation takes place.
.vitem &$return_path$&
-.cindex "&$return_path$&"
+.vindex "&$return_path$&"
When a message is being delivered, this variable contains the return path &--
the sender field that will be sent as part of the envelope. It is not enclosed
in <> characters. At the start of routing an address, &$return_path$& has the
envelope sender.
.vitem &$return_size_limit$&
-.cindex "&$return_size_limit$&"
+.vindex "&$return_size_limit$&"
This is an obsolete name for &$bounce_return_size_limit$&.
.vitem &$runrc$&
.cindex "return code" "from &%run%& expansion"
-.cindex "&$runrc$&"
+.vindex "&$runrc$&"
This variable contains the return code from a command that is run by the
&%${run...}%& expansion item. &*Warning*&: In a router or transport, you cannot
assume the order in which option values are expanded, except for those
another.
.vitem &$self_hostname$&
-.cindex "&%self%& option" "value of host name"
-.cindex "&$self_hostname$&"
+.oindex "&%self%&" "value of host name"
+.vindex "&$self_hostname$&"
When an address is routed to a supposedly remote host that turns out to be the
local host, what happens is controlled by the &%self%& generic router option.
One of its values causes the address to be passed to another router. When this
original router encountered. In other circumstances its contents are null.
.vitem &$sender_address$&
-.cindex "&$sender_address$&"
+.vindex "&$sender_address$&"
When a message is being processed, this variable contains the sender's address
-that was received in the message's envelope. For bounce messages, the value of
-this variable is the empty string. See also &$return_path$&.
+that was received in the message's envelope. The case of letters in the address
+is retained, in both the local part and the domain. For bounce messages, the
+value of this variable is the empty string. See also &$return_path$&.
.vitem &$sender_address_data$&
-.cindex "&$address_data$&"
-.cindex "&$sender_address_data$&"
+.vindex "&$address_data$&"
+.vindex "&$sender_address_data$&"
If &$address_data$& is set when the routers are called from an ACL to verify a
sender address, the final value is preserved in &$sender_address_data$&, to
distinguish it from data from a recipient address. The value does not persist
longer, you can save it in an ACL variable.
.vitem &$sender_address_domain$&
-.cindex "&$sender_address_domain$&"
+.vindex "&$sender_address_domain$&"
The domain portion of &$sender_address$&.
.vitem &$sender_address_local_part$&
-.cindex "&$sender_address_local_part$&"
+.vindex "&$sender_address_local_part$&"
The local part portion of &$sender_address$&.
.vitem &$sender_data$&
-.cindex "&$sender_data$&"
+.vindex "&$sender_data$&"
This variable is set after a lookup success in an ACL &%senders%& condition or
in a router &%senders%& option. It contains the data from the lookup, and the
value remains set until the next &%senders%& test. Thus, you can do things like
expansion that all such lists undergo before being interpreted.
.vitem &$sender_fullhost$&
-.cindex "&$sender_fullhost$&"
+.vindex "&$sender_fullhost$&"
When a message is received from a remote host, this variable contains the host
name and IP address in a single string. It ends with the IP address in square
brackets, followed by a colon and a port number if the logging of ports is
the verified host name or to the host's IP address in square brackets.
.vitem &$sender_helo_name$&
-.cindex "&$sender_hslo_name$&"
+.vindex "&$sender_helo_name$&"
When a message is received from a remote host that has issued a HELO or EHLO
command, the argument of that command is placed in this variable. It is also
set if HELO or EHLO is used when a message is received using SMTP locally via
the &%-bs%& or &%-bS%& options.
.vitem &$sender_host_address$&
-.cindex "&$sender_host_address$&"
+.vindex "&$sender_host_address$&"
When a message is received from a remote host, this variable contains that
host's IP address. For locally submitted messages, it is empty.
.vitem &$sender_host_authenticated$&
-.cindex "&$sender_host_authenticated$&"
+.vindex "&$sender_host_authenticated$&"
This variable contains the name (not the public name) of the authenticator
driver that successfully authenticated the client from which the message was
received. It is empty if there was no successful authentication. See also
&$authenticated_id$&.
+.new
+.vitem &$sender_host_dnssec$&
+.vindex "&$sender_host_dnssec$&"
+If &$sender_host_name$& has been populated (by reference, &%hosts_lookup%& or
+otherwise) then this boolean will have been set true if, and only if, the
+resolver library states that the reverse DNS was authenticated data. At all
+other times, this variable is false.
+
+It is likely that you will need to coerce DNSSEC support on in the resolver
+library, by setting:
+.code
+dns_use_dnssec = 1
+.endd
+
+Exim does not perform DNSSEC validation itself, instead leaving that to a
+validating resolver (eg, unbound, or bind with suitable configuration).
+
+Exim does not (currently) check to see if the forward DNS was also secured
+with DNSSEC, only the reverse DNS.
+
+If you have changed &%host_lookup_order%& so that &`bydns`& is not the first
+mechanism in the list, then this variable will be false.
+.wen
+
+
.vitem &$sender_host_name$&
-.cindex "&$sender_host_name$&"
+.vindex "&$sender_host_name$&"
When a message is received from a remote host, this variable contains the
host's name as obtained by looking up its IP address. For messages received by
other means, this variable is empty.
-.cindex "&$host_lookup_failed$&"
+.vindex "&$host_lookup_failed$&"
If the host name has not previously been looked up, a reference to
&$sender_host_name$& triggers a lookup (for messages from remote hosts).
A looked up name is accepted only if it leads back to the original IP address
any data, or if the forward lookup does not yield the original IP address,
&$sender_host_name$& remains empty, and &$host_lookup_failed$& is set to &"1"&.
-.cindex "&$host_lookup_deferred$&"
+.vindex "&$host_lookup_deferred$&"
However, if either of the lookups cannot be completed (for example, there is a
DNS timeout), &$host_lookup_deferred$& is set to &"1"&, and
&$host_lookup_failed$& remains set to &"0"&.
Once &$host_lookup_failed$& is set to &"1"&, Exim does not try to look up the
host name again if there is a subsequent reference to &$sender_host_name$&
-in the same Exim process, but it does try again if &$sender_host_deferred$&
+in the same Exim process, but it does try again if &$host_lookup_deferred$&
is set to &"1"&.
Exim does not automatically look up every calling host's name. If you want
.vitem &$sender_host_port$&
-.cindex "&$sender_host_port$&"
+.vindex "&$sender_host_port$&"
When a message is received from a remote host, this variable contains the port
number that was used on the remote host.
.vitem &$sender_ident$&
-.cindex "&$sender_ident$&"
+.vindex "&$sender_ident$&"
When a message is received from a remote host, this variable contains the
identification received in response to an RFC 1413 request. When a message has
been received locally, this variable contains the login name of the user that
called Exim.
-.new
.vitem &$sender_rate_$&&'xxx'&
A number of variables whose names begin &$sender_rate_$& are set as part of the
&%ratelimit%& ACL condition. Details are given in section
&<<SECTratelimiting>>&.
-.wen
.vitem &$sender_rcvhost$&
.cindex "DNS" "reverse lookup"
.cindex "reverse DNS lookup"
-.cindex "&$sender_rcvhost$&"
+.vindex "&$sender_rcvhost$&"
This is provided specifically for use in &'Received:'& headers. It starts with
either the verified host name (as obtained from a reverse DNS lookup) or, if
there is no verified host name, the IP address in square brackets. After that
into the string, to improve the formatting of the &'Received:'& header.
.vitem &$sender_verify_failure$&
-.cindex "&$sender_verify_failure$&"
+.vindex "&$sender_verify_failure$&"
In an ACL, when a sender verification fails, this variable contains information
about the failure. The details are the same as for
&$recipient_verify_failure$&.
+.vitem &$sending_ip_address$&
+.vindex "&$sending_ip_address$&"
+This variable is set whenever an outgoing SMTP connection to another host has
+been set up. It contains the IP address of the local interface that is being
+used. This is useful if a host that has more than one IP address wants to take
+on different personalities depending on which one is being used. For incoming
+connections, see &$received_ip_address$&.
+
+.vitem &$sending_port$&
+.vindex "&$sending_port$&"
+This variable is set whenever an outgoing SMTP connection to another host has
+been set up. It contains the local port that is being used. For incoming
+connections, see &$received_port$&.
+
.vitem &$smtp_active_hostname$&
-.cindex "&$smtp_active_hostname$&"
-During an SMTP session, this variable contains the value of the active host
-name, as specified by the &%smtp_active_hostname%& option. The value of
+.vindex "&$smtp_active_hostname$&"
+During an incoming SMTP session, this variable contains the value of the active
+host name, as specified by the &%smtp_active_hostname%& option. The value of
&$smtp_active_hostname$& is saved with any message that is received, so its
value can be consulted during routing and delivery.
-.new
.vitem &$smtp_command$&
-.cindex "&$smtp_command$&"
+.vindex "&$smtp_command$&"
During the processing of an incoming SMTP command, this variable contains the
entire command. This makes it possible to distinguish between HELO and EHLO in
the HELO ACL, and also to distinguish between commands such as these:
command, the address in &$smtp_command$& is the original address before any
rewriting, whereas the values in &$local_part$& and &$domain$& are taken from
the address after SMTP-time rewriting.
-.wen
.vitem &$smtp_command_argument$&
-.new
-.cindex "SMTP command" "argument for"
-.cindex "&$smtp_command_argument$&"
+.cindex "SMTP" "command, argument for"
+.vindex "&$smtp_command_argument$&"
While an ACL is running to check an SMTP command, this variable contains the
argument, that is, the text that follows the command name, with leading white
space removed. Following the introduction of &$smtp_command$&, this variable is
somewhat redundant, but is retained for backwards compatibility.
-.wen
+
+.vitem &$smtp_count_at_connection_start$&
+.vindex "&$smtp_count_at_connection_start$&"
+This variable is set greater than zero only in processes spawned by the Exim
+daemon for handling incoming SMTP connections. The name is deliberately long,
+in order to emphasize what the contents are. When the daemon accepts a new
+connection, it increments this variable. A copy of the variable is passed to
+the child process that handles the connection, but its value is fixed, and
+never changes. It is only an approximation of how many incoming connections
+there actually are, because many other connections may come and go while a
+single connection is being processed. When a child process terminates, the
+daemon decrements its copy of the variable.
.vitem "&$sn0$& &-- &$sn9$&"
These variables are copies of the values of the &$n0$& &-- &$n9$& accumulators
.vitem &$spool_directory$&
-.cindex "&$spool_directory$&"
+.vindex "&$spool_directory$&"
The name of Exim's spool directory.
.vitem &$spool_inodes$&
-.cindex "&$spool_inodes$&"
+.vindex "&$spool_inodes$&"
The number of free inodes in the disk partition where Exim's spool files are
being written. The value is recalculated whenever the variable is referenced.
If the relevant file system does not have the concept of inodes, the value of
is -1. See also the &%check_spool_inodes%& option.
.vitem &$spool_space$&
-.cindex "&$spool_space$&"
+.vindex "&$spool_space$&"
The amount of free space (as a number of kilobytes) in the disk partition where
Exim's spool files are being written. The value is recalculated whenever the
variable is referenced. If the operating system does not have the ability to
.vitem &$thisaddress$&
-.cindex "&$thisaddress$&"
+.vindex "&$thisaddress$&"
This variable is set only during the processing of the &%foranyaddress%&
command in a filter file. Its use is explained in the description of that
command, which can be found in the separate document entitled &'Exim's
interfaces to mail filtering'&.
+.vitem &$tls_bits$&
+.vindex "&$tls_bits$&"
+Contains an approximation of the TLS cipher's bit-strength; the meaning of
+this depends upon the TLS implementation used.
+If TLS has not been negotiated, the value will be 0.
+The value of this is automatically fed into the Cyrus SASL authenticator
+when acting as a server, to specify the "external SSF" (a SASL term).
+
.vitem &$tls_certificate_verified$&
-.cindex "&$tls_certificate_verified$&"
+.vindex "&$tls_certificate_verified$&"
This variable is set to &"1"& if a TLS certificate was verified when the
message was received, and &"0"& otherwise.
.vitem &$tls_cipher$&
-.cindex "&$tls_cipher$&"
+.vindex "&$tls_cipher$&"
When a message is received from a remote host over an encrypted SMTP
connection, this variable is set to the cipher suite that was negotiated, for
example DES-CBC3-SHA. In other circumstances, in particular, for message
-received over unencrypted connections, the variable is empty. See chapter
-&<<CHAPTLS>>& for details of TLS support.
+received over unencrypted connections, the variable is empty. Testing
+&$tls_cipher$& for emptiness is one way of distinguishing between encrypted and
+non-encrypted connections during ACL processing.
+
+The &$tls_cipher$& variable retains its value during message delivery, except
+when an outward SMTP delivery takes place via the &(smtp)& transport. In this
+case, &$tls_cipher$& is cleared before any outgoing SMTP connection is made,
+and then set to the outgoing cipher suite if one is negotiated. See chapter
+&<<CHAPTLS>>& for details of TLS support and chapter &<<CHAPsmtptrans>>& for
+details of the &(smtp)& transport.
.vitem &$tls_peerdn$&
-.cindex "&$tls_peerdn$&"
+.vindex "&$tls_peerdn$&"
When a message is received from a remote host over an encrypted SMTP
connection, and Exim is configured to request a certificate from the client,
the value of the Distinguished Name of the certificate is made available in the
-&$tls_peerdn$& during subsequent processing.
+&$tls_peerdn$& during subsequent processing. Like &$tls_cipher$&, the
+value is retained during message delivery, except during outbound SMTP
+deliveries.
+
+.vitem &$tls_sni$&
+.vindex "&$tls_sni$&"
+.cindex "TLS" "Server Name Indication"
+When a TLS session is being established, if the client sends the Server
+Name Indication extension, the value will be placed in this variable.
+If the variable appears in &%tls_certificate%& then this option and
+some others, described in &<<SECTtlssni>>&,
+will be re-expanded early in the TLS session, to permit
+a different certificate to be presented (and optionally a different key to be
+used) to the client, based upon the value of the SNI extension.
+
+The value will be retained for the lifetime of the message. During outbound
+SMTP deliveries, it reflects the value of the &%tls_sni%& option on
+the transport.
.vitem &$tod_bsdinbox$&
-.cindex "&$tod_bsdinbox$&"
+.vindex "&$tod_bsdinbox$&"
The time of day and the date, in the format required for BSD-style mailbox
files, for example: Thu Oct 17 17:14:09 1995.
.vitem &$tod_epoch$&
-.cindex "&$tod_epoch$&"
+.vindex "&$tod_epoch$&"
The time and date as a number of seconds since the start of the Unix epoch.
+.vitem &$tod_epoch_l$&
+.vindex "&$tod_epoch_l$&"
+The time and date as a number of microseconds since the start of the Unix epoch.
+
.vitem &$tod_full$&
-.cindex "&$tod_full$&"
+.vindex "&$tod_full$&"
A full version of the time and date, for example: Wed, 16 Oct 1995 09:51:40
+0100. The timezone is always given as a numerical offset from UTC, with
positive values used for timezones that are ahead (east) of UTC, and negative
values for those that are behind (west).
.vitem &$tod_log$&
-.cindex "&$tod_log$&"
+.vindex "&$tod_log$&"
The time and date in the format used for writing Exim's log files, for example:
1995-10-12 15:32:29, but without a timezone.
.vitem &$tod_logfile$&
-.cindex "&$tod_logfile$&"
+.vindex "&$tod_logfile$&"
This variable contains the date in the format yyyymmdd. This is the format that
is used for datestamping log files when &%log_file_path%& contains the &`%D`&
flag.
.vitem &$tod_zone$&
-.cindex "&$tod_zone$&"
+.vindex "&$tod_zone$&"
This variable contains the numerical value of the local timezone, for example:
-0500.
.vitem &$tod_zulu$&
-.cindex "&$tod_zulu$&"
+.vindex "&$tod_zulu$&"
This variable contains the UTC date and time in &"Zulu"& format, as specified
by ISO 8601, for example: 20030221154023Z.
.vitem &$value$&
-.cindex "&$value$&"
+.vindex "&$value$&"
This variable contains the result of an expansion lookup, extraction operation,
-or external command, as described above.
+or external command, as described above. It is also used during a
+&*reduce*& expansion.
.vitem &$version_number$&
-.cindex "&$version_number$&"
+.vindex "&$version_number$&"
The version number of Exim.
.vitem &$warn_message_delay$&
-.cindex "&$warn_message_delay$&"
+.vindex "&$warn_message_delay$&"
This variable is set only during the creation of a message warning about a
delivery delay. Details of its use are explained in section &<<SECTcustwarn>>&.
.vitem &$warn_message_recipients$&
-.cindex "&$warn_message_recipients$&"
+.vindex "&$warn_message_recipients$&"
This variable is set only during the creation of a message warning about a
delivery delay. Details of its use are explained in section &<<SECTcustwarn>>&.
.endlist
+.ecindex IIDstrexp
. ////////////////////////////////////////////////////////////////////////////
.chapter "Embedded Perl" "CHAPperl"
-.cindex "Perl" "calling from Exim"
+.scindex IIDperl "Perl" "calling from Exim"
Exim can be built to include an embedded Perl interpreter. When this is done,
Perl subroutines can be called as part of the string expansion process. To make
use of the Perl support, you need version 5.004 or later of Perl installed on
in your &_Local/Makefile_& and then build Exim in the normal way.
-.section "Setting up so Perl can be used"
-.cindex "&%perl_startup%&"
+.section "Setting up so Perl can be used" "SECID85"
+.oindex "&%perl_startup%&"
Access to Perl subroutines is via a global configuration option called
&%perl_startup%& and an expansion string operator &%${perl ...}%&. If there is
no &%perl_startup%& option in the Exim configuration file then no Perl
two ways:
.ilist
-.cindex "&%perl_at_start%&"
+.oindex "&%perl_at_start%&"
Setting &%perl_at_start%& (a boolean option) in the configuration requests
a startup when Exim is entered.
.next
initial startup, even if &%perl_at_start%& is set.
-.section "Calling Perl subroutines"
+.section "Calling Perl subroutines" "SECID86"
When the configuration file includes a &%perl_startup%& option you can make use
of the string expansion item to call the Perl subroutines that are defined
by the &%perl_startup%& code. The operator is used in any of the following
that was passed to &%die%&.
-.section "Calling Exim functions from Perl"
+.section "Calling Exim functions from Perl" "SECID87"
Within any Perl code called from Exim, the function &'Exim::expand_string()'&
is available to call back into Exim's string expansion function. For example,
the Perl code
timestamp. In this case, you should not supply a terminating newline.
-.section "Use of standard output and error by Perl"
+.section "Use of standard output and error by Perl" "SECID88"
.cindex "Perl" "standard output and error"
You should not write to the standard error or output streams from within your
Perl code, as it is not defined how these are set up. In versions of Exim
example, the code for the subroutine is empty, so it does nothing, but you can
include any Perl code that you like. The text of the &%warn%& message is passed
as the first subroutine argument.
-
+.ecindex IIDperl
. ////////////////////////////////////////////////////////////////////////////
chapter describes how they operate.
When a message is received over TCP/IP, the interface and port that were
-actually used are set in &$interface_address$& and &$interface_port$&.
+actually used are set in &$received_ip_address$& and &$received_port$&.
-.section "Starting a listening daemon"
+.section "Starting a listening daemon" "SECID89"
When a listening daemon is started (by means of the &%-bd%& command line
option), the interfaces and ports on which it listens are controlled by the
following options:
-.section "Special IP listening addresses"
+.section "Special IP listening addresses" "SECID90"
The addresses 0.0.0.0 and ::0 are treated specially. They are interpreted
as &"all IPv4 interfaces"& and &"all IPv6 interfaces"&, respectively. In each
case, Exim tells the TCP/IP stack to &"listen on all IPv&'x'& interfaces"&
-.section "Overriding local_interfaces and daemon_smtp_ports"
+.section "Overriding local_interfaces and daemon_smtp_ports" "SECID91"
The &%-oX%& command line option can be used to override the values of
&%daemon_smtp_ports%& and/or &%local_interfaces%& for a particular daemon
instance. Another way of doing this would be to use macros and the &%-D%&
-.section "IPv6 address scopes"
+.section "IPv6 address scopes" "SECID92"
+.cindex "IPv6" "address scopes"
IPv6 addresses have &"scopes"&, and a host with multiple hardware interfaces
can, in principle, have the same link-local IPv6 address on different
interfaces. Thus, additional information is needed, over and above the IP
function.) Of course, this means that the additional functionality of
&[getaddrinfo()]& &-- recognizing scoped addresses &-- is lost.
+.section "Disabling IPv6" "SECID93"
+.cindex "IPv6" "disabling"
+Sometimes it happens that an Exim binary that was compiled with IPv6 support is
+run on a host whose kernel does not support IPv6. The binary will fall back to
+using IPv4, but it may waste resources looking up AAAA records, and trying to
+connect to IPv6 addresses, causing delays to mail delivery. If you set the
+.oindex "&%disable_ipv6%&"
+&%disable_ipv6%& option true, even if the Exim binary has IPv6 support, no IPv6
+activities take place. AAAA records are never looked up, and any IPv6 addresses
+that are listed in &%local_interfaces%&, data for the &(manualroute)& router,
+etc. are ignored. If IP literals are enabled, the &(ipliteral)& router declines
+to handle IPv6 literal addresses.
+
+On the other hand, when IPv6 is in use, there may be times when you want to
+disable it for certain hosts or domains. You can use the &%dns_ipv4_lookup%&
+option to globally suppress the lookup of AAAA records for specified domains,
+and you can use the &%ignore_target_hosts%& generic router option to ignore
+IPv6 addresses in an individual router.
-.section "Examples of starting a listening daemon"
+
+.section "Examples of starting a listening daemon" "SECID94"
The default case in an IPv6 environment is
.code
daemon_smtp_ports = smtp
-.section "Recognising the local host" "SECTreclocipadd"
+.section "Recognizing the local host" "SECTreclocipadd"
The &%local_interfaces%& option is also used when Exim needs to determine
whether or not an IP address refers to the local host. That is, the IP
addresses of all the interfaces on which a daemon is listening are always
-.section "Delivering to a remote host"
+.section "Delivering to a remote host" "SECID95"
Delivery to a remote host is handled by the smtp transport. By default, it
allows the system's TCP/IP functions to choose which interface to use (if
there is more than one) when connecting to a remote host. However, the
. ////////////////////////////////////////////////////////////////////////////
.chapter "Main configuration" "CHAPmainconfig"
-.cindex "configuration file" "main section"
-.cindex "main configuration"
+.scindex IIDconfima "configuration file" "main section"
+.scindex IIDmaiconf "main configuration"
The first part of the run time configuration file contains three types of item:
.ilist
an aid to finding the name of the option you are looking for. Some options are
listed in more than one group.
-.section "Miscellaneous"
+.section "Miscellaneous" "SECID96"
.table2
.row &%bi_command%& "to run for &%-bi%& command line option"
+.row &%disable_ipv6%& "do no IPv6 processing"
.row &%keep_malformed%& "for broken files &-- should not happen"
.row &%localhost_number%& "for unique message ids in clusters"
+.row &%message_body_newlines%& "retain newlines in &$message_body$&"
.row &%message_body_visible%& "how much to show in &$message_body$&"
.row &%mua_wrapper%& "run in &""MUA wrapper""& mode"
.row &%print_topbitchars%& "top-bit characters are printing"
.endtable
-.section "Exim parameters"
+.section "Exim parameters" "SECID97"
.table2
.row &%exim_group%& "override compiled-in value"
.row &%exim_path%& "override compiled-in value"
-.section "Privilege controls"
+.section "Privilege controls" "SECID98"
.table2
.row &%admin_groups%& "groups that are Exim admin users"
.row &%deliver_drop_privilege%& "drop root for delivery processes"
-.section "Logging"
+.section "Logging" "SECID99"
.table2
.row &%hosts_connection_nolog%& "exemption from connect logging"
.row &%log_file_path%& "override compiled-in value"
-.section "Frozen messages"
+.section "Frozen messages" "SECID100"
.table2
.row &%auto_thaw%& "sets time for retrying frozen messages"
.row &%freeze_tell%& "send message when freezing"
-.section "Data lookups"
+.section "Data lookups" "SECID101"
.table2
+.row &%ibase_servers%& "InterBase servers"
+.row &%ldap_ca_cert_dir%& "dir of CA certs to verify LDAP server's"
+.row &%ldap_ca_cert_file%& "file of CA certs to verify LDAP server's"
+.row &%ldap_cert_file%& "client cert file for LDAP"
+.row &%ldap_cert_key%& "client key file for LDAP"
+.row &%ldap_cipher_suite%& "TLS negotiation preference control"
.row &%ldap_default_servers%& "used if no server in query"
+.row &%ldap_require_cert%& "action to take without LDAP server cert"
+.row &%ldap_start_tls%& "require TLS within LDAP"
.row &%ldap_version%& "set protocol version"
.row &%lookup_open_max%& "lookup files held open"
-.row &%mysql_servers%& "as it says"
-.row &%oracle_servers%& "as it says"
-.row &%pgsql_servers%& "as it says"
+.row &%mysql_servers%& "default MySQL servers"
+.row &%oracle_servers%& "Oracle servers"
+.row &%pgsql_servers%& "default PostgreSQL servers"
.row &%sqlite_lock_timeout%& "as it says"
.endtable
-.section "Message ids"
+.section "Message ids" "SECID102"
.table2
.row &%message_id_header_domain%& "used to build &'Message-ID:'& header"
.row &%message_id_header_text%& "ditto"
-.section "Embedded Perl Startup"
+.section "Embedded Perl Startup" "SECID103"
.table2
.row &%perl_at_start%& "always start the interpreter"
.row &%perl_startup%& "code to obey when starting Perl"
-.section "Daemon"
+.section "Daemon" "SECID104"
.table2
.row &%daemon_smtp_ports%& "default ports"
.row &%daemon_startup_retries%& "number of times to retry"
-.section "Resource control"
+.section "Resource control" "SECID105"
.table2
.row &%check_log_inodes%& "before accepting a message"
.row &%check_log_space%& "before accepting a message"
.row &%check_spool_space%& "before accepting a message"
.row &%deliver_queue_load_max%& "no queue deliveries if load high"
.row &%queue_only_load%& "queue incoming if load high"
+.row &%queue_only_load_latch%& "don't re-evaluate load for each message"
.row &%queue_run_max%& "maximum simultaneous queue runners"
.row &%remote_max_parallel%& "parallel SMTP delivery per message"
.row &%smtp_accept_max%& "simultaneous incoming connections"
-.row &%smtp_accept_max_nommail%& "non-mail commands"
+.row &%smtp_accept_max_nonmail%& "non-mail commands"
.row &%smtp_accept_max_nonmail_hosts%& "hosts to which the limit applies"
.row &%smtp_accept_max_per_connection%& "messages per connection"
.row &%smtp_accept_max_per_host%& "connections from one host"
-.section "Policy controls"
+.section "Policy controls" "SECID106"
.table2
.row &%acl_not_smtp%& "ACL for non-SMTP messages"
.row &%acl_not_smtp_mime%& "ACL for non-SMTP MIME parts"
+.row &%acl_not_smtp_start%& "ACL for start of non-SMTP message"
.row &%acl_smtp_auth%& "ACL for AUTH"
.row &%acl_smtp_connect%& "ACL for connection"
.row &%acl_smtp_data%& "ACL for DATA"
+.row &%acl_smtp_dkim%& "ACL for DKIM verification"
.row &%acl_smtp_etrn%& "ACL for ETRN"
.row &%acl_smtp_expn%& "ACL for EXPN"
.row &%acl_smtp_helo%& "ACL for EHLO or HELO"
.row &%message_size_limit%& "for all messages"
.row &%percent_hack_domains%& "recognize %-hack for these domains"
.row &%spamd_address%& "set interface to SpamAssassin"
+.row &%strict_acl_vars%& "object to unset ACL variables"
.endtable
-.section "Callout cache"
+.section "Callout cache" "SECID107"
.table2
.row &%callout_domain_negative_expire%& "timeout for negative domain cache &&&
item"
-.section "TLS"
+.section "TLS" "SECID108"
.table2
+.row &%gnutls_compat_mode%& "use GnuTLS compatibility mode"
+.row &%openssl_options%& "adjust OpenSSL compatibility options"
.row &%tls_advertise_hosts%& "advertise TLS to these hosts"
.row &%tls_certificate%& "location of server certificate"
.row &%tls_crl%& "certificate revocation list"
+.row &%tls_dh_max_bits%& "clamp D-H bit count suggestion"
.row &%tls_dhparam%& "DH parameters for server"
.row &%tls_on_connect_ports%& "specify SSMTP (SMTPS) ports"
.row &%tls_privatekey%& "location of server private key"
.row &%tls_remember_esmtp%& "don't reset after starting TLS"
-.row &%tls_require_ciphers%& "specify acceptable cipers"
+.row &%tls_require_ciphers%& "specify acceptable ciphers"
.row &%tls_try_verify_hosts%& "try to verify client certificate"
.row &%tls_verify_certificates%& "expected client certificates"
.row &%tls_verify_hosts%& "insist on client certificate verify"
-.section "Local user handling"
+.section "Local user handling" "SECID109"
.table2
.row &%finduser_retries%& "useful in NIS environments"
.row &%gecos_name%& "used when creating &'Sender:'&"
-.section "All incoming messages (SMTP and non-SMTP)"
+.section "All incoming messages (SMTP and non-SMTP)" "SECID110"
.table2
.row &%header_maxsize%& "total size of message header"
.row &%header_line_maxsize%& "individual header line limit"
.row &%received_header_text%& "expanded to make &'Received:'&"
.row &%received_headers_max%& "for mail loop detection"
.row &%recipients_max%& "limit per message"
-.row &%recipients_max_reject%& "permanently reject excess"
+.row &%recipients_max_reject%& "permanently reject excess recipients"
.endtable
-.section "Non-SMTP incoming messages"
+.section "Non-SMTP incoming messages" "SECID111"
.table2
.row &%receive_timeout%& "for non-SMTP messages"
.endtable
-.section "Incoming SMTP messages"
+.section "Incoming SMTP messages" "SECID112"
See also the &'Policy controls'& section above.
.table2
-.section "SMTP extensions"
+.section "SMTP extensions" "SECID113"
.table2
.row &%accept_8bitmime%& "advertise 8BITMIME"
.row &%auth_advertise_hosts%& "advertise AUTH to these hosts"
-.section "Processing messages"
+.section "Processing messages" "SECID114"
.table2
.row &%allow_domain_literals%& "recognize domain literal syntax"
.row &%allow_mx_to_ip%& "allow MX to point to IP address"
.row &%check_rfc2047_length%& "check length of RFC 2047 &""encoded &&&
words""&"
.row &%delivery_date_remove%& "from incoming messages"
-.row &%envelope_to_remote%& "from incoming messages"
+.row &%envelope_to_remove%& "from incoming messages"
.row &%extract_addresses_remove_arguments%& "affects &%-t%& processing"
.row &%headers_charset%& "default for translations"
.row &%qualify_domain%& "default for senders"
-.section "System filter"
+.section "System filter" "SECID115"
.table2
.row &%system_filter%& "locate system filter"
.row &%system_filter_directory_transport%& "transport for delivery to a &&&
-.section "Routing and delivery"
+.section "Routing and delivery" "SECID116"
.table2
+.row &%disable_ipv6%& "do no IPv6 processing"
.row &%dns_again_means_nonexist%& "for broken domains"
.row &%dns_check_names_pattern%& "pre-DNS syntax check"
.row &%dns_ipv4_lookup%& "only v4 lookup for these domains"
.row &%dns_retrans%& "parameter for resolver"
.row &%dns_retry%& "parameter for resolver"
+.new
+.row &%dns_use_dnssec%& "parameter for resolver"
+.wen
+.row &%dns_use_edns0%& "parameter for resolver"
.row &%hold_domains%& "hold delivery for these domains"
.row &%local_interfaces%& "for routing checks"
.row &%queue_domains%& "no immediate delivery for these"
.row &%queue_only%& "no immediate delivery at all"
.row &%queue_only_file%& "no immediate delivery if file exists"
.row &%queue_only_load%& "no immediate delivery if load is high"
+.row &%queue_only_load_latch%& "don't re-evaluate load for each message"
.row &%queue_only_override%& "allow command line to override"
.row &%queue_run_in_order%& "order of arrival"
.row &%queue_run_max%& "of simultaneous queue runners"
-.section "Bounce and warning messages"
+.section "Bounce and warning messages" "SECID117"
.table2
.row &%bounce_message_file%& "content of bounce"
.row &%bounce_message_text%& "content of bounce"
.row &%bounce_return_message%& "include original message in bounce"
.row &%bounce_return_size_limit%& "limit on returned message"
.row &%bounce_sender_authentication%& "send authenticated sender with bounce"
+.row &%dsn_from%& "set &'From:'& contents in bounces"
.row &%errors_copy%& "copy bounce messages"
.row &%errors_reply_to%& "&'Reply-to:'& in bounces"
.row &%delay_warning%& "time schedule"
Those options that undergo string expansion before use are marked with
†.
-.option accept_8bitmime main boolean false
+.option accept_8bitmime main boolean true
.cindex "8BITMIME"
.cindex "8-bit characters"
This option causes Exim to send 8BITMIME in its response to an SMTP
EHLO command, and to accept the BODY= parameter on MAIL commands.
However, though Exim is 8-bit clean, it is not a protocol converter, and it
takes no steps to do anything special with messages received by this route.
-Consequently, this option is turned off by default.
+
+Historically Exim kept this option off by default, but the maintainers
+feel that in today's Internet, this causes more problems than it solves.
+It now defaults to true.
+A more detailed analysis of the issues is provided by Dan Bernstein:
+.display
+&url(http://cr.yp.to/smtp/8bitmime.html)
+.endd
.option acl_not_smtp main string&!! unset
.cindex "&ACL;" "for non-SMTP messages"
.cindex "non-SMTP messages" "ACLs for"
-This option defines the ACL that is run when a non-SMTP message is on the point
-of being accepted. See chapter &<<CHAPACL>>& for further details.
+This option defines the ACL that is run when a non-SMTP message has been
+read and is on the point of being accepted. See chapter &<<CHAPACL>>& for
+further details.
-.new
.option acl_not_smtp_mime main string&!! unset
This option defines the ACL that is run for individual MIME parts of non-SMTP
messages. It operates in exactly the same way as &%acl_smtp_mime%& operates for
SMTP messages.
-.wen
+
+.option acl_not_smtp_start main string&!! unset
+.cindex "&ACL;" "at start of non-SMTP message"
+.cindex "non-SMTP messages" "ACLs for"
+This option defines the ACL that is run before Exim starts reading a
+non-SMTP message. See chapter &<<CHAPACL>>& for further details.
.option acl_smtp_auth main string&!! unset
.cindex "&ACL;" "setting up for SMTP commands"
.cindex "DATA" "ACL for"
This option defines the ACL that is run after an SMTP DATA command has been
processed and the message itself has been received, but before the final
-acknowledgement is sent. See chapter &<<CHAPACL>>& for further details.
+acknowledgment is sent. See chapter &<<CHAPACL>>& for further details.
.option acl_smtp_etrn main string&!! unset
.cindex "ETRN" "ACL for"
further details.
.option acl_smtp_quit main string&!! unset
-.cindex "QUIT" "ACL for"
+.cindex "QUIT, ACL for"
This option defines the ACL that is run when an SMTP QUIT command is
received. See chapter &<<CHAPACL>>& for further details.
received. See chapter &<<CHAPACL>>& for further details.
.option acl_smtp_starttls main string&!! unset
-.cindex "STARTTLS" "ACL for"
+.cindex "STARTTLS, ACL for"
This option defines the ACL that is run when an SMTP STARTTLS command is
received. See chapter &<<CHAPACL>>& for further details.
.option admin_groups main "string list&!!" unset
.cindex "admin user"
-.new
This option is expanded just once, at the start of Exim's processing. If the
current group or any of the supplementary groups of an Exim caller is in this
colon-separated list, the caller has admin privileges. If all your system
admin privileges by putting that group in &%admin_groups%&. However, this does
not permit them to read Exim's spool files (whose group owner is the Exim gid).
To permit this, you have to add individuals to the Exim group.
-.wen
.option allow_domain_literals main boolean false
.cindex "domain literal"
.code
auth_advertise_hosts = ${if eq{$tls_cipher}{}{}{*}}
.endd
-.cindex "&$tls_cipher$&"
+.vindex "&$tls_cipher$&"
If &$tls_cipher$& is empty, the session is not encrypted, and the result of
the expansion is empty, thus matching no hosts. Otherwise, the result of the
expansion is *, which matches all hosts.
.option auto_thaw main time 0s
-.new
.cindex "thawing messages"
.cindex "unfreezing messages"
If this option is set to a time greater than zero, a queue runner will try a
&*Note*&: This is an old option, which predates &%timeout_frozen_after%& and
&%ignore_bounce_errors_after%&. It is retained for compatibility, but it is not
thought to be very useful any more, and its use should probably be avoided.
-.wen
+
.option av_scanner main string "see below"
This option is available if Exim is built with the content-scanning extension.
.code
sophie:/var/run/sophie
.endd
-If the value of &%av_scanner%& starts with dollar character, it is expanded
+If the value of &%av_scanner%& starts with a dollar character, it is expanded
before use. See section &<<SECTscanvirus>>& for further details.
-
.option bi_command main string unset
-.cindex "&%-bi%& option"
+.oindex "&%-bi%&"
This option supplies the name of a command that is run when Exim is called with
the &%-bi%& option (see chapter &<<CHAPcommandline>>&). The string value is
just the command name, it is not a complete command line. If an argument is
.option bounce_return_body main boolean true
.cindex "bounce message" "including body"
This option controls whether the body of an incoming message is included in a
-bounce message when &%bounce_return_message%& is true. If it is not set, only
-the message header is included.
+bounce message when &%bounce_return_message%& is true. The default setting
+causes the entire message, both header and body, to be returned (subject to the
+value of &%bounce_return_size_limit%&). If this option is false, only the
+message header is included. In the case of a non-SMTP message containing an
+error that is detected during reception, only those header lines preceding the
+point at which the error was detected are returned.
.cindex "bounce message" "including original"
.option bounce_return_message main boolean true
-If this option is set false, the original message is not included in bounce
-messages generated by Exim. See also &%bounce_return_size_limit%&.
+If this option is set false, none of the original message is included in
+bounce messages generated by Exim. See also &%bounce_return_size_limit%& and
+&%bounce_return_body%&.
.option bounce_return_size_limit main integer 100K
-.cindex "size limit" "of bounce"
+.cindex "size" "of bounce, limit"
.cindex "bounce message" "size limit"
.cindex "limit" "bounce message size"
This option sets a limit in bytes on the size of messages that are returned to
This option defines the &"random"& local part that can be used as part of
callout verification. The default value is
.code
-$primary_host_name-$tod_epoch-testing
+$primary_hostname-$tod_epoch-testing
.endd
See section &<<CALLaddparcall>>& for details of how this value is used.
.oindex "&%check_rfc2047_length%&"
.cindex "RFC 2047" "disabling length check"
-.option check_rfc2047_length " User: main" boolean true
+.option check_rfc2047_length main boolean true
RFC 2047 defines a way of encoding non-ASCII characters in headers using a
system of &"encoded words"&. The RFC specifies a maximum length for an encoded
word; strings to be encoded that exceed this length are supposed to use
.option check_spool_space main integer 0
.cindex "checking disk space"
-.cindex "disk space" "checking"
+.cindex "disk space, checking"
.cindex "spool directory" "checking space"
The four &%check_...%& options allow for checking of disk resources before a
message is accepted.
-.cindex "&$log_inodes$&"
-.cindex "&$log_space$&"
-.cindex "&$spool_inodes$&"
-.cindex "&$spool_space$&"
+.vindex "&$log_inodes$&"
+.vindex "&$log_space$&"
+.vindex "&$spool_inodes$&"
+.vindex "&$spool_space$&"
When any of these options are set, they apply to all incoming messages. If you
want to apply different checks to different kinds of message, you can do so by
-testing the the variables &$log_inodes$&, &$log_space$&, &$spool_inodes$&, and
+testing the variables &$log_inodes$&, &$log_space$&, &$spool_inodes$&, and
&$spool_space$& in an ACL with appropriate additional conditions.
listens. See chapter &<<CHAPinterfaces>>& for details of how it is used. For
backward compatibility, &%daemon_smtp_port%& (singular) is a synonym.
-.new
.option daemon_startup_retries main integer 9
-.cindex "daemon startup" "retrying"
+.cindex "daemon startup, retrying"
This option, along with &%daemon_startup_sleep%&, controls the retrying done by
the daemon at startup when it cannot immediately bind a listening socket
(typically because the socket is already in use): &%daemon_startup_retries%&
.option daemon_startup_sleep main time 30s
See &%daemon_startup_retries%&.
-.wen
.option delay_warning main "time list" 24h
.cindex "warning of delay"
-.cindex "delay warning" "specifying"
+.cindex "delay warning, specifying"
When a message is delayed, Exim sends a warning message to the sender at
intervals specified by this option. The data is a colon-separated list of times
after which to send warning messages. If the value of the option is an empty
.endd
.option delay_warning_condition main string&!! "see below"
-.cindex "&$domain$&"
+.vindex "&$domain$&"
The string is expanded at the time a warning message might be sent. If all the
deferred addresses have the same domain, it is set in &$domain$& during the
expansion. Otherwise &$domain$& is empty. If the result of the expansion is a
forced failure, an empty string, or a string matching any of &"0"&, &"no"& or
&"false"& (the comparison being done caselessly) then the warning message is
-not sent. The default is
+not sent. The default is:
.code
-delay_warning_condition = \
- ${if match{$h_precedence:}{(?i)bulk|list|junk}{no}{yes}}
+delay_warning_condition = ${if or {\
+ { !eq{$h_list-id:$h_list-post:$h_list-subscribe:}{} }\
+ { match{$h_precedence:}{(?i)bulk|list|junk} }\
+ { match{$h_auto-submitted:}{(?i)auto-generated|auto-replied} }\
+ } {no}{yes}}
.endd
-which suppresses the sending of warnings about messages that have &"bulk"&,
-&"list"& or &"junk"& in a &'Precedence:'& header.
+This suppresses the sending of warnings for messages that contain &'List-ID:'&,
+&'List-Post:'&, or &'List-Subscribe:'& headers, or have &"bulk"&, &"list"& or
+&"junk"& in a &'Precedence:'& header, or have &"auto-generated"& or
+&"auto-replied"& in an &'Auto-Submitted:'& header.
.option deliver_drop_privilege main boolean false
.cindex "unprivileged delivery"
removed at the time the message is received, to avoid any problems that might
occur when a delivered message is subsequently sent on to some other recipient.
+.option disable_fsync main boolean false
+.cindex "&[fsync()]&, disabling"
+This option is available only if Exim was built with the compile-time option
+ENABLE_DISABLE_FSYNC. When this is not set, a reference to &%disable_fsync%& in
+a runtime configuration generates an &"unknown option"& error. You should not
+build Exim with ENABLE_DISABLE_FSYNC or set &%disable_fsync%& unless you
+really, really, really understand what you are doing. &'No pre-compiled
+distributions of Exim should ever make this option available.'&
+
+When &%disable_fsync%& is set true, Exim no longer calls &[fsync()]& to force
+updated files' data to be written to disc before continuing. Unexpected events
+such as crashes and power outages may cause data to be lost or scrambled.
+Here be Dragons. &*Beware.*&
+
+
+.option disable_ipv6 main boolean false
+.cindex "IPv6" "disabling"
+If this option is set true, even if the Exim binary has IPv6 support, no IPv6
+activities take place. AAAA records are never looked up, and any IPv6 addresses
+that are listed in &%local_interfaces%&, data for the &%manualroute%& router,
+etc. are ignored. If IP literals are enabled, the &(ipliteral)& router declines
+to handle IPv6 literal addresses.
+
+
.option dns_again_means_nonexist main "domain list&!!" unset
.cindex "DNS" "&""try again""& response; overriding"
DNS lookups give a &"try again"& response for the DNS errors
.code
dns_again_means_nonexist = *.in-addr.arpa
.endd
-This option applies to all DNS lookups that Exim does. The &(dnslookup)& router
-has some options of its own for controlling what happens when lookups for MX or
-SRV records give temporary errors. These more specific options are applied
-after the global option.
+This option applies to all DNS lookups that Exim does. It also applies when the
+&[gethostbyname()]& or &[getipnodebyname()]& functions give temporary errors,
+since these are most likely to be caused by DNS lookup problems. The
+&(dnslookup)& router has some options of its own for controlling what happens
+when lookups for MX or SRV records give temporary errors. These more specific
+options are applied after this global option.
.option dns_check_names_pattern main string "see below"
.cindex "DNS" "pre-check of name syntax"
When this option is set to a non-empty string, it causes Exim to check domain
-names for illegal characters before handing them to the DNS resolver, because
-some resolvers give temporary errors for malformed names. If a domain name
-contains any illegal characters, a &"not found"& result is forced, and the
-resolver is not called. The check is done by matching the domain name against a
-regular expression, which is the value of this option. The default pattern is
+names for characters that are not allowed in host names before handing them to
+the DNS resolver, because some resolvers give temporary errors for names that
+contain unusual characters. If a domain name contains any unwanted characters,
+a &"not found"& result is forced, and the resolver is not called. The check is
+done by matching the domain name against a regular expression, which is the
+value of this option. The default pattern is
.code
dns_check_names_pattern = \
- (?i)^(?>(?(1)\.|())[^\W_](?>[a-z0-9-]*[^\W_])?)+$
+ (?i)^(?>(?(1)\.|())[^\W_](?>[a-z0-9/-]*[^\W_])?)+$
.endd
-which permits only letters, digits, and hyphens in components, but they may not
-start or end with a hyphen.
-If you set &%allow_utf8_domains%&, you must modify this pattern, or set the
-option to an empty string.
+which permits only letters, digits, slashes, and hyphens in components, but
+they must start and end with a letter or digit. Slashes are not, in fact,
+permitted in host names, but they are found in certain NS records (which can be
+accessed in Exim by using a &%dnsdb%& lookup). If you set
+&%allow_utf8_domains%&, you must modify this pattern, or set the option to an
+empty string.
-.new
.option dns_csa_search_limit main integer 5
This option controls the depth of parental searching for CSA SRV records in the
DNS, as described in more detail in section &<<SECTverifyCSA>>&.
This option controls whether or not an IP address, given as a CSA domain, is
reversed and looked up in the reverse DNS, as described in more detail in
section &<<SECTverifyCSA>>&.
-.wen
.option dns_ipv4_lookup main "domain list&!!" unset
.cindex "IPv6" "DNS lookup for AAAA records"
.cindex "DNS" "IPv6 lookup for AAAA records"
-When Exim is compiled with IPv6 support, it looks for IPv6 address records
-(AAAA and, if configured, A6) as well as IPv4 address records when trying to
-find IP addresses for hosts, unless the host's domain matches this list.
+When Exim is compiled with IPv6 support and &%disable_ipv6%& is not set, it
+looks for IPv6 address records (AAAA records) as well as IPv4 address records
+(A records) when trying to find IP addresses for hosts, unless the host's
+domain matches this list.
This is a fudge to help with name servers that give big delays or otherwise do
-not work for the new IPv6 record types. If Exim is handed an IPv6 address
-record as a result of an MX lookup, it always recognizes it, and may as a
-result make an outgoing IPv6 connection. All this option does is to make Exim
-look only for IPv4-style A records when it needs to find an IP address for a
-host name. In due course, when the world's name servers have all been upgraded,
-there should be no need for this option.
+not work for the AAAA record type. In due course, when the world's name
+servers have all been upgraded, there should be no need for this option.
.option dns_retrans main time 0s
See &%dns_retrans%& above.
+.new
+.option dns_use_dnssec main integer -1
+.cindex "DNS" "resolver options"
+.cindex "DNS" "DNSSEC"
+If this option is set to a non-negative number then Exim will initialise the
+DNS resolver library to either use or not use DNSSEC, overriding the system
+default. A value of 0 coerces DNSSEC off, a value of 1 coerces DNSSEC on.
+
+If the resolver library does not support DNSSEC then this option has no effect.
+.wen
+
+
+.option dns_use_edns0 main integer -1
+.cindex "DNS" "resolver options"
+.cindex "DNS" "EDNS0"
+If this option is set to a non-negative number then Exim will initialise the
+DNS resolver library to either use or not use EDNS0 extensions, overriding
+the system default. A value of 0 coerces EDNS0 off, a value of 1 coerces EDNS0
+on.
+
+If the resolver library does not support EDNS0 then this option has no effect.
+
+
.option drop_cr main boolean false
This is an obsolete option that is now a no-op. It used to affect the way Exim
handled CR and LF characters in incoming messages. What happens now is
described in section &<<SECTlineendings>>&.
+.option dsn_from main "string&!!" "see below"
+.cindex "&'From:'& header line" "in bounces"
+.cindex "bounce messages" "&'From:'& line, specifying"
+This option can be used to vary the contents of &'From:'& header lines in
+bounces and other automatically generated messages (&"Delivery Status
+Notifications"& &-- hence the name of the option). The default setting is:
+.code
+dsn_from = Mail Delivery System <Mailer-Daemon@$qualify_domain>
+.endd
+The value is expanded every time it is needed. If the expansion fails, a
+panic is logged, and the default value is used.
.option envelope_to_remove main boolean true
.cindex "&'Envelope-to:'& header line"
rqps@mydomain hostmaster@mydomain.example,\
postmaster@mydomain.example
.endd
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
The address list is expanded before use. The expansion variables &$local_part$&
and &$domain$& are set from the original recipient of the error message, and if
there was any wildcard matching in the pattern, the expansion
.option errors_reply_to main string unset
.cindex "bounce message" "&'Reply-to:'& in"
-Exim's bounce and delivery warning messages contain the header line
+By default, Exim's bounce and delivery warning messages contain the header line
.display
&`From: Mail Delivery System <Mailer-Daemon@`&&'qualify-domain'&&`>`&
.endd
+.oindex &%quota_warn_message%&
where &'qualify-domain'& is the value of the &%qualify_domain%& option.
+A warning message that is generated by the &%quota_warn_message%& option in an
+&(appendfile)& transport may contain its own &'From:'& header line that
+overrides the default.
+
Experience shows that people reply to bounce messages. If the
&%errors_reply_to%& option is set, a &'Reply-To:'& header is added to bounce
and warning messages. For example:
errors_reply_to = postmaster@my.domain.example
.endd
The value of the option is not expanded. It must specify a valid RFC 2822
-address.
+address. However, if a warning message that is generated by the
+&%quota_warn_message%& option in an &(appendfile)& transport contain its
+own &'Reply-To:'& header line, the value of the &%errors_reply_to%& option is
+not used.
.option exim_group main string "compile-time configured"
.option exim_path main string "see below"
-.cindex "Exim binary" "path name"
+.cindex "Exim binary, path name"
This option specifies the path name of the Exim binary, which is used when Exim
needs to re-exec itself. The default is set up to point to the file &'exim'& in
the directory configured at compile time by the BIN_DIRECTORY setting. It
&<<SECTreclocipadd>>& for details.
-.option "extract_addresses_remove_ &~arguments" main boolean true
-.cindex "&%-t%& option"
+. Allow this long option name to split; give it unsplit as a fifth argument
+. for the automatic .oindex that is generated by .option.
+
+.option "extract_addresses_remove_ &~&~arguments" main boolean true &&&
+ extract_addresses_remove_arguments
+.oindex "&%-t%&"
.cindex "command line" "addresses with &%-t%&"
.cindex "Sendmail compatibility" "&%-t%& option"
According to some Sendmail documentation (Sun, IRIX, HP-UX), if any addresses
.option finduser_retries main integer 0
-.cindex "NIS" "looking up users; retrying"
+.cindex "NIS, retrying user lookups"
On systems running NIS or other schemes in which user and group information is
distributed from a remote system, there can be times when &[getpwnam()]& and
related functions fail, even when given valid data, because things time out.
.option gecos_name main string&!! unset
.cindex "HP-UX"
-.cindex "&""gecos""& field" "parsing"
+.cindex "&""gecos""& field, parsing"
Some operating systems, notably HP-UX, use the &"gecos"& field in the system
password file to hold other information in addition to users' real names. Exim
looks up this field for use when it is creating &'Sender:'& or &'From:'&
See &%gecos_name%& above.
+.option gnutls_compat_mode main boolean unset
+This option controls whether GnuTLS is used in compatibility mode in an Exim
+server. This reduces security slightly, but improves interworking with older
+implementations of TLS.
+
.option headers_charset main string "see below"
This option sets a default character set for translating from encoded MIME
&"words"& in header lines, when referenced by an &$h_xxx$& expansion item. The
.option helo_try_verify_hosts main "host list&!!" unset
-.new
.cindex "HELO verifying" "optional"
-.cindex "EHLO verifying" "optional"
+.cindex "EHLO" "verifying, optional"
By default, Exim just checks the syntax of HELO and EHLO commands (see
&%helo_accept_junk_hosts%& and &%helo_allow_chars%&). However, some sites like
to do more extensive checking of the data supplied by these commands. The ACL
-condition &`verify`& &`=`& &`helo`& is provided to make this possible.
+condition &`verify = helo`& is provided to make this possible.
Formerly, it was necessary also to set this option (&%helo_try_verify_hosts%&)
to force the check to occur. From release 4.53 onwards, this is no longer
-necessary. If the check has not been done before &`verify`& &`=`& &`helo`& is
+necessary. If the check has not been done before &`verify = helo`& is
encountered, it is done at that time. Consequently, this option is obsolete.
Its specification is retained here for backwards compatibility.
However, the EHLO or HELO command is not rejected if any of the checks
fail. Processing continues, but the result of the check is remembered, and can
-be detected later in an ACL by the &`verify`& &`=`& &`helo`& condition.
+be detected later in an ACL by the &`verify = helo`& condition.
.option helo_verify_hosts main "host list&!!" unset
.cindex "HELO verifying" "mandatory"
-.cindex "EHLO verifying" "mandatory"
+.cindex "EHLO" "verifying, mandatory"
Like &%helo_try_verify_hosts%&, this option is obsolete, and retained only for
backwards compatibility. For hosts that match this option, Exim checks the host
name given in the HELO or EHLO in the same way as for
rejected with a 550 error, and entries are written to the main and reject logs.
If a MAIL command is received before EHLO or HELO, it is rejected with a 503
error.
-.wen
.option hold_domains main "domain list&!!" unset
.cindex "domain" "delaying delivery"
.option host_lookup main "host list&!!" unset
-.cindex "host name lookup" "forcing"
+.cindex "host name" "lookup, forcing"
Exim does not look up the name of a calling host from its IP address unless it
is required to compare against some host list, or the host matches
&%helo_try_verify_hosts%& or &%helo_verify_hosts%&, or the host matches this
has obtained, to verify that it yields the IP address that it started with. If
this check fails, Exim behaves as if the name lookup failed.
-.cindex "&$host_lookup_failed$&"
-.cindex "&$sender_host_name$&"
+.vindex "&$host_lookup_failed$&"
+.vindex "&$sender_host_name$&"
After any kind of failure, the host name (in &$sender_host_name$&) remains
unset, and &$host_lookup_failed$& is set to the string &"1"&. See also
-&%dns_again_means_nonexist%&, &%helo_lookup_domains%&, and &`verify`& &`=`&
-&`reverse_host_lookup`& in ACLs.
+&%dns_again_means_nonexist%&, &%helo_lookup_domains%&, and
+&`verify = reverse_host_lookup`& in ACLs.
.option host_lookup_order main "string list" &`bydns:byaddr`&
&(smtp)& transport for the local host (see the &%allow_localhost%& option in
that transport). See also &%local_interfaces%&, &%extra_local_interfaces%&, and
chapter &<<CHAPinterfaces>>&, which contains a discussion about local network
-interfaces and recognising the local host.
+interfaces and recognizing the local host.
+
+
+.option ibase_servers main "string list" unset
+.cindex "InterBase" "server list"
+This option provides a list of InterBase servers and associated connection data,
+to be used in conjunction with &(ibase)& lookups (see section &<<SECID72>>&).
+The option is available only if Exim has been built with InterBase support.
+
.option ignore_bounce_errors_after main time 10w
logged.
+.option ldap_ca_cert_dir main string unset
+.cindex "LDAP", "TLS CA certificate directory"
+This option indicates which directory contains CA certificates for verifying
+a TLS certificate presented by an LDAP server.
+While Exim does not provide a default value, your SSL library may.
+Analogous to &%tls_verify_certificates%& but as a client-side option for LDAP
+and constrained to be a directory.
+
+
+.option ldap_ca_cert_file main string unset
+.cindex "LDAP", "TLS CA certificate file"
+This option indicates which file contains CA certificates for verifying
+a TLS certificate presented by an LDAP server.
+While Exim does not provide a default value, your SSL library may.
+Analogous to &%tls_verify_certificates%& but as a client-side option for LDAP
+and constrained to be a file.
+
+
+.option ldap_cert_file main string unset
+.cindex "LDAP" "TLS client certificate file"
+This option indicates which file contains an TLS client certificate which
+Exim should present to the LDAP server during TLS negotiation.
+Should be used together with &%ldap_cert_key%&.
+
+
+.option ldap_cert_key main string unset
+.cindex "LDAP" "TLS client key file"
+This option indicates which file contains the secret/private key to use
+to prove identity to the LDAP server during TLS negotiation.
+Should be used together with &%ldap_cert_file%&, which contains the
+identity to be proven.
+
+
+.option ldap_cipher_suite main string unset
+.cindex "LDAP" "TLS cipher suite"
+This controls the TLS cipher-suite negotiation during TLS negotiation with
+the LDAP server. See &<<SECTreqciphssl>>& for more details of the format of
+cipher-suite options with OpenSSL (as used by LDAP client libraries).
+
+
.option ldap_default_servers main "string list" unset
.cindex "LDAP" "default servers"
This option provides a list of LDAP servers which are tried in turn when an
with LDAP support.
+.option ldap_require_cert main string unset.
+.cindex "LDAP" "policy for LDAP server TLS cert presentation"
+This should be one of the values "hard", "demand", "allow", "try" or "never".
+A value other than one of these is interpreted as "never".
+See the entry "TLS_REQCERT" in your system man page for ldap.conf(5).
+Although Exim does not set a default, the LDAP library probably defaults
+to hard/demand.
+
+
+.option ldap_start_tls main boolean false
+.cindex "LDAP" "whether or not to negotiate TLS"
+If set, Exim will attempt to negotiate TLS with the LDAP server when
+connecting on a regular LDAP port. This is the LDAP equivalent of SMTP's
+"STARTTLS". This is distinct from using "ldaps", which is the LDAP form
+of SSL-on-connect.
+In the event of failure to negotiate TLS, the action taken is controlled
+by &%ldap_require_cert%&.
+
+
.option ldap_version main integer unset
-.cindex "LDAP protocol version" "forcing"
+.cindex "LDAP" "protocol version, forcing"
This option can be used to force Exim to set a specific protocol version for
LDAP. If it option is unset, it is shown by the &%-bP%& command line option as
-1. When this is the case, the default is 3 if LDAP_VERSION3 is defined in
.option localhost_number main string&!! unset
.cindex "host" "locally unique number for"
.cindex "message ids" "with multiple hosts"
-.cindex "&$localhost_number$&"
+.vindex "&$localhost_number$&"
Exim's message ids are normally unique only within the local host. If
uniqueness among a set of hosts is required, each host must set a different
value for the &%localhost_number%& option. The string is expanded immediately
.option log_timezone main boolean false
.cindex "log" "timezone for entries"
-.cindex "&$tod_log$&"
-.cindex "&$tod_zone$&"
+.vindex "&$tod_log$&"
+.vindex "&$tod_zone$&"
By default, the timestamps on log lines are in local time without the
timezone. This means that if your timezone changes twice a year, the timestamps
in log lines are ambiguous for an hour when the clocks go back. One way of
.option lookup_open_max main integer 25
.cindex "too many open files"
-.cindex "open files" "too many"
+.cindex "open files, too many"
.cindex "file" "too many open"
.cindex "lookup" "maximum open files"
.cindex "limit" "open files for lookups"
an argument that is longer behaves as if &[getpwnam()]& failed.
+.option message_body_newlines main bool false
+.cindex "message body" "newlines in variables"
+.cindex "newline" "in message body variables"
+.vindex "&$message_body$&"
+.vindex "&$message_body_end$&"
+By default, newlines in the message body are replaced by spaces when setting
+the &$message_body$& and &$message_body_end$& expansion variables. If this
+option is set true, this no longer happens.
+
.option message_body_visible main integer 500
.cindex "body of message" "visible size"
.cindex "message body" "visible size"
-.cindex "&$message_body$&"
-.cindex "&$message_body_end$&"
+.vindex "&$message_body$&"
+.vindex "&$message_body_end$&"
This option specifies how much of a message's body is to be included in the
&$message_body$& and &$message_body_end$& expansion variables.
.option message_logs main boolean true
-.cindex "message log" "disabling"
+.cindex "message logs" "disabling"
.cindex "log" "message log; disabling"
If this option is turned off, per-message log files are not created in the
&_msglog_& spool sub-directory. This reduces the amount of disk I/O required by
.option message_size_limit main string&!! 50M
.cindex "message" "size limit"
.cindex "limit" "message size"
-.cindex "size of message" "limit"
+.cindex "size" "of message, limit"
This option limits the maximum size of message that Exim will process. The
-value is expanded for each incoming
-connection so, for example, it can be made to depend on the IP address of the
-remote host for messages arriving via TCP/IP. &*Note*&: This limit cannot be
-made to depend on a message's sender or any other properties of an individual
-message, because it has to be advertised in the server's response to EHLO.
-String expansion failure causes a temporary error. A value of zero means no
-limit, but its use is not recommended. See also &%bounce_return_size_limit%&.
+value is expanded for each incoming connection so, for example, it can be made
+to depend on the IP address of the remote host for messages arriving via
+TCP/IP. After expansion, the value must be a sequence of decimal digits,
+optionally followed by K or M.
+
+&*Note*&: This limit cannot be made to depend on a message's sender or any
+other properties of an individual message, because it has to be advertised in
+the server's response to EHLO. String expansion failure causes a temporary
+error. A value of zero means no limit, but its use is not recommended. See also
+&%bounce_return_size_limit%&.
Incoming SMTP messages are failed with a 552 error if the limit is
exceeded; locally-generated messages either get a stderr message or a delivery
the generic transport option &%message_size_limit%&, which limits the size of
message that an individual transport can process.
+If you use a virus-scanner and set this option to to a value larger than the
+maximum size that your virus-scanner is configured to support, you may get
+failures triggered by large mails. The right size to configure for the
+virus-scanner depends upon what data is passed and the options in use but it's
+probably safest to just set it to a little larger than this value. Eg, with a
+default Exim message size of 50M and a default ClamAV StreamMaxLength of 10M,
+some problems may result.
+
+A value of 0 will disable size limit checking; Exim will still advertise the
+SIZE extension in an EHLO response, but without a limit, so as to permit
+SMTP clients to still indicate the message size along with the MAIL verb.
+
.option move_frozen_messages main boolean false
.cindex "frozen messages" "moving"
.option mysql_servers main "string list" unset
.cindex "MySQL" "server list"
This option provides a list of MySQL servers and associated connection data, to
-be used in conjunction with &(mysql)& lookups (see section &<<SECTsql>>&). The
+be used in conjunction with &(mysql)& lookups (see section &<<SECID72>>&). The
option is available only if Exim has been built with MySQL support.
.option never_users main "string list&!!" unset
-.new
This option is expanded just once, at the start of Exim's processing. Local
message deliveries are normally run in processes that are setuid to the
recipient, and remote deliveries are normally run under Exim's own uid and gid.
It is usually desirable to prevent any deliveries from running as root, as a
safety precaution.
-.wen
When Exim is built, an option called FIXED_NEVER_USERS can be set to a
list of users that must not be used for local deliveries. This list is fixed in
transport driver.
+.option openssl_options main "string list" "+no_sslv2"
+.cindex "OpenSSL "compatibility options"
+This option allows an administrator to adjust the SSL options applied
+by OpenSSL to connections. It is given as a space-separated list of items,
+each one to be +added or -subtracted from the current value.
+
+This option is only available if Exim is built against OpenSSL. The values
+available for this option vary according to the age of your OpenSSL install.
+The &"all"& value controls a subset of flags which are available, typically
+the bug workaround options. The &'SSL_CTX_set_options'& man page will
+list the values known on your system and Exim should support all the
+&"bug workaround"& options and many of the &"modifying"& options. The Exim
+names lose the leading &"SSL_OP_"& and are lower-cased.
+
+Note that adjusting the options can have severe impact upon the security of
+SSL as used by Exim. It is possible to disable safety checks and shoot
+yourself in the foot in various unpleasant ways. This option should not be
+adjusted lightly. An unrecognised item will be detected at startup, by
+invoking Exim with the &%-bV%& flag.
+
+Historical note: prior to release 4.80, Exim defaulted this value to
+"+dont_insert_empty_fragments", which may still be needed for compatibility
+with some clients, but which lowers security by increasing exposure to
+some now infamous attacks.
+
+An example:
+.code
+# Make both old MS and old Eudora happy:
+openssl_options = -all +microsoft_big_sslv3_buffer \
+ +dont_insert_empty_fragments
+.endd
+
+Possible options may include:
+.ilist
+&`all`&
+.next
+&`allow_unsafe_legacy_renegotiation`&
+.next
+&`cipher_server_preference`&
+.next
+&`dont_insert_empty_fragments`&
+.next
+&`ephemeral_rsa`&
+.next
+&`legacy_server_connect`&
+.next
+&`microsoft_big_sslv3_buffer`&
+.next
+&`microsoft_sess_id_bug`&
+.next
+&`msie_sslv2_rsa_padding`&
+.next
+&`netscape_challenge_bug`&
+.next
+&`netscape_reuse_cipher_change_bug`&
+.next
+&`no_compression`&
+.next
+&`no_session_resumption_on_renegotiation`&
+.next
+&`no_sslv2`&
+.next
+&`no_sslv3`&
+.next
+&`no_ticket`&
+.next
+&`no_tlsv1`&
+.next
+&`no_tlsv1_1`&
+.next
+&`no_tlsv1_2`&
+.next
+&`single_dh_use`&
+.next
+&`single_ecdh_use`&
+.next
+&`ssleay_080_client_dh_bug`&
+.next
+&`sslref2_reuse_cert_type_bug`&
+.next
+&`tls_block_padding_bug`&
+.next
+&`tls_d5_bug`&
+.next
+&`tls_rollback_bug`&
+.endlist
+
+
.option oracle_servers main "string list" unset
.cindex "Oracle" "server list"
This option provides a list of Oracle servers and associated connection data,
-to be used in conjunction with &(oracle)& lookups (see section &<<SECTsql>>&).
+to be used in conjunction with &(oracle)& lookups (see section &<<SECID72>>&).
The option is available only if Exim has been built with Oracle support.
.cindex "PostgreSQL lookup type" "server list"
This option provides a list of PostgreSQL servers and associated connection
data, to be used in conjunction with &(pgsql)& lookups (see section
-&<<SECTsql>>&). The option is available only if Exim has been built with
+&<<SECID72>>&). The option is available only if Exim has been built with
PostgreSQL support.
.option pid_file_path main string&!! "set at compile time"
.cindex "daemon" "pid file path"
-.cindex "pid file" "path for"
+.cindex "pid file, path for"
This option sets the name of the file to which the Exim daemon writes its
process id. The string is expanded, so it can contain, for example, references
to the host name:
.option pipelining_advertise_hosts main "host list&!!" *
-.cindex "PIPELINING advertising" "suppressing"
+.cindex "PIPELINING" "suppressing advertising"
This option can be used to suppress the advertisement of the SMTP
-PIPELINING extension to specific hosts. When PIPELINING is not
-advertised and &%smtp_enforce_sync%& is true, an Exim server enforces strict
-synchronization for each SMTP command and response.
-When PIPELINING is advertised, Exim assumes that clients will use it; &"out
-of order"& commands that are &"expected"& do not count as protocol errors (see
-&%smtp_max_synprot_errors%&).
+PIPELINING extension to specific hosts. See also the &*no_pipelining*&
+control in section &<<SECTcontrols>>&. When PIPELINING is not advertised and
+&%smtp_enforce_sync%& is true, an Exim server enforces strict synchronization
+for each SMTP command and response. When PIPELINING is advertised, Exim assumes
+that clients will use it; &"out of order"& commands that are &"expected"& do
+not count as protocol errors (see &%smtp_max_synprot_errors%&).
.option preserve_message_logs main boolean false
.cindex "name" "of local host"
.cindex "host" "name of local"
.cindex "local host" "name of"
-.cindex "&$primary_hostname$&"
+.vindex "&$primary_hostname$&"
This specifies the name of the current host. It is used in the default EHLO or
HELO command for outgoing SMTP messages (changeable via the &%helo_data%&
option in the &(smtp)& transport), and as the default for &%qualify_domain%&.
is set, code values of 128 and above are also considered to be printing
characters.
+This option also affects the header syntax checks performed by the
+&(autoreply)& transport, and whether Exim uses RFC 2047 encoding of
+the user's full name when constructing From: and Sender: addresses (as
+described in section &<<SECTconstr>>&). Setting this option can cause
+Exim to generate eight bit message headers that do not conform to the
+standards.
+
.option process_log_path main string unset
.cindex "process log path"
.option prod_requires_admin main boolean true
-.cindex "&%-M%& option"
-.cindex "&%-R%& option"
-.cindex "&%-q%& option"
+.oindex "&%-M%&"
+.oindex "&%-R%&"
+.oindex "&%-q%&"
The &%-M%&, &%-R%&, and &%-q%& command-line options require the caller to be an
admin user unless &%prod_requires_admin%& is set false. See also
&%queue_list_requires_admin%&.
.option queue_list_requires_admin main boolean true
-.cindex "&%-bp%& option"
+.oindex "&%-bp%&"
The &%-bp%& command-line option, which lists the messages that are on the
queue, requires the caller to be an admin user unless
&%queue_list_requires_admin%& is set false. See also &%prod_requires_admin%&.
This option can be set to a colon-separated list of absolute path names, each
one optionally preceded by &"smtp"&. When Exim is receiving a message,
it tests for the existence of each listed path using a call to &[stat()]&. For
-each path that exists, the corresponding queuing option is set.
+each path that exists, the corresponding queueing option is set.
For paths with no prefix, &%queue_only%& is set; for paths prefixed by
&"smtp"&, &%queue_smtp_domains%& is set to match all domains. So, for example,
.code
.cindex "message" "queueing by load"
If the system load average is higher than this value, incoming messages from
all sources are queued, and no automatic deliveries are started. If this
-happens during local or remote SMTP input, all subsequent messages on the same
-connection are queued. Deliveries will subsequently be performed by queue
-runner processes. This option has no effect on ancient operating systems on
-which Exim cannot determine the load average. See also
-&%deliver_queue_load_max%& and &%smtp_load_reserve%&.
+happens during local or remote SMTP input, all subsequent messages received on
+the same SMTP connection are queued by default, whatever happens to the load in
+the meantime, but this can be changed by setting &%queue_only_load_latch%&
+false.
+
+Deliveries will subsequently be performed by queue runner processes. This
+option has no effect on ancient operating systems on which Exim cannot
+determine the load average. See also &%deliver_queue_load_max%& and
+&%smtp_load_reserve%&.
+
+
+.option queue_only_load_latch main boolean true
+.cindex "load average" "re-evaluating per message"
+When this option is true (the default), once one message has been queued
+because the load average is higher than the value set by &%queue_only_load%&,
+all subsequent messages received on the same SMTP connection are also queued.
+This is a deliberate choice; even though the load average may fall below the
+threshold, it doesn't seem right to deliver later messages on the same
+connection when not delivering earlier ones. However, there are special
+circumstances such as very long-lived connections from scanning appliances
+where this is not the best strategy. In such cases, &%queue_only_load_latch%&
+should be set false. This causes the value of the load average to be
+re-evaluated for each message.
.option queue_only_override main boolean true
If this option is set, queue runs happen in order of message arrival instead of
in an arbitrary order. For this to happen, a complete list of the entire queue
must be set up before the deliveries start. When the queue is all held in a
-single directory (the default),
-
-a single list is created for both the ordered and the non-ordered cases.
-However, if &%split_spool_directory%& is set, a single list is not created when
-&%queue_run_in_order%& is false. In this case, the sub-directories are
-processed one at a time (in a random order), and this avoids setting up one
-huge list for the whole queue. Thus, setting &%queue_run_in_order%& with
-&%split_spool_directory%& may degrade performance when the queue is large,
-because of the extra work in setting up the single, large list. In most
-situations, &%queue_run_in_order%& should not be set.
+single directory (the default), a single list is created for both the ordered
+and the non-ordered cases. However, if &%split_spool_directory%& is set, a
+single list is not created when &%queue_run_in_order%& is false. In this case,
+the sub-directories are processed one at a time (in a random order), and this
+avoids setting up one huge list for the whole queue. Thus, setting
+&%queue_run_in_order%& with &%split_spool_directory%& may degrade performance
+when the queue is large, because of the extra work in setting up the single,
+large list. In most situations, &%queue_run_in_order%& should not be set.
however, interlock with other processes, so additional queue runners can be
started by other means, or by killing and restarting the daemon.
-.new
Setting this option to zero does not suppress queue runs; rather, it disables
the limit, allowing any number of simultaneous queue runner processes to be
run. If you do not want queue runs to occur, omit the &%-q%&&'xx'& setting on
the daemon's command line.
-.wen
.option queue_smtp_domains main "domain list&!!" unset
.cindex "queueing incoming messages"
&"Received:"& and conform to the RFC 2822 specification for &'Received:'&
header lines. The default setting is:
-.new
.code
received_header_text = Received: \
${if def:sender_rcvhost {from $sender_rcvhost\n\t}\
{${if def:sender_ident \
- {from ${quote_local_part: $sender_ident} }}\
+ {from ${quote_local_part:$sender_ident} }}\
${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\
by $primary_hostname \
${if def:received_protocol {with $received_protocol}} \
id $message_exim_id\
${if def:received_for {\n\tfor $received_for}}
.endd
-.wen
The reference to the TLS cipher is omitted when Exim is built without TLS
support. The use of conditional expansions ensures that this works for both
If it is purely remote deliveries you want to control, use
&%queue_smtp_domains%& instead of &%queue_only%&. This has the added benefit of
-doing the SMTP routing before queuing, so that several messages for the same
+doing the SMTP routing before queueing, so that several messages for the same
host will eventually get delivered down the same connection.
Chapter &<<CHAPretry>>& describes Exim's mechanisms for controlling the
intervals between delivery attempts for messages that cannot be delivered
straight away. This option sets an overall limit to the length of time between
-retries.
+retries. It cannot be set greater than 24 hours; any attempt to do so forces
+the default value.
.option return_path_remove main boolean true
RFC 1413 identification calls are made to any client host which matches an item
in the list.
-
-.option rfc1413_query_timeout main time 30s
+.option rfc1413_query_timeout main time 5s
.cindex "RFC 1413" "query timeout"
.cindex "timeout" "for RFC 1413 call"
This sets the timeout on RFC 1413 identification calls. If it is set to zero,
This option controls the setting of the SO_KEEPALIVE option on incoming
TCP/IP socket connections. When set, it causes the kernel to probe idle
connections periodically, by sending packets with &"old"& sequence numbers. The
-other end of the connection should send an acknowledgement if the connection is
+other end of the connection should send an acknowledgment if the connection is
still okay or a reset if the connection has been aborted. The reason for doing
this is that it has the beneficial effect of freeing up certain types of
connection that can get stuck when the remote host is disconnected without
control (in Exim) when incoming SMTP is being handled by &'inetd'&. If the
value is set to zero, no limit is applied. However, it is required to be
non-zero if either &%smtp_accept_max_per_host%& or &%smtp_accept_queue%& is
-set. See also &%smtp_accept_reserve%&.
+set. See also &%smtp_accept_reserve%& and &%smtp_load_reserve%&.
+A new SMTP connection is immediately rejected if the &%smtp_accept_max%& limit
+has been reached. If not, Exim first checks &%smtp_accept_max_per_host%&. If
+that limit has not been reached for the client host, &%smtp_accept_reserve%&
+and &%smtp_load_reserve%& are then checked before accepting the connection.
.option smtp_accept_max_nonmail main integer 10
When a new message is expected, one occurrence of RSET is not counted. This
allows a client to send one RSET between messages (this is not necessary,
-but some clients do it). Exim also allows one uncounted occurence of HELO
+but some clients do it). Exim also allows one uncounted occurrence of HELO
or EHLO, and one occurrence of STARTTLS between messages. After
starting up a TLS session, another EHLO is expected, and so it too is not
counted. The first occurrence of AUTH in a connection, or immediately
live with.
+. Allow this long option name to split; give it unsplit as a fifth argument
+. for the automatic .oindex that is generated by .option.
-.option smtp_accept_max_per_connection main integer 1000
-.cindex "SMTP incoming message count" "limiting"
+.option "smtp_accept_max_per_ &~&~connection" main integer 1000 &&&
+ smtp_accept_max_per_connection
+.cindex "SMTP" "limiting incoming message count"
.cindex "limit" "messages per SMTP connection"
The value of this option limits the number of MAIL commands that Exim is
prepared to accept over a single SMTP connection, whether or not each command
host (strictly, from a single IP address) to the Exim daemon. The option is
expanded, to enable different limits to be applied to different hosts by
reference to &$sender_host_address$&. Once the limit is reached, additional
-connection attempts from the same host are rejected with error code 421. The
-default value of zero imposes no limit. If this option is set, it is required
-that &%smtp_accept_max%& be non-zero.
+connection attempts from the same host are rejected with error code 421. This
+is entirely independent of &%smtp_accept_reserve%&. The option's default value
+of zero imposes no limit. If this option is set greater than zero, it is
+required that &%smtp_accept_max%& be non-zero.
&*Warning*&: When setting this option you should not use any expansion
constructions that take an appreciable amount of time. The expansion and test
.cindex "SMTP" "incoming connection count"
.cindex "queueing incoming messages"
.cindex "message" "queueing by SMTP connection count"
-If the number of simultaneous incoming SMTP calls handled via the listening
-daemon exceeds this value, messages received by SMTP are just placed on the
-queue; no delivery processes are started automatically. A value of zero implies
-no limit, and clearly any non-zero value is useful only if it is less than the
-&%smtp_accept_max%& value (unless that is zero). See also &%queue_only%&,
-&%queue_only_load%&, &%queue_smtp_domains%&, and the various &%-od%&&'x'&
-command line options.
+If the number of simultaneous incoming SMTP connections being handled via the
+listening daemon exceeds this value, messages received by SMTP are just placed
+on the queue; no delivery processes are started automatically. The count is
+fixed at the start of an SMTP connection. It cannot be updated in the
+subprocess that receives messages, and so the queueing or not queueing applies
+to all messages received in the same connection.
+A value of zero implies no limit, and clearly any non-zero value is useful only
+if it is less than the &%smtp_accept_max%& value (unless that is zero). See
+also &%queue_only%&, &%queue_only_load%&, &%queue_smtp_domains%&, and the
+various &%-od%&&'x'& command line options.
-.option smtp_accept_queue_per_connection main integer 10
+
+. Allow this long option name to split; give it unsplit as a fifth argument
+. for the automatic .oindex that is generated by .option.
+
+.option "smtp_accept_queue_per_ &~&~connection" main integer 10 &&&
+ smtp_accept_queue_per_connection
.cindex "queueing incoming messages"
.cindex "message" "queueing by message count"
This option limits the number of delivery processes that Exim starts
that are specified in &%smtp_reserve_hosts%&. The value set in
&%smtp_accept_max%& includes this reserve pool. The specified hosts are not
restricted to this number of connections; the option specifies a minimum number
-of connection slots for them, not a maximum. It is a guarantee that that group
-of hosts can always get at least &%smtp_accept_reserve%& connections.
+of connection slots for them, not a maximum. It is a guarantee that this group
+of hosts can always get at least &%smtp_accept_reserve%& connections. However,
+the limit specified by &%smtp_accept_max_per_host%& is still applied to each
+individual host.
For example, if &%smtp_accept_max%& is set to 50 and &%smtp_accept_reserve%& is
set to 5, once there are 45 active connections (from any hosts), new
-connections are accepted only from hosts listed in &%smtp_reserve_hosts%&.
-See also &%smtp_accept_max_per_host%&.
+connections are accepted only from hosts listed in &%smtp_reserve_hosts%&,
+provided the other criteria for acceptance are met.
.option smtp_active_hostname main string&!! unset
.cindex "host" "name in SMTP responses"
.cindex "SMTP" "host name in responses"
-.cindex "&$primary_hostname$&"
+.vindex "&$primary_hostname$&"
This option is provided for multi-homed servers that want to masquerade as
-several different hosts. At the start of an SMTP connection, its value is
-expanded and used instead of the value of &$primary_hostname$& in SMTP
+several different hosts. At the start of an incoming SMTP connection, its value
+is expanded and used instead of the value of &$primary_hostname$& in SMTP
responses. For example, it is used as domain name in the response to an
incoming HELO or EHLO command.
-.cindex "&$smtp_active_hostname$&"
-It is also used in HELO commands for callout verification. The active hostname
-is placed in the &$smtp_active_hostname$& variable, which is saved with any
-messages that are received. It is therefore available for use in routers and
-transports when the message is later delivered.
+.vindex "&$smtp_active_hostname$&"
+The active hostname is placed in the &$smtp_active_hostname$& variable, which
+is saved with any messages that are received. It is therefore available for use
+in routers and transports when the message is later delivered.
If this option is unset, or if its expansion is forced to fail, or if the
expansion results in an empty string, the value of &$primary_hostname$& is
value of &%smtp_active_hostname%& depends on the incoming interface address.
For example:
.code
-smtp_active_hostname = ${if eq{$interface_address}{10.0.0.1}\
+smtp_active_hostname = ${if eq{$received_ip_address}{10.0.0.1}\
{cox.mydomain}{box.mydomain}}
.endd
+Although &$smtp_active_hostname$& is primarily concerned with incoming
+messages, it is also used as the default for HELO commands in callout
+verification if there is no remote transport from which to obtain a
+&%helo_data%& value.
+
.option smtp_banner main string&!! "see below"
.cindex "SMTP" "welcome banner"
.cindex "banner for SMTP"
.option smtp_check_spool_space main boolean true
.cindex "checking disk space"
-.cindex "disk space" "checking"
+.cindex "disk space, checking"
.cindex "spool directory" "checking space"
When this option is set, if an incoming SMTP session encounters the SIZE
option on a MAIL command, it checks that there is enough space in the
.option smtp_etrn_command main string&!! unset
.cindex "ETRN" "command to be run"
-.cindex "&$domain$&"
+.vindex "&$domain$&"
If this option is set, the given command is run whenever an SMTP ETRN
command is received from a host that is permitted to issue such commands (see
chapter &<<CHAPACL>>&). The string is split up into separate arguments which
can send them messages, and the rate at which an individual message can specify
recipients.
-.new
Exim has two rate-limiting facilities. This section describes the older
facility, which can limit rates within a single connection. The newer
&%ratelimit%& ACL condition can limit rates across all connections. See section
&<<SECTratelimiting>>& for details of the newer facility.
-.wen
When a host matches &%smtp_ratelimit_hosts%&, the values of
&%smtp_ratelimit_mail%& and &%smtp_ratelimit_rcpt%& are used to control the
.option smtp_receive_timeout main time 5m
.cindex "timeout" "for SMTP input"
-.cindex "SMTP timeout" "input"
+.cindex "SMTP" "input timeout"
This sets a timeout value for SMTP reception. It applies to all forms of SMTP
input, including batch SMTP. If a line of input (either an SMTP command or a
data line) is not received within this time, the SMTP connection is dropped and
means that it was in the DATA phase, reading the contents of a message.
-.cindex "&%-os%& option"
+.oindex "&%-os%&"
The value set by this option can be overridden by the
&%-os%& command-line option. A setting of zero time disables the timeout, but
this should never be used for SMTP over TCP/IP. (It can be useful in some cases
.option smtp_return_error_details main boolean false
.cindex "SMTP" "details policy failures"
-.cindex "policy control rejection" "returning details"
+.cindex "policy control" "rejection, returning details"
In the default state, Exim uses bland messages such as
&"Administrative prohibition"& when it rejects SMTP commands for policy
reasons. Many sysadmins like this because it gives away little information
-to spammers. However, some other syadmins who are applying strict checking
+to spammers. However, some other sysadmins who are applying strict checking
policies want to give out much fuller information about failures. Setting
&%smtp_return_error_details%& true causes Exim to be more forthcoming. For
example, instead of &"Administrative prohibition"&, it might give:
.option split_spool_directory main boolean false
.cindex "multiple spool directories"
.cindex "spool directory" "split"
-.cindex "directories" "multiple"
+.cindex "directories, multiple"
If this option is set, it causes Exim to split its input directory into 62
subdirectories, each with a single alphanumeric character as its name. The
sixth character of the message id is used to allocate messages to
By using this option to override the compiled-in path, it is possible to run
tests of Exim without using the standard spool.
-.new
.option sqlite_lock_timeout main time 5s
-.cindex "sqlite" "lock timeout"
+.cindex "sqlite lookup type" "lock timeout"
This option controls the timeout that the &(sqlite)& lookup uses when trying to
access an SQLite database. See section &<<SECTsqlite>>& for more details.
-.wen
+
+.option strict_acl_vars main boolean false
+.cindex "&ACL;" "variables, handling unset"
+This option controls what happens if a syntactically valid but undefined ACL
+variable is referenced. If it is false (the default), an empty string
+is substituted; if it is true, an error is generated. See section
+&<<SECTaclvariables>>& for details of ACL variables.
.option strip_excess_angle_brackets main boolean false
-.cindex "angle brackets" "excess"
+.cindex "angle brackets, excess"
If this option is set, redundant pairs of angle brackets round &"route-addr"&
items in addresses are stripped. For example, &'<<xxx@a.b.c.d>>'& is
treated as &'<xxx@a.b.c.d>'&. If this is in the envelope and the message is
.option system_filter_directory_transport main string&!! unset
-.cindex "&$address_file$&"
+.vindex "&$address_file$&"
This sets the name of the transport driver that is to be used when the
&%save%& command in a system message filter specifies a path ending in &"/"&,
implying delivery of each message into a separate file in some directory.
.option system_filter_pipe_transport main string&!! unset
.cindex "&(pipe)& transport" "for system filter"
-.cindex "&$address_pipe$&"
+.vindex "&$address_pipe$&"
This specifies the transport driver that is to be used when a &%pipe%& command
is used in a system filter. During the delivery, the variable &$address_pipe$&
contains the pipe command.
This specifies the transport driver that is to be used when a &%mail%& command
is used in a system filter.
+
.option system_filter_user main string unset
.cindex "uid (user id)" "system filter"
-If this option is not set, the system filter is run in the main Exim delivery
-process, as root. When the option is set, the system filter runs in a separate
-process, as the given user. Unless the string consists entirely of digits, it
+If this option is set to root, the system filter is run in the main Exim
+delivery process, as root. Otherwise, the system filter runs in a separate
+process, as the given user, defaulting to the Exim run-time user.
+Unless the string consists entirely of digits, it
is looked up in the password data. Failure to find the named user causes a
configuration error. The gid is either taken from the password data, or
specified by &%system_filter_group%&. When the uid is specified numerically,
If the system filter generates any pipe, file, or reply deliveries, the uid
under which the filter is run is used when transporting them, unless a
-transport option overrides. Normally you should set &%system_filter_user%& if
-your system filter generates these kinds of delivery.
+transport option overrides.
.option tcp_nodelay main boolean true
.cindex "frozen messages" "timing out"
.cindex "timeout" "frozen messages"
If &%timeout_frozen_after%& is set to a time greater than zero, a frozen
-message of any kind that has been on the queue for longer than the given
-time is automatically cancelled at the next queue run. If it is a bounce
-message, it is just discarded; otherwise, a bounce is sent to the sender, in a
-similar manner to cancellation by the &%-Mg%& command line option. If you want
-to timeout frozen bounce messages earlier than other kinds of frozen message,
-see &%ignore_bounce_errors_after%&.
+message of any kind that has been on the queue for longer than the given time
+is automatically cancelled at the next queue run. If the frozen message is a
+bounce message, it is just discarded; otherwise, a bounce is sent to the
+sender, in a similar manner to cancellation by the &%-Mg%& command line option.
+If you want to timeout frozen bounce messages earlier than other kinds of
+frozen message, see &%ignore_bounce_errors_after%&.
+
+&*Note:*& the default value of zero means no timeouts; with this setting,
+frozen messages remain on the queue forever (except for any frozen bounce
+messages that are released by &%ignore_bounce_errors_after%&).
.option timezone main string unset
-.cindex "timezone" "setting"
+.cindex "timezone, setting"
The value of &%timezone%& is used to set the environment variable TZ while
running Exim (if it is different on entry). This ensures that all timestamps
created by Exim are in the required timezone. If you want all your timestamps
.option tls_certificate main string&!! unset
.cindex "TLS" "server certificate; location of"
-.cindex "certificate for server" "location of"
+.cindex "certificate" "server, location of"
The value of this option is expanded, and must then be the absolute path to a
file which contains the server's certificates. The server's private key is also
assumed to be in this file if &%tls_privatekey%& is unset. See chapter
use when sending messages as a client, you must set the &%tls_certificate%&
option in the relevant &(smtp)& transport.
+If the option contains &$tls_sni$& and Exim is built against OpenSSL, then
+if the OpenSSL build supports TLS extensions and the TLS client sends the
+Server Name Indication extension, then this option and others documented in
+&<<SECTtlssni>>& will be re-expanded.
.option tls_crl main string&!! unset
.cindex "TLS" "server certificate revocation list"
This option specifies a certificate revocation list. The expanded value must
be the name of a file that contains a CRL in PEM format.
+See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
+
+
+.option tls_dh_max_bits main integer 2236
+.cindex "TLS" "D-H bit count"
+The number of bits used for Diffie-Hellman key-exchange may be suggested by
+the chosen TLS library. That value might prove to be too high for
+interoperability. This option provides a maximum clamp on the value
+suggested, trading off security for interoperability.
+
+The value must be at least 1024.
+
+The value 2236 was chosen because, at time of adding the option, it was the
+hard-coded maximum value supported by the NSS cryptographic library, as used
+by Thunderbird, while GnuTLS was suggesting 2432 bits as normal.
+
+If you prefer more security and are willing to break some clients, raise this
+number.
+
+Note that the value passed to GnuTLS for *generating* a new prime may be a
+little less than this figure, because GnuTLS is inexact and may produce a
+larger prime than requested.
+
.option tls_dhparam main string&!! unset
.cindex "TLS" "D-H parameters for server"
-The value of this option is expanded, and must then be the absolute path to
-a file which contains the server's DH parameter values.
-This is used only for OpenSSL. When Exim is linked with GnuTLS, this option is
-ignored. See section &<<SECTopenvsgnu>>& for further details.
+The value of this option is expanded and indicates the source of DH parameters
+to be used by Exim.
+
+If it is a filename starting with a &`/`&, then it names a file from which DH
+parameters should be loaded. If the file exists, it should hold a PEM-encoded
+PKCS#3 representation of the DH prime. If the file does not exist, for
+OpenSSL it is an error. For GnuTLS, Exim will attempt to create the file and
+fill it with a generated DH prime. For OpenSSL, if the DH bit-count from
+loading the file is greater than &%tls_dh_max_bits%& then it will be ignored,
+and treated as though the &%tls_dhparam%& were set to "none".
+
+If this option expands to the string "none", then no DH parameters will be
+loaded by Exim.
+
+If this option expands to the string "historic" and Exim is using GnuTLS, then
+Exim will attempt to load a file from inside the spool directory. If the file
+does not exist, Exim will attempt to create it.
+See section &<<SECTgnutlsparam>>& for further details.
+
+If Exim is using OpenSSL and this option is empty or unset, then Exim will load
+a default DH prime; the default is the 2048 bit prime described in section
+2.2 of RFC 5114, "2048-bit MODP Group with 224-bit Prime Order Subgroup", which
+in IKE is assigned number 23.
+
+Otherwise, the option must expand to the name used by Exim for any of a number
+of DH primes specified in RFC 2409, RFC 3526 and RFC 5114. As names, Exim uses
+"ike" followed by the number used by IKE, of "default" which corresponds to
+"ike23".
+
+The available primes are:
+&`ike1`&, &`ike2`&, &`ike5`&,
+&`ike14`&, &`ike15`&, &`ike16`&, &`ike17`&, &`ike18`&,
+&`ike22`&, &`ike23`& (aka &`default`&) and &`ike24`&.
+
+Some of these will be too small to be accepted by clients.
+Some may be too large to be accepted by clients.
.option tls_on_connect_ports main "string list" unset
.option tls_privatekey main string&!! unset
.cindex "TLS" "server private key; location of"
The value of this option is expanded, and must then be the absolute path to a
-file which contains the server's private key. If this option is unset, the
-private key is assumed to be in the same file as the server's certificates. See
-chapter &<<CHAPTLS>>& for further details.
+file which contains the server's private key. If this option is unset, or if
+the expansion is forced to fail, or the result is an empty string, the private
+key is assumed to be in the same file as the server's certificates. See chapter
+&<<CHAPTLS>>& for further details.
+
+See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
.option tls_remember_esmtp main boolean false
directory containing certificate files. This does not work with GnuTLS; the
option must be set to the name of a single file if you are using GnuTLS.
+These certificates should be for the certificate authorities trusted, rather
+than the public cert of individual clients. With both OpenSSL and GnuTLS, if
+the value is a file then the certificates are sent by Exim as a server to
+connecting clients, defining the list of accepted certificate authorities.
+Thus the values defined should be considered public data. To avoid this,
+use OpenSSL with a directory.
+
+See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
+
.option tls_verify_hosts main "host list&!!" unset
.cindex "TLS" "client certificate verification"
.cindex "certificate" "verification of client"
This option, along with &%tls_try_verify_hosts%&, controls the checking of
-certificates from clients.
-The expected certificates are defined by &%tls_verify_certificates%&, which
-must be set. A configuration error occurs if either &%tls_verify_hosts%& or
-&%tls_try_verify_hosts%& is set and &%tls_verify_certificates%& is not set.
+certificates from clients. The expected certificates are defined by
+&%tls_verify_certificates%&, which must be set. A configuration error occurs if
+either &%tls_verify_hosts%& or &%tls_try_verify_hosts%& is set and
+&%tls_verify_certificates%& is not set.
Any client that matches &%tls_verify_hosts%& is constrained by
-&%tls_verify_certificates%&. The client must present one of the listed
-certificates. If it does not, the connection is aborted.
+&%tls_verify_certificates%&. When the client initiates a TLS session, it must
+present one of the listed certificates. If it does not, the connection is
+aborted. &*Warning*&: Including a host in &%tls_verify_hosts%& does not require
+the host to use TLS. It can still send SMTP commands through unencrypted
+connections. Forcing a client to use TLS has to be done separately using an
+ACL to reject inappropriate commands when the connection is not encrypted.
A weaker form of checking is provided by &%tls_try_verify_hosts%&. If a client
matches this option (but not &%tls_verify_hosts%&), Exim requests a
.option trusted_groups main "string list&!!" unset
-.cindex "trusted group"
-.cindex "group" "trusted"
-.new
+.cindex "trusted groups"
+.cindex "groups" "trusted"
This option is expanded just once, at the start of Exim's processing. If this
option is set, any process that is running in one of the listed groups, or
which has one of them as a supplementary group, is trusted. The groups can be
details of what trusted callers are permitted to do. If neither
&%trusted_groups%& nor &%trusted_users%& is set, only root and the Exim user
are trusted.
-.wen
.option trusted_users main "string list&!!" unset
-.cindex "trusted user"
+.cindex "trusted users"
.cindex "user" "trusted"
-.new
This option is expanded just once, at the start of Exim's processing. If this
option is set, any process that is running as one of the listed users is
trusted. The users can be specified numerically or by name. See section
&<<SECTtrustedadmin>>& for details of what trusted callers are permitted to do.
If neither &%trusted_groups%& nor &%trusted_users%& is set, only root and the
Exim user are trusted.
-.wen
.option unknown_login main string&!! unset
.cindex "uid (user id)" "unknown caller"
-.cindex "&$caller_uid$&"
+.vindex "&$caller_uid$&"
This is a specialized feature for use in unusual configurations. By default, if
the uid of the caller of Exim cannot be looked up using &[getpwuid()]&, Exim
gives up. The &%unknown_login%& option can be used to set a login name to be
See &%unknown_login%&.
.option untrusted_set_sender main "address list&!!" unset
-.cindex "trusted user"
+.cindex "trusted users"
.cindex "sender" "setting by untrusted user"
-.cindex "untrusted user" "setting sender"
+.cindex "untrusted user setting sender"
.cindex "user" "untrusted setting sender"
.cindex "envelope sender"
When an untrusted user submits a message to Exim using the standard input, Exim
.code
exim -f '<>' user@domain.example
.endd
-.cindex "&$sender_ident$&"
+.vindex "&$sender_ident$&"
The &%untrusted_set_sender%& option allows you to permit untrusted users to set
other envelope sender addresses in a controlled way. When it is set, untrusted
users are allowed to set envelope sender addresses that match any of the
.cindex "reject log" "disabling"
If this option is set false, Exim no longer writes anything to the reject log.
See chapter &<<CHAPlog>>& for details of what Exim writes to its logs.
+.ecindex IIDconfima
+.ecindex IIDmaiconf
. ////////////////////////////////////////////////////////////////////////////
.chapter "Generic options for routers" "CHAProutergeneric"
-.cindex "options" "generic; for routers"
-.cindex "generic options" "router"
+.scindex IIDgenoprou1 "options" "generic; for routers"
+.scindex IIDgenoprou2 "generic options" "router"
This chapter describes the generic options that apply to all routers.
Those that are preconditions are marked with ‡ in the &"use"& field.
.option address_data routers string&!! unset
.cindex "router" "data attached to address"
-.new
The string is expanded just before the router is run, that is, after all the
precondition tests have succeeded. If the expansion is forced to fail, the
router declines, the value of &%address_data%& remains unchanged, and the
&%more%& option controls what happens next. Other expansion failures cause
delivery of the address to be deferred.
-.wen
-.cindex "&$address_data$&"
+.vindex "&$address_data$&"
When the expansion succeeds, the value is retained with the address, and can be
accessed using the variable &$address_data$& in the current router, subsequent
routers, and the eventual transport.
This makes the configuration file less messy, and also reduces the number of
lookups (though Exim does cache lookups).
+.vindex "&$sender_address_data$&"
+.vindex "&$address_data$&"
The &%address_data%& facility is also useful as a means of passing information
from one router to another, and from a router to a transport. In addition, if
-
-.cindex "&$sender_address_data$&"
-.cindex "&$address_data$&"
-When &$address_data$& is set by a router when verifying a recipient address
-from an ACL, it remains available for use in the rest of the ACL statement.
-After verifying a sender, the value is transferred to &$sender_address_data$&.
-
+&$address_data$& is set by a router when verifying a recipient address from an
+ACL, it remains available for use in the rest of the ACL statement. After
+verifying a sender, the value is transferred to &$sender_address_data$&.
.option address_test routers&!? boolean true
-.cindex "&%-bt%& option"
+.oindex "&%-bt%&"
.cindex "router" "skipping when address testing"
If this option is set false, the router is skipped when routing is being tested
by means of the &%-bt%& command line option. This can be a convenience when
routed because Exim has run out of routers. The default message is
&"Unrouteable address"&. This option is useful only on routers that have
&%more%& set false, or on the very last router in a configuration, because the
-value that is used is taken from the last router that is considered. &new("This
+value that is used is taken from the last router that is considered. This
includes a router that is skipped because its preconditions are not met, as
-well as a router that declines.") For example, using the default configuration,
+well as a router that declines. For example, using the default configuration,
you could put:
.code
cannot_route_message = Remote domain not found in DNS
turned on by &"+caseful"& as a list item. See section &<<SECTcasletadd>>& for
more details.
-.cindex "&$local_part$&"
-.cindex "&$original_local_part$&"
-.cindex "&$parent_local_part$&"
+.vindex "&$local_part$&"
+.vindex "&$original_local_part$&"
+.vindex "&$parent_local_part$&"
The value of the &$local_part$& variable is forced to lower case while a
router is running unless &%caseful_local_part%& is set. When a router assigns
an address to a transport, the value of &$local_part$& when the transport runs
.option check_local_user routers&!? boolean false
-.cindex "local user" "checking in router"
+.cindex "local user, checking in router"
.cindex "router" "checking for local user"
.cindex "&_/etc/passwd_&"
-.cindex "&$home$&"
+.vindex "&$home$&"
When this option is true, Exim checks that the local part of the recipient
address (with affixes removed if relevant) is the name of an account on the
local system. The check is done by calling the &[getpwnam()]& function rather
If the result is any other value, the router is run (as this is the last
precondition to be evaluated, all the other preconditions must be true).
+This option is unique in that multiple &%condition%& options may be present.
+All &%condition%& options must succeed.
+
The &%condition%& option provides a means of applying custom conditions to the
running of routers. Note that in the case of a simple conditional expansion,
the default expansion values are exactly what is wanted. For example:
.code
condition = ${if >{$message_age}{600}{true}{}}
.endd
+
+A multiple condition example, which succeeds:
+.code
+condition = ${if >{$message_age}{600}}
+condition = ${if !eq{${lc:$local_part}}{postmaster}}
+condition = foobar
+.endd
+
If the expansion fails (other than forced failure) delivery is deferred. Some
of the other precondition options are common special cases that could in fact
be specified using &%condition%&.
-
.option debug_print routers string&!! unset
.cindex "testing" "variables in drivers"
If this option is set and debugging is enabled (see the &%-d%& command line
.option domains routers&!? "domain list&!!" unset
.cindex "router" "restricting to specific domains"
-.cindex "&$domain_data$&"
+.vindex "&$domain_data$&"
If this option is set, the router is skipped unless the current domain matches
the list. If the match is achieved by means of a file lookup, the data that the
lookup returned for the domain is placed in &$domain_data$& for use in string
.option errors_to routers string&!! unset
.cindex "envelope sender"
.cindex "router" "changing address for errors"
-If a router successfully handles an address, it may queue the address for
-delivery or it may generate child addresses. In both cases, if there is a
-delivery problem during later processing, the resulting bounce message is sent
-to the address that results from expanding this string, provided that the
-address verifies successfully. &%errors_to%& is expanded before
-&%headers_add%&, &%headers_remove%&, and &%transport%&.
-
-If the option is unset, or the expansion is forced to fail, or the result of
+If a router successfully handles an address, it may assign the address to a
+transport for delivery or it may generate child addresses. In both cases, if
+there is a delivery problem during later processing, the resulting bounce
+message is sent to the address that results from expanding this string,
+provided that the address verifies successfully. The &%errors_to%& option is
+expanded before &%headers_add%&, &%headers_remove%&, and &%transport%&.
+
+The &%errors_to%& setting associated with an address can be overridden if it
+subsequently passes through other routers that have their own &%errors_to%&
+settings, or if the message is delivered by a transport with a &%return_path%&
+setting.
+
+If &%errors_to%& is unset, or the expansion is forced to fail, or the result of
the expansion fails to verify, the errors address associated with the incoming
address is used. At top level, this is the envelope sender. A non-forced
expansion failure causes delivery to be deferred.
If an address for which &%errors_to%& has been set ends up being delivered over
SMTP, the envelope sender for that delivery is the &%errors_to%& value, so that
any bounces that are generated by other MTAs on the delivery route are also
-sent there. The most common use of &%errors_to%& is probably to direct mailing
-list bounces to the manager of the list, as described in section
-&<<SECTmailinglists>>&.
-
-The &%errors_to%& setting associated with an address can be overridden if it
-subsequently passes through other routers that have their own &%errors_to%&
-settings,
-or if it is delivered by a transport with a &%return_path%& setting.
-
-You can set &%errors_to%& to the empty string by either of these settings:
+sent there. You can set &%errors_to%& to the empty string by either of these
+settings:
.code
errors_to =
-errors_to =
+errors_to = ""
.endd
An expansion item that yields an empty string has the same effect. If you do
this, a locally detected delivery error for addresses processed by this router
address is delivered to a remote host, the return path is set to &`<>`&, unless
overridden by the &%return_path%& option on the transport.
-.cindex "&$address_data$&"
+.vindex "&$address_data$&"
If for some reason you want to discard local errors, but use a non-empty
MAIL command for remote delivery, you can preserve the original return
path in &$address_data$& in the router, and reinstate it in the transport by
setting &%return_path%&.
+The most common use of &%errors_to%& is to direct mailing list bounces to the
+manager of the list, as described in section &<<SECTmailinglists>>&, or to
+implement VERP (Variable Envelope Return Paths) (see section &<<SECTverp>>&).
+
.option expn routers&!? boolean true
.option fallback_hosts routers "string list" unset
-.new
.cindex "router" "fallback hosts"
.cindex "fallback" "hosts specified on router"
String expansion is not applied to this option. The argument must be a
each name or address. In fact, the format of each item is exactly the same as
defined for the list of hosts in a &(manualroute)& router (see section
&<<SECTformatonehostitem>>&).
-.wen
If a router queues an address for a remote transport, this host list is
associated with the address, and used instead of the transport's fallback host
.option headers_add routers string&!! unset
-.new
.cindex "header lines" "adding"
.cindex "router" "adding header lines"
This option specifies a string of text that is expanded at routing time, and
message is in the process of being transported. This means that references to
header lines in string expansions in the transport's configuration do not
&"see"& the added header lines.
-.wen
The &%headers_add%& option is expanded after &%errors_to%&, but before
&%headers_remove%& and &%transport%&. If the expanded string is empty, or if
&*Warning 1*&: The &%headers_add%& option cannot be used for a &(redirect)&
router that has the &%one_time%& option set.
-.new
+.cindex "duplicate addresses"
+.oindex "&%unseen%&"
&*Warning 2*&: If the &%unseen%& option is set on the router, all header
additions are deleted when the address is passed on to subsequent routers.
-.wen
+For a &%redirect%& router, if a generated address is the same as the incoming
+address, this can lead to duplicate addresses with different header
+modifications. Exim does not do duplicate deliveries (except, in certain
+circumstances, to pipes -- see section &<<SECTdupaddr>>&), but it is undefined
+which of the duplicates is discarded, so this ambiguous situation should be
+avoided. The &%repeat_use%& option of the &%redirect%& router may be of help.
.option headers_remove routers string&!! unset
-.new
.cindex "header lines" "removing"
.cindex "router" "removing header lines"
This option specifies a string of text that is expanded at routing time, and
the message is in the process of being transported. This means that references
to header lines in string expansions in the transport's configuration still
&"see"& the original header lines.
-.wen
The &%headers_remove%& option is expanded after &%errors_to%& and
&%headers_add%&, but before &%transport%&. If the expansion is forced to fail,
&*Warning 1*&: The &%headers_remove%& option cannot be used for a &(redirect)&
router that has the &%one_time%& option set.
-.new
&*Warning 2*&: If the &%unseen%& option is set on the router, all header
removal requests are deleted when the address is passed on to subsequent
-routers.
-.wen
+routers, and this can lead to problems with duplicates -- see the similar
+warning for &%headers_add%& above.
.option ignore_target_hosts routers "host list&!!" unset
Similarly, if &%ignore_target_hosts%& is set on an &(ipliteral)& router, the
router declines if presented with one of the listed addresses.
-.new
You can use this option to disable the use of IPv4 or IPv6 for mail delivery by
means of the first or the second of the following settings, respectively:
.code
.endd
The pattern in the first line matches all IPv4 addresses, whereas the pattern
in the second line matches all IPv6 addresses.
-.wen
This option may also be useful for ignoring link-local and site-local IPv6
addresses. Because, like all host lists, the value of &%ignore_target_hosts%&
is expanded before use as a list, it is possible to make it dependent on the
domain that is being routed.
-.cindex "&$host_address$&"
+.vindex "&$host_address$&"
During its expansion, &$host_address$& is set to the IP address that is being
checked.
.option local_part_prefix routers&!? "string list" unset
.cindex "router" "prefix for local part"
-.cindex "prefix" "for local part; used in router"
+.cindex "prefix" "for local part, used in router"
If this option is set, the router is skipped unless the local part starts with
one of the given strings, or &%local_part_prefix_optional%& is true. See
section &<<SECTrouprecon>>& for a list of the order in which preconditions are
Wildcarding can be used to set up multiple user mailboxes, as described in
section &<<SECTmulbox>>&.
-.new
-.cindex "&$local_part$&"
-.cindex "&$local_part_prefix$&"
+.vindex "&$local_part$&"
+.vindex "&$local_part_prefix$&"
During the testing of the &%local_parts%& option, and while the router is
running, the prefix is removed from the local part, and is available in the
expansion variable &$local_part_prefix$&. When a message is being delivered, if
behaviour of the router. If the callout feature of verification is in use, this
means that the full address, including the prefix, will be used during the
callout.
-.wen
The prefix facility is commonly used to handle local parts of the form
&%owner-something%&. Another common use is to support local parts of the form
check_local_user
transport = local_delivery
.endd
+For security, it would probably be a good idea to restrict the use of this
+router to locally-generated messages, using a condition such as this:
+.code
+ condition = ${if match {$sender_host_address}\
+ {\N^(|127\.0\.0\.1)$\N}}
+.endd
+
If both &%local_part_prefix%& and &%local_part_suffix%& are set for a router,
both conditions must be met if not optional. Care must be taken if wildcards
are used in both a prefix and a suffix on the same router. Different
.code
local_parts = dbm;/usr/local/specials/$domain
.endd
-.cindex "&$local_part_data$&"
+.vindex "&$local_part_data$&"
If the match is achieved by a lookup, the data that the lookup returned
for the local part is placed in the variable &$local_part_data$& for use in
expansions of the router's private options. You might use this option, for
deliveries stand out more visibly from remote ones. In the &"local"& style, the
recipient address is given just as the local part, without a domain. The use of
this style is controlled by this option. It defaults to true for the &(accept)&
-router, and false for all the others. &new("This option applies only when a
+router, and false for all the others. This option applies only when a
router assigns an address to a transport. It has no effect on routers that
-redirect addresses.")
+redirect addresses.
If this option is set false, and the router declines to handle the address, no
further routers are tried, routing fails, and the address is bounced.
-.cindex "&%self%& option"
+.oindex "&%self%&"
However, if the router explicitly passes an address to the following router by
means of the setting
.code
does not affect the behaviour if one of the precondition tests fails. In that
case, the address is always passed to the next router.
-.new
Note that &%address_data%& is not considered to be a precondition. If its
expansion is forced to fail, the router declines, and the value of &%more%&
controls what happens next.
-.wen
.option pass_on_timeout routers boolean false
.option pass_router routers string unset
.cindex "router" "go to after &""pass""&"
-When a router returns &"pass"&, the address is normally handed on to the next
+Routers that recognize the generic &%self%& option (&(dnslookup)&,
+&(ipliteral)&, and &(manualroute)&) are able to return &"pass"&, forcing
+routing to continue, and overriding a false setting of &%more%&. When one of
+these routers returns &"pass"&, the address is normally handed on to the next
router in sequence. This can be changed by setting &%pass_router%& to the name
of another router. However (unlike &%redirect_router%&) the named router must
be below the current router, to avoid loops. Note that this option applies only
to the special case of &"pass"&. It does not apply when a router returns
-&"decline"&.
+&"decline"& because it cannot handle an address.
.option router_home_directory routers string&!! unset
.cindex "router" "home directory for"
.cindex "home directory" "for router"
-.cindex "&$home$&"
+.vindex "&$home$&"
This option sets a home directory for use while the router is running. (Compare
&%transport_home_directory%&, which sets a home directory for later
transporting.) In particular, if used on a &(redirect)& router, this option
While the router is running, &%router_home_directory%& overrides the value of
&$home$& that came from &%check_local_user%&.
-When a router accepts an address and routes it to a transport (including the
-cases when a redirect router generates a pipe, file, or autoreply delivery),
-the home directory setting for the transport is taken from the first of these
-values that is set:
+When a router accepts an address and assigns it to a local transport (including
+the cases when a &(redirect)& router generates a pipe, file, or autoreply
+delivery), the home directory setting for the transport is taken from the first
+of these values that is set:
.ilist
The &%home_directory%& option on the transport;
rewritten.
.vitem &%pass%&
-.cindex "&%more%& option"
-.cindex "&$self_hostname$&"
+.oindex "&%more%&"
+.vindex "&$self_hostname$&"
The router passes the address to the next router, or to the router named in the
&%pass_router%& option if it is set. This overrides &%no_more%&. During
subsequent routing and delivery, the variable &$self_hostname$& contains the
code to support this option is not included in the Exim binary unless
SUPPORT_TRANSLATE_IP_ADDRESS=yes is set in &_Local/Makefile_&.
-.cindex "&$host_address$&"
+.vindex "&$host_address$&"
The &%translate_ip_address%& string is expanded for every IP address generated
by the router, with the generated address set in &$host_address$&. If the
expansion is forced to fail, no action is taken.
If the transport does not specify a home directory, and
&%transport_home_directory%& is not set for the router, the home directory for
-the tranport is taken from the password data if &%check_local_user%& is set for
+the transport is taken from the password data if &%check_local_user%& is set for
the router. Otherwise it is taken from &%router_home_directory%& if that option
is set; if not, no home directory is set for the transport.
the value of &%unseen%& contains expansion items (and therefore, presumably, is
sometimes true and sometimes false).
-.new
.cindex "copy of message (&%unseen%& option)"
-The &%unseen%& option can be used to cause copies of messages to be delivered
-to some other destination, while also carrying out a normal delivery. In
-effect, the current address is made into a &"parent"& that has two children &--
-one that is delivered as specified by this router, and a clone that goes on to
-be routed further. For this reason, &%unseen%& may not be combined with the
+Setting the &%unseen%& option has a similar effect to the &%unseen%& command
+qualifier in filter files. It can be used to cause copies of messages to be
+delivered to some other destination, while also carrying out a normal delivery.
+In effect, the current address is made into a &"parent"& that has two children
+&-- one that is delivered as specified by this router, and a clone that goes on
+to be routed further. For this reason, &%unseen%& may not be combined with the
&%one_time%& option in a &(redirect)& router.
-.wen
&*Warning*&: Header lines added to the address (or specified for removal) by
this router or by previous routers affect the &"unseen"& copy of the message
only. The clone that continues to be processed by further routers starts with
-no added headers and none specified for removal. However, any data that was set
-by the &%address_data%& option in the current or previous routers is passed on.
-Setting the &%unseen%& option has a similar effect to the &%unseen%& command
-qualifier in filter files.
+no added headers and none specified for removal. For a &%redirect%& router, if
+a generated address is the same as the incoming address, this can lead to
+duplicate addresses with different header modifications. Exim does not do
+duplicate deliveries (except, in certain circumstances, to pipes -- see section
+&<<SECTdupaddr>>&), but it is undefined which of the duplicates is discarded,
+so this ambiguous situation should be avoided. The &%repeat_use%& option of the
+&%redirect%& router may be of help.
+Unlike the handling of header modifications, any data that was set by the
+&%address_data%& option in the current or previous routers &'is'& passed on to
+subsequent routers.
.option user routers string&!! "see below"
.option verify_only routers&!? boolean false
.cindex "EXPN" "with &%verify_only%&"
-.cindex "&%-bv%& option"
+.oindex "&%-bv%&"
.cindex "router" "used only when verifying"
If this option is set, the router is used only when verifying an address or
testing with the &%-bv%& option, not when actually doing a delivery, testing
or testing sender verification using &%-bvs%&.
See section &<<SECTrouprecon>>& for a list of the order in which preconditions
are evaluated.
+.ecindex IIDgenoprou1
+.ecindex IIDgenoprou2
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The accept router"
+.chapter "The accept router" "CHID4"
.cindex "&(accept)& router"
.cindex "routers" "&(accept)&"
The &(accept)& router has no private options of its own. Unless it is being
. ////////////////////////////////////////////////////////////////////////////
.chapter "The dnslookup router" "CHAPdnslookup"
-.cindex "&(dnslookup)& router"
-.cindex "routers" "&(dnslookup)&"
+.scindex IIDdnsrou1 "&(dnslookup)& router"
+.scindex IIDdnsrou2 "routers" "&(dnslookup)&"
The &(dnslookup)& router looks up the hosts that handle mail for the
recipient's domain in the DNS. A transport must always be set for this router,
unless &%verify_only%& is set.
.cindex "MX record" "pointing to local host"
.cindex "local host" "MX pointing to"
-.cindex "&%self%& option" "in &(dnslookup)& router"
+.oindex "&%self%&" "in &(dnslookup)& router"
If the host pointed to by the highest priority MX record, or looked up as an
address record, is the local host, or matches &%hosts_treat_as_local%&, what
happens is controlled by the generic &%self%& option.
case routing fails.
+.section "Declining addresses by dnslookup" "SECTdnslookupdecline"
+.cindex "&(dnslookup)& router" "declines"
+There are a few cases where a &(dnslookup)& router will decline to accept
+an address; if such a router is expected to handle "all remaining non-local
+domains", then it is important to set &%no_more%&.
+
+Reasons for a &(dnslookup)& router to decline currently include:
+.ilist
+The domain does not exist in DNS
+.next
+The domain exists but the MX record's host part is just "."; this is a common
+convention (borrowed from SRV) used to indicate that there is no such service
+for this domain and to not fall back to trying A/AAAA records.
+.next
+Ditto, but for SRV records, when &%check_srv%& is set on this router.
+.next
+MX record points to a non-existent host.
+.next
+MX record points to an IP address and the main section option
+&%allow_mx_to_ip%& is not set.
+.next
+MX records exist and point to valid hosts, but all hosts resolve only to
+addresses blocked by the &%ignore_target_hosts%& generic option on this router.
+.next
+The domain is not syntactically valid (see also &%allow_utf8_domains%& and
+&%dns_check_names_pattern%& for handling one variant of this)
+.next
+&%check_secondary_mx%& is set on this router but the local host can
+not be found in the MX records (see below)
+.endlist
+
+
-.section "Private options for dnslookup"
+.section "Private options for dnslookup" "SECID118"
.cindex "options" "&(dnslookup)& router"
The private options for the &(dnslookup)& router are as follows:
.cindex "MX record" "required to exist"
.cindex "SRV record" "required to exist"
A domain that matches &%mx_domains%& is required to have either an MX or an SRV
-record in order to be recognised. (The name of this option could be improved.)
+record in order to be recognized. (The name of this option could be improved.)
For example, if all the mail hosts in &'fict.example'& are known to have MX
records, except for those in &'discworld.fict.example'&, you could use this
setting:
&'klingon.dictionary.fict.example'& is looked up, and if this fails,
&'klingon.dictionary.ref.example'& is tried. Note that the &%qualify_single%&
and &%search_parents%& options can cause some widening to be undertaken inside
-the DNS resolver. &new("&%widen_domains%& is not applied to sender addresses
-when verifying, unless &%rewrite_headers%& is false (not the default).")
+the DNS resolver. &%widen_domains%& is not applied to sender addresses
+when verifying, unless &%rewrite_headers%& is false (not the default).
-.section "Effect of qualify_single and search_parents"
+.section "Effect of qualify_single and search_parents" "SECID119"
When a domain from an envelope recipient is changed by the resolver as a result
of the &%qualify_single%& or &%search_parents%& options, Exim rewrites the
corresponding address in the message's header lines unless &%rewrite_headers%&
.endd
that may happen while processing a router precondition before the router is
entered. No widening ever takes place for these lookups.
+.ecindex IIDdnsrou1
+.ecindex IIDdnsrou2
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The ipliteral router"
+.chapter "The ipliteral router" "CHID5"
.cindex "&(ipliteral)& router"
.cindex "domain literal" "routing"
.cindex "routers" "&(ipliteral)&"
This router has no private options. Unless it is being used purely for
verification (see &%verify_only%&) a transport is required to be defined by the
generic &%transport%& option. The router accepts the address if its domain part
-takes the form of an RFC 2822 domain literal, that is, an IP address enclosed
-in square brackets. For example, the &(ipliteral)& router handles the address
+takes the form of an RFC 2822 domain literal. For example, the &(ipliteral)&
+router handles the address
.code
root@[192.168.1.1]
.endd
-by setting up delivery to the host with that IP address.
+by setting up delivery to the host with that IP address. IPv4 domain literals
+consist of an IPv4 address enclosed in square brackets. IPv6 domain literals
+are similar, but the address is preceded by &`ipv6:`&. For example:
+.code
+postmaster@[ipv6:fe80::a00:20ff:fe86:a061.5678]
+.endd
+Exim allows &`ipv4:`& before IPv4 addresses, for consistency, and on the
+grounds that sooner or later somebody will try it.
-.cindex "&%self%& option" "in &(ipliteral)& router"
+.oindex "&%self%&" "in &(ipliteral)& router"
If the IP address matches something in &%ignore_target_hosts%&, the router
declines. If an IP literal turns out to refer to the local host, the generic
&%self%& option determines what happens.
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The iplookup router"
+.chapter "The iplookup router" "CHID6"
.cindex "&(iplookup)& router"
.cindex "routers" "&(iplookup)&"
The &(iplookup)& router was written to fulfil a specific requirement in
protocols is to be used.
-.option query iplookup string&!! "&`$local_part@$domain $local_part@$domain`&"
+.option query iplookup string&!! "see below"
This defines the content of the query that is sent to the remote hosts. The
-repetition serves as a way of checking that a response is to the correct query
-in the default case (see &%response_pattern%& below).
+default value is:
+.code
+$local_part@$domain $local_part@$domain
+.endd
+The repetition serves as a way of checking that a response is to the correct
+query in the default case (see &%response_pattern%& below).
.option reroute iplookup string&!! unset
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The manualroute router"
-.cindex "&(manualroute)& router"
-.cindex "routers" "&(manualroute)&"
+.chapter "The manualroute router" "CHID7"
+.scindex IIDmanrou1 "&(manualroute)& router"
+.scindex IIDmanrou2 "routers" "&(manualroute)&"
.cindex "domain" "manually routing"
The &(manualroute)& router is so-called because it provides a way of manually
routing an address according to its domain. It is mainly used when you want to
generic &%transport%& option must specify a transport, unless the router is
being used purely for verification (see &%verify_only%&).
-.cindex "&$host$&"
+.vindex "&$host$&"
In the case of verification, matching the domain pattern is sufficient for the
router to accept the address. When actually routing an address for delivery,
an address that matches a domain pattern is queued for the associated
.cindex "options" "&(manualroute)& router"
The private options for the &(manualroute)& router are as follows:
+.option host_all_ignored manualroute string defer
+See &%host_find_failed%&.
.option host_find_failed manualroute string freeze
This option controls what happens when &(manualroute)& tries to find an IP
address for a host, and the host does not exist. The option can be set to one
-of
+of the following values:
.code
decline
defer
fail
freeze
+ignore
pass
.endd
-The default assumes that this state is a serious configuration error. The
-difference between &"pass"& and &"decline"& is that the former forces the
-address to be passed to the next router (or the router defined by
+The default (&"freeze"&) assumes that this state is a serious configuration
+error. The difference between &"pass"& and &"decline"& is that the former
+forces the address to be passed to the next router (or the router defined by
&%pass_router%&),
-.cindex "&%more%& option"
+.oindex "&%more%&"
overriding &%no_more%&, whereas the latter passes the address to the next
router only if &%more%& is true.
-This option applies only to a definite &"does not exist"& state; if a host
-lookup gets a temporary error, delivery is deferred unless the generic
-&%pass_on_timeout%& option is set.
+The value &"ignore"& causes Exim to completely ignore a host whose IP address
+cannot be found. If all the hosts in the list are ignored, the behaviour is
+controlled by the &%host_all_ignored%& option. This takes the same values
+as &%host_find_failed%&, except that it cannot be set to &"ignore"&.
+
+The &%host_find_failed%& option applies only to a definite &"does not exist"&
+state; if a host lookup gets a temporary error, delivery is deferred unless the
+generic &%pass_on_timeout%& option is set.
.option hosts_randomize manualroute boolean false
deferred.
-.option route_list manualroute " "string list" " semicolon-separated""
+.option route_list manualroute "string list" unset
This string is a list of routing rules, in the form defined below. Note that,
unlike most string lists, the items are separated by semicolons. This is so
that they may contain colon-separated host lists.
-.section "Routing rules in route_list"
+.section "Routing rules in route_list" "SECID120"
The value of &%route_list%& is a string consisting of a sequence of routing
rules, separated by semicolons. If a semicolon is needed in a rule, it can be
entered as two semicolons. Alternatively, the list separator can be changed as
-.section "Routing rules in route_data"
+.section "Routing rules in route_data" "SECID121"
The use of &%route_list%& is convenient when there are only a small number of
routing rules. For larger numbers, it is easier to use a file or database to
hold the routing information, and use the &%route_data%& option instead.
-.section "Format of the list of hosts"
-.new
+.section "Format of the list of hosts" "SECID122"
A list of hosts, whether obtained via &%route_data%& or &%route_list%&, is
always separately expanded before use. If the expansion fails, the router
declines. The result of the expansion must be a colon-separated list of names
and/or IP addresses, optionally also including ports. The format of each item
in the list is described in the next section. The list separator can be changed
as described in section &<<SECTlistconstruct>>&.
-.wen
If the list of hosts was obtained from a &%route_list%& item, the following
variables are set during its expansion:
&$1$& is also set when partial matching is done in a file lookup.
.next
-.cindex "&$value$&"
+.vindex "&$value$&"
If the pattern that matched the domain was a lookup item, the data that was
looked up is available in the expansion variable &$value$&. For example:
.code
.section "Format of one host item" "SECTformatonehostitem"
-.new
Each item in the list of hosts is either a host name or an IP address,
optionally with an attached port number. When no port is given, an IP address
is not enclosed in brackets. When a port is specified, it overrides the port
route_list = * "</ [10.1.1.1]:1225 / [::1]:1226"
.endd
.endlist
-.wen
.section "How the list of hosts is used" "SECThostshowused"
When an address is routed to an &(smtp)& transport by &(manualroute)&, each of
.code
route_list = * x.y.z:p.q.r/MX:e.f.g
.endd
-.new
If this feature is used with a port specifier, the port must come last. For
example:
.code
route_list = * dom1.tld/mx::1225
.endd
-.wen
If the &%hosts_randomize%& option is set, the order of the items in the list is
randomized before any lookups are done. Exim then scans the list; for any name
that is not followed by &`/MX`& it looks up an IP address. If this turns out to
be an interface on the local host and the item is not the first in the list,
Exim discards it and any subsequent items. If it is the first item, what
happens is controlled by the
-.cindex "&%self%& option" "in &(manualroute)& router"
+.oindex "&%self%&" "in &(manualroute)& router"
&%self%& option of the router.
A name on the list that is followed by &`/MX`& is replaced with the list of
If no IP address for a host can be found, what happens is controlled by the
&%host_find_failed%& option.
-.cindex "&$host$&"
+.vindex "&$host$&"
When an address is routed to a local transport, IP addresses are not looked up.
The host list is passed to the transport in the &$host$& variable.
-.section "Manualroute examples"
+.section "Manualroute examples" "SECID123"
In some of the examples that follow, the presence of the &%remote_smtp%&
transport, as defined in the default configuration file, is assumed:
${lookup{$domain}dbm{/domain2/hosts}{$value}fail} \
batch_pipe
.endd
-.cindex "&$domain$&"
-.cindex "&$host$&"
+.vindex "&$domain$&"
+.vindex "&$host$&"
The first of these just passes the domain in the &$host$& variable, which
doesn't achieve much (since it is also in &$domain$&), but the second does a
file lookup to find a value to pass, causing the router to decline to handle
makes clear the distinction between the domain name
&'darksite.ethereal.example'& and the UUCP host name &'darksite'&.
.endlist
+.ecindex IIDmanrou1
+.ecindex IIDmanrou2
. ////////////////////////////////////////////////////////////////////////////
.chapter "The queryprogram router" "CHAPdriverlast"
-.cindex "&(queryprogram)& router"
-.cindex "routers" "&(queryprogram)&"
+.scindex IIDquerou1 "&(queryprogram)& router"
+.scindex IIDquerou2 "routers" "&(queryprogram)&"
.cindex "routing" "by external program"
The &(queryprogram)& router routes an address by running an external command
and acting on its output. This is an expensive way to route, and is intended
.option command_group queryprogram string unset
.cindex "gid (group id)" "in &(queryprogram)& router"
-This option specifies a gid to be set when running the command. It must be set
-if &%command_user%& specifies a numerical uid. If it begins with a digit, it is
-interpreted as the numerical value of the gid. Otherwise it is looked up using
-&[getgrnam()]&.
+This option specifies a gid to be set when running the command while routing an
+address for deliver. It must be set if &%command_user%& specifies a numerical
+uid. If it begins with a digit, it is interpreted as the numerical value of the
+gid. Otherwise it is looked up using &[getgrnam()]&.
.option command_user queryprogram string unset
.cindex "uid (user id)" "for &(queryprogram)&"
This option must be set. It specifies the uid which is set when running the
-command. If it begins with a digit it is interpreted as the numerical value of
-the uid. Otherwise, it is looked up using &[getpwnam()]& to obtain a value for
-the uid and, if &%command_group%& is not set, a value for the gid also.
+command while routing an address for delivery. If the value begins with a digit,
+it is interpreted as the numerical value of the uid. Otherwise, it is looked up
+using &[getpwnam()]& to obtain a value for the uid and, if &%command_group%& is
+not set, a value for the gid also.
+
+&*Warning:*& Changing uid and gid is possible only when Exim is running as
+root, which it does during a normal delivery in a conventional configuration.
+However, when an address is being verified during message reception, Exim is
+usually running as the Exim user, not as root. If the &(queryprogram)& router
+is called from a non-root process, Exim cannot change uid or gid before running
+the command. In this circumstance the command runs under the current uid and
+gid.
.option current_directory queryprogram string /
goes on to try a call to &[getipnodebyname()]& or &[gethostbyname()]&, and the
result of the lookup is the result of that call.
-.cindex "&$address_data$&"
+.vindex "&$address_data$&"
If the DATA field is set, its value is placed in the &$address_data$&
variable. For example, this return line
.code
.endd
routes the address to the default transport, passing a list of two hosts. When
the transport runs, the string &"rule1"& is in &$address_data$&.
+.ecindex IIDquerou1
+.ecindex IIDquerou2
. ////////////////////////////////////////////////////////////////////////////
.chapter "The redirect router" "CHAPredirect"
-.cindex "&(redirect)& router"
-.cindex "routers" "&(redirect)&"
+.scindex IIDredrou1 "&(redirect)& router"
+.scindex IIDredrou2 "routers" "&(redirect)&"
.cindex "alias file" "in a &(redirect)& router"
.cindex "address redirection" "&(redirect)& router"
The &(redirect)& router handles several kinds of address redirection. Its most
.next
It can cause an automatic reply to be generated.
.next
-It can be forced to fail, with a custom error message.
+It can be forced to fail, optionally with a custom error message.
.next
-It can be temporarily deferred.
+It can be temporarily deferred, optionally with a custom message.
.next
It can be discarded.
.endlist
-.section "Redirection data"
+.section "Redirection data" "SECID124"
The router operates by interpreting a text string which it obtains either by
expanding the contents of the &%data%& option, or by reading the entire
contents of a file whose name is given in the &%file%& option. These two
-.section "Forward files and address verification"
+.section "Forward files and address verification" "SECID125"
.cindex "address redirection" "while verifying"
It is usual to set &%no_verify%& on &(redirect)& routers which handle users'
&_.forward_& files, as in the example above. There are two reasons for this:
.ilist
When Exim is receiving an incoming SMTP message from a remote host, it is
-running under the Exim uid, not as root.
-No additional groups are set up, even if the Exim uid is a member of other
-groups (that is, the &[initgroups()]& function is not run).
-Exim is unable to change uid to read the file as the user, and it may not be
-able to read it as the Exim user. So in practice the router may not be able to
-operate.
+running under the Exim uid, not as root. Exim is unable to change uid to read
+the file as the user, and it may not be able to read it as the Exim user. So in
+practice the router may not be able to operate.
.next
However, even when the router can operate, the existence of a &_.forward_& file
is unimportant when verifying an address. What should be checked is whether the
-.section "Interpreting redirection data"
+.section "Interpreting redirection data" "SECID126"
.cindex "Sieve filter" "specifying in redirection data"
.cindex "filter" "specifying in redirection data"
The contents of the data string, whether obtained from &%data%& or &%file%&,
&"item"& refers to what remains after any surrounding double quotes have been
removed.
-.cindex "&$local_part$&"
+.vindex "&$local_part$&"
&*Warning*&: If you use an Exim expansion to construct a redirection address,
and the expansion contains a reference to &$local_part$&, you should make use
of the &%quote_local_part%& expansion operator, in case the local part contains
.section "Redirecting to a local mailbox" "SECTredlocmai"
.cindex "routing" "loops in"
-.cindex "loop while routing" "avoidance of"
+.cindex "loop" "while routing, avoidance of"
.cindex "address redirection" "to local mailbox"
A redirection item may safely be the same as the address currently under
consideration. This does not cause a routing loop, because a router is
.cindex "backslash in alias file"
.cindex "alias file" "backslash in"
For compatibility with other MTAs, such unqualified local parts may be
-preceeded by &"\"&, but this is not a requirement for loop prevention. However,
+preceded by &"\"&, but this is not a requirement for loop prevention. However,
it does make a difference if more than one domain is being handled
synonymously.
the router to decline. Instead, the alias item
.cindex "black hole"
.cindex "abandoning mail"
-.code
-:blackhole:
-.endd
-can be used. It does what its name implies. No delivery is done, and no error
-message is generated. This has the same effect as specifing &_/dev/null_&, but
-can be independently disabled.
+&':blackhole:'& can be used. It does what its name implies. No delivery is
+done, and no error message is generated. This has the same effect as specifing
+&_/dev/null_& as a destination, but it can be independently disabled.
-&*Warning*&: If &`:blackhole:`& appears anywhere in a redirection list, no
+&*Warning*&: If &':blackhole:'& appears anywhere in a redirection list, no
delivery is done for the original local part, even if other redirection items
are present. If you are generating a multi-item list (for example, by reading a
database) and need the ability to provide a no-op item, you must use
.cindex "delivery" "forcing failure"
.cindex "delivery" "forcing deferral"
.cindex "failing delivery" "forcing"
-.cindex "deferred delivery" "forcing"
+.cindex "deferred delivery, forcing"
.cindex "customizing" "failure message"
An attempt to deliver a particular address can be deferred or forced to fail by
redirection items of the form
:defer:
:fail:
.endd
-respectively. When a redirection list contains such an item, it applies to the
-entire redirection; any other items in the list are ignored (&':blackhole:'& is
-different). Any text following &':fail:'& or &':defer:'& is placed in the error
-text associated with the failure. For example, an alias file might contain:
+respectively. When a redirection list contains such an item, it applies
+to the entire redirection; any other items in the list are ignored. Any
+text following &':fail:'& or &':defer:'& is placed in the error text
+associated with the failure. For example, an alias file might contain:
.code
X.Employee: :fail: Gone away, no forwarding address
.endd
In the case of an address that is being verified from an ACL or as the subject
of a
-.cindex "VRFY error text" "display of"
+.cindex "VRFY" "error text, display of"
VRFY command, the text is included in the SMTP error response by
default.
-.cindex "EXPN error text" "display of"
-The text is not included in the response to an EXPN command.
+.cindex "EXPN" "error text, display of"
+The text is not included in the response to an EXPN command. In non-SMTP cases
+the text is included in the error message that Exim generates.
+
+.cindex "SMTP" "error codes"
+By default, Exim sends a 451 SMTP code for a &':defer:'&, and 550 for
+&':fail:'&. However, if the message starts with three digits followed by a
+space, optionally followed by an extended code of the form &'n.n.n'&, also
+followed by a space, and the very first digit is the same as the default error
+code, the code from the message is used instead. If the very first digit is
+incorrect, a panic error is logged, and the default code is used. You can
+suppress the use of the supplied code in a redirect router by setting the
+&%forbid_smtp_code%& option true. In this case, any SMTP code is quietly
+ignored.
-.cindex "&$acl_verify_message$&"
+.vindex "&$acl_verify_message$&"
In an ACL, an explicitly provided message overrides the default, but the
default message is available in the variable &$acl_verify_message$& and can
-therefore be included in a custom message if this is desired. Exim sends a 451
-SMTP code for a &':defer:'&, and 550 for &':fail:'&. In non-SMTP cases the text
-is included in the error message that Exim generates.
+therefore be included in a custom message if this is desired.
Normally the error text is the rest of the redirection list &-- a comma does
not terminate it &-- but a newline does act as a terminator. Newlines are not
Sometimes it is useful to use a single-key search type with a default (see
chapter &<<CHAPfdlookup>>&) to look up aliases. However, there may be a need
for exceptions to the default. These can be handled by aliasing them to
-.code
-:unknown:
-.endd
-This differs from &':fail:'& in that it causes the &(redirect)& router to
-decline, whereas &':fail:'& forces routing to fail. A lookup which results in
-an empty redirection list has the same effect.
+&':unknown:'&. This differs from &':fail:'& in that it causes the &(redirect)&
+router to decline, whereas &':fail:'& forces routing to fail. A lookup which
+results in an empty redirection list has the same effect.
.endlist
-.section "Duplicate addresses"
+.section "Duplicate addresses" "SECTdupaddr"
.cindex "duplicate addresses"
-.cindex "address duplicate" "discarding"
+.cindex "address duplicate, discarding"
.cindex "pipe" "duplicated"
Exim removes duplicate addresses from the list to which it is delivering, so as
to deliver just one copy to each address. This does not apply to deliveries
-.section "Repeated redirection expansion"
+.section "Repeated redirection expansion" "SECID128"
.cindex "repeated redirection expansion"
.cindex "address redirection" "repeated for each delivery attempt"
When a message cannot be delivered to all of its recipients immediately,
can be used to avoid this.
-.section "Errors in redirection lists"
+.section "Errors in redirection lists" "SECID129"
.cindex "address redirection" "errors"
If &%skip_syntax_errors%& is set, a malformed address that causes a parsing
error is skipped, and an entry is written to the main log. This may be useful
-.section "Private options for the redirect router"
+.section "Private options for the redirect router" "SECID130"
.cindex "options" "&(redirect)& router"
The private options for the &(redirect)& router are as follows:
.option file_transport redirect string&!! unset
-.cindex "&$address_file$&"
+.vindex "&$address_file$&"
A &(redirect)& router sets up a direct delivery to a file when a path name not
ending in a slash is specified as a new &"address"&. The transport used is
specified by this option, which, after expansion, must be the name of a
it is running, the file name is in &$address_file$&.
+.option filter_prepend_home redirect boolean true
+When this option is true, if a &(save)& command in an Exim filter specifies a
+relative path, and &$home$& is defined, it is automatically prepended to the
+relative path. If this option is set false, this action does not happen. The
+relative path is then passed to the transport unmodified.
+
+
.option forbid_blackhole redirect boolean false
If this option is true, the &':blackhole:'& item may not appear in a
redirection list.
locks out the Sieve's &"keep"& facility.
-.new
.option forbid_filter_dlfunc redirect boolean false
.cindex "filter" "locking out certain features"
If this option is true, string expansions in Exim filters are not allowed to
make use of the &%dlfunc%& expansion facility to run dynamically loaded
functions.
-.wen
.option forbid_filter_existstest redirect boolean false
-.new
.cindex "expansion" "statting a file"
If this option is true, string expansions in Exim filters are not allowed to
make use of the &%exists%& condition or the &%stat%& expansion item.
-.wen
.option forbid_filter_logwrite redirect boolean false
If this option is true, use of the logging facility in Exim filters is not
&%allow_filter%& is true.
+.cindex "SMTP" "error codes"
+.option forbid_smtp_code redirect boolean false
+If this option is set true, any SMTP error codes that are present at the start
+of messages specified for &`:defer:`& or &`:fail:`& are quietly ignored, and
+the default codes (451 and 550, respectively) are always used.
+
+
.option hide_child_in_errmsg redirect boolean false
to pipe or file deliveries or auto-replies) &%forbid_file%&, &%forbid_pipe%&,
and &%forbid_filter_reply%& are forced to be true when &%one_time%& is set.
-.new
&*Warning 3*&: The &%unseen%& generic router option may not be set with
&%one_time%&.
-.wen
The original top-level address is remembered with each of the generated
addresses, and is output in any log messages. However, any intermediate parent
.option pipe_transport redirect string&!! unset
-.cindex "&$address_pipe$&"
+.vindex "&$address_pipe$&"
A &(redirect)& router sets up a direct delivery to a pipe when a string
starting with a vertical bar character is specified as a new &"address"&. The
transport used is specified by this option, which, after expansion, must be the
.option qualify_domain redirect string&!! unset
-.cindex "&$qualify_recipient$&"
-If this option is set and an unqualified address (one without a domain) is
-generated, it is qualified with the domain specified by expanding this string,
-instead of the global setting in &%qualify_recipient%&. If the expansion fails,
-the router declines. If you want to revert to the default, you can have the
-expansion generate &$qualify_recipient$&.
-
+.vindex "&$qualify_recipient$&"
+If this option is set, and an unqualified address (one without a domain) is
+generated, and that address would normally be qualified by the global setting
+in &%qualify_recipient%&, it is instead qualified with the domain specified by
+expanding this string. If the expansion fails, the router declines. If you want
+to revert to the default, you can have the expansion generate
+&$qualify_recipient$&.
+
+This option applies to all unqualified addresses generated by Exim filters,
+but for traditional &_.forward_& files, it applies only to addresses that are
+not preceded by a backslash. Sieve filters cannot generate unqualified
+addresses.
.option qualify_preserve_domain redirect boolean false
.cindex "domain" "in redirection; preserving"
.cindex "preserving domain in redirection"
.cindex "address redirection" "domain; preserving"
-If this is set and an unqualified address (one without a domain) is generated,
-it is qualified with the domain of the
-parent address (the immediately preceding ancestor) instead of the local
-&%qualify_domain%& or global &%qualify_recipient%& value.
+If this option is set, the router's local &%qualify_domain%& option must not be
+set (a configuration error occurs if it is). If an unqualified address (one
+without a domain) is generated, it is qualified with the domain of the parent
+address (the immediately preceding ancestor) instead of the global
+&%qualify_recipient%& value. In the case of a traditional &_.forward_& file,
+this applies whether or not the address is preceded by a backslash.
.option repeat_use redirect boolean true
and are rewritten according to the global rewriting rules.
-.new
.option sieve_subaddress redirect string&!! unset
The value of this option is passed to a Sieve filter to specify the
:subaddress part of an address.
The value of this option is passed to a Sieve filter to specify the :user part
of an address. However, if it is unset, the entire original local part
(including any prefix or suffix) is used for :user.
-.wen
.option sieve_vacation_directory redirect string&!! unset
-.new
.cindex "Sieve filter" "vacation directory"
To enable the &"vacation"& extension for Sieve filters, you must set
&%sieve_vacation_directory%& to the directory where vacation databases are held
(do not put anything else in that directory), and ensure that the
&%reply_transport%& option refers to an &(autoreply)& transport. Each user
needs their own directory; Exim will create it if necessary.
-.wen
local_part_prefix = real-
transport = local_delivery
.endd
+For security, it would probably be a good idea to restrict the use of this
+router to locally-generated messages, using a condition such as this:
+.code
+ condition = ${if match {$sender_host_address}\
+ {\N^(|127\.0\.0\.1)$\N}}
+.endd
+
.option syntax_errors_text redirect string&!! unset
See &%skip_syntax_errors%& above.
.option syntax_errors_to redirect string unset
See &%skip_syntax_errors%& above.
+.ecindex IIDredrou1
+.ecindex IIDredrou2
.chapter "Environment for running local transports" "CHAPenvironment" &&&
"Environment for local transports"
-.cindex "local transports" "environment for"
-.cindex "environment for local transports"
-.cindex "transport" "local; environment for"
+.scindex IIDenvlotra1 "local transports" "environment for"
+.scindex IIDenvlotra2 "environment for local transports"
+.scindex IIDenvlotra3 "transport" "local; environment for"
Local transports handle deliveries to files and pipes. (The &(autoreply)&
transport can be thought of as similar to a pipe.) Exim always runs transports
in subprocesses, under specified uids and gids. Typical deliveries to local
-.section "Concurrent deliveries"
+.section "Concurrent deliveries" "SECID131"
.cindex "concurrent deliveries"
.cindex "simultaneous deliveries"
-If two different messages for the same local recpient arrive more or less
+If two different messages for the same local recipient arrive more or less
simultaneously, the two delivery processes are likely to run concurrently. When
the &(appendfile)& transport is used to write to a file, Exim applies locking
rules to stop concurrent processes from writing to the same file at the same
gid associated with the user is used. If &%user%& is numeric, &%group%& must be
set.
-.cindex "&%initgroups%& option"
+.oindex "&%initgroups%&"
When the uid is taken from the transport's configuration, the &[initgroups()]&
function is called for the groups associated with that uid if the
&%initgroups%& option is set for the transport. When the uid is not specified
receive the message is used, and if &%group%& is not set, the corresponding
original gid is also used.
-.new
This is the detailed preference order for obtaining a gid; the first of the
following that is set is used:
Of course, an error will still occur if the uid that is chosen is on the
&%never_users%& list.
-.wen
-.section "Current and home directories"
+.section "Current and home directories" "SECID132"
.cindex "current directory for local transport"
.cindex "home directory" "for local transport"
.cindex "transport" "local; home directory for"
-.section "Expansion variables derived from the address"
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
-.cindex "&$original_domain$&"
+.section "Expansion variables derived from the address" "SECID133"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
+.vindex "&$original_domain$&"
Normally a local delivery is handling a single address, and in that case the
variables such as &$domain$& and &$local_part$& are set during local
deliveries. However, in some circumstances more than one address may be handled
other means). In this case, the variables associated with the local part are
never set, &$domain$& is set only if all the addresses have the same domain,
and &$original_domain$& is never set.
+.ecindex IIDenvlotra1
+.ecindex IIDenvlotra2
+.ecindex IIDenvlotra3
. ////////////////////////////////////////////////////////////////////////////
.chapter "Generic options for transports" "CHAPtransportgeneric"
-
-.cindex "generic options" "transport"
-.cindex "options" "generic; for transports"
-.cindex "transport" "generic options for"
+.scindex IIDgenoptra1 "generic options" "transport"
+.scindex IIDgenoptra2 "options" "generic; for transports"
+.scindex IIDgenoptra3 "transport" "generic options for"
The following generic options apply to all transports:
.option home_directory transports string&!! unset
.cindex "transport" "home directory for"
-.cindex "&$home$&"
-This option specifies a home directory setting for the transport, overriding
-any value that may be set by the router. The home directory is placed in
-&$home$& while expanding the transport's private options. It is also used as
-the current directory if no current directory is set by the
+.vindex "&$home$&"
+This option specifies a home directory setting for a local transport,
+overriding any value that may be set by the router. The home directory is
+placed in &$home$& while expanding the transport's private options. It is also
+used as the current directory if no current directory is set by the
&%current_directory%& option on the transport or the
-&%transport_current_directory%& option on the router.
-If the expansion fails for any reason, including forced failure, an error is
-logged, and delivery is deferred.
+&%transport_current_directory%& option on the router. If the expansion fails
+for any reason, including forced failure, an error is logged, and delivery is
+deferred.
.option initgroups transports boolean false
.option message_size_limit transports string&!! 0
.cindex "limit" "message size per transport"
-.cindex "size of message" "limit"
+.cindex "size" "of message, limit"
.cindex "transport" "message size; limiting"
This option controls the size of messages passed through the transport. It is
-expanded before use; the result of the expansion must be a sequence of digits,
-optionally followed by K or M.
-If the expansion fails for any reason, including forced failure, or if the
-result is not of the required form, delivery is deferred.
-If the value is greater than zero and the size of a message exceeds this
-limit, the address is failed. If there is any chance that the resulting bounce
-message could be routed to the same transport, you should ensure that
-&%return_size_limit%& is less than the transport's &%message_size_limit%&, as
-otherwise the bounce message will fail to get delivered.
+expanded before use; the result of the expansion must be a sequence of decimal
+digits, optionally followed by K or M. If the expansion fails for any reason,
+including forced failure, or if the result is not of the required form,
+delivery is deferred. If the value is greater than zero and the size of a
+message exceeds this limit, the address is failed. If there is any chance that
+the resulting bounce message could be routed to the same transport, you should
+ensure that &%return_size_limit%& is less than the transport's
+&%message_size_limit%&, as otherwise the bounce message will fail to get
+delivered.
.option rcpt_include_affixes transports boolean false
-.cindex "prefix" "for local part; including in envelope"
-.cindex "suffix" "for local part; including in envelope"
+.cindex "prefix" "for local part, including in envelope"
+.cindex "suffix for local part" "including in envelope"
.cindex "local part" "prefix"
.cindex "local part" "suffix"
When this option is false (the default), and an address that has had any
.code
RCPT TO:<xyz@some.domain>
.endd
-&new("This is also the case when an ACL-time callout is being used to verify a
-recipient address.") However, if &%rcpt_include_affixes%& is set true, the
+This is also the case when an ACL-time callout is being used to verify a
+recipient address. However, if &%rcpt_include_affixes%& is set true, the
whole local part is included in the RCPT command. This option applies to BSMTP
deliveries by the &(appendfile)& and &(pipe)& transports as well as to the
&(lmtp)& and &(smtp)& transports.
only effect is to change the address that is placed in the &'Return-path:'&
header line, if one is added to the message (see the next option).
-.cindex "&$return_path$&"
+&*Note:*& A changed return path is not logged unless you add
+&%return_path_on_delivery%& to the log selector.
+
+.vindex "&$return_path$&"
The expansion can refer to the existing value via &$return_path$&. This is
either the message's envelope sender, or an address set by the
&%errors_to%& option on a router. If the expansion is forced to fail, no
replacement occurs; if it fails for another reason, delivery is deferred. This
option can be used to support VERP (Variable Envelope Return Paths) &-- see
-chapter &<<CHAPSMTP>>&.
+section &<<SECTverp>>&.
-&*Note*&: If a delivery error is detected locally,
-including the case when a remote server rejects a message at SMTP time,
-the bounce message is not sent to the value of this option, but to the
-previously set errors address (which defaults to the incoming sender address).
+&*Note*&: If a delivery error is detected locally, including the case when a
+remote server rejects a message at SMTP time, the bounce message is not sent to
+the value of this option. It is sent to the previously set errors address.
+This defaults to the incoming sender address, but can be changed by setting
+&%errors_to%& in a router.
If the shadow transport did not succeed, the error message is put in
parentheses afterwards. Shadow transports can be used for a number of different
purposes, including keeping more detailed log information than Exim normally
-provides, and implementing automatic acknowledgement policies based on message
+provides, and implementing automatic acknowledgment policies based on message
headers that some sites insist on.
individual users or via a system filter.
When the message is about to be written out, the command specified by
-&%transport_filter%& is started up in a separate, &new(parallel) process, and
+&%transport_filter%& is started up in a separate, parallel process, and
the entire message, including the header lines, is passed to it on its standard
input (this in fact is done from a third process, to avoid deadlock). The
command must be specified as an absolute path.
The standard error for the filter process is set to the same destination as its
standard output; this is read and written to the message's ultimate
-destination. &new("The process that writes the message to the filter, the
+destination. The process that writes the message to the filter, the
filter itself, and the original process that reads the result and delivers it
-are all run in parallel, like a shell pipeline.")
+are all run in parallel, like a shell pipeline.
The filter can perform any transformations it likes, but of course should take
-care not to break RFC 2822 syntax. A demonstration Perl script is provided in
-&_util/transport-filter.pl_&; this makes a few arbitrary modifications just to
-show the possibilities. Exim does not check the result, except to test for a
-final newline when SMTP is in use. All messages transmitted over SMTP must end
-with a newline, so Exim supplies one if it is missing.
+care not to break RFC 2822 syntax. Exim does not check the result, except to
+test for a final newline when SMTP is in use. All messages transmitted over
+SMTP must end with a newline, so Exim supplies one if it is missing.
-.new
.cindex "content scanning" "per user"
A transport filter can be used to provide content-scanning on a per-user basis
at delivery time if the only required effect of the scan is to modify the
message. For example, a content scan could insert a new header line containing
a spam score. This could be interpreted by a filter in the user's MUA. It is
not possible to discard a message at this stage.
-.wen
.cindex "SMTP" "SIZE"
A problem might arise if the filter increases the size of a message that is
the &%size_addition%& option on the &(smtp)& transport, either to allow for
additions to the message, or to disable the use of SIZE altogether.
-.cindex "&$pipe_addresses$&"
+.vindex "&$pipe_addresses$&"
The value of the &%transport_filter%& option is the command string for starting
the filter, which is run directly from Exim, not under a shell. The string is
parsed by Exim in the same way as a command string for the &(pipe)& transport:
-Exim breaks it up into arguments and then expands each argument separately.
-&new("Any kind of expansion failure causes delivery to be deferred.") The
-special argument &$pipe_addresses$& is replaced by a number of arguments, one
-for each address that applies to this delivery. (This isn't an ideal name for
-this feature here, but as it was already implemented for the &(pipe)&
-transport, it seemed sensible not to change it.)
-
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+Exim breaks it up into arguments and then expands each argument separately (see
+section &<<SECThowcommandrun>>&). Any kind of expansion failure causes delivery
+to be deferred. The special argument &$pipe_addresses$& is replaced by a number
+of arguments, one for each address that applies to this delivery. (This isn't
+an ideal name for this feature here, but as it was already implemented for the
+&(pipe)& transport, it seemed sensible not to change it.)
+
+.vindex "&$host$&"
+.vindex "&$host_address$&"
The expansion variables &$host$& and &$host_address$& are available when the
transport is a remote one. They contain the name and IP address of the host to
which the message is being sent. For example:
transport_filter = /some/directory/transport-filter.pl \
$host $host_address $sender_address $pipe_addresses
.endd
-The filter process is run under the same uid and gid as the normal delivery.
-For remote deliveries this is the Exim uid/gid by default.
-.new
-The command should normally yield a zero return code. Transport filters are not
-supposed to fail. A non-zero code is taken to mean that the transport filter
-encountered some serious problem. Delivery of the message is deferred; the
-message remains on the queue and is tried again later. It is not possible to
-cause a message to be bounced from a transport filter.
-.wen
+Two problems arise if you want to use more complicated expansion items to
+generate transport filter commands, both of which due to the fact that the
+command is split up &'before'& expansion.
+.ilist
+If an expansion item contains white space, you must quote it, so that it is all
+part of the same command item. If the entire option setting is one such
+expansion item, you have to take care what kind of quoting you use. For
+example:
+.code
+transport_filter = '/bin/cmd${if eq{$host}{a.b.c}{1}{2}}'
+.endd
+This runs the command &(/bin/cmd1)& if the host name is &'a.b.c'&, and
+&(/bin/cmd2)& otherwise. If double quotes had been used, they would have been
+stripped by Exim when it read the option's value. When the value is used, if
+the single quotes were missing, the line would be split into two items,
+&`/bin/cmd${if`& and &`eq{$host}{a.b.c}{1}{2}`&, and an error would occur when
+Exim tried to expand the first one.
+.next
+Except for the special case of &$pipe_addresses$& that is mentioned above, an
+expansion cannot generate multiple arguments, or a command name followed by
+arguments. Consider this example:
+.code
+transport_filter = ${lookup{$host}lsearch{/a/file}\
+ {$value}{/bin/cat}}
+.endd
+The result of the lookup is interpreted as the name of the command, even
+if it contains white space. The simplest way round this is to use a shell:
+.code
+transport_filter = /bin/sh -c ${lookup{$host}lsearch{/a/file}\
+ {$value}{/bin/cat}}
+.endd
+.endlist
+
+The filter process is run under the same uid and gid as the normal delivery.
+For remote deliveries this is the Exim uid/gid by default. The command should
+normally yield a zero return code. Transport filters are not supposed to fail.
+A non-zero code is taken to mean that the transport filter encountered some
+serious problem. Delivery of the message is deferred; the message remains on
+the queue and is tried again later. It is not possible to cause a message to be
+bounced from a transport filter.
If a transport filter is set on an autoreply transport, the original message is
passed through the filter as it is being copied into the newly generated
.option transport_filter_timeout transports time 5m
-.new
-.cindex "transport filter" "timeout"
+.cindex "transport" "filter, timeout"
When Exim is reading the output of a transport filter, it a applies a timeout
that can be set by this option. Exceeding the timeout is normally treated as a
temporary delivery failure. However, if a transport filter is used with a
way as a timeout in the pipe command itself. By default, a timeout is a hard
error, but if the &(pipe)& transport's &%timeout_defer%& option is set true, it
becomes a temporary error.
-.wen
.option user transports string&!! "Exim user"
.cindex "uid (user id)" "local delivery"
-.cindex "transport user" "specifying"
+.cindex "transport" "user, specifying"
This option specifies the user under whose uid the delivery process is to be
run, overriding any uid that may have been set by the router. If the user is
given as a name, the uid is looked up from the password data, and the
sure you know what you are doing. When a remote transport is running, it needs
to be able to access Exim's hints databases, because each host may have its own
retry data.
+.ecindex IIDgenoptra1
+.ecindex IIDgenoptra2
+.ecindex IIDgenoptra3
copy of the message is delivered each time.
.cindex "batched local delivery"
-.cindex "&%batch_max%&"
-.cindex "&%batch_id%&"
+.oindex "&%batch_max%&"
+.oindex "&%batch_id%&"
In special cases, it may be desirable to handle several addresses at once in a
local transport, for example:
acceptable.
.endlist
-The three local transports (&(appendfile)&, &(lmtp)&, and &(pipe)&) all have
-the same options for controlling multiple (&"batched"&) deliveries, namely
-&%batch_max%& and &%batch_id%&. To save repeating the information for each
-transport, these options are described here.
+These three local transports all have the same options for controlling multiple
+(&"batched"&) deliveries, namely &%batch_max%& and &%batch_id%&. To save
+repeating the information for each transport, these options are described here.
The &%batch_max%& option specifies the maximum number of addresses that can be
-delivered together in a single run of the transport. Its default value is one.
-When more than one address is routed to a transport that has a &%batch_max%&
-value greater than one, the addresses are delivered in a batch (that is, in a
-single run of the transport), subject to certain conditions:
+delivered together in a single run of the transport. Its default value is one
+(no batching). When more than one address is routed to a transport that has a
+&%batch_max%& value greater than one, the addresses are delivered in a batch
+(that is, in a single run of the transport with multiple recipients), subject
+to certain conditions:
.ilist
-.cindex "&$local_part$&"
+.vindex "&$local_part$&"
If any of the transport's options contain a reference to &$local_part$&, no
batching is possible.
.next
-.cindex "&$domain$&"
+.vindex "&$domain$&"
If any of the transport's options contain a reference to &$domain$&, only
addresses with the same domain are batched.
.next
.cindex "customizing" "batching condition"
If &%batch_id%& is set, it is expanded for each address, and only those
addresses with the same expanded value are batched. This allows you to specify
-customized batching conditions.
-Failure of the expansion for any reason, including forced failure, disables
-batching, but it does not stop the delivery from taking place.
+customized batching conditions. Failure of the expansion for any reason,
+including forced failure, disables batching, but it does not stop the delivery
+from taking place.
.next
Batched addresses must also have the same errors address (where to send
delivery errors), the same header additions and removals, the same user and
be the same.
.endlist
-.cindex "&'Envelope-to:'& header line"
-If the generic &%envelope_to_add%& option is set for the transport, the
-&'Envelope-to:'& header that is added to the message contains all the addresses
-that are batched together.
-
-The &(appendfile)& and &(pipe)& transports have an option called &%use_bsmtp%&,
-which causes them to deliver the message in &"batched SMTP"& format, with the
-envelope represented as SMTP commands. The &%check_string%& and
-&%escape_string%& options are forced to the values
+In the case of the &(appendfile)& and &(pipe)& transports, batching applies
+both when the file or pipe command is specified in the transport, and when it
+is specified by a &(redirect)& router, but all the batched addresses must of
+course be routed to the same file or pipe command. These two transports have an
+option called &%use_bsmtp%&, which causes them to deliver the message in
+&"batched SMTP"& format, with the envelope represented as SMTP commands. The
+&%check_string%& and &%escape_string%& options are forced to the values
.code
check_string = "."
escape_string = ".."
given in section &<<SECTbatchSMTP>>&. The &(lmtp)& transport does not have a
&%use_bsmtp%& option, because it always delivers using the SMTP protocol.
+.cindex "&'Envelope-to:'& header line"
+If the generic &%envelope_to_add%& option is set for a batching transport, the
+&'Envelope-to:'& header that is added to the message contains all the addresses
+that are being processed together. If you are using a batching &(appendfile)&
+transport without &%use_bsmtp%&, the only way to preserve the recipient
+addresses is to set the &%envelope_to_add%& option.
+
.cindex "&(pipe)& transport" "with multiple addresses"
-.cindex "&$pipe_addresses$&"
-If you are not using BSMTP, but are using a &(pipe)& transport, you can include
-&$pipe_addresses$& as part of the command. This is not a true variable; it is
-a bit of magic that causes each of the recipient addresses to be inserted into
-the command as a separate argument. This provides a way of accessing all the
-addresses that are being delivered in the batch.
+.vindex "&$pipe_addresses$&"
+If you are using a &(pipe)& transport without BSMTP, and setting the
+transport's &%command%& option, you can include &$pipe_addresses$& as part of
+the command. This is not a true variable; it is a bit of magic that causes each
+of the recipient addresses to be inserted into the command as a separate
+argument. This provides a way of accessing all the addresses that are being
+delivered in the batch. &*Note:*& This is not possible for pipe commands that
+are specified by a &(redirect)& router.
-If you are using a batching &(appendfile)& transport without &%use_bsmtp%&, the
-only way to preserve the recipient addresses is to set the &%envelope_to_add%&
-option. This causes an &'Envelope-to:'& header line to be added to the message,
-containing all the recipients.
. ////////////////////////////////////////////////////////////////////////////
.chapter "The appendfile transport" "CHAPappendfile"
-.cindex "&(appendfile)& transport"
-.cindex "transports" "&(appendfile)&"
+.scindex IIDapptra1 "&(appendfile)& transport"
+.scindex IIDapptra2 "transports" "&(appendfile)&"
.cindex "directory creation"
.cindex "creating directories"
The &(appendfile)& transport delivers a message by appending it to an existing
included.
.cindex "quota" "system"
-Exim recognises system quota errors, and generates an appropriate message. Exim
+Exim recognizes system quota errors, and generates an appropriate message. Exim
also supports its own quota control within the transport, for use when the
system facility is unavailable or cannot be used for some reason.
the message is created. Only one of these two options can be set, and for
normal deliveries to mailboxes, one of them &'must'& be set.
-.cindex "&$address_file$&"
-.cindex "&$local_part$&"
+.vindex "&$address_file$&"
+.vindex "&$local_part$&"
However, &(appendfile)& is also used for delivering messages to files or
directories whose names (or parts of names) are obtained from alias,
forwarding, or filtering operations (for example, a &%save%& command in a
-.section "Private options for appendfile"
+.section "Private options for appendfile" "SECID134"
.cindex "options" "&(appendfile)& transport"
&<<SECTopdir>>& for further details of this form of delivery.
-.option directory_file appendfile string&!! &`q${base62:$tod_epoch}-$inode`&
+.option directory_file appendfile string&!! "see below"
.cindex "base62"
-.cindex "&$inode$&"
+.vindex "&$inode$&"
When &%directory%& is set, but neither &%maildir_format%& nor
&%mailstore_format%& is set, &(appendfile)& delivers each message into a file
-whose name is obtained by expanding this string. The default value generates a
-unique name from the current time, in base 62 form, and the inode of the file.
-The variable &$inode$& is available only when expanding this option.
+whose name is obtained by expanding this string. The default value is:
+.code
+q${base62:$tod_epoch}-$inode
+.endd
+This generates a unique name from the current time, in base 62 form, and the
+inode of the file. The variable &$inode$& is available only when expanding this
+option.
.option directory_mode appendfile "octal integer" 0700
.option file_must_exist appendfile boolean false
-If this option is true, the file specified by the &%file%& option must exist,
-and an error occurs if it does not. Otherwise, it is created if it does not
-exist.
+If this option is true, the file specified by the &%file%& option must exist.
+A temporary error occurs if it does not, causing delivery to be deferred.
+If this option is false, the file is created if it does not exist.
.option lock_fcntl_timeout appendfile time 0s
.cindex "timeout" "mailbox locking"
-.cindex "mailbox locking" "blocking and non-blocking"
+.cindex "mailbox" "locking, blocking and non-blocking"
.cindex "locking files"
By default, the &(appendfile)& transport uses non-blocking calls to &[fcntl()]&
when locking an open mailbox file. If the call fails, the delivery process
.option lockfile_mode appendfile "octal integer" 0600
This specifies the mode of the created lock file, when a lock file is being
-used (see &%use_lockfile%&).
+used (see &%use_lockfile%& and &%use_mbx_lock%&).
.option lockfile_timeout appendfile time 30m
.cindex "maildir format" "quota; directories included in"
.cindex "quota" "maildir; directories included in"
This option is relevant only when &%maildir_use_size_file%& is set. It defines
-a regular expression for specifying directories that should be included in the
-quota calculation. The default value is
+a regular expression for specifying directories, relative to the quota
+directory (see &%quota_directory%&), that should be included in the quota
+calculation. The default value is:
.code
maildir_quota_directory_regex = ^(?:cur|new|\..*)$
.endd
-which includes the &_cur_& and &_new_& directories, and any maildir++ folders
+This includes the &_cur_& and &_new_& directories, and any maildir++ folders
(directories whose names begin with a dot). If you want to exclude the
&_Trash_&
folder from the count (as some sites do), you need to change this setting to
maildir_quota_directory_regex = ^(?:cur|new|\.(?!Trash).*)$
.endd
This uses a negative lookahead in the regular expression to exclude the
-directory whose name is &_.Trash_&.
+directory whose name is &_.Trash_&. When a directory is excluded from quota
+calculations, quota processing is bypassed for any messages that are delivered
+directly into that directory.
.option maildir_retries appendfile integer 10
section &<<SECTmaildirdelivery>>& below.
-.option maildir_use_size_file appendfile boolean false
+.option maildir_use_size_file appendfile&!! boolean false
.cindex "maildir format" "&_maildirsize_& file"
-Setting this option true enables support for &_maildirsize_& files. Exim
+The result of string expansion for this option must be a valid boolean value.
+If it is true, it enables support for &_maildirsize_& files. Exim
creates a &_maildirsize_& file in a maildir if one does not exist, taking the
quota from the &%quota%& option of the transport. If &%quota%& is unset, the
-value is zero. See section &<<SECTmaildirdelivery>>& below for further details.
+value is zero. See &%maildir_quota_directory_regex%& above and section
+&<<SECTmaildirdelivery>>& below for further details.
+
+.option maildirfolder_create_regex appendfile string unset
+.cindex "maildir format" "&_maildirfolder_& file"
+.cindex "&_maildirfolder_&, creating"
+The value of this option is a regular expression. If it is unset, it has no
+effect. Otherwise, before a maildir delivery takes place, the pattern is
+matched against the name of the maildir directory, that is, the directory
+containing the &_new_& and &_tmp_& subdirectories that will be used for the
+delivery. If there is a match, Exim checks for the existence of a file called
+&_maildirfolder_& in the directory, and creates it if it does not exist.
+See section &<<SECTmaildirdelivery>>& for more details.
.option mailstore_format appendfile boolean false
.cindex "locking files"
.cindex "file" "locking"
.cindex "file" "MBX format"
-.cindex "MBX format" "specifying"
+.cindex "MBX format, specifying"
This option is available only if Exim has been compiled with SUPPORT_MBX
set in &_Local/Makefile_&. If &%mbx_format%& is set with the &%file%& option,
the message is appended to the mailbox file in MBX format instead of
message_prefix = "From ${if def:return_path{$return_path}\
{MAILER-DAEMON}} $tod_bsdinbox\n"
.endd
-
+&*Note:*& If you set &%use_crlf%& true, you must change any occurrences of
+&`\n`& to &`\r\n`& in &%message_prefix%&.
.option message_suffix appendfile string&!! "see below"
The string specified here is expanded and output at the end of every message.
.code
message_suffix =
.endd
+&*Note:*& If you set &%use_crlf%& true, you must change any occurrences of
+&`\n`& to &`\r\n`& in &%message_suffix%&.
.option mode appendfile "octal integer" 0600
If the output file is created, it is given this mode. If it already exists and
has wider permissions, they are reduced to this mode. If it has narrower
permissions, an error occurs unless &%mode_fail_narrower%& is false. However,
-if the delivery is the result of a &%save%& command in a filter file specifing
+if the delivery is the result of a &%save%& command in a filter file specifying
a particular mode, the mode of the output file is always forced to take that
value, and this option is ignored.
Nevertheless, it seems best to stick to the &'used'& figure, because this is
the obvious value which users understand most easily.
-.new
The value of the option is expanded, and must then be a numerical value
(decimal point allowed), optionally followed by one of the letters K, M, or G,
for kilobytes, megabytes, or gigabytes. If Exim is running on a system with
large file support (Linux and FreeBSD have this), mailboxes larger than 2G can
be handled.
-.wen
&*Note*&: A value of zero is interpreted as &"no quota"&.
This option applies when the &%directory%& option is set. It limits the total
number of files in the directory (compare the inode limit in system quotas). It
can only be used if &%quota%& is also set. The value is expanded; an expansion
-failure causes delivery to be deferred.
+failure causes delivery to be deferred. A value of zero is interpreted as
+&"no quota"&.
.option quota_is_inclusive appendfile boolean true
maildir_tag = ,S=$message_size
quota_size_regex = ,S=(\d+)
.endd
-.new
An alternative to &$message_size$& is &$message_linecount$&, which contains the
number of lines in the message.
-.wen
The regular expression should not assume that the length is at the end of the
file name (even though &%maildir_tag%& puts it there) because maildir MUAs
sometimes add other information onto the ends of message file names.
+Section &<<SECID136>>& contains further information.
.option quota_warn_message appendfile string&!! "see below"
If &%quota%& is not set, a setting of &%quota_warn_threshold%& that ends with a
percent sign is ignored.
-.new
The warning message itself is specified by the &%quota_warn_message%& option,
and it must start with a &'To:'& header line containing the recipient(s) of the
warning message. These do not necessarily have to include the recipient(s) of
the original message. A &'Subject:'& line should also normally be supplied. You
-can include any other header lines that you want.
-.wen
+can include any other header lines that you want. If you do not include a
+&'From:'& line, the default is:
+.code
+From: Mail Delivery System <mailer-daemon@$qualify_domain_sender>
+.endd
+.oindex &%errors_reply_to%&
+If you supply a &'Reply-To:'& line, it overrides the global &%errors_reply_to%&
+option.
The &%quota%& option does not have to be set in order to use this option; they
are independent of one another except when the threshold is specified as a
of batched SMTP, the byte sequence written to the file is then an exact image
of what would be sent down a real SMTP connection.
-The contents of the &%message_prefix%& and &%message_suffix%& options are
-written verbatim, so must contain their own carriage return characters if these
-are needed. In cases where these options have non-empty defaults, the values
-end with a single linefeed, so they must be changed to end with &`\r\n`& if
-&%use_crlf%& is set.
+&*Note:*& The contents of the &%message_prefix%& and &%message_suffix%& options
+(which are used to supply the traditional &"From&~"& and blank line separators
+in Berkeley-style mailboxes) are written verbatim, so must contain their own
+carriage return characters if these are needed. In cases where these options
+have non-empty defaults, the values end with a single linefeed, so they must be
+changed to end with &`\r\n`& if &%use_crlf%& is set.
.option use_fcntl_lock appendfile boolean "see below"
/tmp/.<device-number>.<inode-number>
.endd
using the device and inode numbers of the open mailbox file, in accordance with
-the MBX locking rules.
+the MBX locking rules. This file is created with a mode that is specified by
+the &%lockfile_mode%& option.
If Exim fails to lock the file, there are two possible courses of action,
depending on the value of the locking timeout. This is obtained from
.cindex "maildir format" "description of"
If the &%maildir_format%& option is true, Exim delivers each message by writing
it to a file whose name is &_tmp/<stime>.H<mtime>P<pid>.<host>_& in the
-given directory. If the delivery is successful, the file is renamed into the
+directory that is defined by the &%directory%& option (the &"delivery
+directory"&). If the delivery is successful, the file is renamed into the
&_new_& subdirectory.
In the file name, <&'stime'&> is the current time of day in seconds, and
opening it. If any response other than ENOENT (does not exist) is given,
Exim waits 2 seconds and tries again, up to &%maildir_retries%& times.
+Before Exim carries out a maildir delivery, it ensures that subdirectories
+called &_new_&, &_cur_&, and &_tmp_& exist in the delivery directory. If they
+do not exist, Exim tries to create them and any superior directories in their
+path, subject to the &%create_directory%& and &%create_file%& options. If the
+&%maildirfolder_create_regex%& option is set, and the regular expression it
+contains matches the delivery directory, Exim also ensures that a file called
+&_maildirfolder_& exists in the delivery directory. If a missing directory or
+&_maildirfolder_& file cannot be created, delivery is deferred.
+
+These features make it possible to use Exim to create all the necessary files
+and directories in a maildir mailbox, including subdirectories for maildir++
+folders. Consider this example:
+.code
+maildir_format = true
+directory = /var/mail/$local_part\
+ ${if eq{$local_part_suffix}{}{}\
+ {/.${substr_1:$local_part_suffix}}}
+maildirfolder_create_regex = /\.[^/]+$
+.endd
+If &$local_part_suffix$& is empty (there was no suffix for the local part),
+delivery is into a toplevel maildir with a name like &_/var/mail/pimbo_& (for
+the user called &'pimbo'&). The pattern in &%maildirfolder_create_regex%& does
+not match this name, so Exim will not look for or create the file
+&_/var/mail/pimbo/maildirfolder_&, though it will create
+&_/var/mail/pimbo/{cur,new,tmp}_& if necessary.
+
+However, if &$local_part_suffix$& contains &`-eximusers`& (for example),
+delivery is into the maildir++ folder &_/var/mail/pimbo/.eximusers_&, which
+does match &%maildirfolder_create_regex%&. In this case, Exim will create
+&_/var/mail/pimbo/.eximusers/maildirfolder_& as well as the three maildir
+directories &_/var/mail/pimbo/.eximusers/{cur,new,tmp}_&.
+
+&*Warning:*& Take care when setting &%maildirfolder_create_regex%& that it does
+not inadvertently match the toplevel maildir directory, because a
+&_maildirfolder_& file at top level would completely break quota calculations.
+
.cindex "quota" "in maildir delivery"
.cindex "maildir++"
If Exim is required to check a &%quota%& setting before a maildir delivery, and
-.section "Using tags to record message sizes"
+.section "Using tags to record message sizes" "SECID135"
If &%maildir_tag%& is set, the string is expanded for each delivery.
When the maildir file is renamed into the &_new_& sub-directory, the
tag is added to its name. However, if adding the tag takes the length of the
name to the point where the test &[stat()]& call fails with ENAMETOOLONG,
the tag is dropped and the maildir file is created with no tag.
-.cindex "&$message_size$&"
+
+.vindex "&$message_size$&"
Tags can be used to encode the size of files in their names; see
&%quota_size_regex%& above for an example. The expansion of &%maildir_tag%&
happens after the message has been written. The value of the &$message_size$&
be deferred. The expanded tag may contain any printing characters except &"/"&.
Non-printing characters in the string are ignored; if the resulting string is
empty, it is ignored. If it starts with an alphanumeric character, a leading
-colon is inserted.
+colon is inserted; this default has not proven to be the path that popular
+maildir implementations have chosen (but changing it in Exim would break
+backwards compatibility).
+For one common implementation, you might set:
+.code
+maildir_tag = ,S=${message_size}
+.endd
+but you should check the documentation of the other software to be sure.
+
+It is advisable to also set &%quota_size_regex%& when setting &%maildir_tag%&
+as this allows Exim to extract the size from your tag, instead of having to
+&[stat()]& each message file.
-.section "Using a maildirsize file"
+.section "Using a maildirsize file" "SECID136"
.cindex "quota" "in maildir delivery"
.cindex "maildir format" "&_maildirsize_& file"
If &%maildir_use_size_file%& is true, Exim implements the maildir++ rules for
storing quota and message size information in a file called &_maildirsize_&
-within the maildir directory. If this file does not exist, Exim creates it,
-setting the quota from the &%quota%& option of the transport. If the maildir
-directory itself does not exist, it is created before any attempt to write a
-&_maildirsize_& file.
+within the toplevel maildir directory. If this file does not exist, Exim
+creates it, setting the quota from the &%quota%& option of the transport. If
+the maildir directory itself does not exist, it is created before any attempt
+to write a &_maildirsize_& file.
The &_maildirsize_& file is used to hold information about the sizes of
messages in the maildir, thus speeding up quota calculations. The quota value
file is maintained (with a zero quota setting), but no quota is imposed.
A regular expression is available for controlling which directories in the
-maildir participate in quota calculations. See the description of the
-&%maildir_quota_directory_regex%& option above for details.
-
+maildir participate in quota calculations when a &_maildirsizefile_& is in use.
+See the description of the &%maildir_quota_directory_regex%& option above for
+details.
-.section "Mailstore delivery"
+.section "Mailstore delivery" "SECID137"
.cindex "mailstore format" "description of"
If the &%mailstore_format%& option is true, each message is written as two
files in the given directory. A unique base name is constructed from the
greater than one. Finally, &%mailstore_suffix%& is expanded and the result
appended to the file, followed by a newline if it does not end with one.
-.new
If expansion of &%mailstore_prefix%& or &%mailstore_suffix%& ends with a forced
failure, it is ignored. Other expansion errors are treated as serious
configuration errors, and delivery is deferred. The variable
&$mailstore_basename$& is available for use during these expansions.
-.wen
-.section "Non-special new file delivery"
+.section "Non-special new file delivery" "SECID138"
If neither &%maildir_format%& nor &%mailstore_format%& is set, a single new
file is created directly in the named directory. For example, when delivering
messages into files in batched SMTP format for later delivery to some host (see
might be used. A message is written to a file with a temporary name, which is
then renamed when the delivery is complete. The final name is obtained by
expanding the contents of the &%directory_file%& option.
+.ecindex IIDapptra1
+.ecindex IIDapptra2
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The autoreply transport"
-.cindex "transports" "&(autoreply)&"
-.cindex "&(autoreply)& transport"
+.chapter "The autoreply transport" "CHID8"
+.scindex IIDauttra1 "transports" "&(autoreply)&"
+.scindex IIDauttra2 "&(autoreply)& transport"
The &(autoreply)& transport is not a true transport in that it does not cause
-the message to be transmitted. Instead, it generates a new mail message.
+the message to be transmitted. Instead, it generates a new mail message as an
+automatic reply to the incoming message. &'References:'& and
+&'Auto-Submitted:'& header lines are included. These are constructed according
+to the rules in RFCs 2822 and 3834, respectively.
If the router that passes the message to this transport does not have the
&%unseen%& option set, the original message (for the current recipient) is not
of the original message that is included in the generated message when
&%return_message%& is set. They do not apply to the generated message itself.
-.cindex "&$sender_address$&"
+.vindex "&$sender_address$&"
If the &(autoreply)& transport receives return code 2 from Exim when it submits
the message, indicating that there were no recipients, it does not treat this
as an error. This means that autoreplies sent to &$sender_address$& when this
-.section "Private options for autoreply"
+.section "Private options for autoreply" "SECID139"
.cindex "options" "&(autoreply)& transport"
.option bcc autoreply string&!! unset
.option never_mail autoreply "address list&!!" unset
If any run of the transport creates a message with a recipient that matches any
item in the list, that recipient is quietly discarded. If all recipients are
-discarded, no message is created.
+discarded, no message is created. This applies both when the recipients are
+generated by a filter and when they are specified in the transport.
.option to autoreply string&!! unset
This specifies recipients of the message and the contents of the &'To:'& header
when the message is specified by the transport.
+.ecindex IIDauttra1
+.ecindex IIDauttra2
is passed to the new process using the standard input and output to operate the
LMTP protocol.
-.new
.option ignore_quota lmtp boolean false
.cindex "LMTP" "ignoring quota errors"
If this option is set true, the string &`IGNOREQUOTA`& is added to RCPT
commands, provided that the LMTP server has advertised support for IGNOREQUOTA
in its response to the LHLO command.
-.wen
.option socket lmtp string&!! unset
This option must be set if &%command%& is not set. The result of expansion must
.option timeout lmtp time 5m
-The transport is aborted if the created process
-or Unix domain socket
-does not respond to LMTP commands or message input within this timeout.
-
-
-Here is an example of a typical LMTP transport:
+The transport is aborted if the created process or Unix domain socket does not
+respond to LMTP commands or message input within this timeout. Delivery
+is deferred, and will be tried again later. Here is an example of a typical
+LMTP transport:
.code
lmtp:
driver = lmtp
. ////////////////////////////////////////////////////////////////////////////
.chapter "The pipe transport" "CHAPpipetransport"
-.cindex "transports" "&(pipe)&"
-.cindex "&(pipe)& transport"
+.scindex IIDpiptra1 "transports" "&(pipe)&"
+.scindex IIDpiptra2 "&(pipe)& transport"
The &(pipe)& transport is used to deliver messages via a pipe to a command
running in another process. One example is the use of &(pipe)& as a
pseudo-remote transport for passing messages to some other delivery mechanism
following ways:
.ilist
-.cindex "&$local_part$&"
+.vindex "&$local_part$&"
A router routes one address to a transport in the normal way, and the
transport is configured as a &(pipe)& transport. In this case, &$local_part$&
contains the local part of the address (as usual), and the command that is run
is specified by the &%command%& option on the transport.
.next
-.cindex "&$pipe_addresses$&"
-If the &%batch_max%& option is set greater than 1 (the default), the transport
-can be called upon to handle more than one address in a single run. In this
-case, &$local_part$& is not set (because it is not unique). However, the
-pseudo-variable &$pipe_addresses$& (described in section
-&<<SECThowcommandrun>>& below) contains all the addresses that are being
-handled.
+.vindex "&$pipe_addresses$&"
+If the &%batch_max%& option is set greater than 1 (the default is 1), the
+transport can handle more than one address in a single run. In this case, when
+more than one address is routed to the transport, &$local_part$& is not set
+(because it is not unique). However, the pseudo-variable &$pipe_addresses$&
+(described in section &<<SECThowcommandrun>>& below) contains all the addresses
+that are routed to the transport.
.next
-.cindex "&$address_pipe$&"
+.vindex "&$address_pipe$&"
A router redirects an address directly to a pipe command (for example, from an
-alias or forward file). In this case, &$local_part$& contains the local part
-that was redirected, and &$address_pipe$& contains the text of the pipe
-command itself. The &%command%& option on the transport is ignored.
+alias or forward file). In this case, &$address_pipe$& contains the text of the
+pipe command, and the &%command%& option on the transport is ignored. If only
+one address is being transported (&%batch_max%& is not greater than one, or
+only one address was redirected to this pipe command), &$local_part$& contains
+the local part that was redirected.
.endlist
other cases, the uid and gid have to be specified explicitly, either on the
transport or on the router that handles the address. Current and &"home"&
directories are also controllable. See chapter &<<CHAPenvironment>>& for
-details of the local delivery environment.
-
+details of the local delivery environment and chapter &<<CHAPbatching>>&
+for a discussion of local delivery batching.
-.section "Concurrent delivery"
+.section "Concurrent delivery" "SECID140"
If two messages arrive at almost the same time, and both are routed to a pipe
delivery, the two pipe transports may be run concurrently. You must ensure that
any pipe commands you set up are robust against this happening. If the commands
-.section "Returned status and data"
+.section "Returned status and data" "SECID141"
.cindex "&(pipe)& transport" "returned data"
If the command exits with a non-zero return code, the delivery is deemed to
have failed, unless either the &%ignore_status%& option is set (in which case
logged, but are not included in the bounce message, which merely contains
&"local delivery failed"&.
+If the command exits on a signal and the &%freeze_signal%& option is set then
+the message will be frozen in the queue. If that option is not set, a bounce
+will be sent as normal.
+
If the return code is greater than 128 and the command being run is a shell
script, it normally means that the script was terminated by a signal whose
-value is the return code minus 128.
+value is the return code minus 128. The &%freeze_signal%& option does not
+apply in this case.
If Exim is unable to run the command (that is, if &[execve()]& fails), the
return code is set to 127. This is the value that a shell returns if it is
to ensure that it is all in one argument. The expansion is done in this way,
argument by argument, so that the number of arguments cannot be changed as a
result of expansion, and quotes or backslashes in inserted variables do not
-interact with external quoting.
+interact with external quoting. However, this leads to problems if you want to
+generate multiple arguments (or the command name plus arguments) from a single
+expansion. In this situation, the simplest solution is to use a shell. For
+example:
+.code
+command = /bin/sh -c ${lookup{$local_part}lsearch{/some/file}}
+.endd
.cindex "transport" "filter"
.cindex "filter" "transport filter"
-.cindex "&$pipe_addresses$&"
+.vindex "&$pipe_addresses$&"
Special handling takes place when an argument consists of precisely the text
&`$pipe_addresses`&. This is not a general expansion variable; the only
place this string is recognized is when it appears as an argument for a pipe or
user's home directory if &%check_local_user%& is set.
-.section "Private options for pipe"
+.section "Private options for pipe" "SECID142"
.cindex "options" "&(pipe)& transport"
frozen, whatever the setting of &%ignore_status%&.
+.option freeze_signal pipe boolean false
+.cindex "signal exit"
+.cindex "&(pipe)& transport", "signal exit"
+Normally if the process run by a command in a pipe transport exits on a signal,
+a bounce message is sent. If &%freeze_signal%& is set, the message will be
+frozen in Exim's queue instead.
+
+
.option ignore_status pipe boolean false
If this option is true, the status returned by the subprocess that is set up to
run the command is ignored, and Exim behaves as if zero had been returned.
from the transport unless the status value is one of those listed in
&%temp_errors%&; these cause the delivery to be deferred and tried again later.
-.new
&*Note*&: This option does not apply to timeouts, which do not return a status.
See the &%timeout_defer%& option for how timeouts are handled.
-.wen
.option log_defer_output pipe boolean false
.cindex "&(pipe)& transport" "logging output"
.code
message_prefix =
.endd
+&*Note:*& If you set &%use_crlf%& true, you must change any occurrences of
+&`\n`& to &`\r\n`& in &%message_prefix%&.
+
.option message_suffix pipe string&!! "see below"
The string specified here is expanded and output at the end of every message.
.code
message_suffix =
.endd
+&*Note:*& If you set &%use_crlf%& true, you must change any occurrences of
+&`\n`& to &`\r\n`& in &%message_suffix%&.
-.option path pipe string &`/bin:/usr/bin`&
+
+.option path pipe string "see below"
This option specifies the string that is set up in the PATH environment
-variable of the subprocess. If the &%command%& option does not yield an
-absolute path name, the command is sought in the PATH directories, in the usual
-way. &*Warning*&: This does not apply to a command specified as a transport
-filter.
+variable of the subprocess. The default is:
+.code
+/bin:/usr/bin
+.endd
+If the &%command%& option does not yield an absolute path name, the command is
+sought in the PATH directories, in the usual way. &*Warning*&: This does not
+apply to a command specified as a transport filter.
+
+
+.option permit_coredump pipe boolean false
+Normally Exim inhibits core-dumps during delivery. If you have a need to get
+a core-dump of a pipe command, enable this command. This enables core-dumps
+during delivery and affects both the Exim binary and the pipe command run.
+It is recommended that this option remain off unless and until you have a need
+for it and that this only be enabled when needed, as the risk of excessive
+resource consumption can be quite high. Note also that Exim is typically
+installed as a setuid binary and most operating systems will inhibit coredumps
+of these by default, so further OS-specific action may be required.
.option pipe_as_creator pipe boolean false
and kills the whole process group on a timeout. However, this can be defeated
if one of the processes starts a new process group.
-.new
.option timeout_defer pipe boolean false
A timeout in a &(pipe)& transport, either in the command that the transport
runs, or in a transport filter that is associated with it, is by default
treated as a hard error, and the delivery fails. However, if &%timeout_defer%&
is set true, both kinds of timeout become temporary errors, causing the
delivery to be deferred.
-.wen
.option umask pipe "octal integer" 022
This specifies the umask setting for the subprocess that runs the command.
you can do so by setting the &%message_prefix%& option. See section
&<<SECTbatchSMTP>>& for details of batch SMTP.
+.option use_classresources pipe boolean false
+.cindex "class resources (BSD)"
+This option is available only when Exim is running on FreeBSD, NetBSD, or
+BSD/OS. If it is set true, the &[setclassresources()]& function is used to set
+resource limits when a &(pipe)& transport is run to perform a delivery. The
+limits for the uid under which the pipe is to run are obtained from the login
+class database.
+
.option use_crlf pipe boolean false
.cindex "carriage return"
The contents of the &%message_prefix%& and &%message_suffix%& options are
written verbatim, so must contain their own carriage return characters if these
-are needed. Since the default values for both &%message_prefix%& and
-&%message_suffix%& end with a single linefeed, their values must be changed to
-end with &`\r\n`& if &%use_crlf%& is set.
+are needed. When &%use_bsmtp%& is not set, the default values for both
+&%message_prefix%& and &%message_suffix%& end with a single linefeed, so their
+values must be changed to end with &`\r\n`& if &%use_crlf%& is set.
.option use_shell pipe boolean false
-.cindex "&$pipe_addresses$&"
+.vindex "&$pipe_addresses$&"
If this option is set, it causes the command to be passed to &_/bin/sh_&
instead of being run directly from the transport, as described in section
&<<SECThowcommandrun>>&. This is less secure, but is needed in some situations
-.section "Using an external local delivery agent"
+.section "Using an external local delivery agent" "SECID143"
.cindex "local delivery" "using an external agent"
.cindex "&'procmail'&"
.cindex "external local delivery"
envelope_to_add
check_string = "From "
escape_string = ">From "
+ umask = 077
user = $local_part
group = mail
Note the unsetting of &%message_prefix%& and &%message_suffix%&, and the use of
&%return_output%& to cause any text written by Cyrus to be returned to the
sender.
+.ecindex IIDpiptra1
+.ecindex IIDpiptra2
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
.chapter "The smtp transport" "CHAPsmtptrans"
-.cindex "transports" "&(smtp)&"
-.cindex "&(smtp)& transport"
+.scindex IIDsmttra1 "transports" "&(smtp)&"
+.scindex IIDsmttra2 "&(smtp)& transport"
The &(smtp)& transport delivers messages over TCP/IP connections using the SMTP
or LMTP protocol. The list of hosts to try can either be taken from the address
that is being processed (having been set up by the router), or specified
&<<CHAPretry>>&) is applied to each IP address independently.
-.section "Multiple messages on a single connection"
+.section "Multiple messages on a single connection" "SECID144"
The sending of multiple messages over a single TCP/IP connection can arise in
two ways:
-.section "Use of the $host variable"
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+.section "Use of the $host and $host_address variables" "SECID145"
+.vindex "&$host$&"
+.vindex "&$host_address$&"
At the start of a run of the &(smtp)& transport, the values of &$host$& and
&$host_address$& are the name and IP address of the first host on the host list
passed by the router. However, when the transport is about to connect to a
&%serialize_hosts%&, and the various TLS options are expanded.
+.section "Use of $tls_cipher and $tls_peerdn" "usecippeer"
+.vindex &$tls_bits$&
+.vindex &$tls_cipher$&
+.vindex &$tls_peerdn$&
+.vindex &$tls_sni$&
+At the start of a run of the &(smtp)& transport, the values of &$tls_bits$&,
+&$tls_cipher$&, &$tls_peerdn$& and &$tls_sni$&
+are the values that were set when the message was received.
+These are the values that are used for options that are expanded before any
+SMTP connections are made. Just before each connection is made, these four
+variables are emptied. If TLS is subsequently started, they are set to the
+appropriate values for the outgoing connection, and these are the values that
+are in force when any authenticators are run and when the
+&%authenticated_sender%& option is expanded.
+
-.section "Private options for smtp"
+.section "Private options for smtp" "SECID146"
.cindex "options" "&(smtp)& transport"
The private options of the &(smtp)& transport are as follows:
+.option address_retry_include_sender smtp boolean true
+.cindex "4&'xx'& responses" "retrying after"
+When an address is delayed because of a 4&'xx'& response to a RCPT command, it
+is the combination of sender and recipient that is delayed in subsequent queue
+runs until the retry time is reached. You can delay the recipient without
+reference to the sender (which is what earlier versions of Exim did), by
+setting &%address_retry_include_sender%& false. However, this can lead to
+problems with servers that regularly issue 4&'xx'& responses to RCPT commands.
+
.option allow_localhost smtp boolean false
.cindex "local host" "sending to"
.cindex "fallback" "hosts specified on transport"
.option authenticated_sender smtp string&!! unset
.cindex "Cyrus"
-When Exim has authenticated as a client, this option sets a value for the
-AUTH= item on outgoing MAIL commands, overriding any existing
-authenticated sender value. If the string expansion is forced to fail, the
-option is ignored. Other expansion failures cause delivery to be deferred. If
-the result of expansion is an empty string, that is also ignored.
+When Exim has authenticated as a client, or if &%authenticated_sender_force%&
+is true, this option sets a value for the AUTH= item on outgoing MAIL commands,
+overriding any existing authenticated sender value. If the string expansion is
+forced to fail, the option is ignored. Other expansion failures cause delivery
+to be deferred. If the result of expansion is an empty string, that is also
+ignored.
+
+The expansion happens after the outgoing connection has been made and TLS
+started, if required. This means that the &$host$&, &$host_address$&,
+&$tls_cipher$&, and &$tls_peerdn$& variables are set according to the
+particular connection.
If the SMTP session is not authenticated, the expansion of
&%authenticated_sender%& still happens (and can cause the delivery to be
-deferred if it fails), but no AUTH= item is added to MAIL commands.
+deferred if it fails), but no AUTH= item is added to MAIL commands
+unless &%authenticated_sender_force%& is true.
This option allows you to use the &(smtp)& transport in LMTP mode to
deliver mail to Cyrus IMAP and provide the proper local part as the
value.
+.option authenticated_sender_force smtp boolean false
+If this option is set true, the &%authenticated_sender%& option's value
+is used for the AUTH= item on outgoing MAIL commands, even if Exim has not
+authenticated as a client.
+
+
.option command_timeout smtp time 5m
This sets a timeout for receiving a response to an SMTP command that has been
sent out. It is also used when waiting for the initial banner line from the
.option dns_search_parents smtp boolean false
-.cindex "&%search_parents%&"
If the &%hosts%& or &%fallback_hosts%& option is being used, and the
&%gethostbyname%& option is false, the RES_DNSRCH resolver option is set.
See the &%search_parents%& option in chapter &<<CHAPdnslookup>>& for more
details.
+.new
+.option dscp smtp string&!! unset
+.cindex "DCSP"
+.cindex "DiffServ"
+This option causes the DSCP value associated with a socket to be set to one
+of a number of fixed strings or to numeric value.
+The &%-bI:dscp%& option may be used to ask Exim which names it knows of.
+Common values include &`throughput`&, &`mincost`&, and on newer systems
+&`ef`&, &`af41`&, etc. Numeric values may be in the range 0 to 0x3F.
+
+The outbound packets from Exim will be marked with this value in the header
+(for IPv4, the TOS field; for IPv6, the TCLASS field); there is no guarantee
+that these packets will have any effect, not be stripped by networking
+equipment, or do much of anything without cooperation with your Network
+Engineer and those of all network operators between the source and destination.
+.wen
+
.option fallback_hosts smtp "string list" unset
-.new
.cindex "fallback" "hosts specified on transport"
String expansion is not applied to this option. The argument must be a
colon-separated list of host names or IP addresses, optionally also including
&<<SECTlistconstruct>>&. Each individual item in the list is the same as an
item in a &%route_list%& setting for the &(manualroute)& router, as described
in section &<<SECTformatonehostitem>>&.
-.wen
Fallback hosts can also be specified on routers, which associate them with the
addresses they process. As for the &%hosts%& option without &%hosts_override%&,
line containing just &"."& that terminates a message. Its value must not be
zero.
-
.option gethostbyname smtp boolean false
If this option is true when the &%hosts%& and/or &%fallback_hosts%& options are
being used, names are looked up using &[gethostbyname()]&
instead of using the DNS. Of course, that function may in fact use the DNS, but
it may also consult other sources of information such as &_/etc/hosts_&.
-.option helo_data smtp string&!! &`$primary_hostname`&
-.cindex "HELO argument" "setting"
-.cindex "EHLO argument" "setting"
-.new
-The value of this option is expanded, and used as the argument for the EHLO or
-HELO command that starts the outgoing SMTP session. The variables &$host$& and
-&$host_address$& are set to the identity of the remote host, and can be used to
-generate different values for different servers.
-.wen
+.option gnutls_compat_mode smtp boolean unset
+This option controls whether GnuTLS is used in compatibility mode in an Exim
+server. This reduces security slightly, but improves interworking with older
+implementations of TLS.
+
+.option helo_data smtp string&!! "see below"
+.cindex "HELO" "argument, setting"
+.cindex "EHLO" "argument, setting"
+.cindex "LHLO argument setting"
+The value of this option is expanded after a connection to a another host has
+been set up. The result is used as the argument for the EHLO, HELO, or LHLO
+command that starts the outgoing SMTP or LMTP session. The default value of the
+option is:
+.code
+$primary_hostname
+.endd
+During the expansion, the variables &$host$& and &$host_address$& are set to
+the identity of the remote host, and the variables &$sending_ip_address$& and
+&$sending_port$& are set to the local IP address and port number that are being
+used. These variables can be used to generate different values for different
+servers or different local IP addresses. For example, if you want the string
+that is used for &%helo_data%& to be obtained by a DNS lookup of the outgoing
+interface address, you could use this:
+.code
+helo_data = ${lookup dnsdb{ptr=$sending_ip_address}{$value}\
+ {$primary_hostname}}
+.endd
+The use of &%helo_data%& applies both to sending messages and when doing
+callouts.
.option hosts smtp "string list&!!" unset
Hosts are associated with an address by a router such as &(dnslookup)&, which
&%hosts%& are also used, whether or not the address has its own hosts, if
&%hosts_override%& is set.
-.new
The string is first expanded, before being interpreted as a colon-separated
list of host names or IP addresses, possibly including port numbers. The
separator may be changed to something other than colon, as described in section
item in a &%route_list%& setting for the &(manualroute)& router, as described
in section &<<SECTformatonehostitem>>&. However, note that the &`/MX`& facility
of the &(manualroute)& router is not available here.
-.wen
If the expansion fails, delivery is deferred. Unless the failure was caused by
the inability to complete a lookup, the error is logged to the panic log as
.option hosts_avoid_esmtp smtp "host list&!!" unset
-.cindex "ESMTP" "avoiding use of"
+.cindex "ESMTP, avoiding use of"
.cindex "HELO" "forcing use of"
.cindex "EHLO" "avoiding use of"
.cindex "PIPELINING" "avoiding the use of"
facilities such as AUTH, PIPELINING, SIZE, and STARTTLS.
+.option hosts_avoid_pipelining smtp "host list&!!" unset
+.cindex "PIPELINING" "avoiding the use of"
+Exim will not use the SMTP PIPELINING extension when delivering to any host
+that matches this list, even if the server host advertises PIPELINING support.
+
+
.option hosts_avoid_tls smtp "host list&!!" unset
.cindex "TLS" "avoiding for certain hosts"
Exim will not try to start a TLS session when delivering to any host that
If this option is set, and either the list of hosts is taken from the
&%hosts%& or the &%fallback_hosts%& option, or the hosts supplied by the router
were not obtained from MX records (this includes fallback hosts from the
-router), and were not randomizied by the router, the order of trying the hosts
+router), and were not randomized by the router, the order of trying the hosts
is randomized each time the transport runs. Randomizing the order of a host
list can be used to do crude load sharing.
.option interface smtp "string list&!!" unset
.cindex "bind IP address"
.cindex "IP address" "binding"
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+.vindex "&$host$&"
+.vindex "&$host_address$&"
This option specifies which interface to bind to when making an outgoing SMTP
-call. The variables &$host$& and &$host_address$& refer to the host to which a
-connection is about to be made during the expansion of the string. Forced
-expansion failure, or an empty string result causes the option to be ignored.
-Otherwise, after expansion,
-the string must be a list of IP addresses, colon-separated by default, but the
-separator can be changed in the usual way.
-For example:
+call. The value is an IP address, not an interface name such as
+&`eth0`&. Do not confuse this with the interface address that was used when a
+message was received, which is in &$received_ip_address$&, formerly known as
+&$interface_address$&. The name was changed to minimize confusion with the
+outgoing interface address. There is no variable that contains an outgoing
+interface address because, unless it is set by this option, its value is
+unknown.
+
+During the expansion of the &%interface%& option the variables &$host$& and
+&$host_address$& refer to the host to which a connection is about to be made
+during the expansion of the string. Forced expansion failure, or an empty
+string result causes the option to be ignored. Otherwise, after expansion, the
+string must be a list of IP addresses, colon-separated by default, but the
+separator can be changed in the usual way. For example:
.code
interface = <; 192.168.123.123 ; 3ffe:ffff:836f::fe86:a061
.endd
This option controls the setting of SO_KEEPALIVE on outgoing TCP/IP socket
connections. When set, it causes the kernel to probe idle connections
periodically, by sending packets with &"old"& sequence numbers. The other end
-of the connection should send a acknowledgement if the connection is still okay
+of the connection should send a acknowledgment if the connection is still okay
or a reset if the connection has been aborted. The reason for doing this is
that it has the beneficial effect of freeing up certain types of connection
that can get stuck when the remote host is disconnected without tidying up the
unreachable hosts.
-.new
.option lmtp_ignore_quota smtp boolean false
.cindex "LMTP" "ignoring quota errors"
If this option is set true when the &%protocol%& option is set to &"lmtp"&, the
string &`IGNOREQUOTA`& is added to RCPT commands, provided that the LMTP server
has advertised support for IGNOREQUOTA in its response to the LHLO command.
-.wen
.option max_rcpt smtp integer 100
.cindex "RCPT" "maximum number of outgoing"
.option multi_domain smtp boolean true
-.cindex "&$domain$&"
+.vindex "&$domain$&"
When this option is set, the &(smtp)& transport can handle a number of
addresses containing a mixture of different domains provided they all resolve
to the same list of hosts. Turning the option off restricts the transport to
.option port smtp string&!! "see below"
.cindex "port" "sending TCP/IP"
.cindex "TCP/IP" "setting outgoing port"
-This option specifies the TCP/IP port on the server to which Exim connects. If
-it begins with a digit it is taken as a port number; otherwise it is looked up
-using &[getservbyname()]&. The default value is normally &"smtp"&, but if
-&%protocol%& is set to &"lmtp"&, the default is &"lmtp"&.
-If the expansion fails, or if a port number cannot be found, delivery is
-deferred.
+This option specifies the TCP/IP port on the server to which Exim connects.
+&*Note:*& Do not confuse this with the port that was used when a message was
+received, which is in &$received_port$&, formerly known as &$interface_port$&.
+The name was changed to minimize confusion with the outgoing port. There is no
+variable that contains an outgoing port.
+
+If the value of this option begins with a digit it is taken as a port number;
+otherwise it is looked up using &[getservbyname()]&. The default value is
+normally &"smtp"&, but if &%protocol%& is set to &"lmtp"&, the default is
+&"lmtp"&. If the expansion fails, or if a port number cannot be found, delivery
+is deferred.
.option protocol smtp string smtp
.cindex "LMTP" "over TCP/IP"
+.cindex "ssmtp protocol" "outbound"
+.cindex "TLS" "SSL-on-connect outbound"
+.vindex "&$port$&"
If this option is set to &"lmtp"& instead of &"smtp"&, the default value for
the &%port%& option changes to &"lmtp"&, and the transport operates the LMTP
protocol (RFC 2033) instead of SMTP. This protocol is sometimes used for local
deliveries into closed message stores. Exim also has support for running LMTP
over a pipe to a local process &-- see chapter &<<CHAPLMTP>>&.
+If this option is set to &"smtps"&, the default vaule for the &%port%& option
+changes to &"smtps"&, and the transport initiates TLS immediately after
+connecting, as an outbound SSL-on-connect, instead of using STARTTLS to upgrade.
+The Internet standards bodies strongly discourage use of this mode.
+
.option retry_include_ip_address smtp boolean true
Exim normally includes both the host name and the IP address in the key it
.option tls_certificate smtp string&!! unset
-.cindex "TLS client certificate" "location of"
-.cindex "certificate for client" "location of"
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+.cindex "TLS" "client certificate, location of"
+.cindex "certificate" "client, location of"
+.vindex "&$host$&"
+.vindex "&$host_address$&"
The value of this option must be the absolute path to a file which contains the
client's certificate, for possible use when sending a message over an encrypted
connection. The values of &$host$& and &$host_address$& are set to the name and
be the name of a file that contains a CRL in PEM format.
+.new
+.option tls_dh_min_bits smtp integer 1024
+.cindex "TLS" "Diffie-Hellman minimum acceptable size"
+When establishing a TLS session, if a ciphersuite which uses Diffie-Hellman
+key agreement is negotiated, the server will provide a large prime number
+for use. This option establishes the minimum acceptable size of that number.
+If the parameter offered by the server is too small, then the TLS handshake
+will fail.
+
+Only supported when using GnuTLS.
+.wen
+
+
.option tls_privatekey smtp string&!! unset
-.cindex "TLS client private key" "location of"
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+.cindex "TLS" "client private key, location of"
+.vindex "&$host$&"
+.vindex "&$host_address$&"
The value of this option must be the absolute path to a file which contains the
client's private key. This is used when sending a message over an encrypted
connection using a client certificate. The values of &$host$& and
&$host_address$& are set to the name and address of the server during the
-expansion. If this option is unset, the private key is assumed to be in the
-same file as the certificate. See chapter &<<CHAPTLS>>& for details of TLS.
+expansion. If this option is unset, or the expansion is forced to fail, or the
+result is an empty string, the private key is assumed to be in the same file as
+the certificate. See chapter &<<CHAPTLS>>& for details of TLS.
.option tls_require_ciphers smtp string&!! unset
.cindex "TLS" "requiring specific ciphers"
.cindex "cipher" "requiring specific"
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+.vindex "&$host$&"
+.vindex "&$host_address$&"
The value of this option must be a list of permitted cipher suites, for use
when setting up an outgoing encrypted connection. (There is a global option of
the same name for controlling incoming connections.) The values of &$host$& and
+.option tls_sni smtp string&!! unset
+.cindex "TLS" "Server Name Indication"
+.vindex "&$tls_sni$&"
+If this option is set then it sets the $tls_sni variable and causes any
+TLS session to pass this value as the Server Name Indication extension to
+the remote side, which can be used by the remote side to select an appropriate
+certificate and private key for the session.
+
+See &<<SECTtlssni>>& for more information.
+
+Note that for OpenSSL, this feature requires a build of OpenSSL that supports
+TLS extensions.
+
+
+
+
.option tls_tempfail_tryclear smtp boolean true
+.cindex "4&'xx'& responses" "to STARTTLS"
When the server host is not in &%hosts_require_tls%&, and there is a problem in
setting up a TLS session, this option determines whether or not Exim should try
to deliver the message unencrypted. If it is set false, delivery to the
.option tls_verify_certificates smtp string&!! unset
.cindex "TLS" "server certificate verification"
.cindex "certificate" "verification of server"
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+.vindex "&$host$&"
+.vindex "&$host_address$&"
The value of this option must be the absolute path to a file containing
permitted server certificates, for use when setting up an encrypted connection.
Alternatively, if you are using OpenSSL, you can set
Exim never tries more than this number of IP addresses; if it hits this limit
and they are all timed out, the email address is bounced, even though not all
possible IP addresses have been tried.
+.ecindex IIDsmttra1
+.ecindex IIDsmttra2
. ////////////////////////////////////////////////////////////////////////////
.chapter "Address rewriting" "CHAPrewrite"
-.cindex "rewriting" "addresses"
+.scindex IIDaddrew "rewriting" "addresses"
There are some circumstances in which Exim automatically rewrites domains in
addresses. The two most common are when an address is given without a domain
(referred to as an &"unqualified address"&) or when an address contains an
do this. The new RFCs do not contain this suggestion.
-.section "Explicitly configured address rewriting"
+.section "Explicitly configured address rewriting" "SECID147"
This chapter describes the rewriting rules that can be used in the
main rewrite section of the configuration file, and also in the generic
&%headers_rewrite%& option that can be set on any transport.
addresses and addresses in header lines. Each rule specifies the types of
address to which it applies.
-Rewriting of addresses in header lines applies only to those headers that
-were received with the message, and, in the case of transport rewriting, those
-that were added by a system filter. That is, it applies only to those headers
-that are common to all copies of the message. Header lines that are added by
-individual routers or transports (and which are therefore specific to
-individual recipient addresses) are not rewritten.
+Whether or not addresses in header lines are rewritten depends on the origin of
+the headers and the type of rewriting. Global rewriting, that is, rewriting
+rules from the rewrite section of the configuration file, is applied only to
+those headers that were received with the message. Header lines that are added
+by ACLs or by a system filter or by individual routers or transports (which
+are specific to individual recipient addresses) are not rewritten by the global
+rules.
+
+Rewriting at transport time, by means of the &%headers_rewrite%& option,
+applies all headers except those added by routers and transports. That is, as
+well as the headers that were received with the message, it also applies to
+headers that were added by an ACL or a system filter.
+
In general, rewriting addresses from your own system or domain has some
legitimacy. Rewriting other addresses should be done only with great care and
-.section "When does rewriting happen?"
+.section "When does rewriting happen?" "SECID148"
.cindex "rewriting" "timing of"
.cindex "&ACL;" "rewriting addresses in"
Configured address rewriting can take place at several different stages of a
message's processing.
-.cindex "&$sender_address$&"
+.vindex "&$sender_address$&"
At the start of an ACL for MAIL, the sender address may have been rewritten
by a special SMTP-time rewrite rule (see section &<<SECTrewriteS>>&), but no
ordinary rewrite rules have yet been applied. If, however, the sender address
RCPT ACL. Otherwise, when the sender address is not verified, it is
rewritten as soon as a message's header lines have been received.
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
Similarly, at the start of an ACL for RCPT, the current recipient's address
may have been rewritten by a special SMTP-time rewrite rule, but no ordinary
rewrite rules have yet been applied to it. However, the behaviour is different
as they were before (that is, they contain the unrewritten &-- except for
SMTP-time rewriting &-- address).
-Once a message's header lines have been received, all the envelope recipient
-addresses are permanently rewritten, and rewriting is also applied to the
-addresses in the header lines (if configured).
+As soon as a message's header lines have been received, all the envelope
+recipient addresses are permanently rewritten, and rewriting is also applied to
+the addresses in the header lines (if configured). This happens before adding
+any header lines that were specified in MAIL or RCPT ACLs, and
.cindex "&[local_scan()]& function" "address rewriting; timing of"
-Thus, all the rewriting is completed before the DATA ACL and
-&[local_scan()]& functions are run.
+before the DATA ACL and &[local_scan()]& functions are run.
When an address is being routed, either for delivery or for verification,
rewriting is applied immediately to child addresses that are generated by
redirection, unless &%no_rewrite%& is set on the router.
-.cindex "envelope sender" "rewriting"
+.cindex "envelope sender" "rewriting at transport time"
.cindex "rewriting" "at transport time"
+.cindex "header lines" "rewriting at transport time"
At transport time, additional rewriting of addresses in header lines can be
specified by setting the generic &%headers_rewrite%& option on a transport.
This option contains rules that are identical in form to those in the rewrite
-section of the configuration file. In addition, the outgoing envelope sender
-can be rewritten by means of the &%return_path%& transport option. However, it
-is not possible to rewrite envelope recipients at transport time.
+section of the configuration file. They are applied to the original message
+header lines and any that were added by ACLs or a system filter. They are not
+applied to header lines that are added by routers or the transport.
+
+The outgoing envelope sender can be rewritten by means of the &%return_path%&
+transport option. However, it is not possible to rewrite envelope recipients at
+transport time.
-.section "Testing the rewriting rules that apply on input"
+.section "Testing the rewriting rules that apply on input" "SECID149"
.cindex "rewriting" "testing"
.cindex "testing" "rewriting"
Exim's input rewriting configuration appears in a part of the run time
set for a particular transport.
-.section "Rewriting rules"
+.section "Rewriting rules" "SECID150"
.cindex "rewriting" "rules"
The rewrite section of the configuration file consists of lines of rewriting
rules in the form
(or has not) already been rewritten. However, a rewrite of &'From:'& may assume
that the envelope sender has already been rewritten.
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
The variables &$local_part$& and &$domain$& can be used in the replacement
string to refer to the address that is being rewritten. Note that lookup-driven
rewriting can be done by a rule of the form
refer to the address that is being rewritten.
-.section "Rewriting patterns"
+.section "Rewriting patterns" "SECID151"
.cindex "rewriting" "patterns"
.cindex "address list" "in a rewriting pattern"
The source pattern in a rewriting rule is any item which may appear in an
.endlist
-.section "Rewriting replacements"
+.section "Rewriting replacements" "SECID152"
.cindex "rewriting" "replacements"
If the replacement string for a rule is a single asterisk, addresses that
match the pattern and the flags are &'not'& rewritten, and no subsequent
specifies that &'hatta@lookingglass.fict.example'& is never to be rewritten in
&'From:'& headers.
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
If the replacement string is not a single asterisk, it is expanded, and must
yield a fully qualified address. Within the expansion, the variables
&$local_part$& and &$domain$& refer to the address that is being rewritten.
-.section "Rewriting flags"
+.section "Rewriting flags" "SECID153"
There are three different kinds of flag that may appear on rewriting rules:
.ilist
-.section "Flags specifying which headers and envelope addresses to rewrite"
+.section "Flags specifying which headers and envelope addresses to rewrite" &&&
+ "SECID154"
.cindex "rewriting" "flags"
If none of the following flag letters, nor the &"S"& flag (see section
&<<SECTrewriteS>>&) are present, a main rewriting rule applies to all headers
&`s`& rewrite the &'Sender:'& header
&`t`& rewrite the &'To:'& header
.endd
+"All headers" means all of the headers listed above that can be selected
+individually, plus their &'Resent-'& versions. It does not include
+other headers such as &'Subject:'& etc.
+
You should be particularly careful about rewriting &'Sender:'& headers, and
restrict this to special known cases in your own domains.
required to be a regular expression, and it is matched against the whole of the
data for the command, including any surrounding angle brackets.
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
This form of rewrite rule allows for the handling of addresses that are not
compliant with RFCs 2821 and 2822 (for example, &"bang paths"& in batched SMTP
input). Because the input is not required to be a syntactically valid address,
original address in the MAIL or RCPT command.
-.section "Flags controlling the rewriting process"
+.section "Flags controlling the rewriting process" "SECID155"
There are four flags which control the way the rewriting process works. These
take effect only when a rule is invoked, that is, when the address is of the
correct type (matches the flags) and matches the pattern:
.endlist
-.section "Rewriting examples"
+.section "Rewriting examples" "SECID156"
Here is an example of the two common rewriting paradigms:
.code
*@*.hitch.fict.example $1@hitch.fict.example
to be local. If the bang path addresses are received via SMTP, it is safer to
use the &"S"& flag to rewrite them as they are received, so that relay checking
can be done on the rewritten addresses.
+.ecindex IIDaddrew
. ////////////////////////////////////////////////////////////////////////////
.chapter "Retry configuration" "CHAPretry"
-.cindex "retry configuration" "description of"
-.cindex "configuration file" "retry section"
-The &"retry"& section of the run time configuration file contains a list of
-retry rules which control how often Exim tries to deliver messages that cannot
-be delivered at the first attempt. If there are no retry rules, temporary
-errors are treated as permanent. The &%-brt%& command line option can be used
-to test which retry rule will be used for a given address or domain.
+.scindex IIDretconf1 "retry" "configuration, description of"
+.scindex IIDregconf2 "configuration file" "retry section"
+The &"retry"& section of the runtime configuration file contains a list of
+retry rules that control how often Exim tries to deliver messages that cannot
+be delivered at the first attempt. If there are no retry rules (the section is
+empty or not present), there are no retries. In this situation, temporary
+errors are treated as permanent. The default configuration contains a single,
+general-purpose retry rule (see section &<<SECID57>>&). The &%-brt%& command
+line option can be used to test which retry rule will be used for a given
+address, domain and error.
The most common cause of retries is temporary failure to deliver to a remote
host because the host is down, or inaccessible because of a network problem.
subsequent delivery attempts from queue runs occur only when the retry time for
the local address is reached.
+.section "Changing retry rules" "SECID157"
+If you change the retry rules in your configuration, you should consider
+whether or not to delete the retry data that is stored in Exim's spool area in
+files with names like &_db/retry_&. Deleting any of Exim's hints files is
+always safe; that is why they are called &"hints"&.
+
+The hints retry data contains suggested retry times based on the previous
+rules. In the case of a long-running problem with a remote host, it might
+record the fact that the host has timed out. If your new rules increase the
+timeout time for such a host, you should definitely remove the old retry data
+and let Exim recreate it, based on the new rules. Otherwise Exim might bounce
+messages that it should now be retaining.
-.section "Retry rules"
+
+.section "Format of retry rules" "SECID158"
.cindex "retry" "rules"
Each retry rule occupies one line and consists of three or four parts,
separated by white space: a pattern, an error name, an optional list of sender
The pattern is any single item that may appear in an address list (see section
&<<SECTaddresslist>>&). It is in fact processed as a one-item address list,
which means that it is expanded before being tested against the address that
-has been delayed. Address list processing treats a plain domain name as if it
-were preceded by &"*@"&, which makes it possible for many retry rules to start
-with just a domain. For example,
+has been delayed. A negated address list item is permitted. Address
+list processing treats a plain domain name as if it were preceded by &"*@"&,
+which makes it possible for many retry rules to start with just a domain. For
+example,
.code
lookingglass.fict.example * F,24h,30m;
.endd
.endd
-.section "Choosing which retry rule to use for address errors"
+.section "Choosing which retry rule to use for address errors" "SECID159"
When Exim is looking for a retry rule after a routing attempt has failed (for
example, after a DNS timeout), each line in the retry configuration is tested
against the complete address only if &%retry_use_local_part%& is set for the
&%retry_use_local_part%& is set for the transport (it defaults true for all
local transports).
-When Exim is looking for a retry rule after a remote delivery attempt has
-failed, what happens depends on the type of failure. After a 4&'xx'& SMTP
-response for a recipient address, the whole address is used when searching the
-retry rules. The rule that is found is used to create a retry time for the
-failing address.
+.cindex "4&'xx'& responses" "retry rules for"
+However, when Exim is looking for a retry rule after a remote delivery attempt
+suffers an address error (a 4&'xx'& SMTP response for a recipient address), the
+whole address is always used as the key when searching the retry rules. The
+rule that is found is used to create a retry time for the combination of the
+failing address and the message's sender. It is the combination of sender and
+recipient that is delayed in subsequent queue runs until its retry time is
+reached. You can delay the recipient without regard to the sender by setting
+&%address_retry_include_sender%& false in the &(smtp)& transport but this can
+lead to problems with servers that regularly issue 4&'xx'& responses to RCPT
+commands.
+
-.section "Choosing which retry rule to use for host errors"
+.section "Choosing which retry rule to use for host and message errors" &&&
+ "SECID160"
For a temporary error that is not related to an individual address (for
example, a connection timeout), each line in the retry configuration is checked
twice. First, the name of the remote host is used as a domain name (preceded by
&'a.b.c.example'&, the second rule is used. The second rule is also used if
routing to &'a.b.c.example'& suffers a temporary failure.
-.new
&*Note*&: The host name is used when matching the patterns, not its IP address.
However, if a message is routed directly to an IP address without the use of a
host name, for example, if a &(manualroute)& router contains a setting such as:
.endd
then the &"host name"& that is used when searching for a retry rule is the
textual form of the IP address.
-.wen
-.section "Retry rules for specific errors"
+.section "Retry rules for specific errors" "SECID161"
.cindex "retry" "specific errors; specifying"
The second field in a retry rule is the name of a particular error, or an
asterisk, which matches any error. The errors that can be tested for are:
Authentication failed when trying to send to a host in the
&%hosts_require_auth%& list in an &(smtp)& transport.
+.vitem &%data_4xx%&
+A 4&'xx'& error was received for an outgoing DATA command, either immediately
+after the command, or after sending the message's data.
+
+.vitem &%mail_4xx%&
+A 4&'xx'& error was received for an outgoing MAIL command.
+
.vitem &%rcpt_4xx%&
-A 4&'xx'& error was received for an outgoing RCPT command. Either the first or
-both of the x's can be given as specific digits, for example: &`rcpt_45x`& or
-&`rcpt_436`&. For example, to recognize 452 errors given to RCPT commands by a
-particular host, and have retries every ten minutes and a one-hour timeout, you
-could set up a retry rule of this form:
+A 4&'xx'& error was received for an outgoing RCPT command.
+.endlist
+
+For the three 4&'xx'& errors, either the first or both of the x's can be given
+as specific digits, for example: &`mail_45x`& or &`rcpt_436`&. For example, to
+recognize 452 errors given to RCPT commands for addresses in a certain domain,
+and have retries every ten minutes with a one-hour timeout, you could set up a
+retry rule of this form:
.code
-the.host.name rcpt_452 F,1h,10m
+the.domain.name rcpt_452 F,1h,10m
.endd
These errors apply to both outgoing SMTP (the &(smtp)& transport) and outgoing
LMTP (either the &(lmtp)& transport, or the &(smtp)& transport in LMTP mode).
-Note, however, that they apply only to responses to RCPT commands.
+
+.vlist
+.vitem &%lost_connection%&
+A server unexpectedly closed the SMTP connection. There may, of course,
+legitimate reasons for this (host died, network died), but if it repeats a lot
+for the same host, it indicates something odd.
.vitem &%refused_MX%&
A connection to a host obtained from an MX record was refused.
.vitem &%timeout%&
There was a timeout while connecting or during an SMTP session.
+.vitem &%tls_required%&
+The server was required to use TLS (it matched &%hosts_require_tls%& in the
+&(smtp)& transport), but either did not offer TLS, or it responded with 4&'xx'&
+to STARTTLS, or there was a problem setting up the TLS connection.
+
.vitem &%quota%&
A mailbox quota was exceeded in a local delivery by the &(appendfile)&
transport.
-.section "Retry rules for specified senders"
+.section "Retry rules for specified senders" "SECID162"
.cindex "retry" "rules; sender-specific"
You can specify retry rules that apply only when the failing message has a
specific sender. In particular, this can be used to define retry rules that
apply only to bounce messages. The third item in a retry rule can be of this
form:
-.code
-senders=<address list>
+.display
+&`senders=`&<&'address list'&>
.endd
The retry timings themselves are then the fourth item. For example:
.code
* rcpt_4xx senders=: F,1h,30m
.endd
-matches 4&'xx'& errors for bounce messages sent to any host. If the address
-list contains white space, it must be enclosed in quotes. For example:
+matches recipient 4&'xx'& errors for bounce messages sent to any address at any
+host. If the address list contains white space, it must be enclosed in quotes.
+For example:
.code
-a.domain auth_failed senders="xb.dom : yc.dom" G,8h,10m,1.5
+a.domain rcpt_452 senders="xb.dom : yc.dom" G,8h,10m,1.5
.endd
-.new
&*Warning*&: This facility can be unhelpful if it is used for host errors
-(those that do not depend on the recipient). The reason is that the sender is
-used only to match the retry rule. Once the rule has been found for a host
-error, its contents are used to set a retry time for the host, and this will
-apply to all messages, not just those with specific senders.
-.wen
+(which do not depend on the recipient). The reason is that the sender is used
+only to match the retry rule. Once the rule has been found for a host error,
+its contents are used to set a retry time for the host, and this will apply to
+all messages, not just those with specific senders.
When testing retry rules using &%-brt%&, you can supply a sender using the
&%-f%& command line option, like this:
-.section "Retry parameters"
+.section "Retry parameters" "SECID163"
.cindex "retry" "parameters in rules"
The third (or fourth, if a senders list is present) field in a retry rule is a
sequence of retry parameter sets, separated by semicolons. Each set consists of
specifies a starting value for the interval, and the second a multiplier, which
is used to increase the size of the interval at each retry.
.next
-.new
&'H'&: retry at randomized intervals. The arguments are as for &'G'&. For each
retry, the previous interval is multiplied by the factor in order to get a
-maximum for the next interval. The mininum interval is the first argument of
+maximum for the next interval. The minimum interval is the first argument of
the parameter, and an actual interval is chosen randomly between them. Such a
rule has been found to be helpful in cluster configurations when all the
members of the cluster restart at once, and may therefore synchronize their
queue processing times.
-.wen
.endlist
When computing the next retry time, the algorithm definitions are scanned in
computed from the rule's parameters until one that is greater than the previous
interval is found. The main configuration variable
.cindex "limit" "retry interval"
-.cindex "retry interval" "maximum"
-.cindex "&%retry_interval_max%&"
-&%retry_interval_max%& limits the maximum interval between retries.
+.cindex "retry" "interval, maximum"
+.oindex "&%retry_interval_max%&"
+&%retry_interval_max%& limits the maximum interval between retries. It
+cannot be set greater than &`24h`&, which is its default value.
A single remote domain may have a number of hosts associated with it, and each
host may have more than one IP address. Retry algorithms are selected on the
deliveries that have been deferred.
-.section "Retry rule examples"
+.section "Retry rule examples" "SECID164"
Here are some example retry rules:
.code
alice@wonderland.fict.example quota_5d F,7d,3h
-.section "Timeout of retry data"
+.section "Timeout of retry data" "SECID165"
.cindex "timeout" "of retry data"
-.cindex "&%retry_data_expire%&"
+.oindex "&%retry_data_expire%&"
.cindex "hints database" "data expiry"
.cindex "retry" "timeout of data"
Exim timestamps the data that it writes to its retry hints database. When it
down all the time, which is not a justified assumption.
If a host really is permanently dead, this behaviour causes a burst of retries
-every now and again, but only if messages routed to it are rare. It there is a
+every now and again, but only if messages routed to it are rare. If there is a
message at least once every 7 days the retry data never expires.
-.section "Long-term failures"
-.cindex "delivery failure" "long-term"
+.section "Long-term failures" "SECID166"
+.cindex "delivery failure, long-term"
.cindex "retry" "after long-term failure"
Special processing happens when an email address has been failing for so long
that the cutoff time for the last algorithm is reached. For example, using the
post-cutoff retry time is not used.
If the delivery is remote, there are two possibilities, controlled by the
-.cindex "&%delay_after_cutoff%&"
+.oindex "&%delay_after_cutoff%&"
&%delay_after_cutoff%& option of the &(smtp)& transport. The option is true by
default. Until the post-cutoff retry time for one of the IP addresses is
reached, the failing email address is bounced immediately, without a delivery
deliver to permanently failing IP addresses than when &%delay_after_cutoff%& is
true.
+.section "Deliveries that work intermittently" "SECID167"
+.cindex "retry" "intermittently working deliveries"
+Some additional logic is needed to cope with cases where a host is
+intermittently available, or when a message has some attribute that prevents
+its delivery when others to the same address get through. In this situation,
+because some messages are successfully delivered, the &"retry clock"& for the
+host or address keeps getting reset by the successful deliveries, and so
+failing messages remain on the queue for ever because the cutoff time is never
+reached.
+
+Two exceptional actions are applied to prevent this happening. The first
+applies to errors that are related to a message rather than a remote host.
+Section &<<SECToutSMTPerr>>& has a discussion of the different kinds of error;
+examples of message-related errors are 4&'xx'& responses to MAIL or DATA
+commands, and quota failures. For this type of error, if a message's arrival
+time is earlier than the &"first failed"& time for the error, the earlier time
+is used when scanning the retry rules to decide when to try next and when to
+time out the address.
+
+The exceptional second action applies in all cases. If a message has been on
+the queue for longer than the cutoff time of any applicable retry rule for a
+given address, a delivery is attempted for that address, even if it is not yet
+time, and if this delivery fails, the address is timed out. A new retry time is
+not computed in this case, so that other messages for the same address are
+considered immediately.
+.ecindex IIDretconf1
+.ecindex IIDregconf2
-.section "Ultimate address timeout"
-.cindex "retry" "ultimate address timeout"
-An additional rule is needed to cope with cases where a host is intermittently
-available, or when a message has some attribute that prevents its delivery when
-others to the same address get through. In this situation, because some
-messages are successfully delivered, the &"retry clock"& for the address keeps
-getting restarted, and so a message could remain on the queue for ever. To
-prevent this, if a message has been on the queue for longer than the cutoff
-time of any applicable retry rule for a given address, a delivery is attempted
-for that address, even if it is not yet time, and if this delivery fails, the
-address is timed out. A new retry time is not computed in this case, so that
-other messages for the same address are considered immediately.
. ////////////////////////////////////////////////////////////////////////////
.chapter "SMTP authentication" "CHAPSMTPAUTH"
-.cindex "SMTP" "authentication configuration"
-.cindex "authentication"
+.scindex IIDauthconf1 "SMTP" "authentication configuration"
+.scindex IIDauthconf2 "authentication"
The &"authenticators"& section of Exim's run time configuration is concerned
with SMTP authentication. This facility is an extension to the SMTP protocol,
described in RFC 2554, which allows a client SMTP host to authenticate itself
&`$ `&&*&`telnet server.example 25`&*&
&`Trying 192.168.34.25...`&
&`Connected to server.example.`&
-&`Escape character is '^]'.`&
+&`Escape character is '^]'.`&
&`220 server.example ESMTP Exim 4.20 ...`&
&*&`ehlo client.example`&*&
&`250-server.example Hello client.example [10.8.4.5]`&
.code
AUTH_CRAM_MD5=yes
AUTH_CYRUS_SASL=yes
+AUTH_DOVECOT=yes
+AUTH_GSASL=yes
+AUTH_HEIMDAL_GSSAPI=yes
AUTH_PLAINTEXT=yes
AUTH_SPA=yes
.endd
in &_Local/Makefile_&, respectively. The first of these supports the CRAM-MD5
authentication mechanism (RFC 2195), and the second provides an interface to
-the Cyrus SASL authentication library. The third can be configured to support
+the Cyrus SASL authentication library.
+The third is an interface to Dovecot's authentication system, delegating the
+work via a socket interface.
+The fourth provides an interface to the GNU SASL authentication library, which
+provides mechanisms but typically not data sources.
+The fifth provides direct access to Heimdal GSSAPI, geared for Kerberos, but
+supporting setting a server keytab.
+The sixth can be configured to support
the PLAIN authentication mechanism (RFC 2595) or the LOGIN mechanism, which is
-not formally documented, but used by several MUAs. The fourth authenticator
+not formally documented, but used by several MUAs. The seventh authenticator
supports Microsoft's &'Secure Password Authentication'& mechanism.
The authenticators are configured using the same syntax as other drivers (see
cram:
driver = cram_md5
public_name = CRAM-MD5
- server_secret = ${if eq{$1}{ph10}{secret1}fail}
+ server_secret = ${if eq{$auth1}{ph10}{secret1}fail}
client_name = ph10
client_secret = secret2
.endd
authenticators, followed by general discussion of the way authentication works
in Exim.
+&*Beware:*& the meaning of &$auth1$&, &$auth2$&, ... varies on a per-driver and
+per-mechanism basis. Please read carefully to determine which variables hold
+account labels such as usercodes and which hold passwords or other
+authenticating data.
+Note that some mechanisms support two different identifiers for accounts: the
+&'authentication id'& and the &'authorization id'&. The contractions &'authn'&
+and &'authz'& are commonly encountered. The American spelling is standard here.
+Conceptually, authentication data such as passwords are tied to the identifier
+used to authenticate; servers may have rules to permit one user to act as a
+second user, so that after login the session is treated as though that second
+user had logged in. That second user is the &'authorization id'&. A robust
+configuration might confirm that the &'authz'& field is empty or matches the
+&'authn'& field. Often this is just ignored. The &'authn'& can be considered
+as verified data, the &'authz'& as an unverified request which the server might
+choose to honour.
-.section "Generic options for authenticators"
+A &'realm'& is a text string, typically a domain name, presented by a server
+to a client to help it select an account and credentials to use. In some
+mechanisms, the client and server provably agree on the realm, but clients
+typically can not treat the realm as secure data to be blindly trusted.
+
+
+
+.section "Generic options for authenticators" "SECID168"
.cindex "authentication" "generic options"
.cindex "options" "generic; for authenticators"
+.option client_condition authenticators string&!! unset
+When Exim is authenticating as a client, it skips any authenticator whose
+&%client_condition%& expansion yields &"0"&, &"no"&, or &"false"&. This can be
+used, for example, to skip plain text authenticators when the connection is not
+encrypted by a setting such as:
+.code
+client_condition = ${if !eq{$tls_cipher}{}}
+.endd
+(Older documentation incorrectly states that &$tls_cipher$& contains the cipher
+used for incoming messages. In fact, during SMTP delivery, it contains the
+cipher used for the delivery.)
+
.option driver authenticators string unset
This option must always be set. It specifies which of the available
See section &<<SECTauthexiser>>& below for further discussion.
+.option server_condition authenticators string&!! unset
+This option must be set for a &%plaintext%& server authenticator, where it
+is used directly to control authentication. See section &<<SECTplainserver>>&
+for details.
+
+For the &(gsasl)& authenticator, this option is required for various
+mechanisms; see chapter &<<CHAPgsasl>>& for details.
+
+For the other authenticators, &%server_condition%& can be used as an additional
+authentication or authorization mechanism that is applied after the other
+authenticator conditions succeed. If it is set, it is expanded when the
+authenticator would otherwise return a success code. If the expansion is forced
+to fail, authentication fails. Any other expansion failure causes a temporary
+error code to be returned. If the result of a successful expansion is an empty
+string, &"0"&, &"no"&, or &"false"&, authentication fails. If the result of the
+expansion is &"1"&, &"yes"&, or &"true"&, authentication succeeds. For any
+other result, a temporary error code is returned, with the expanded string as
+the error text.
+
+
.option server_debug_print authenticators string&!! unset
If this option is set and authentication debugging is enabled (see the &%-d%&
command line option), the string is expanded and included in the debugging
.option server_set_id authenticators string&!! unset
-.cindex "&$authenticated_id$&"
+.vindex "&$authenticated_id$&"
When an Exim server successfully authenticates a client, this string is
expanded using data from the authentication, and preserved for any incoming
messages in the variable &$authenticated_id$&. It is also included in the log
.next
If the value of the AUTH= parameter is &"<>"&, it is ignored.
.next
-.cindex "&$authenticated_sender$&"
+.vindex "&$authenticated_sender$&"
If &%acl_smtp_mailauth%& is defined, the ACL it specifies is run. While it is
running, the value of &$authenticated_sender$& is set to the value obtained
from the AUTH= parameter. If the ACL does not yield &"accept"&, the value of
&$authenticated_id$&, which is a string obtained from the authentication
process, and which is not usually a complete email address.
-.cindex "&$sender_address$&"
+.vindex "&$sender_address$&"
Whenever an AUTH= value is ignored, the incident is logged. The ACL for
MAIL, if defined, is run after AUTH= is accepted or ignored. It can
therefore make use of &$authenticated_sender$&. The converse is not true: the
The &%server_advertise_condition%& controls the advertisement of individual
authentication mechanisms. For example, it can be used to restrict the
-advertisement of a patricular mechanism to encrypted connections, by a setting
+advertisement of a particular mechanism to encrypted connections, by a setting
such as:
.code
server_advertise_condition = ${if eq{$tls_cipher}{}{no}{yes}}
.endd
-.cindex "&$tls_cipher$&"
+.vindex "&$tls_cipher$&"
If the session is encrypted, &$tls_cipher$& is not empty, and so the expansion
yields &"yes"&, which allows the advertisement to happen.
fails. If there is no matching advertised mechanism, the AUTH command is
rejected with a 504 error.
-.cindex "&$received_protocol$&"
-.cindex "&$sender_host_authenticated$&"
+.vindex "&$received_protocol$&"
+.vindex "&$sender_host_authenticated$&"
When a message is received from an authenticated host, the value of
&$received_protocol$& is set to &"esmtpa"& or &"esmtpsa"& instead of &"esmtp"&
or &"esmtps"&, and &$sender_host_authenticated$& contains the name (not the
-.section "Testing server authentication"
+.section "Testing server authentication" "SECID169"
.cindex "authentication" "testing a server"
.cindex "AUTH" "testing a server"
.cindex "base64 encoding" "creating authentication test data"
-.section "Authentication by an Exim client"
+.section "Authentication by an Exim client" "SECID170"
.cindex "authentication" "on an Exim client"
The &(smtp)& transport has two options called &%hosts_require_auth%& and
&%hosts_try_auth%&. When the &(smtp)& transport connects to a server that
of these options, Exim (as a client) tries to authenticate as follows:
.ilist
-For each authenticator that is configured as a client, it searches the
-authentication mechanisms announced by the server for one whose name
-matches the public name of the authenticator.
-.next
-.cindex "&$host$&"
-.cindex "&$host_address$&"
-When it finds one that matches, it runs the authenticator's client code.
-The variables &$host$& and &$host_address$& are available for any string
-expansions that the client might do. They are set to the server's name and
-IP address. If any expansion is forced to fail, the authentication attempt
-is abandoned,
-and Exim moves on to the next authenticator.
-Otherwise an expansion failure causes delivery to be
-deferred.
+For each authenticator that is configured as a client, in the order in which
+they are defined in the configuration, it searches the authentication
+mechanisms announced by the server for one whose name matches the public name
+of the authenticator.
+.next
+.vindex "&$host$&"
+.vindex "&$host_address$&"
+When it finds one that matches, it runs the authenticator's client code. The
+variables &$host$& and &$host_address$& are available for any string expansions
+that the client might do. They are set to the server's name and IP address. If
+any expansion is forced to fail, the authentication attempt is abandoned, and
+Exim moves on to the next authenticator. Otherwise an expansion failure causes
+delivery to be deferred.
.next
If the result of the authentication attempt is a temporary error or a timeout,
Exim abandons trying to send the message to the host for the moment. It will
&%qualify_domain%& is treated as authenticated. However, if the
&%authenticated_sender%& option is set on the &(smtp)& transport, it overrides
the authenticated sender that was received with the message.
+.ecindex IIDauthconf1
+.ecindex IIDauthconf2
. ////////////////////////////////////////////////////////////////////////////
.chapter "The plaintext authenticator" "CHAPplaintext"
-.cindex "&(plaintext)& authenticator"
-.cindex "authenticators" "&(plaintext)&"
+.scindex IIDplaiauth1 "&(plaintext)& authenticator"
+.scindex IIDplaiauth2 "authenticators" "&(plaintext)&"
The &(plaintext)& authenticator can be configured to support the PLAIN and
LOGIN authentication mechanisms, both of which transfer authentication data as
plain (unencrypted) text (though base64 encoded). The use of plain text is a
-security risk. If you use one of these mechanisms without also making use of
-SMTP encryption (see chapter &<<CHAPTLS>>&) you should not use the same
-passwords for SMTP connections as you do for login accounts.
-
+security risk; you are strongly advised to insist on the use of SMTP encryption
+(see chapter &<<CHAPTLS>>&) if you use the PLAIN or LOGIN mechanisms. If you do
+use unencrypted plain text, you should not use the same passwords for SMTP
+connections as you do for login accounts.
-.section "Using plaintext in a server"
+.section "Plaintext options" "SECID171"
.cindex "options" "&(plaintext)& authenticator (server)"
-When running as a server, &(plaintext)& performs the authentication test by
-expanding a string. It has the following options:
+When configured as a server, &(plaintext)& uses the following options:
+
+.option server_condition authenticators string&!! unset
+This is actually a global authentication option, but it must be set in order to
+configure the &(plaintext)& driver as a server. Its use is described below.
.option server_prompts plaintext string&!! unset
The contents of this option, after expansion, must be a colon-separated list of
prompt strings. If expansion fails, a temporary authentication rejection is
given.
-.option server_condition plaintext string&!! unset
-This option must be set in order to configure the driver as a server. Its use
-is described below.
-
+.section "Using plaintext in a server" "SECTplainserver"
.cindex "AUTH" "in &(plaintext)& authenticator"
.cindex "binary zero" "in &(plaintext)& authenticator"
.cindex "numerical variables (&$1$& &$2$& etc)" &&&
"in &(plaintext)& authenticator"
+.vindex "&$auth1$&, &$auth2$&, etc"
.cindex "base64 encoding" "in &(plaintext)& authenticator"
-The data sent by the client with the AUTH command, or in response to
-subsequent prompts, is base64 encoded, and so may contain any byte values
-when decoded. If any data is supplied with the command, it is treated as a
-list of strings, separated by NULs (binary zeros), which are placed in the
-expansion variables &$1$&, &$2$&, etc. If there are more strings in
-&%server_prompts%& than the number of strings supplied with the AUTH
-command, the remaining prompts are used to obtain more data. Each response from
-the client may be a list of NUL-separated strings.
-
-.cindex "&$authenticated_id$&"
+
+When running as a server, &(plaintext)& performs the authentication test by
+expanding a string. The data sent by the client with the AUTH command, or in
+response to subsequent prompts, is base64 encoded, and so may contain any byte
+values when decoded. If any data is supplied with the command, it is treated as
+a list of strings, separated by NULs (binary zeros), the first three of which
+are placed in the expansion variables &$auth1$&, &$auth2$&, and &$auth3$&
+(neither LOGIN nor PLAIN uses more than three strings).
+
+For compatibility with previous releases of Exim, the values are also placed in
+the expansion variables &$1$&, &$2$&, and &$3$&. However, the use of these
+variables for this purpose is now deprecated, as it can lead to confusion in
+string expansions that also use them for other things.
+
+If there are more strings in &%server_prompts%& than the number of strings
+supplied with the AUTH command, the remaining prompts are used to obtain more
+data. Each response from the client may be a list of NUL-separated strings.
+
+.vindex "&$authenticated_id$&"
Once a sufficient number of data strings have been received,
&%server_condition%& is expanded. If the expansion is forced to fail,
authentication fails. Any other expansion failure causes a temporary error code
-.section "The PLAIN authentication mechanism"
+.section "The PLAIN authentication mechanism" "SECID172"
.cindex "PLAIN authentication mechanism"
.cindex "authentication" "PLAIN mechanism"
.cindex "binary zero" "in &(plaintext)& authenticator"
public_name = PLAIN
server_prompts = :
server_condition = \
- ${if and {{eq{$2}{username}}{eq{$3}{mysecret}}}{yes}{no}}
- server_set_id = $2
+ ${if and {{eq{$auth2}{username}}{eq{$auth3}{mysecret}}}}
+ server_set_id = $auth2
.endd
+Note that the default result strings from &%if%& (&"true"& or an empty string)
+are exactly what we want here, so they need not be specified. Obviously, if the
+password contains expansion-significant characters such as dollar, backslash,
+or closing brace, they have to be escaped.
+
The &%server_prompts%& setting specifies a single, empty prompt (empty items at
the end of a string list are ignored). If all the data comes as part of the
AUTH command, as is commonly the case, the prompt is not used. This
authenticating clients it could make sense.
A more sophisticated instance of this authenticator could use the user name in
-&$2$& to look up a password in a file or database, and maybe do an encrypted
+&$auth2$& to look up a password in a file or database, and maybe do an encrypted
comparison (see &%crypteq%& in chapter &<<CHAPexpand>>&). Here is a example of
this approach, where the passwords are looked up in a DBM file. &*Warning*&:
This is an incorrect example:
.code
server_condition = \
- ${if eq{$3}{${lookup{$2}dbm{/etc/authpwd}}}{yes}{no}}
+ ${if eq{$auth3}{${lookup{$auth2}dbm{/etc/authpwd}}}}
.endd
-The expansion uses the user name (&$2$&) as the key to look up a password,
-which it then compares to the supplied password (&$3$&). Why is this example
+The expansion uses the user name (&$auth2$&) as the key to look up a password,
+which it then compares to the supplied password (&$auth3$&). Why is this example
incorrect? It works fine for existing users, but consider what happens if a
non-existent user name is given. The lookup fails, but as no success/failure
strings are given for the lookup, it yields an empty string. Thus, to defeat
the authentication, all a client has to do is to supply a non-existent user
name and an empty password. The correct way of writing this test is:
.code
-server_condition = ${lookup{$2}dbm{/etc/authpwd}\
- {${if eq{$value}{$3}{yes}{no}}}{no}}
+server_condition = ${lookup{$auth2}dbm{/etc/authpwd}\
+ {${if eq{$value}{$auth3}}} {false}}
.endd
In this case, if the lookup succeeds, the result is checked; if the lookup
-fails, authentication fails. If &%crypteq%& is being used instead of &%eq%&,
-the first example is in fact safe, because &%crypteq%& always fails if its
-second argument is empty. However, the second way of writing the test makes the
-logic clearer.
+fails, &"false"& is returned and authentication fails. If &%crypteq%& is being
+used instead of &%eq%&, the first example is in fact safe, because &%crypteq%&
+always fails if its second argument is empty. However, the second way of
+writing the test makes the logic clearer.
-
-.section "The LOGIN authentication mechanism"
+.section "The LOGIN authentication mechanism" "SECID173"
.cindex "LOGIN authentication mechanism"
.cindex "authentication" "LOGIN mechanism"
The LOGIN authentication mechanism is not documented in any RFC, but is in use
public_name = LOGIN
server_prompts = User Name : Password
server_condition = \
- ${if and {{eq{$1}{username}}{eq{$2}{mysecret}}}{yes}{no}}
- server_set_id = $1
+ ${if and {{eq{$auth1}{username}}{eq{$auth2}{mysecret}}}}
+ server_set_id = $auth1
.endd
Because of the way plaintext operates, this authenticator accepts data supplied
with the AUTH command (in contravention of the specification of LOGIN), but
driver = plaintext
public_name = LOGIN
server_prompts = Username:: : Password::
- server_condition = ${if ldapauth \
- {user="cn=${quote_ldap_dn:$1},ou=people,o=example.org" \
- pass=${quote:$2} \
- ldap://ldap.example.org/}{yes}{no}}
- server_set_id = uid=$1,ou=people,o=example.org
-.endd
-Note the use of the &%quote_ldap_dn%& operator to correctly quote the DN for
-authentication. However, the basic &%quote%& operator, rather than any of the
-LDAP quoting operators, is the correct one to use for the password, because
-quoting is needed only to make the password conform to the Exim syntax. At the
-LDAP level, the password is an uninterpreted string.
-
-
-
-.section "Support for different kinds of authentication"
+ server_condition = ${if and{{ \
+ !eq{}{$auth1} }{ \
+ ldapauth{\
+ user="uid=${quote_ldap_dn:$auth1},ou=people,o=example.org" \
+ pass=${quote:$auth2} \
+ ldap://ldap.example.org/} }} }
+ server_set_id = uid=$auth1,ou=people,o=example.org
+.endd
+We have to check that the username is not empty before using it, because LDAP
+does not permit empty DN components. We must also use the &%quote_ldap_dn%&
+operator to correctly quote the DN for authentication. However, the basic
+&%quote%& operator, rather than any of the LDAP quoting operators, is the
+correct one to use for the password, because quoting is needed only to make
+the password conform to the Exim syntax. At the LDAP level, the password is an
+uninterpreted string.
+
+
+.section "Support for different kinds of authentication" "SECID174"
A number of string expansion features are provided for the purpose of
interfacing to different ways of user authentication. These include checking
traditionally encrypted passwords from &_/etc/passwd_& (or equivalent), PAM,
-Radius, &%ldapauth%&, and &'pwcheck'&. For details see section
+Radius, &%ldapauth%&, &'pwcheck'&, and &'saslauthd'&. For details see section
&<<SECTexpcond>>&.
-.section "Using plaintext in a client"
+.section "Using plaintext in a client" "SECID175"
.cindex "options" "&(plaintext)& authenticator (client)"
-The &(plaintext)& authenticator has just one client option:
-
+The &(plaintext)& authenticator has two client options:
+.option client_ignore_invalid_base64 plaintext boolean false
+If the client receives a server prompt that is not a valid base64 string,
+authentication is abandoned by default. However, if this option is set true,
+the error in the challenge is ignored and the client sends the response as
+usual.
.option client_send plaintext string&!! unset
The string is a colon-separated list of authentication data strings. Each
string is independently expanded before being sent to the server. The first
string is sent with the AUTH command; any more strings are sent in response
-to prompts from the server.
+to prompts from the server. Before each string is expanded, the value of the
+most recent prompt is placed in the next &$auth$&<&'n'&> variable, starting
+with &$auth1$& for the first prompt. Up to three prompts are stored in this
+way. Thus, the prompt that is received in response to sending the first string
+(with the AUTH command) can be used in the expansion of the second string, and
+so on. If an invalid base64 string is received when
+&%client_ignore_invalid_base64%& is set, an empty string is put in the
+&$auth$&<&'n'&> variable.
&*Note*&: You cannot use expansion to create multiple strings, because
splitting takes priority and happens first.
The initial colon means that the first string is empty, so no data is sent with
the AUTH command itself. The remaining strings are sent in response to
prompts.
+.ecindex IIDplaiauth1
+.ecindex IIDplaiauth2
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The cram_md5 authenticator"
-.cindex "&(cram_md5)& authenticator"
-.cindex "authenticators" "&(cram_md5)&"
+.chapter "The cram_md5 authenticator" "CHID9"
+.scindex IIDcramauth1 "&(cram_md5)& authenticator"
+.scindex IIDcramauth2 "authenticators" "&(cram_md5)&"
.cindex "CRAM-MD5 authentication mechanism"
.cindex "authentication" "CRAM-MD5 mechanism"
The CRAM-MD5 authentication mechanism is described in RFC 2195. The server
available in plain text at either end.
-.section "Using cram_md5 as a server"
+.section "Using cram_md5 as a server" "SECID176"
.cindex "options" "&(cram_md5)& authenticator (server)"
This authenticator has one server option, which must be set to configure the
authenticator as a server:
.option server_secret cram_md5 string&!! unset
.cindex "numerical variables (&$1$& &$2$& etc)" "in &(cram_md5)& authenticator"
When the server receives the client's response, the user name is placed in
-the expansion variable &$1$&, and &%server_secret%& is expanded to obtain the
-password for that user. The server then computes the CRAM-MD5 digest that the
-client should have sent, and checks that it received the correct string. If the
-expansion of &%server_secret%& is forced to fail, authentication fails. If the
-expansion fails for some other reason, a temporary error code is returned to
-the client.
+the expansion variable &$auth1$&, and &%server_secret%& is expanded to
+obtain the password for that user. The server then computes the CRAM-MD5 digest
+that the client should have sent, and checks that it received the correct
+string. If the expansion of &%server_secret%& is forced to fail, authentication
+fails. If the expansion fails for some other reason, a temporary error code is
+returned to the client.
+
+For compatibility with previous releases of Exim, the user name is also placed
+in &$1$&. However, the use of this variables for this purpose is now
+deprecated, as it can lead to confusion in string expansions that also use
+numeric variables for other things.
For example, the following authenticator checks that the user name given by the
client is &"ph10"&, and if so, uses &"secret"& as the password. For any other
fixed_cram:
driver = cram_md5
public_name = CRAM-MD5
- server_secret = ${if eq{$1}{ph10}{secret}fail}
- server_set_id = $1
+ server_secret = ${if eq{$auth1}{ph10}{secret}fail}
+ server_set_id = $auth1
.endd
-.cindex "&$authenticated_id$&"
+.vindex "&$authenticated_id$&"
If authentication succeeds, the setting of &%server_set_id%& preserves the user
-name in &$authenticated_id$&. A more tyical configuration might look up the
+name in &$authenticated_id$&. A more typical configuration might look up the
secret string in a file, using the user name as the key. For example:
.code
lookup_cram:
driver = cram_md5
public_name = CRAM-MD5
- server_secret = ${lookup{$1}lsearch{/etc/authpwd}{$value}fail}
- server_set_id = $1
+ server_secret = ${lookup{$auth1}lsearch{/etc/authpwd}\
+ {$value}fail}
+ server_set_id = $auth1
.endd
Note that this expansion explicitly forces failure if the lookup fails
-because &$1$& contains an unknown user name.
+because &$auth1$& contains an unknown user name.
+As another example, if you wish to re-use a Cyrus SASL sasldb2 file without
+using the relevant libraries, you need to know the realm to specify in the
+lookup and then ask for the &"userPassword"& attribute for that user in that
+realm, with:
+.code
+cyrusless_crammd5:
+ driver = cram_md5
+ public_name = CRAM-MD5
+ server_secret = ${lookup{$auth1:mail.example.org:userPassword}\
+ dbmjz{/etc/sasldb2}}
+ server_set_id = $auth1
+.endd
-.section "Using cram_md5 as a client"
+.section "Using cram_md5 as a client" "SECID177"
.cindex "options" "&(cram_md5)& authenticator (client)"
When used as a client, the &(cram_md5)& authenticator has two options:
expanded and the result used as the secret string when computing the response.
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+.vindex "&$host$&"
+.vindex "&$host_address$&"
Different user names and secrets can be used for different servers by referring
to &$host$& or &$host_address$& in the options. Forced failure of either
expansion string is treated as an indication that this authenticator is not
client_name = ph10
client_secret = secret
.endd
+.ecindex IIDcramauth1
+.ecindex IIDcramauth2
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The cyrus_sasl authenticator"
-.cindex "&(cyrus_sasl)& authenticator"
-.cindex "authenticators" "&(cyrus_sasl)&"
+.chapter "The cyrus_sasl authenticator" "CHID10"
+.scindex IIDcyrauth1 "&(cyrus_sasl)& authenticator"
+.scindex IIDcyrauth2 "authenticators" "&(cyrus_sasl)&"
.cindex "Cyrus" "SASL library"
+.cindex "Kerberos"
The code for this authenticator was provided by Matthew Byng-Maddick of A L
Digital Ltd (&url(http://www.aldigital.co.uk)).
by default. You may also find you need to set environment variables,
depending on the driver you are using.
-
-.section "Using cyrus_sasl as a server"
-The &(cyrus_sasl)& authenticator has four private options. It puts the
-username (on a successful authentication) into &$1$&.
-
-.option server_hostname cyrus_sasl string&!! &`$primary_hostname`&
-This option selects the hostname that is used when communicating with
-the library. It is up to the underlying SASL plug-in what it does with
-this data.
-
-
-.option server_mech cyrus_sasl string &`public_name`&
-This option selects the authentication mechanism this driver should
-use. It allows you to use a different underlying mechanism from the
-advertised name. For example:
+The application name provided by Exim is &"exim"&, so various SASL options may
+be set in &_exim.conf_& in your SASL directory. If you are using GSSAPI for
+Kerberos, note that because of limitations in the GSSAPI interface,
+changing the server keytab might need to be communicated down to the Kerberos
+layer independently. The mechanism for doing so is dependent upon the Kerberos
+implementation.
+
+For example, for older releases of Heimdal, the environment variable KRB5_KTNAME
+may be set to point to an alternative keytab file. Exim will pass this
+variable through from its own inherited environment when started as root or the
+Exim user. The keytab file needs to be readable by the Exim user.
+With newer releases of Heimdal, a setuid Exim may cause Heimdal to discard the
+environment variable. In practice, for those releases, the Cyrus authenticator
+is not a suitable interface for GSSAPI (Kerberos) support. Instead, consider
+the &(heimdal_gssapi)& authenticator, described in chapter &<<CHAPheimdalgss>>&
+
+
+.section "Using cyrus_sasl as a server" "SECID178"
+The &(cyrus_sasl)& authenticator has four private options. It puts the username
+(on a successful authentication) into &$auth1$&. For compatibility with
+previous releases of Exim, the username is also placed in &$1$&. However, the
+use of this variable for this purpose is now deprecated, as it can lead to
+confusion in string expansions that also use numeric variables for other
+things.
+
+
+.option server_hostname cyrus_sasl string&!! "see below"
+This option selects the hostname that is used when communicating with the
+library. The default value is &`$primary_hostname`&. It is up to the underlying
+SASL plug-in what it does with this data.
+
+
+.option server_mech cyrus_sasl string "see below"
+This option selects the authentication mechanism this driver should use. The
+default is the value of the generic &%public_name%& option. This option allows
+you to use a different underlying mechanism from the advertised name. For
+example:
.code
sasl:
driver = cyrus_sasl
public_name = X-ANYTHING
server_mech = CRAM-MD5
- server_set_id = $1
+ server_set_id = $auth1
.endd
-.option server_realm cyrus_sasl string unset
+.option server_realm cyrus_sasl string&!! unset
This specifies the SASL realm that the server claims to be in.
sasl_cram_md5:
driver = cyrus_sasl
public_name = CRAM-MD5
- server_set_id = $1
+ server_set_id = $auth1
sasl_plain:
driver = cyrus_sasl
public_name = PLAIN
- server_set_id = $1
+ server_set_id = $auth2
.endd
Cyrus SASL does implement the LOGIN authentication method, even though it is
not a standard method. It is disabled by default in the source distribution,
but it is present in many binary distributions.
+.ecindex IIDcyrauth1
+.ecindex IIDcyrauth2
+
+
+
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+.chapter "The dovecot authenticator" "CHAPdovecot"
+.scindex IIDdcotauth1 "&(dovecot)& authenticator"
+.scindex IIDdcotauth2 "authenticators" "&(dovecot)&"
+This authenticator is an interface to the authentication facility of the
+Dovecot POP/IMAP server, which can support a number of authentication methods.
+If you are using Dovecot to authenticate POP/IMAP clients, it might be helpful
+to use the same mechanisms for SMTP authentication. This is a server
+authenticator only. There is only one option:
+
+.option server_socket dovecot string unset
+
+This option must specify the socket that is the interface to Dovecot
+authentication. The &%public_name%& option must specify an authentication
+mechanism that Dovecot is configured to support. You can have several
+authenticators for different mechanisms. For example:
+.code
+dovecot_plain:
+ driver = dovecot
+ public_name = PLAIN
+ server_socket = /var/run/dovecot/auth-client
+ server_set_id = $auth2
+
+dovecot_ntlm:
+ driver = dovecot
+ public_name = NTLM
+ server_socket = /var/run/dovecot/auth-client
+ server_set_id = $auth1
+.endd
+If the SMTP connection is encrypted, or if &$sender_host_address$& is equal to
+&$received_ip_address$& (that is, the connection is local), the &"secured"&
+option is passed in the Dovecot authentication command. If, for a TLS
+connection, a client certificate has been verified, the &"valid-client-cert"&
+option is passed. When authentication succeeds, the identity of the user
+who authenticated is placed in &$auth1$&.
+.ecindex IIDdcotauth1
+.ecindex IIDdcotauth2
+
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+.chapter "The gsasl authenticator" "CHAPgsasl"
+.scindex IIDgsaslauth1 "&(gsasl)& authenticator"
+.scindex IIDgsaslauth2 "authenticators" "&(gsasl)&"
+.cindex "authentication" "GNU SASL"
+.cindex "authentication" "SASL"
+.cindex "authentication" "EXTERNAL"
+.cindex "authentication" "ANONYMOUS"
+.cindex "authentication" "PLAIN"
+.cindex "authentication" "LOGIN"
+.cindex "authentication" "DIGEST-MD5"
+.cindex "authentication" "CRAM-MD5"
+.cindex "authentication" "SCRAM-SHA-1"
+The &(gsasl)& authenticator provides server integration for the GNU SASL
+library and the mechanisms it provides. This is new as of the 4.80 release
+and there are a few areas where the library does not let Exim smoothly
+scale to handle future authentication mechanisms, so no guarantee can be
+made that any particular new authentication mechanism will be supported
+without code changes in Exim.
+
+
+.option server_channelbinding gsasl boolean false
+Some authentication mechanisms are able to use external context at both ends
+of the session to bind the authentication to that context, and fail the
+authentication process if that context differs. Specifically, some TLS
+ciphersuites can provide identifying information about the cryptographic
+context.
+
+This means that certificate identity and verification becomes a non-issue,
+as a man-in-the-middle attack will cause the correct client and server to
+see different identifiers and authentication will fail.
+
+This is currently only supported when using the GnuTLS library. This is
+only usable by mechanisms which support "channel binding"; at time of
+writing, that's the SCRAM family.
+
+This defaults off to ensure smooth upgrade across Exim releases, in case
+this option causes some clients to start failing. Some future release
+of Exim may switch the default to be true.
+
+
+.option server_hostname gsasl string&!! "see below"
+This option selects the hostname that is used when communicating with the
+library. The default value is &`$primary_hostname`&.
+Some mechanisms will use this data.
+
+
+.option server_mech gsasl string "see below"
+This option selects the authentication mechanism this driver should use. The
+default is the value of the generic &%public_name%& option. This option allows
+you to use a different underlying mechanism from the advertised name. For
+example:
+.code
+sasl:
+ driver = gsasl
+ public_name = X-ANYTHING
+ server_mech = CRAM-MD5
+ server_set_id = $auth1
+.endd
+
+
+.option server_password gsasl string&!! unset
+Various mechanisms need access to the cleartext password on the server, so
+that proof-of-possession can be demonstrated on the wire, without sending
+the password itself.
+
+The data available for lookup varies per mechanism.
+In all cases, &$auth1$& is set to the &'authentication id'&.
+The &$auth2$& variable will always be the &'authorization id'& (&'authz'&)
+if available, else the empty string.
+The &$auth3$& variable will always be the &'realm'& if available,
+else the empty string.
+
+A forced failure will cause authentication to defer.
+
+If using this option, it may make sense to set the &%server_condition%&
+option to be simply "true".
+
+
+.option server_realm gsasl string&!! unset
+This specifies the SASL realm that the server claims to be in.
+Some mechanisms will use this data.
+
+
+.option server_scram_iter gsasl string&!! unset
+This option provides data for the SCRAM family of mechanisms.
+&$auth1$& is not available at evaluation time.
+(This may change, as we receive feedback on use)
+
+
+.option server_scram_salt gsasl string&!! unset
+This option provides data for the SCRAM family of mechanisms.
+&$auth1$& is not available at evaluation time.
+(This may change, as we receive feedback on use)
+
+
+.option server_service gsasl string &`smtp`&
+This is the SASL service that the server claims to implement.
+Some mechanisms will use this data.
+
+
+.section "&(gsasl)& auth variables" "SECTgsaslauthvar"
+.vindex "&$auth1$&, &$auth2$&, etc"
+These may be set when evaluating specific options, as detailed above.
+They will also be set when evaluating &%server_condition%&.
+
+Unless otherwise stated below, the &(gsasl)& integration will use the following
+meanings for these variables:
+
+.ilist
+.vindex "&$auth1$&"
+&$auth1$&: the &'authentication id'&
+.next
+.vindex "&$auth2$&"
+&$auth2$&: the &'authorization id'&
+.next
+.vindex "&$auth3$&"
+&$auth3$&: the &'realm'&
+.endlist
+
+On a per-mechanism basis:
+
+.ilist
+.cindex "authentication" "EXTERNAL"
+EXTERNAL: only &$auth1$& is set, to the possibly empty &'authorization id'&;
+the &%server_condition%& option must be present.
+.next
+.cindex "authentication" "ANONYMOUS"
+ANONYMOUS: only &$auth1$& is set, to the possibly empty &'anonymous token'&;
+the &%server_condition%& option must be present.
+.next
+.cindex "authentication" "GSSAPI"
+GSSAPI: &$auth1$& will be set to the &'GSSAPI Display Name'&;
+&$auth2$& will be set to the &'authorization id'&,
+the &%server_condition%& option must be present.
+.endlist
+
+An &'anonymous token'& is something passed along as an unauthenticated
+identifier; this is analogous to FTP anonymous authentication passing an
+email address, or software-identifier@, as the "password".
+
+
+An example showing the password having the realm specified in the callback
+and demonstrating a Cyrus SASL to GSASL migration approach is:
+.code
+gsasl_cyrusless_crammd5:
+ driver = gsasl
+ public_name = CRAM-MD5
+ server_realm = imap.example.org
+ server_password = ${lookup{$auth1:$auth3:userPassword}\
+ dbmjz{/etc/sasldb2}{$value}fail}
+ server_set_id = ${quote:$auth1}
+ server_condition = yes
+.endd
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+.chapter "The heimdal_gssapi authenticator" "CHAPheimdalgss"
+.scindex IIDheimdalgssauth1 "&(heimdal_gssapi)& authenticator"
+.scindex IIDheimdalgssauth2 "authenticators" "&(heimdal_gssapi)&"
+.cindex "authentication" "GSSAPI"
+.cindex "authentication" "Kerberos"
+The &(heimdal_gssapi)& authenticator provides server integration for the
+Heimdal GSSAPI/Kerberos library, permitting Exim to set a keytab pathname
+reliably.
+
+.option server_hostname heimdal_gssapi string&!! "see below"
+This option selects the hostname that is used, with &%server_service%&,
+for constructing the GSS server name, as a &'GSS_C_NT_HOSTBASED_SERVICE'&
+identifier. The default value is &`$primary_hostname`&.
+
+.option server_keytab heimdal_gssapi string&!! unset
+If set, then Heimdal will not use the system default keytab (typically
+&_/etc/krb5.keytab_&) but instead the pathname given in this option.
+The value should be a pathname, with no &"file:"& prefix.
+
+.option server_service heimdal_gssapi string&!! "smtp"
+This option specifies the service identifier used, in conjunction with
+&%server_hostname%&, for building the identifer for finding credentials
+from the keytab.
+
+
+.section "&(heimdal_gssapi)& auth variables" "SECTheimdalgssauthvar"
+Beware that these variables will typically include a realm, thus will appear
+to be roughly like an email address already. The &'authzid'& in &$auth2$& is
+not verified, so a malicious client can set it to anything.
+
+The &$auth1$& field should be safely trustable as a value from the Key
+Distribution Center. Note that these are not quite email addresses.
+Each identifier is for a role, and so the left-hand-side may include a
+role suffix. For instance, &"joe/admin@EXAMPLE.ORG"&.
+
+.vindex "&$auth1$&, &$auth2$&, etc"
+.ilist
+.vindex "&$auth1$&"
+&$auth1$&: the &'authentication id'&, set to the GSS Display Name.
+.next
+.vindex "&$auth2$&"
+&$auth2$&: the &'authorization id'&, sent within SASL encapsulation after
+authentication. If that was empty, this will also be set to the
+GSS Display Name.
+.endlist
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "The spa authenticator"
-.cindex "&(spa)& authenticator"
-.cindex "authenticators" "&(spa)&"
+.chapter "The spa authenticator" "CHAPspa"
+.scindex IIDspaauth1 "&(spa)& authenticator"
+.scindex IIDspaauth2 "authenticators" "&(spa)&"
.cindex "authentication" "Microsoft Secure Password"
.cindex "authentication" "NTLM"
.cindex "Microsoft Secure Password Authentication"
-.section "Using spa as a server"
+.section "Using spa as a server" "SECID179"
.cindex "options" "&(spa)& authenticator (server)"
The &(spa)& authenticator has just one server option:
.option server_password spa string&!! unset
.cindex "numerical variables (&$1$& &$2$& etc)" "in &(spa)& authenticator"
This option is expanded, and the result must be the cleartext password for the
-authenticating user, whose name is at this point in &$1$&. For example:
+authenticating user, whose name is at this point in &$auth1$&. For
+compatibility with previous releases of Exim, the user name is also placed in
+&$1$&. However, the use of this variable for this purpose is now deprecated, as
+it can lead to confusion in string expansions that also use numeric variables
+for other things. For example:
.code
spa:
driver = spa
public_name = NTLM
- server_password = ${lookup{$1}lsearch{/etc/exim/spa_clearpass}\
- {$value}fail}
+ server_password = \
+ ${lookup{$auth1}lsearch{/etc/exim/spa_clearpass}{$value}fail}
.endd
If the expansion is forced to fail, authentication fails. Any other expansion
failure causes a temporary error code to be returned.
-.section "Using spa as a client"
+.section "Using spa as a client" "SECID180"
.cindex "options" "&(spa)& authenticator (client)"
The &(spa)& authenticator has the following client options:
client_password = msn_plaintext_password
client_domain = DOMAIN_OR_UNSET
.endd
+.ecindex IIDspaauth1
+.ecindex IIDspaauth2
.chapter "Encrypted SMTP connections using TLS/SSL" "CHAPTLS" &&&
"Encrypted SMTP connections"
-.cindex "encryption" "on SMTP connection"
-.cindex "SMTP" "encryption"
+.scindex IIDencsmtp1 "encryption" "on SMTP connection"
+.scindex IIDencsmtp2 "SMTP" "encryption"
.cindex "TLS" "on SMTP connection"
.cindex "OpenSSL"
.cindex "GnuTLS"
-.section "Support for the legacy &""ssmtp""& (aka &""smtps""&) protocol"
+.section "Support for the legacy &""ssmtp""& (aka &""smtps""&) protocol" &&&
+ "SECID284"
.cindex "ssmtp protocol"
.cindex "smtps protocol"
.cindex "SMTP" "ssmtp protocol"
port. The protocol was called &"ssmtp"& or &"smtps"&, and port 465 was
allocated for this purpose.
-This approach was abandoned when encrypted SMTP was standardised, but there are
+This approach was abandoned when encrypted SMTP was standardized, but there are
still some legacy clients that use it. Exim supports these clients by means of
the &%tls_on_connect_ports%& global option. Its value must be a list of port
numbers; the most common use is expected to be:
The &%tls_verify_certificates%& option must contain the name of a file, not the
name of a directory (for OpenSSL it can be either).
.next
-The &%tls_dhparam%& option is ignored, because early versions of GnuTLS had no
-facility for varying its Diffie-Hellman parameters. I understand that this has
-changed, but Exim has not been updated to provide this facility.
+The default value for &%tls_dhparam%& differs for historical reasons.
.next
-.cindex "&$tls_peerdn$&"
+.vindex "&$tls_peerdn$&"
Distinguished Name (DN) strings reported by the OpenSSL library use a slash for
separating fields; GnuTLS uses commas, in accordance with RFC 2253. This
affects the value of the &$tls_peerdn$& variable.
.next
OpenSSL identifies cipher suites using hyphens as separators, for example:
-DES-CBC3-SHA. GnuTLS uses underscores, for example: RSA_ARCFOUR_SHA. What is
-more, OpenSSL complains if underscores are present in a cipher list. To make
-life simpler, Exim changes underscores to hyhens for OpenSSL and hyphens to
-underscores for GnuTLS when processing lists of cipher suites in the
+DES-CBC3-SHA. GnuTLS historically used underscores, for example:
+RSA_ARCFOUR_SHA. What is more, OpenSSL complains if underscores are present
+in a cipher list. To make life simpler, Exim changes underscores to hyphens
+for OpenSSL and passes the string unchanged to GnuTLS (expecting the library
+to handle its own older variants) when processing lists of cipher suites in the
&%tls_require_ciphers%& options (the global option and the &(smtp)& transport
option).
.next
The &%tls_require_ciphers%& options operate differently, as described in the
sections &<<SECTreqciphssl>>& and &<<SECTreqciphgnu>>&.
+.next
+.new
+The &%tls_dh_min_bits%& SMTP transport option is only honoured by GnuTLS.
+When using OpenSSL, this option is ignored.
+(If an API is found to let OpenSSL be configured in this way,
+let the Exim Maintainers know and we'll likely use it).
+.wen
+.next
+Some other recently added features may only be available in one or the other.
+This should be documented with the feature. If the documentation does not
+explicitly state that the feature is infeasible in the other TLS
+implementation, then patches are welcome.
.endlist
-.section "GnuTLS parameter computation"
-GnuTLS uses RSA and D-H parameters that take a substantial amount of time to
-compute. It is unreasonable to re-compute them for every TLS session.
+.section "GnuTLS parameter computation" "SECTgnutlsparam"
+This section only applies if &%tls_dhparam%& is set to &`historic`& or to
+an explicit path; if the latter, then the text about generation still applies,
+but not the chosen filename.
+By default, as of Exim 4.80 a hard-coded D-H prime is used.
+See the documentation of &%tls_dhparam%& for more information.
+
+GnuTLS uses D-H parameters that may take a substantial amount of time
+to compute. It is unreasonable to re-compute them for every TLS session.
Therefore, Exim keeps this data in a file in its spool directory, called
-&_gnutls-params_&. The file is owned by the Exim user and is readable only by
-its owner. Every Exim process that start up GnuTLS reads the RSA and D-H
+&_gnutls-params-NNNN_& for some value of NNNN, corresponding to the number
+of bits requested.
+The file is owned by the Exim user and is readable only by
+its owner. Every Exim process that start up GnuTLS reads the D-H
parameters from this file. If the file does not exist, the first Exim process
that needs it computes the data and writes it to a temporary file which is
renamed once it is complete. It does not matter if several Exim processes do
this simultaneously (apart from wasting a few resources). Once a file is in
place, new Exim processes immediately start using it.
-.new
For maximum security, the parameters that are stored in this file should be
recalculated periodically, the frequency depending on your paranoia level.
+If you are avoiding using the fixed D-H primes published in RFCs, then you
+are concerned about some advanced attacks and will wish to do this; if you do
+not regenerate then you might as well stick to the standard primes.
+
Arranging this is easy in principle; just delete the file when you want new
values to be computed. However, there may be a problem. The calculation of new
parameters needs random numbers, and these are obtained from &_/dev/random_&.
a substantial amount of time, causing timeouts on incoming connections.
The solution is to generate the parameters externally to Exim. They are stored
-in &_gnutls-params_& in PEM format, which means that they can be generated
-externally using the &(certtool)& command that is part of GnuTLS.
+in &_gnutls-params-N_& in PEM format, which means that they can be
+generated externally using the &(certtool)& command that is part of GnuTLS.
To replace the parameters with new ones, instead of deleting the file
and letting Exim re-create it, you can generate new parameters using
&(certtool)& and, when this has been done, replace Exim's cache file by
renaming. The relevant commands are something like this:
.code
+# ls
+[ look for file; assume gnutls-params-2236 is the most recent ]
# rm -f new-params
# touch new-params
# chown exim:exim new-params
+# chmod 0600 new-params
+# certtool --generate-dh-params --bits 2236 >>new-params
+# openssl dhparam -noout -text -in new-params | head
+[ check the first line, make sure it's not more than 2236;
+ if it is, then go back to the start ("rm") and repeat
+ until the size generated is at most the size requested ]
# chmod 0400 new-params
-# certtool --generate-privkey --bits 512 >new-params
-# echo "" >>new-params
-# certtool --generate-dh-params --bits 1024 >> new-params
-# mv new-params gnutls-params
+# mv new-params gnutls-params-2236
.endd
If Exim never has to generate the parameters itself, the possibility of
stalling is removed.
-.wen
+
+The filename changed in Exim 4.80, to gain the -bits suffix. The value which
+Exim will choose depends upon the version of GnuTLS in use. For older GnuTLS,
+the value remains hard-coded in Exim as 1024. As of GnuTLS 2.12.x, there is
+a way for Exim to ask for the "normal" number of bits for D-H public-key usage,
+and Exim does so. This attempt to remove Exim from TLS policy decisions
+failed, as GnuTLS 2.12 returns a value higher than the current hard-coded limit
+of the NSS library. Thus Exim gains the &%tls_dh_max_bits%& global option,
+which applies to all D-H usage, client or server. If the value returned by
+GnuTLS is greater than &%tls_dh_max_bits%& then the value will be clamped down
+to &%tls_dh_max_bits%&. The default value has been set at the current NSS
+limit, which is still much higher than Exim historically used.
+
+The filename and bits used will change as the GnuTLS maintainers change the
+value for their parameter &`GNUTLS_SEC_PARAM_NORMAL`&, as clamped by
+&%tls_dh_max_bits%&. At the time of writing (mid 2012), GnuTLS 2.12 recommends
+2432 bits, while NSS is limited to 2236 bits.
+
+In fact, the requested value will be *lower* than &%tls_dh_max_bits%&, to
+increase the chance of the generated prime actually being within acceptable
+bounds, as GnuTLS has been observed to overshoot. Note the check step in the
+procedure above. There is no sane procedure available to Exim to double-check
+the size of the generated prime, so it might still be too large.
.section "Requiring specific ciphers in OpenSSL" "SECTreqciphssl"
.cindex "TLS" "requiring specific ciphers (OpenSSL)"
-.cindex "&%tls_require_ciphers%&" "OpenSSL"
+.oindex "&%tls_require_ciphers%&" "OpenSSL"
There is a function in the OpenSSL library that can be passed a list of cipher
suites before the cipher negotiation takes place. This specifies which ciphers
are acceptable. The list is colon separated and may contain names like
DES-CBC3-SHA. Exim passes the expanded value of &%tls_require_ciphers%&
-directly to this function call. The following quotation from the OpenSSL
+directly to this function call.
+Many systems will install the OpenSSL manual-pages, so you may have
+&'ciphers(1)'& available to you.
+The following quotation from the OpenSSL
documentation specifies what forms of item are allowed in the cipher string:
.ilist
not be moved to the end of the list.
.endlist
+The OpenSSL &'ciphers(1)'& command may be used to test the results of a given
+string:
+.code
+# note single-quotes to get ! past any shell history expansion
+$ openssl ciphers 'HIGH:!MD5:!SHA1'
+.endd
+This example will let the library defaults be permitted on the MX port, where
+there's probably no identity verification anyway, but ups the ante on the
+submission ports where the administrator might have some influence on the
+choice of clients used:
+.code
+# OpenSSL variant; see man ciphers(1)
+tls_require_ciphers = ${if =={$received_port}{25}\
+ {DEFAULT}\
+ {HIGH:!MD5:!SHA1}}
+.endd
-.section "Requiring specific ciphers in GnuTLS" "SECTreqciphgnu"
-.cindex "TLS" "requiring specific ciphers (GnuTLS)"
-.cindex "&%tls_require_ciphers%&" "GnuTLS"
-The GnuTLS library does not have a combined function like OpenSSL. Instead,
-it allows the caller to specify separate lists of key-exchange methods,
-main cipher algorithms, and MAC algorithms. Unfortunately, these lists are
-numerical, and the library does not have a function for turning names into
-numbers. Consequently, the list of recognized names has to be built into
-the application.
-At present, Exim permits only the list of main cipher algorithms to be
-changed. The &%tls_require_ciphers%& option is in the same format as for
-OpenSSL. Exim searches each item for the name of available algorithm. For
-example, if the list contains RSA_AES_SHA then AES is recognized.
+.section "Requiring specific ciphers or other parameters in GnuTLS" &&&
+ "SECTreqciphgnu"
+.cindex "GnuTLS" "specifying parameters for"
+.cindex "TLS" "specifying ciphers (GnuTLS)"
+.cindex "TLS" "specifying key exchange methods (GnuTLS)"
+.cindex "TLS" "specifying MAC algorithms (GnuTLS)"
+.cindex "TLS" "specifying protocols (GnuTLS)"
+.cindex "TLS" "specifying priority string (GnuTLS)"
+.oindex "&%tls_require_ciphers%&" "GnuTLS"
+The GnuTLS library allows the caller to provide a "priority string", documented
+as part of the &[gnutls_priority_init]& function. This is very similar to the
+ciphersuite specification in OpenSSL.
-The cipher algorithms list starts out with a default set of algorithms. If
-the first item in &%tls_require_ciphers%& does &'not'& start with an
-exclamation mark, all the default items are deleted. Thus, only those specified
-can be used. If the first item in &%tls_require_ciphers%& &'does'& start with
-an exclamation mark, the defaults are left on the list.
+The &%tls_require_ciphers%& option is treated as the GnuTLS priority string.
-Then, any item that starts with an exclamation mark causes the relevant
-algorithms to be removed from the list, and any item that does not start
-with an exclamation mark causes the relevant algorithms to be added to the
-list. Thus,
-.code
-tls_require_ciphers = !RSA_ARCFOUR_SHA
-.endd
-allows all the defaults except those that use ARCFOUR, whereas
-.code
-tls_require_ciphers = AES : 3DES
-.endd
-allows only cipher suites that use AES and 3DES. The currently recognized
-algorithms are: AES_256, AES_128, AES (both of the preceding), 3DES, and
-ARCFOUR_128. Unrecognized algorithms are ignored. In a server, the order of the
-list is unimportant; the server will advertise the availability of all the
-relevant cipher suites. However, in a client, the order of the list specifies a
-preference order for the algorithms. The first one in the client's list that is
-also advertised by the server is tried first. The default order is as listed
-above.
+The &%tls_require_ciphers%& option is available both as an global option,
+controlling how Exim behaves as a server, and also as an option of the
+&(smtp)& transport, controlling how Exim behaves as a client. In both cases
+the value is string expanded. The resulting string is not an Exim list and
+the string is given to the GnuTLS library, so that Exim does not need to be
+aware of future feature enhancements of GnuTLS.
+
+Documentation of the strings accepted may be found in the GnuTLS manual, under
+"Priority strings". This is online as
+&url(http://www.gnu.org/software/gnutls/manual/html_node/Priority-Strings.html),
+but beware that this relates to GnuTLS 3, which may be newer than the version
+installed on your system. If you are using GnuTLS 3,
+&url(http://www.gnu.org/software/gnutls/manual/html_node/Listing-the-ciphersuites-in-a-priority-string.html, then the example code)
+on that site can be used to test a given string.
+Prior to Exim 4.80, an older API of GnuTLS was used, and Exim supported three
+additional options, "&%gnutls_require_kx%&", "&%gnutls_require_mac%&" and
+"&%gnutls_require_protocols%&". &%tls_require_ciphers%& was an Exim list.
+This example will let the library defaults be permitted on the MX port, where
+there's probably no identity verification anyway, and lowers security further
+by increasing compatibility; but this ups the ante on the submission ports
+where the administrator might have some influence on the choice of clients
+used:
+.code
+# GnuTLS variant
+tls_require_ciphers = ${if =={$received_port}{25}\
+ {NORMAL:%COMPAT}\
+ {SECURE128}}
+.endd
-.section "Configuring an Exim server to use TLS"
+.section "Configuring an Exim server to use TLS" "SECID182"
.cindex "TLS" "configuring an Exim server"
When Exim has been built with TLS support, it advertises the availability of
the STARTTLS command to client hosts that match &%tls_advertise_hosts%&,
but not to any others. The default value of this option is unset, which means
that STARTTLS is not advertised at all. This default is chosen because you
-need to set some other options in order to make TLS avaliable, and also it is
+need to set some other options in order to make TLS available, and also it is
sensible for systems that want to use TLS only as a client.
If a client issues a STARTTLS command and there is some configuration
tls_certificate = /some/file/name
tls_privatekey = /some/file/name
.endd
-The first file contains the server's X509 certificate, and the second contains
-the private key that goes with it. These files need to be readable by the Exim
-user, and must always be given as full path names. They can be the same file if
-both the certificate and the key are contained within it. If &%tls_privatekey%&
-is not set, this is assumed to be the case. The certificate file may also
-contain intermediate certificates that need to be sent to the client to enable
-it to authenticate the server's certificate.
+These options are, in fact, expanded strings, so you can make them depend on
+the identity of the client that is connected if you wish. The first file
+contains the server's X509 certificate, and the second contains the private key
+that goes with it. These files need to be readable by the Exim user, and must
+always be given as full path names. They can be the same file if both the
+certificate and the key are contained within it. If &%tls_privatekey%& is not
+set, or if its expansion is forced to fail or results in an empty string, this
+is assumed to be the case. The certificate file may also contain intermediate
+certificates that need to be sent to the client to enable it to authenticate
+the server's certificate.
If you do not understand about certificates and keys, please try to find a
source of this background information, which is not Exim-specific. (There are a
few comments below in section &<<SECTcerandall>>&.)
&*Note*&: These options do not apply when Exim is operating as a client &--
-they apply only in the case of a server. For a client, you must set the options
-of the same name in an &(smtp)& transport.
+they apply only in the case of a server. If you need to use a certificate in an
+Exim client, you must set the options of the same names in an &(smtp)&
+transport.
-With just these options, Exim will work as a server with clients such as
-Netscape. It does not require the client to have a certificate (but see below
-for how to insist on this). There is one other option that may be needed in
-other situations. If
+With just these options, an Exim server will be able to use TLS. It does not
+require the client to have a certificate (but see below for how to insist on
+this). There is one other option that may be needed in other situations. If
.code
tls_dhparam = /some/file/name
.endd
is set, the SSL library is initialized for the use of Diffie-Hellman ciphers
-with the parameters contained in the file. This increases the set of cipher
-suites that the server supports. See the command
+with the parameters contained in the file.
+Set this to &`none`& to disable use of DH entirely, by making no prime
+available:
+.code
+tls_dhparam = none
+.endd
+This may also be set to a string identifying a standard prime to be used for
+DH; if it is set to &`default`& or, for OpenSSL, is unset, then the prime
+used is &`ike23`&. There are a few standard primes available, see the
+documetnation for &%tls_dhparam%& for the complete list.
+
+See the command
.code
openssl dhparam
.endd
-for a way of generating this data.
-At present, &%tls_dhparam%& is used only when Exim is linked with OpenSSL. It
-is ignored if GnuTLS is being used.
+for a way of generating file data.
The strings supplied for these three options are expanded every time a client
host connects. It is therefore possible to use different certificates and keys
.cindex "cipher" "logging"
.cindex "log" "TLS cipher"
-.cindex "&$tls_cipher$&"
+.vindex "&$tls_cipher$&"
The variable &$tls_cipher$& is set to the cipher suite that was negotiated for
an incoming TLS connection. It is included in the &'Received:'& header of an
incoming message (by default &-- you can, of course, change this), and it is
also included in the log line that records a message's arrival, keyed by
&"X="&, unless the &%tls_cipher%& log selector is turned off. The &%encrypted%&
condition can be used to test for specific cipher suites in ACLs.
-
-The ACLs that run for subsequent SMTP commands can check the name of the cipher
-suite and vary their actions accordingly. The cipher suite names are those used
-by OpenSSL. These may differ from the names used elsewhere. For example,
-OpenSSL uses the name DES-CBC3-SHA for the cipher suite which in other contexts
-is known as TLS_RSA_WITH_3DES_EDE_CBC_SHA. Check the OpenSSL
+(For outgoing SMTP deliveries, &$tls_cipher$& is reset &-- see section
+&<<SECID185>>&.)
+
+Once TLS has been established, the ACLs that run for subsequent SMTP commands
+can check the name of the cipher suite and vary their actions accordingly. The
+cipher suite names vary, depending on which TLS library is being used. For
+example, OpenSSL uses the name DES-CBC3-SHA for the cipher suite which in other
+contexts is known as TLS_RSA_WITH_3DES_EDE_CBC_SHA. Check the OpenSSL or GnuTLS
documentation for more details.
-
-.section "Requesting and verifying client certificates"
+.section "Requesting and verifying client certificates" "SECID183"
.cindex "certificate" "verification of client"
.cindex "TLS" "client certificate verification"
If you want an Exim server to request a certificate when negotiating a TLS
example, you can insist on a certificate before accepting a message for
relaying, but not when the message is destined for local delivery.
-.cindex "&$tls_peerdn$&"
+.vindex "&$tls_peerdn$&"
When a client supplies a certificate (whether it verifies or not), the value of
the Distinguished Name of the certificate is made available in the variable
&$tls_peerdn$& during subsequent processing of the message.
certificate is supplied, &$tls_peerdn$& is empty.
-.section "Revoked certificates"
+.section "Revoked certificates" "SECID184"
.cindex "TLS" "revoked certificates"
.cindex "revocation list"
.cindex "certificate" "revocation list"
CRL in PEM format.
-.section "Configuring an Exim client to use TLS"
+.section "Configuring an Exim client to use TLS" "SECID185"
.cindex "cipher" "logging"
.cindex "log" "TLS cipher"
.cindex "log" "distinguished name"
unknown state), opens a new one to the same host, and then tries the delivery
unencrypted.
-
The &%tls_certificate%& and &%tls_privatekey%& options of the &(smtp)&
transport provide the client with a certificate, which is passed to the server
if it requests it. If the server is Exim, it will request a certificate only if
-&%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client. &*Note*&:
-These options must be set in the &(smtp)& transport for Exim to use TLS when it
-is operating as a client. Exim does not assume that a server certificate (set
-by the global options of the same name) should also be used when operating as a
-client.
+&%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client.
-If &%tls_verify_certificates%& is set, it must name a file or,
+If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it
+must name a file or,
for OpenSSL only (not GnuTLS), a directory, that contains a collection of
expected server certificates. The client verifies the server's certificate
against this collection, taking into account any revoked certificates that are
the current host is abandoned, and the &(smtp)& transport tries to deliver to
alternative hosts, if any.
-.cindex "&$host$&"
-.cindex "&$host_address$&"
+ &*Note*&:
+These options must be set in the &(smtp)& transport for Exim to use TLS when it
+is operating as a client. Exim does not assume that a server certificate (set
+by the global options of the same name) should also be used when operating as a
+client.
+
+.vindex "&$host$&"
+.vindex "&$host_address$&"
All the TLS options in the &(smtp)& transport are expanded before use, with
&$host$& and &$host_address$& containing the name and address of the server to
which the client is connected. Forced failure of an expansion causes Exim to
behave as if the relevant option were unset.
+.vindex &$tls_bits$&
+.vindex &$tls_cipher$&
+.vindex &$tls_peerdn$&
+.vindex &$tls_sni$&
+Before an SMTP connection is established, the
+&$tls_bits$&, &$tls_cipher$&, &$tls_peerdn$& and &$tls_sni$&
+variables are emptied. (Until the first connection, they contain the values
+that were set when the message was received.) If STARTTLS is subsequently
+successfully obeyed, these variables are set to the relevant values for the
+outgoing connection.
+
+
+
+.section "Use of TLS Server Name Indication" "SECTtlssni"
+.cindex "TLS" "Server Name Indication"
+.vindex "&$tls_sni$&"
+.oindex "&%tls_sni%&"
+With TLS1.0 or above, there is an extension mechanism by which extra
+information can be included at various points in the protocol. One of these
+extensions, documented in RFC 6066 (and before that RFC 4366) is
+&"Server Name Indication"&, commonly &"SNI"&. This extension is sent by the
+client in the initial handshake, so that the server can examine the servername
+within and possibly choose to use different certificates and keys (and more)
+for this session.
+
+This is analagous to HTTP's &"Host:"& header, and is the main mechanism by
+which HTTPS-enabled web-sites can be virtual-hosted, many sites to one IP
+address.
+
+With SMTP to MX, there are the same problems here as in choosing the identity
+against which to validate a certificate: you can't rely on insecure DNS to
+provide the identity which you then cryptographically verify. So this will
+be of limited use in that environment.
+
+With SMTP to Submission, there is a well-defined hostname which clients are
+connecting to and can validate certificates against. Thus clients &*can*&
+choose to include this information in the TLS negotiation. If this becomes
+wide-spread, then hosters can choose to present different certificates to
+different clients. Or even negotiate different cipher suites.
+
+The &%tls_sni%& option on an SMTP transport is an expanded string; the result,
+if not empty, will be sent on a TLS session as part of the handshake. There's
+nothing more to it. Choosing a sensible value not derived insecurely is the
+only point of caution. The &$tls_sni$& variable will be set to this string
+for the lifetime of the client connection (including during authentication).
+
+Except during SMTP client sessions, if &$tls_sni$& is set then it is a string
+received from a client.
+It can be logged with the &%log_selector%& item &`+tls_sni`&.
+
+If the string &`tls_sni`& appears in the main section's &%tls_certificate%&
+option (prior to expansion) then the following options will be re-expanded
+during TLS session handshake, to permit alternative values to be chosen:
+
+.ilist
+.vindex "&%tls_certificate%&"
+&%tls_certificate%&
+.next
+.vindex "&%tls_crl%&"
+&%tls_crl%&
+.next
+.vindex "&%tls_privatekey%&"
+&%tls_privatekey%&
+.next
+.vindex "&%tls_verify_certificates%&"
+&%tls_verify_certificates%&
+.endlist
+
+Great care should be taken to deal with matters of case, various injection
+attacks in the string (&`../`& or SQL), and ensuring that a valid filename
+can always be referenced; it is important to remember that &$tls_sni$& is
+arbitrary unverified data provided prior to authentication.
+
+The Exim developers are proceeding cautiously and so far no other TLS options
+are re-expanded.
+
+When Exim is built againt OpenSSL, OpenSSL must have been built with support
+for TLS Extensions. This holds true for OpenSSL 1.0.0+ and 0.9.8+ with
+enable-tlsext in EXTRACONFIGURE. If you invoke &(openssl s_client -h)& and
+see &`-servername`& in the output, then OpenSSL has support.
+
+When Exim is built against GnuTLS, SNI support is available as of GnuTLS
+0.5.10. (Its presence predates the current API which Exim uses, so if Exim
+built, then you have SNI support).
+
.section "Multiple messages on the same encrypted TCP/IP connection" &&&
.endd
-.section "Certificate chains"
+.section "Certificate chains" "SECID186"
The file named by &%tls_certificate%& may contain more than one
certificate. This is useful in the case where the certificate that is being
sent is validated by an intermediate certificate which the other end does
install if the receiving end is a client MUA that can interact with a user.
-.section "Self-signed certificates"
+.section "Self-signed certificates" "SECID187"
.cindex "certificate" "self-signed"
You can create a self-signed certificate using the &'req'& command provided
with OpenSSL, like this:
user certificates, see the &'General implementation overview'& chapter of the
Open-source PKI book, available online at
&url(http://ospkibook.sourceforge.net/).
+.ecindex IIDencsmtp1
+.ecindex IIDencsmtp2
. ////////////////////////////////////////////////////////////////////////////
.chapter "Access control lists" "CHAPACL"
-.cindex "&ACL;" "description"
+.scindex IIDacl "&ACL;" "description"
.cindex "control of incoming mail"
.cindex "message" "controlling incoming"
.cindex "policy control" "access control lists"
one very small ACL:
.code
begin acl
-
small_acl:
accept hosts = one.host.only
.endd
&<<CHAPdefconfil>>&.
-.section "Testing ACLs"
+.section "Testing ACLs" "SECID188"
The &%-bh%& command line option provides a way of testing your ACL
configuration locally by running a fake SMTP session with which you interact.
The host &'relay-test.mail-abuse.org'& provides a service for checking your
-.section "Specifying when ACLs are used"
+.section "Specifying when ACLs are used" "SECID189"
.cindex "&ACL;" "options for specifying"
In order to cause an ACL to be used, you have to name it in one of the relevant
options in the main part of the configuration. These options are:
.cindex "HELO" "ACL for"
.cindex "EHLO" "ACL for"
.cindex "MAIL" "ACL for"
-.cindex "QUIT" "ACL for"
+.cindex "QUIT, ACL for"
.cindex "RCPT" "ACL for"
-.cindex "STARTTLS" "ACL for"
+.cindex "STARTTLS, ACL for"
.cindex "VRFY" "ACL for"
-.cindex "SMTP connection" "ACL for"
-.cindex "non-smtp message" "ACL for"
+.cindex "SMTP" "connection, ACL for"
+.cindex "non-SMTP messages" "ACLs for"
+.cindex "MIME content scanning" "ACL for"
.table2 140pt
-.row &~&%acl_not_smtp%& "ACL for non-SMTP messages"
-.row &~&%acl_smtp_auth%& "ACL for AUTH"
-.row &~&%acl_smtp_connect%& "ACL for start of SMTP connection"
-.row &~&%acl_smtp_data%& "ACL after DATA is complete"
-.row &~&%acl_smtp_etrn%& "ACL for ETRN"
-.row &~&%acl_smtp_expn%& "ACL for EXPN"
-.row &~&%acl_smtp_helo%& "ACL for HELO or EHLO"
-.row &~&%acl_smtp_mail%& "ACL for MAIL"
-.row &~&%acl_smtp_mailauth%& "ACL for the AUTH parameter of MAIL"
-.row &~&%acl_smtp_mime%& "ACL for content-scanning MIME parts"
-.row &~&%acl_smtp_predata%& "ACL at start of DATA command"
-.row &~&%acl_smtp_quit%& "ACL for QUIT"
-.row &~&%acl_smtp_rcpt%& "ACL for RCPT"
-.row &~&%acl_smtp_starttls%& "ACL for STARTTLS"
-.row &~&%acl_smtp_vrfy%& "ACL for VRFY"
+.irow &%acl_not_smtp%& "ACL for non-SMTP messages"
+.irow &%acl_not_smtp_mime%& "ACL for non-SMTP MIME parts"
+.irow &%acl_not_smtp_start%& "ACL at start of non-SMTP message"
+.irow &%acl_smtp_auth%& "ACL for AUTH"
+.irow &%acl_smtp_connect%& "ACL for start of SMTP connection"
+.irow &%acl_smtp_data%& "ACL after DATA is complete"
+.irow &%acl_smtp_etrn%& "ACL for ETRN"
+.irow &%acl_smtp_expn%& "ACL for EXPN"
+.irow &%acl_smtp_helo%& "ACL for HELO or EHLO"
+.irow &%acl_smtp_mail%& "ACL for MAIL"
+.irow &%acl_smtp_mailauth%& "ACL for the AUTH parameter of MAIL"
+.irow &%acl_smtp_mime%& "ACL for content-scanning MIME parts"
+.irow &%acl_smtp_notquit%& "ACL for non-QUIT terminations"
+.irow &%acl_smtp_predata%& "ACL at start of DATA command"
+.irow &%acl_smtp_quit%& "ACL for QUIT"
+.irow &%acl_smtp_rcpt%& "ACL for RCPT"
+.irow &%acl_smtp_starttls%& "ACL for STARTTLS"
+.irow &%acl_smtp_vrfy%& "ACL for VRFY"
.endtable
For example, if you set
testing as possible at RCPT time.
-.section "The non-SMTP ACL"
-.cindex "non-smtp message" "ACL for"
-The non-SMTP ACL applies to all non-interactive incoming messages, that is, it
-applies to batch SMTP as well as to non-SMTP messages. (Batch SMTP is not
-really SMTP.) This ACL is run just before the &[local_scan()]& function. Any
+.section "The non-SMTP ACLs" "SECID190"
+.cindex "non-SMTP messages" "ACLs for"
+The non-SMTP ACLs apply to all non-interactive incoming messages, that is, they
+apply to batched SMTP as well as to non-SMTP messages. (Batched SMTP is not
+really SMTP.) Many of the ACL conditions (for example, host tests, and tests on
+the state of the SMTP connection such as encryption and authentication) are not
+relevant and are forbidden in these ACLs. However, the sender and recipients
+are known, so the &%senders%& and &%sender_domains%& conditions and the
+&$sender_address$& and &$recipients$& variables can be used. Variables such as
+&$authenticated_sender$& are also available. You can specify added header lines
+in any of these ACLs.
+
+The &%acl_not_smtp_start%& ACL is run right at the start of receiving a
+non-SMTP message, before any of the message has been read. (This is the
+analogue of the &%acl_smtp_predata%& ACL for SMTP input.) In the case of
+batched SMTP input, it runs after the DATA command has been reached. The
+result of this ACL is ignored; it cannot be used to reject a message. If you
+really need to, you could set a value in an ACL variable here and reject based
+on that in the &%acl_not_smtp%& ACL. However, this ACL can be used to set
+controls, and in particular, it can be used to set
+.code
+control = suppress_local_fixups
+.endd
+This cannot be used in the other non-SMTP ACLs because by the time they are
+run, it is too late.
+
+The &%acl_not_smtp_mime%& ACL is available only when Exim is compiled with the
+content-scanning extension. For details, see chapter &<<CHAPexiscan>>&.
+
+The &%acl_not_smtp%& ACL is run just before the &[local_scan()]& function. Any
kind of rejection is treated as permanent, because there is no way of sending a
-temporary error for these kinds of message. Many of the ACL conditions (for
-example, host tests, and tests on the state of the SMTP connection such as
-encryption and authentication) are not relevant and are forbidden in this ACL.
+temporary error for these kinds of message.
-.section "The connect ACL"
-.cindex "SMTP connection" "ACL for"
-The ACL test specified by &%acl_smtp_connect%& happens after the test specified
-by &%host_reject_connection%& (which is now an anomaly) and any TCP Wrappers
-testing (if configured).
+.section "The SMTP connect ACL" "SECID191"
+.cindex "SMTP" "connection, ACL for"
+.oindex &%smtp_banner%&
+The ACL test specified by &%acl_smtp_connect%& happens at the start of an SMTP
+session, after the test specified by &%host_reject_connection%& (which is now
+an anomaly) and any TCP Wrappers testing (if configured). If the connection is
+accepted by an &%accept%& verb that has a &%message%& modifier, the contents of
+the message override the banner message that is otherwise specified by the
+&%smtp_banner%& option.
-.section "The DATA ACLs"
+.section "The EHLO/HELO ACL" "SECID192"
+.cindex "EHLO" "ACL for"
+.cindex "HELO" "ACL for"
+The ACL test specified by &%acl_smtp_helo%& happens when the client issues an
+EHLO or HELO command, after the tests specified by &%helo_accept_junk_hosts%&,
+&%helo_allow_chars%&, &%helo_verify_hosts%&, and &%helo_try_verify_hosts%&.
+Note that a client may issue more than one EHLO or HELO command in an SMTP
+session, and indeed is required to issue a new EHLO or HELO after successfully
+setting up encryption following a STARTTLS command.
+
+If the command is accepted by an &%accept%& verb that has a &%message%&
+modifier, the message may not contain more than one line (it will be truncated
+at the first newline and a panic logged if it does). Such a message cannot
+affect the EHLO options that are listed on the second and subsequent lines of
+an EHLO response.
+
+
+.section "The DATA ACLs" "SECID193"
.cindex "DATA" "ACLs for"
Two ACLs are associated with the DATA command, because it is two-stage
command, with two responses being sent to the client.
your resources.
-.section "The MIME ACL"
+.section "The SMTP DKIM ACL" "SECTDKIMACL"
+The &%acl_smtp_dkim%& ACL is available only when Exim is compiled with DKIM support
+enabled (which is the default).
+
+The ACL test specified by &%acl_smtp_dkim%& happens after a message has been
+received, and is executed for each DKIM signature found in a message. If not
+otherwise specified, the default action is to accept.
+
+For details on the operation of DKIM, see chapter &<<CHID12>>&.
+
+
+.section "The SMTP MIME ACL" "SECID194"
The &%acl_smtp_mime%& option is available only when Exim is compiled with the
content-scanning extension. For details, see chapter &<<CHAPexiscan>>&.
.section "The QUIT ACL" "SECTQUITACL"
-.cindex "QUIT" "ACL for"
+.cindex "QUIT, ACL for"
The ACL for the SMTP QUIT command is anomalous, in that the outcome of the ACL
does not affect the response code to QUIT, which is always 221. Thus, the ACL
does not in fact control any access. For this reason, the only verbs that are
messages, recipients, etc., and log the totals at QUIT time using one or
more &%logwrite%& modifiers on a &%warn%& verb.
-.new
&*Warning*&: Only the &$acl_c$&&'x'& variables can be used for this, because
the &$acl_m$&&'x'& variables are reset at the end of each incoming message.
-.wen
You do not need to have a final &%accept%&, but if you do, you can use a
&%message%& modifier to specify custom text that is sent as part of the 221
connection is closed. In these special cases, the QUIT ACL does not run.
+.section "The not-QUIT ACL" "SECTNOTQUITACL"
+.vindex &$acl_smtp_notquit$&
+The not-QUIT ACL, specified by &%acl_smtp_notquit%&, is run in most cases when
+an SMTP session ends without sending QUIT. However, when Exim itself is is bad
+trouble, such as being unable to write to its log files, this ACL is not run,
+because it might try to do things (such as write to log files) that make the
+situation even worse.
+
+Like the QUIT ACL, this ACL is provided to make it possible to do customized
+logging or to gather statistics, and its outcome is ignored. The &%delay%&
+modifier is forbidden in this ACL, and the only permitted verbs are &%accept%&
+and &%warn%&.
+
+.vindex &$smtp_notquit_reason$&
+When the not-QUIT ACL is running, the variable &$smtp_notquit_reason$& is set
+to a string that indicates the reason for the termination of the SMTP
+connection. The possible values are:
+.table2
+.irow &`acl-drop`& "Another ACL issued a &%drop%& command"
+.irow &`bad-commands`& "Too many unknown or non-mail commands"
+.irow &`command-timeout`& "Timeout while reading SMTP commands"
+.irow &`connection-lost`& "The SMTP connection has been lost"
+.irow &`data-timeout`& "Timeout while reading message data"
+.irow &`local-scan-error`& "The &[local_scan()]& function crashed"
+.irow &`local-scan-timeout`& "The &[local_scan()]& function timed out"
+.irow &`signal-exit`& "SIGTERM or SIGINT"
+.irow &`synchronization-error`& "SMTP synchronization error"
+.irow &`tls-failed`& "TLS failed to start"
+.endtable
+In most cases when an SMTP connection is closed without having received QUIT,
+Exim sends an SMTP response message before actually closing the connection.
+With the exception of the &`acl-drop`& case, the default message can be
+overridden by the &%message%& modifier in the not-QUIT ACL. In the case of a
+&%drop%& verb in another ACL, it is the message from the other ACL that is
+used.
+
-.section "Finding an ACL to use"
+.section "Finding an ACL to use" "SECID195"
.cindex "&ACL;" "finding which to use"
-The value of an &%acl_smtp_%&&'xxx'& option is expanded before use, so you can
-use different ACLs in different circumstances. The resulting string does not
-have to be the name of an ACL in the configuration file; there are other
-possibilities. Having expanded the string, Exim searches for an ACL as follows:
+The value of an &%acl_smtp_%&&'xxx'& option is expanded before use, so
+you can use different ACLs in different circumstances. For example,
+.code
+acl_smtp_rcpt = ${if ={25}{$interface_port} \
+ {acl_check_rcpt} {acl_check_rcpt_submit} }
+.endd
+In the default configuration file there are some example settings for
+providing an RFC 4409 message submission service on port 587 and a
+non-standard &"smtps"& service on port 465. You can use a string
+expansion like this to choose an ACL for MUAs on these ports which is
+more appropriate for this purpose than the default ACL on port 25.
+
+The expanded string does not have to be the name of an ACL in the
+configuration file; there are other possibilities. Having expanded the
+string, Exim searches for an ACL as follows:
.ilist
If the string begins with a slash, Exim uses it as a file name, and reads its
-.section "ACL return codes"
+.section "ACL return codes" "SECID196"
.cindex "&ACL;" "return codes"
Except for the QUIT ACL, which does not affect the SMTP return code (see
section &<<SECTQUITACL>>& above), the result of running an ACL is either
-.section "Unset ACL options"
+.section "Unset ACL options" "SECID197"
.cindex "&ACL;" "unset options"
The default actions when any of the &%acl_%&&'xxx'& options are unset are not
all the same. &*Note*&: These defaults apply only when the relevant ACL is
not defined at all. For any defined ACL, the default action when control
reaches the end of the ACL statements is &"deny"&.
+For &%acl_smtp_quit%& and &%acl_not_smtp_start%& there is no default because
+these two are ACLs that are used only for their side effects. They cannot be
+used to accept or reject anything.
+
For &%acl_not_smtp%&, &%acl_smtp_auth%&, &%acl_smtp_connect%&,
&%acl_smtp_data%&, &%acl_smtp_helo%&, &%acl_smtp_mail%&, &%acl_smtp_mailauth%&,
-&%acl_smtp_mime%&, &%acl_smtp_predata%&, &%acl_smtp_quit%&, and
-&%acl_smtp_starttls%&, the action when the ACL is not defined is &"accept"&.
+&%acl_smtp_mime%&, &%acl_smtp_predata%&, and &%acl_smtp_starttls%&, the action
+when the ACL is not defined is &"accept"&.
For the others (&%acl_smtp_etrn%&, &%acl_smtp_expn%&, &%acl_smtp_rcpt%&, and
&%acl_smtp_vrfy%&), the action when the ACL is not defined is &"deny"&.
-.section "Data for message ACLs"
+.section "Data for message ACLs" "SECID198"
.cindex "&ACL;" "data for message ACL"
-.cindex &$domain$&
-.cindex &$local_part$&
-.cindex &$sender_address$&
-.cindex &$sender_host_address$&
-.cindex &$smtp_command$&
+.vindex &$domain$&
+.vindex &$local_part$&
+.vindex &$sender_address$&
+.vindex &$sender_host_address$&
+.vindex &$smtp_command$&
When a MAIL or RCPT ACL, or either of the DATA ACLs, is running, the variables
that contain information about the host and the message's sender (for example,
&$sender_host_address$& and &$sender_address$&) are set, and can be used in ACL
statements. In the case of RCPT (but not MAIL or DATA), &$domain$& and
-&$local_part$& are set from the argument address. &new("The entire SMTP command
-is available in &$smtp_command$&.")
+&$local_part$& are set from the argument address. The entire SMTP command
+is available in &$smtp_command$&.
When an ACL for the AUTH parameter of MAIL is running, the variables that
contain information about the host are set, but &$sender_address$& is not yet
set. Section &<<SECTauthparamail>>& contains a discussion of this parameter and
how it is used.
-.cindex "&$message_size$&"
+.vindex "&$message_size$&"
The &$message_size$& variable is set to the value of the SIZE parameter on
the MAIL command at MAIL, RCPT and pre-data time, or to -1 if
that parameter is not given. The value is updated to the true message size by
the time the final DATA ACL is run (after the message data has been
received).
-.cindex "&$rcpt_count$&"
-.cindex "&$recipients_count$&"
+.vindex "&$rcpt_count$&"
+.vindex "&$recipients_count$&"
The &$rcpt_count$& variable increases by one for each RCPT command received.
The &$recipients_count$& variable increases by one each time a RCPT command is
accepted, so while an ACL for RCPT is being processed, it contains the number
.section "Data for non-message ACLs" "SECTdatfornon"
.cindex "&ACL;" "data for non-message ACL"
-.cindex &$smtp_command_argument$&
-.cindex &$smtp_command$&
+.vindex &$smtp_command_argument$&
+.vindex &$smtp_command$&
When an ACL is being run for AUTH, EHLO, ETRN, EXPN, HELO, STARTTLS, or VRFY,
the remainder of the SMTP command line is placed in &$smtp_command_argument$&,
-&new("and the entire SMTP command is available in &$smtp_command$&.")
+and the entire SMTP command is available in &$smtp_command$&.
These variables can be tested using a &%condition%& condition. For example,
here is an ACL for use with AUTH, which insists that either the session is
encrypted, or the CRAM-MD5 authentication method is used. In other words, it
-.section "Format of an ACL"
+.section "Format of an ACL" "SECID199"
.cindex "&ACL;" "format of"
-.cindex "&ACL;" "verbs; definition of"
+.cindex "&ACL;" "verbs, definition of"
An individual ACL consists of a number of statements. Each statement starts
with a verb, optionally followed by a number of conditions and &"modifiers"&.
Modifiers can change the way the verb operates, define error and log messages,
test a sender address in the ACL that is run for a VRFY command.
-.section "ACL verbs"
+.section "ACL verbs" "SECID200"
The ACL verbs are as follows:
.ilist
-.cindex "&%accept%&" "ACL verb"
+.cindex "&%accept%& ACL verb"
&%accept%&: If all the conditions are met, the ACL returns &"accept"&. If any
of the conditions are not met, what happens depends on whether &%endpass%&
appears among the conditions (for syntax see below). If the failing condition
fails, the ACL yields &"deny"&, because the failing condition is after
&%endpass%&.
+The &%endpass%& feature has turned out to be confusing to many people, so its
+use is not recommended nowadays. It is always possible to rewrite an ACL so
+that &%endpass%& is not needed, and it is no longer used in the default
+configuration.
+
+.cindex "&%message%& ACL modifier" "with &%accept%&"
+If a &%message%& modifier appears on an &%accept%& statement, its action
+depends on whether or not &%endpass%& is present. In the absence of &%endpass%&
+(when an &%accept%& verb either accepts or passes control to the next
+statement), &%message%& can be used to vary the message that is sent when an
+SMTP command is accepted. For example, in a RCPT ACL you could have:
+.display
+&`accept `&<&'some conditions'&>
+&` message = OK, I will allow you through today`&
+.endd
+You can specify an SMTP response code, optionally followed by an &"extended
+response code"& at the start of the message, but the first digit must be the
+same as would be sent by default, which is 2 for an &%accept%& verb.
+
+If &%endpass%& is present in an &%accept%& statement, &%message%& specifies
+an error message that is used when access is denied. This behaviour is retained
+for backward compatibility, but current &"best practice"& is to avoid the use
+of &%endpass%&.
+
+
.next
-.cindex "&%defer%&" "ACL verb"
-&%defer%&: If all the conditions are met, the ACL returns &"defer"& which, in
+.cindex "&%defer%& ACL verb"
+&%defer%&: If all the conditions are true, the ACL returns &"defer"& which, in
an SMTP session, causes a 4&'xx'& response to be given. For a non-SMTP ACL,
&%defer%& is the same as &%deny%&, because there is no way of sending a
temporary error. For a RCPT command, &%defer%& is much the same as using a
&(redirect)& router and &`:defer:`& while verifying, but the &%defer%& verb can
be used in any ACL, and even for a recipient it might be a simpler approach.
+
+
.next
-.cindex "&%deny%&" "ACL verb"
+.cindex "&%deny%& ACL verb"
&%deny%&: If all the conditions are met, the ACL returns &"deny"&. If any of
the conditions are not met, control is passed to the next ACL statement. For
example,
.endd
rejects commands from hosts that are on a DNS black list.
+
.next
-.cindex "&%discard%&" "ACL verb"
+.cindex "&%discard%& ACL verb"
&%discard%&: This verb behaves like &%accept%&, except that it returns
&"discard"& from the ACL instead of &"accept"&. It is permitted only on ACLs
-that are concerned with receiving messages, and it causes recipients to be
-discarded. If the &%log_message%& modifier is set when &%discard%& operates,
+that are concerned with receiving messages. When all the conditions are true,
+the sending entity receives a &"success"& response. However, &%discard%& causes
+recipients to be discarded. If it is used in an ACL for RCPT, just the one
+recipient is discarded; if used for MAIL, DATA or in the non-SMTP ACL, all the
+message's recipients are discarded. Recipients that are discarded before DATA
+do not appear in the log line when the &%received_recipients%& log selector is set.
+
+If the &%log_message%& modifier is set when &%discard%& operates,
its contents are added to the line that is automatically written to the log.
+The &%message%& modifier operates exactly as it does for &%accept%&.
+
-If &%discard%& is used in an ACL for RCPT, just the one recipient is
-discarded; if used for MAIL, DATA or in the non-SMTP ACL, all the
-message's recipients are discarded. Recipients that are discarded before
-DATA do not appear in the log line when the &%log_recipients%& log selector
-is set.
.next
-.cindex "&%drop%&" "ACL verb"
+.cindex "&%drop%& ACL verb"
&%drop%&: This verb behaves like &%deny%&, except that an SMTP connection is
forcibly closed after the 5&'xx'& error message has been sent. For example:
.code
The connection is always dropped after sending a 550 response.
.next
-.cindex "&%require%&" "ACL verb"
+.cindex "&%require%& ACL verb"
&%require%&: If all the conditions are met, control is passed to the next ACL
statement. If any of the conditions are not met, the ACL returns &"deny"&. For
example, when checking a RCPT command,
.code
-require verify = sender
+require message = Sender did not verify
+ verify = sender
.endd
passes control to subsequent statements only if the message's sender can be
-verified. Otherwise, it rejects the command.
+verified. Otherwise, it rejects the command. Note the positioning of the
+&%message%& modifier, before the &%verify%& condition. The reason for this is
+discussed in section &<<SECTcondmodproc>>&.
.next
-.cindex "&%warn%&" "ACL verb"
-&%warn%&: If all the conditions are met, a header line is added to an incoming
-message and/or a line is written to Exim's main log. In all cases, control
-passes to the next ACL statement. The text of the added header line and the log
-line are specified by modifiers; if they are not present, a &%warn%& verb just
-checks its conditions and obeys any &"immediate"& modifiers such as &%set%& and
-&%logwrite%&. There is more about adding header lines in section
-&<<SECTaddheadwarn>>&.
+.cindex "&%warn%& ACL verb"
+&%warn%&: If all the conditions are true, a line specified by the
+&%log_message%& modifier is written to Exim's main log. Control always passes
+to the next ACL statement. If any condition is false, the log line is not
+written. If an identical log line is requested several times in the same
+message, only one copy is actually written to the log. If you want to force
+duplicates to be written, use the &%logwrite%& modifier instead.
-If any condition on a &%warn%& statement cannot be completed (that is, there is
-some sort of defer), no header lines are added and the configured log line is
-not written. No further conditions or modifiers in the &%warn%& statement are
-processed. The incident is logged, but the ACL continues to be processed, from
-the next statement onwards.
+If &%log_message%& is not present, a &%warn%& verb just checks its conditions
+and obeys any &"immediate"& modifiers (such as &%control%&, &%set%&,
+&%logwrite%&, and &%add_header%&) that appear before the first failing
+condition. There is more about adding header lines in section
+&<<SECTaddheadacl>>&.
-If a &%message%& modifier is present on a &%warn%& verb in an ACL that is not
-testing an incoming message, it is ignored, and the incident is logged.
+If any condition on a &%warn%& statement cannot be completed (that is, there is
+some sort of defer), the log line specified by &%log_message%& is not written.
+This does not include the case of a forced failure from a lookup, which
+is considered to be a successful completion. After a defer, no further
+conditions or modifiers in the &%warn%& statement are processed. The incident
+is logged, and the ACL continues to be processed, from the next statement
+onwards.
-A &%warn%& statement may use the &%log_message%& modifier to cause a line to be
-written to the main log when the statement's conditions are true.
-If an identical log line is requested several times in the same message, only
-one copy is actually written to the log. If you want to force duplicates to be
-written, use the &%logwrite%& modifier instead.
-.cindex "&$acl_verify_message$&"
+.vindex "&$acl_verify_message$&"
When one of the &%warn%& conditions is an address verification that fails, the
text of the verification failure message is in &$acl_verify_message$&. If you
want this logged, you must set it up explicitly. For example:
There are some special variables that can be set during ACL processing. They
can be used to pass information between different ACLs, different invocations
of the same ACL in the same SMTP connection, and between ACLs and the routers,
-transports, and filters that are used to deliver a message. There are two sets
-of these variables:
-
+transports, and filters that are used to deliver a message. The names of these
+variables must begin with &$acl_c$& or &$acl_m$&, followed either by a digit or
+an underscore, but the remainder of the name can be any sequence of
+alphanumeric characters and underscores that you choose. There is no limit on
+the number of ACL variables. The two sets act as follows:
.ilist
-The values of &$acl_c0$& to &$acl_c9$& persist throughout an SMTP connection.
-They are never reset. Thus, a value that is set while receiving one message is
-still available when receiving the next message on the same SMTP connection.
-.next
-The values of &$acl_m0$& to &$acl_m9$& persist only while a message is being
-received. They are reset afterwards. They are also reset by MAIL, RSET,
-EHLO, HELO, and after starting up a TLS session.
+The values of those variables whose names begin with &$acl_c$& persist
+throughout an SMTP connection. They are never reset. Thus, a value that is set
+while receiving one message is still available when receiving the next message
+on the same SMTP connection.
+.next
+The values of those variables whose names begin with &$acl_m$& persist only
+while a message is being received. They are reset afterwards. They are also
+reset by MAIL, RSET, EHLO, HELO, and after starting up a TLS session.
.endlist
When a message is accepted, the current values of all the ACL variables are
preserved with the message and are subsequently made available at delivery
-time. The ACL variables are set by modifier called &%set%&. For example:
+time. The ACL variables are set by a modifier called &%set%&. For example:
.code
accept hosts = whatever
set acl_m4 = some value
+accept authenticated = *
+ set acl_c_auth = yes
.endd
&*Note*&: A leading dollar sign is not used when naming a variable that is to
be set. If you want to set a variable without taking any action, you can use a
&%warn%& verb without any other modifiers or conditions.
+.oindex &%strict_acl_vars%&
+What happens if a syntactically valid but undefined ACL variable is
+referenced depends on the setting of the &%strict_acl_vars%& option. If it is
+false (the default), an empty string is substituted; if it is true, an
+error is generated.
+Versions of Exim before 4.64 have a limited set of numbered variables, but
+their names are compatible, so there is no problem with upgrading.
-.section "Condition and modifier processing"
+
+.section "Condition and modifier processing" "SECTcondmodproc"
.cindex "&ACL;" "conditions; processing"
.cindex "&ACL;" "modifiers; processing"
An exclamation mark preceding a condition negates its result. For example:
deny domains = *.dom.example
!verify = recipient
.endd
-.new
causes the ACL to return &"deny"& if the recipient domain ends in
&'dom.example'& and the recipient address cannot be verified. Sometimes
negation can be used on the right-hand side of a condition. For example, these
.endd
However, for many conditions (&%verify%& being a good example), only left-hand
side negation of the whole condition is possible.
-.wen
The arguments of conditions and modifiers are expanded. A forced failure
of an expansion causes a condition to be ignored, that is, it behaves as if the
The ACL modifiers are as follows:
.vlist
+.vitem &*add_header*&&~=&~<&'text'&>
+This modifier specifies one or more header lines that are to be added to an
+incoming message, assuming, of course, that the message is ultimately
+accepted. For details, see section &<<SECTaddheadacl>>&.
+
+.vitem &*continue*&&~=&~<&'text'&>
+.cindex "&%continue%& ACL modifier"
+.cindex "database" "updating in ACL"
+This modifier does nothing of itself, and processing of the ACL always
+continues with the next condition or modifier. The value of &%continue%& is in
+the side effects of expanding its argument. Typically this could be used to
+update a database. It is really just a syntactic tidiness, to avoid having to
+write rather ugly lines like this:
+.display
+&`condition = ${if eq{0}{`&<&'some expansion'&>&`}{true}{true}}`&
+.endd
+Instead, all you need is
+.display
+&`continue = `&<&'some expansion'&>
+.endd
+
.vitem &*control*&&~=&~<&'text'&>
-.cindex "&%control%&" "ACL modifier"
+.cindex "&%control%& ACL modifier"
This modifier affects the subsequent processing of the SMTP connection or of an
incoming message that is accepted. The effect of the first type of control
lasts for the duration of the connection, whereas the effect of the second type
in several different ways. For example:
. ==== As this is a nested list, any displays it contains must be indented
-. ==== as otherwise they are too far to the left.
+. ==== as otherwise they are too far to the left. That comment applies only
+. ==== when xmlto and fop are used; formatting with sdop gets it right either
+. ==== way.
.ilist
It can be at the end of an &%accept%& statement:
If you want to apply a control unconditionally, you can use it with a
&%require%& verb. For example:
.code
- require control = no_multiline_response
+ require control = no_multiline_responses
.endd
.endlist
.vitem &*delay*&&~=&~<&'time'&>
-.cindex "&%delay%&" "ACL modifier"
-.cindex "&%-bh%& option"
-This modifier causes Exim to wait for the time interval before proceeding. The
-time is given in the usual Exim notation. This modifier may appear in any ACL.
-The delay happens as soon as the modifier is processed. However, when testing
-Exim using the &%-bh%& option, the delay is not actually imposed (an
-appropriate message is output instead).
+.cindex "&%delay%& ACL modifier"
+.oindex "&%-bh%&"
+This modifier may appear in any ACL. It causes Exim to wait for the time
+interval before proceeding. However, when testing Exim using the &%-bh%&
+option, the delay is not actually imposed (an appropriate message is output
+instead). The time is given in the usual Exim notation, and the delay happens
+as soon as the modifier is processed. In an SMTP session, pending output is
+flushed before the delay is imposed.
Like &%control%&, &%delay%& can be used with &%accept%& or &%deny%&, for
example:
accept ...
.endd
+If &%delay%& is encountered when the SMTP PIPELINING extension is in use,
+responses to several commands are no longer buffered and sent in one packet (as
+they would normally be) because all output is flushed before imposing the
+delay. This optimization is disabled so that a number of small delays do not
+appear to the client as one large aggregated delay that might provoke an
+unwanted timeout. You can, however, disable output flushing for &%delay%& by
+using a &%control%& modifier to set &%no_delay_flush%&.
+
+
.vitem &*endpass*&
-.cindex "&%endpass%&" "ACL modifier"
-This modifier, which has no argument, is recognized only in &%accept%&
-statements. It marks the boundary between the conditions whose failure causes
-control to pass to the next statement, and the conditions whose failure causes
-the ACL to return &"deny"&. See the description of &%accept%& above.
+.cindex "&%endpass%& ACL modifier"
+This modifier, which has no argument, is recognized only in &%accept%& and
+&%discard%& statements. It marks the boundary between the conditions whose
+failure causes control to pass to the next statement, and the conditions whose
+failure causes the ACL to return &"deny"&. This concept has proved to be
+confusing to some people, so the use of &%endpass%& is no longer recommended as
+&"best practice"&. See the description of &%accept%& above for more details.
+
.vitem &*log_message*&&~=&~<&'text'&>
-.cindex "&%log_message%&" "ACL modifier"
+.cindex "&%log_message%& ACL modifier"
This modifier sets up a message that is used as part of the log message if the
ACL denies access or a &%warn%& statement's conditions are true. For example:
.code
require log_message = wrong cipher suite $tls_cipher
encrypted = DES-CBC3-SHA
.endd
-&%log_message%& adds to any underlying error message that may exist because of
-the condition failure. For example, while verifying a recipient address, a
-&':fail:'& redirection might have already set up a message. Although the
-message is usually defined before the conditions to which it applies, the
-expansion does not happen until Exim decides that access is to be denied. This
-means that any variables that are set by the condition are available for
-inclusion in the message. For example, the &$dnslist_$&<&'xxx'&> variables are
-set after a DNS black list lookup succeeds. If the expansion of &%log_message%&
-fails, or if the result is an empty string, the modifier is ignored.
-
-.cindex "&$acl_verify_message$&"
+&%log_message%& is also used when recipients are discarded by &%discard%&. For
+example:
+.display
+&`discard `&<&'some conditions'&>
+&` log_message = Discarded $local_part@$domain because...`&
+.endd
+When access is denied, &%log_message%& adds to any underlying error message
+that may exist because of a condition failure. For example, while verifying a
+recipient address, a &':fail:'& redirection might have already set up a
+message.
+
+The message may be defined before the conditions to which it applies, because
+the string expansion does not happen until Exim decides that access is to be
+denied. This means that any variables that are set by the condition are
+available for inclusion in the message. For example, the &$dnslist_$&<&'xxx'&>
+variables are set after a DNS black list lookup succeeds. If the expansion of
+&%log_message%& fails, or if the result is an empty string, the modifier is
+ignored.
+
+.vindex "&$acl_verify_message$&"
If you want to use a &%warn%& statement to log the result of an address
verification, you can use &$acl_verify_message$& to include the verification
error message.
more than once while receiving a single email message, only one copy is
actually logged. If you want to log multiple copies, use &%logwrite%& instead
of &%log_message%&. In the absence of &%log_message%& and &%logwrite%&, nothing
-is logged for a succesful &%warn%& statement.
+is logged for a successful &%warn%& statement.
If &%log_message%& is not present and there is no underlying error message (for
example, from the failure of address verification), but &%message%& is present,
both &%log_message%& and &%message%&, a default built-in message is used for
logging rejections.
+
+.vitem "&*log_reject_target*&&~=&~<&'log name list'&>"
+.cindex "&%log_reject_target%& ACL modifier"
+.cindex "logging in ACL" "specifying which log"
+This modifier makes it possible to specify which logs are used for messages
+about ACL rejections. Its argument is a colon-separated list of words that can
+be &"main"&, &"reject"&, or &"panic"&. The default is &`main:reject`&. The list
+may be empty, in which case a rejection is not logged at all. For example, this
+ACL fragment writes no logging information when access is denied:
+.display
+&`deny `&<&'some conditions'&>
+&` log_reject_target =`&
+.endd
+This modifier can be used in SMTP and non-SMTP ACLs. It applies to both
+permanent and temporary rejections. Its effect lasts for the rest of the
+current ACL.
+
+
.vitem &*logwrite*&&~=&~<&'text'&>
-.cindex "&%logwrite%&" "ACL modifier"
+.cindex "&%logwrite%& ACL modifier"
.cindex "logging in ACL" "immediate"
This modifier writes a message to a log file as soon as it is encountered when
processing an ACL. (Compare &%log_message%&, which, except in the case of
-&%warn%&, is used only if the ACL statement denies access.) The &%logwrite%&
-modifier can be used to log special incidents in ACLs. For example:
+&%warn%& and &%discard%&, is used only if the ACL statement denies
+access.) The &%logwrite%& modifier can be used to log special incidents in
+ACLs. For example:
.display
&`accept `&<&'some special conditions'&>
&` control = freeze`&
logwrite = :panic: text for panic log only
.endd
+
.vitem &*message*&&~=&~<&'text'&>
-.cindex "&%message%&" "ACL modifier"
-This modifier sets up a text string that is expanded and used as an error
-message if the current statement causes the ACL to deny access. The expansion
-happens at the time Exim decides that access is to be denied, not at the time
-it processes &%message%&. If the expansion fails, or generates an empty string,
-the modifier is ignored. For ACLs that are triggered by SMTP commands, the
-message is returned as part of the SMTP error response.
-
-The &%message%& modifier is also used with the &%warn%& verb to specify one or
-more header lines to be added to an incoming message when all the conditions
-are true. See section &<<SECTaddheadwarn>>& for more details. If &%message%& is
-used with &%warn%& in an ACL that is not concerned with receiving a message, it
-has no effect.
-
-The text is literal; any quotes are taken as literals, but because the string
-is expanded, backslash escapes are processed anyway. If the message contains
-newlines, this gives rise to a multi-line SMTP response. Like &%log_message%&,
-the contents of &%message%& are not expanded until after a condition has
-failed.
+.cindex "&%message%& ACL modifier"
+This modifier sets up a text string that is expanded and used as a response
+message when an ACL statement terminates the ACL with an &"accept"&, &"deny"&,
+or &"defer"& response. (In the case of the &%accept%& and &%discard%& verbs,
+there is some complication if &%endpass%& is involved; see the description of
+&%accept%& for details.)
+
+The expansion of the message happens at the time Exim decides that the ACL is
+to end, not at the time it processes &%message%&. If the expansion fails, or
+generates an empty string, the modifier is ignored. Here is an example where
+&%message%& must be specified first, because the ACL ends with a rejection if
+the &%hosts%& condition fails:
+.code
+require message = Host not recognized
+ hosts = 10.0.0.0/8
+.endd
+(Once a condition has failed, no further conditions or modifiers are
+processed.)
+
+.cindex "SMTP" "error codes"
+.oindex "&%smtp_banner%&
+For ACLs that are triggered by SMTP commands, the message is returned as part
+of the SMTP response. The use of &%message%& with &%accept%& (or &%discard%&)
+is meaningful only for SMTP, as no message is returned when a non-SMTP message
+is accepted. In the case of the connect ACL, accepting with a message modifier
+overrides the value of &%smtp_banner%&. For the EHLO/HELO ACL, a customized
+accept message may not contain more than one line (otherwise it will be
+truncated at the first newline and a panic logged), and it cannot affect the
+EHLO options.
+
+When SMTP is involved, the message may begin with an overriding response code,
+consisting of three digits optionally followed by an &"extended response code"&
+of the form &'n.n.n'&, each code being followed by a space. For example:
+.code
+deny message = 599 1.2.3 Host not welcome
+ hosts = 192.168.34.0/24
+.endd
+The first digit of the supplied response code must be the same as would be sent
+by default. A panic occurs if it is not. Exim uses a 550 code when it denies
+access, but for the predata ACL, note that the default success code is 354, not
+2&'xx'&.
+
+Notwithstanding the previous paragraph, for the QUIT ACL, unlike the others,
+the message modifier cannot override the 221 response code.
+
+The text in a &%message%& modifier is literal; any quotes are taken as
+literals, but because the string is expanded, backslash escapes are processed
+anyway. If the message contains newlines, this gives rise to a multi-line SMTP
+response.
-.cindex "&$acl_verify_message$&"
+.vindex "&$acl_verify_message$&"
If &%message%& is used on a statement that verifies an address, the message
specified overrides any message that is generated by the verification process.
However, the original message is available in the variable
routers to be passed back as part of the SMTP response, you should either not
use a &%message%& modifier, or make use of &$acl_verify_message$&.
+For compatibility with previous releases of Exim, a &%message%& modifier that
+is used with a &%warn%& verb behaves in a similar way to the &%add_header%&
+modifier, but this usage is now deprecated. However, &%message%& acts only when
+all the conditions are true, wherever it appears in an ACL command, whereas
+&%add_header%& acts as soon as it is encountered. If &%message%& is used with
+&%warn%& in an ACL that is not concerned with receiving a message, it has no
+effect.
+
+
.vitem &*set*&&~<&'acl_name'&>&~=&~<&'value'&>
-.cindex "&%set%&" "ACL modifier"
+.cindex "&%set%& ACL modifier"
This modifier puts a value into one of the ACL variables (see section
&<<SECTaclvariables>>&).
.endlist
+
+
.section "Use of the control modifier" "SECTcontrols"
-.cindex "&%control%&" "ACL modifier"
+.cindex "&%control%& ACL modifier"
The &%control%& modifier supports the following settings:
.vlist
-.vitem &*control&~=&~caseful_local_part*&
-See below.
-
-.vitem &*control&~=&~caselower_local_part*&
+.vitem &*control&~=&~allow_auth_unadvertised*&
+This modifier allows a client host to use the SMTP AUTH command even when it
+has not been advertised in response to EHLO. Furthermore, because there are
+apparently some really broken clients that do this, Exim will accept AUTH after
+HELO (rather than EHLO) when this control is set. It should be used only if you
+really need it, and you should limit its use to those broken clients that do
+not work without it. For example:
+.code
+warn hosts = 192.168.34.25
+ control = allow_auth_unadvertised
+.endd
+Normally, when an Exim server receives an AUTH command, it checks the name of
+the authentication mechanism that is given in the command to ensure that it
+matches an advertised mechanism. When this control is set, the check that a
+mechanism has been advertised is bypassed. Any configured mechanism can be used
+by the client. This control is permitted only in the connection and HELO ACLs.
+
+
+.vitem &*control&~=&~caseful_local_part*& &&&
+ &*control&~=&~caselower_local_part*&
.cindex "&ACL;" "case of local part in"
.cindex "case of local parts"
-.cindex "&$local_part$&"
+.vindex "&$local_part$&"
These two controls are permitted only in the ACL specified by &%acl_smtp_rcpt%&
(that is, during RCPT processing). By default, the contents of &$local_part$&
are lower cased before ACL processing. If &"caseful_local_part"& is specified,
Notice that we put back the lower cased version afterwards, assuming that
is what is wanted for subsequent tests.
-.vitem &*control&~=&~enforce_sync*&
-See below.
-.vitem &*control&~=&~no_enforce_sync*&
+.vitem &*control&~=&~debug/*&<&'options'&>
+.cindex "&ACL;" "enabling debug logging"
+.cindex "debugging" "enabling from an ACL"
+This control turns on debug logging, almost as though Exim had been invoked
+with &`-d`&, with the output going to a new logfile, by default called
+&'debuglog'&. The filename can be adjusted with the &'tag'& option, which
+may access any variables already defined. The logging may be adjusted with
+the &'opts'& option, which takes the same values as the &`-d`& command-line
+option. Some examples (which depend on variables that don't exist in all
+contexts):
+.code
+ control = debug
+ control = debug/tag=.$sender_host_address
+ control = debug/opts=+expand+acl
+ control = debug/tag=.$message_exim_id/opts=+expand
+.endd
+
+
+.vitem &*control&~=&~enforce_sync*& &&&
+ &*control&~=&~no_enforce_sync*&
.cindex "SMTP" "synchronization checking"
.cindex "synchronization checking in SMTP"
These controls make it possible to be selective about when SMTP synchronization
work with.
-.new
.vitem &*control&~=&~fakedefer/*&<&'message'&>
.cindex "fake defer"
-.cindex "defer" "fake"
+.cindex "defer, fake"
This control works in exactly the same way as &%fakereject%& (described below)
except that it causes an SMTP 450 response after the message data instead of a
550 response. You must take care when using &%fakedefer%& because it causes the
messages to be duplicated when the sender retries. Therefore, you should not
use &%fakedefer%& if the message is to be delivered normally.
-.wen
.vitem &*control&~=&~fakereject/*&<&'message'&>
.cindex "fake rejection"
-.cindex "rejection" "fake"
+.cindex "rejection, fake"
This control is permitted only for the MAIL, RCPT, and DATA ACLs, in other
words, only when an SMTP message is being received. If Exim accepts the
message, instead the final 250 response, a 550 rejection message is sent.
550-If it was a legitimate message, it may still be
550 delivered to the target recipient(s).
.endd
-This facilty should be used with extreme caution.
+This facility should be used with extreme caution.
.vitem &*control&~=&~freeze*&
.cindex "frozen messages" "forcing in ACL"
current message, not to any subsequent ones that may be received in the same
SMTP connection.
+This modifier can optionally be followed by &`/no_tell`&. If the global option
+&%freeze_tell%& is set, it is ignored for the current message (that is, nobody
+is told about the freezing), provided all the &*control=freeze*& modifiers that
+are obeyed for the current message have the &`/no_tell`& option.
+
+.vitem &*control&~=&~no_delay_flush*&
+.cindex "SMTP" "output flushing, disabling for delay"
+Exim normally flushes SMTP output before implementing a delay in an ACL, to
+avoid unexpected timeouts in clients when the SMTP PIPELINING extension is in
+use. This control, as long as it is encountered before the &%delay%& modifier,
+disables such output flushing.
+
+.vitem &*control&~=&~no_callout_flush*&
+.cindex "SMTP" "output flushing, disabling for callout"
+Exim normally flushes SMTP output before performing a callout in an ACL, to
+avoid unexpected timeouts in clients when the SMTP PIPELINING extension is in
+use. This control, as long as it is encountered before the &%verify%& condition
+that causes the callout, disables such output flushing.
+
.vitem &*control&~=&~no_mbox_unspool*&
This control is available when Exim is compiled with the content scanning
extension. Content scanning may require a copy of the current message, or parts
the same SMTP connection. It is provided for debugging purposes and is unlikely
to be useful in production.
-.vitem &*control&~=&~no_multiline_response*&
-.cindex "multiline responses" "suppressing"
+.vitem &*control&~=&~no_multiline_responses*&
+.cindex "multiline responses, suppressing"
This control is permitted for any ACL except the one for non-SMTP messages.
It seems that there are broken clients in use that cannot handle multiline
SMTP responses, despite the fact that RFC 821 defined them over 20 years ago.
The setting of the switch can, of course, be made conditional on the
calling host. Its effect lasts until the end of the SMTP connection.
+.vitem &*control&~=&~no_pipelining*&
+.cindex "PIPELINING" "suppressing advertising"
+This control turns off the advertising of the PIPELINING extension to SMTP in
+the current session. To be useful, it must be obeyed before Exim sends its
+response to an EHLO command. Therefore, it should normally appear in an ACL
+controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also
+&%pipelining_advertise_hosts%&.
+
.vitem &*control&~=&~queue_only*&
-.cindex "&%queue_only%&"
+.oindex "&%queue_only%&"
.cindex "queueing incoming messages"
This control is permitted only for the MAIL, RCPT, DATA, and non-SMTP ACLs, in
other words, only when a message is being received. If the message is accepted,
latter is the one defined by &%acl_smtp_predata%&). Setting it tells Exim that
the current message is a submission from a local MUA. In this case, Exim
operates in &"submission mode"&, and applies certain fixups to the message if
-necessary. For example, it add a &'Date:'& header line if one is not present.
+necessary. For example, it adds a &'Date:'& header line if one is not present.
This control is not permitted in the &%acl_smtp_data%& ACL, because that is too
late (the message has already been created).
The control applies only to the current message, not to any subsequent ones
that may be received in the same SMTP connection.
-.new
.vitem &*control&~=&~suppress_local_fixups*&
-.cindex "submission fixups" "suppressing"
+.cindex "submission fixups, suppressing"
This control applies to locally submitted (non TCP/IP) messages, and is the
-complement of &`control`& &`=`& &`submission`&. It disables the fixups that are
+complement of &`control = submission`&. It disables the fixups that are
normally applied to locally-submitted messages. Specifically:
.ilist
There is no check that &'From:'& corresponds to the actual sender.
.endlist ilist
-This feature may be useful when a remotely-originated message is accepted,
-passed to some scanning program, and then re-submitted for delivery.
+This control may be useful when a remotely-originated message is accepted,
+passed to some scanning program, and then re-submitted for delivery. It can be
+used only in the &%acl_smtp_mail%&, &%acl_smtp_rcpt%&, &%acl_smtp_predata%&,
+and &%acl_not_smtp_start%& ACLs, because it has to be set before the message's
+data is read.
+
+&*Note:*& This control applies only to the current message, not to any others
+that are being submitted at the same time using &%-bs%& or &%-bS%&.
.endlist vlist
+
+.section "Summary of message fixup control" "SECTsummesfix"
All four possibilities for message fixups can be specified:
.ilist
Locally submitted, fixups applied: the default.
.next
-Locally submitted, no fixups applied: use &`control`& &`=`&
-&`suppress_local_fixups`&.
+Locally submitted, no fixups applied: use
+&`control = suppress_local_fixups`&.
.next
Remotely submitted, no fixups applied: the default.
.next
-Remotely submitted, fixups applied: use &`control`& &`=`& &`submission`&.
+Remotely submitted, fixups applied: use &`control = submission`&.
.endlist
-.wen
-
-.section "Adding header lines with the warn verb" "SECTaddheadwarn"
+.section "Adding header lines in ACLs" "SECTaddheadacl"
.cindex "header lines" "adding in an ACL"
.cindex "header lines" "position of added lines"
-.cindex "&%warn%&" "ACL verb"
-.cindex "&%message%&" "ACL modifier"
-The &%message%& modifier can be used on a &%warn%& statement to add an extra
-header line to an incoming message, as in this example:
+.cindex "&%message%& ACL modifier"
+The &%add_header%& modifier can be used to add one or more extra header lines
+to an incoming message, as in this example:
.code
-warn message = X-blacklisted-at: $dnslist_domain
- dnslists = sbl.spamhaus.org : \
+warn dnslists = sbl.spamhaus.org : \
dialup.mail-abuse.org
+ add_header = X-blacklisted-at: $dnslist_domain
.endd
-If an identical header line is requested several times (provoked, for example,
-by multiple RCPT commands), only one copy is actually added to the message.
-If the text of the &%message%& modifier contains one or more newlines that are
-not followed by a space or a tab, it is assumed to contain multiple header
+The &%add_header%& modifier is permitted in the MAIL, RCPT, PREDATA, DATA,
+MIME, and non-SMTP ACLs (in other words, those that are concerned with
+receiving a message). The message must ultimately be accepted for
+&%add_header%& to have any significant effect. You can use &%add_header%& with
+any ACL verb, including &%deny%& (though this is potentially useful only in a
+RCPT ACL).
+
+If the data for the &%add_header%& modifier contains one or more newlines that
+are not followed by a space or a tab, it is assumed to contain multiple header
lines. Each one is checked for valid syntax; &`X-ACL-Warn:`& is added to the
front of any line that is not a valid header line.
-By default, new lines are added at the end of the existing header lines.
-However, you can specify that any particular header line should be added right
-at the start (before all the &'Received:'& lines), immediately after the first
-block of &'Received:'& lines, or immediately before any line that is not a
-&'Received:'& or &'Resent-something:'& header.
+Added header lines are accumulated during the MAIL, RCPT, and predata ACLs.
+They are added to the message before processing the DATA and MIME ACLs.
+However, if an identical header line is requested more than once, only one copy
+is actually added to the message. Further header lines may be accumulated
+during the DATA and MIME ACLs, after which they are added to the message, again
+with duplicates suppressed. Thus, it is possible to add two identical header
+lines to an SMTP message, but only if one is added before DATA and one after.
+In the case of non-SMTP messages, new headers are accumulated during the
+non-SMTP ACLs, and are added to the message after all the ACLs have run. If a
+message is rejected after DATA or by the non-SMTP ACL, all added header lines
+are included in the entry that is written to the reject log.
+
+.cindex "header lines" "added; visibility of"
+Header lines are not visible in string expansions until they are added to the
+message. It follows that header lines defined in the MAIL, RCPT, and predata
+ACLs are not visible until the DATA ACL and MIME ACLs are run. Similarly,
+header lines that are added by the DATA or MIME ACLs are not visible in those
+ACLs. Because of this restriction, you cannot use header lines as a way of
+passing data between (for example) the MAIL and RCPT ACLs. If you want to do
+this, you can use ACL variables, as described in section
+&<<SECTaclvariables>>&.
+
+The &%add_header%& modifier acts immediately it is encountered during the
+processing of an ACL. Notice the difference between these two cases:
+.display
+&`accept add_header = ADDED: some text`&
+&` `&<&'some condition'&>
+
+&`accept `&<&'some condition'&>
+&` add_header = ADDED: some text`&
+.endd
+In the first case, the header line is always added, whether or not the
+condition is true. In the second case, the header line is added only if the
+condition is true. Multiple occurrences of &%add_header%& may occur in the same
+ACL statement. All those that are encountered before a condition fails are
+honoured.
+
+.cindex "&%warn%& ACL verb"
+For compatibility with previous versions of Exim, a &%message%& modifier for a
+&%warn%& verb acts in the same way as &%add_header%&, except that it takes
+effect only if all the conditions are true, even if it appears before some of
+them. Furthermore, only the last occurrence of &%message%& is honoured. This
+usage of &%message%& is now deprecated. If both &%add_header%& and &%message%&
+are present on a &%warn%& verb, both are processed according to their
+specifications.
+
+By default, new header lines are added to a message at the end of the existing
+header lines. However, you can specify that any particular header line should
+be added right at the start (before all the &'Received:'& lines), immediately
+after the first block of &'Received:'& lines, or immediately before any line
+that is not a &'Received:'& or &'Resent-something:'& header.
This is done by specifying &":at_start:"&, &":after_received:"&, or
&":at_start_rfc:"& (or, for completeness, &":at_end:"&) before the text of the
header line, respectively. (Header text cannot start with a colon, as there has
to be a header name first.) For example:
.code
-warn message = :after_received:X-My-Header: something or other...
+warn add_header = \
+ :after_received:X-My-Header: something or other...
.endd
-If more than one header is supplied in a single warn statement, each one is
-treated independently and can therefore be placed differently. If you add
-more than one line at the start, or after the Received: block, they will
-end up in reverse order.
+If more than one header line is supplied in a single &%add_header%& modifier,
+each one is treated independently and can therefore be placed differently. If
+you add more than one line at the start, or after the Received: block, they end
+up in reverse order.
&*Warning*&: This facility currently applies only to header lines that are
added in an ACL. It does NOT work for header lines that are added in a
system filter or in a router or transport.
-.new
-.cindex "header lines" "added; visibility of"
-Header lines that are added by an ACL at MAIL or RCPT time are not visible in
-string expansions in ACLs for subsequent RCPT commands or in the
-&%acl_smtp_predata%& ACL. However, they are visible in string expansions in the
-ACL that is run after DATA is complete (the &%acl_smtp_data%& ACL). This is
-also true for header lines that are added in the &%acl_smtp_predata%& ACL.
-However, header lines that are added in the &%acl_smtp_data%& itself are not
-visible during that ACL. If a message is rejected after DATA, all added header
-lines are included in the entry that is written to the reject log.
-.wen
-
-If you want to preserve data between MAIL, RCPT, and the
-&%acl_smtp_predata%& ACLs, you can use ACL variables, as described in section
-&<<SECTaclvariables>>&.
-
-
.vitem &*acl&~=&~*&<&'name&~of&~acl&~or&~ACL&~string&~or&~file&~name&~'&>
.cindex "&ACL;" "nested"
.cindex "&ACL;" "indirect"
-.cindex "&%acl%&" "ACL condition"
+.cindex "&%acl%& ACL condition"
The possible values of the argument are the same as for the
&%acl_smtp_%&&'xxx'& options. The named or inline ACL is run. If it returns
&"accept"& the condition is true; if it returns &"deny"& the condition is
for different local users or different local domains.
.vitem &*authenticated&~=&~*&<&'string&~list'&>
-.cindex "&%authenticated%&" "ACL condition"
+.cindex "&%authenticated%& ACL condition"
.cindex "authentication" "ACL checking"
.cindex "&ACL;" "testing for authentication"
If the SMTP connection is not authenticated, the condition is false. Otherwise,
.endd
.vitem &*condition&~=&~*&<&'string'&>
-.cindex "&%condition%&" "ACL condition"
+.cindex "&%condition%& ACL condition"
.cindex "customizing" "ACL condition"
.cindex "&ACL;" "customized test"
-.cindex "&ACL;" "testing; customized"
+.cindex "&ACL;" "testing, customized"
This feature allows you to make up custom conditions. If the result of
expanding the string is an empty string, the number zero, or one of the strings
&"no"& or &"false"&, the condition is false. If the result is any non-zero
number, or one of the strings &"yes"& or &"true"&, the condition is true. For
-any other values, some error is assumed to have occurred, and the ACL returns
-&"defer"&.
+any other value, some error is assumed to have occurred, and the ACL returns
+&"defer"&. However, if the expansion is forced to fail, the condition is
+ignored. The effect is to treat it as true, whether it is positive or
+negative.
.vitem &*decode&~=&~*&<&'location'&>
-.cindex "&%decode%&" "ACL condition"
+.cindex "&%decode%& ACL condition"
This condition is available only when Exim is compiled with the
-content-scanning extension, and it is allowed only the the ACL defined by
+content-scanning extension, and it is allowed only in the ACL defined by
&%acl_smtp_mime%&. It causes the current MIME part to be decoded into a file.
-For details, see chapter &<<CHAPexiscan>>&.
+If all goes well, the condition is true. It is false only if there are
+problems such as a syntax error or a memory shortage. For more details, see
+chapter &<<CHAPexiscan>>&.
.vitem &*demime&~=&~*&<&'extension&~list'&>
-.cindex "&%demime%&" "ACL condition"
+.cindex "&%demime%& ACL condition"
This condition is available only when Exim is compiled with the
content-scanning extension. Its use is described in section
&<<SECTdemimecond>>&.
.vitem &*dnslists&~=&~*&<&'list&~of&~domain&~names&~and&~other&~data'&>
-.cindex "&%dnslists%&" "ACL condition"
+.cindex "&%dnslists%& ACL condition"
.cindex "DNS list" "in ACL"
.cindex "black list (DNS)"
.cindex "&ACL;" "testing a DNS list"
&"RBL lists"&, after the original Realtime Blackhole List, but note that the
use of the lists at &'mail-abuse.org'& now carries a charge. There are too many
different variants of this condition to describe briefly here. See sections
-&<<SECTmorednslists>>&--&<<SECTmorednslistslast>>& for details.
+&<<SECTmorednslists>>&&--&<<SECTmorednslistslast>>& for details.
.vitem &*domains&~=&~*&<&'domain&~list'&>
-.cindex "&%domains%&" "ACL condition"
+.cindex "&%domains%& ACL condition"
.cindex "domain" "ACL checking"
.cindex "&ACL;" "testing a recipient domain"
-.cindex "&$domain_data$&"
+.vindex "&$domain_data$&"
This condition is relevant only after a RCPT command. It checks that the domain
of the recipient address is in the domain list. If percent-hack processing is
enabled, it is done before this test is done. If the check succeeds with a
lookup, the result of the lookup is placed in &$domain_data$& until the next
&%domains%& test.
+&*Note carefully*& (because many people seem to fall foul of this): you cannot
+use &%domains%& in a DATA ACL.
+
+
.vitem &*encrypted&~=&~*&<&'string&~list'&>
-.cindex "&%encrypted%&" "ACL condition"
+.cindex "&%encrypted%& ACL condition"
.cindex "encryption" "checking in an ACL"
.cindex "&ACL;" "testing for encryption"
If the SMTP connection is not encrypted, the condition is false. Otherwise, the
encrypted = *
.endd
+
.vitem &*hosts&~=&~*&<&'&~host&~list'&>
-.cindex "&%hosts%&" "ACL condition"
+.cindex "&%hosts%& ACL condition"
.cindex "host" "ACL checking"
.cindex "&ACL;" "testing the client host"
This condition tests that the calling host matches the host list. If you have
.code
accept hosts = 10.9.8.7 : dbm;/etc/friendly/hosts
.endd
-The reason for this lies in the left-to-right way that Exim processes lists.
-It can test IP addresses without doing any DNS lookups, but when it reaches an
-item that requires a host name, it fails if it cannot find a host name to
-compare with the pattern. If the above list is given in the opposite order, the
-&%accept%& statement fails for a host whose name cannot be found, even if its
-IP address is 10.9.8.7.
+The lookup in this example uses the host name for its key. This is implied by
+the lookup type &"dbm"&. (For a host address lookup you would use &"net-dbm"&
+and it wouldn't matter which way round you had these two items.)
+
+The reason for the problem with host names lies in the left-to-right way that
+Exim processes lists. It can test IP addresses without doing any DNS lookups,
+but when it reaches an item that requires a host name, it fails if it cannot
+find a host name to compare with the pattern. If the above list is given in the
+opposite order, the &%accept%& statement fails for a host whose name cannot be
+found, even if its IP address is 10.9.8.7.
If you really do want to do the name check first, and still recognize the IP
address even if the name lookup fails, you can rewrite the ACL like this:
is not in the list, so the first &%accept%& statement fails. The second
statement can then check the IP address.
-.cindex "&$host_data$&"
+.vindex "&$host_data$&"
If a &%hosts%& condition is satisfied by means of a lookup, the result
of the lookup is made available in the &$host_data$& variable. This
allows you, for example, to set up a statement like this:
which gives a custom error message for each denied host.
.vitem &*local_parts&~=&~*&<&'local&~part&~list'&>
-.cindex "&%local_parts%&" "ACL condition"
+.cindex "&%local_parts%& ACL condition"
.cindex "local part" "ACL checking"
.cindex "&ACL;" "testing a local part"
-.cindex "&$local_part_data$&"
+.vindex "&$local_part_data$&"
This condition is relevant only after a RCPT command. It checks that the local
part of the recipient address is in the list. If percent-hack processing is
enabled, it is done before this test. If the check succeeds with a lookup, the
the next &%local_parts%& test.
.vitem &*malware&~=&~*&<&'option'&>
-.cindex "&%malware%&" "ACL condition"
+.cindex "&%malware%& ACL condition"
.cindex "&ACL;" "virus scanning"
.cindex "&ACL;" "scanning for viruses"
This condition is available only when Exim is compiled with the
viruses. For details, see chapter &<<CHAPexiscan>>&.
.vitem &*mime_regex&~=&~*&<&'list&~of&~regular&~expressions'&>
-.cindex "&%mime_regex%&" "ACL condition"
+.cindex "&%mime_regex%& ACL condition"
.cindex "&ACL;" "testing by regex matching"
This condition is available only when Exim is compiled with the
-content-scanning extension, and it is allowed only the the ACL defined by
+content-scanning extension, and it is allowed only in the ACL defined by
&%acl_smtp_mime%&. It causes the current MIME part to be scanned for a match
with any of the regular expressions. For details, see chapter
&<<CHAPexiscan>>&.
-.new
.vitem &*ratelimit&~=&~*&<&'parameters'&>
.cindex "rate limiting"
This condition can be used to limit the rate at which a user or host submits
messages. Details are given in section &<<SECTratelimiting>>&.
-.wen
.vitem &*recipients&~=&~*&<&'address&~list'&>
-.cindex "&%recipients%&" "ACL condition"
+.cindex "&%recipients%& ACL condition"
.cindex "recipient" "ACL checking"
.cindex "&ACL;" "testing a recipient"
This condition is relevant only after a RCPT command. It checks the entire
recipient address against a list of recipients.
.vitem &*regex&~=&~*&<&'list&~of&~regular&~expressions'&>
-.cindex "&%regex%&" "ACL condition"
+.cindex "&%regex%& ACL condition"
.cindex "&ACL;" "testing by regex matching"
This condition is available only when Exim is compiled with the
content-scanning extension, and is available only in the DATA, MIME, and
any of the regular expressions. For details, see chapter &<<CHAPexiscan>>&.
.vitem &*sender_domains&~=&~*&<&'domain&~list'&>
-.cindex "&%sender_domains%&" "ACL condition"
+.cindex "&%sender_domains%& ACL condition"
.cindex "sender" "ACL checking"
.cindex "&ACL;" "testing a sender domain"
-.cindex "&$domain$&"
-.cindex "&$sender_address_domain$&"
+.vindex "&$domain$&"
+.vindex "&$sender_address_domain$&"
This condition tests the domain of the sender of the message against the given
domain list. &*Note*&: The domain of the sender address is in
&$sender_address_domain$&. It is &'not'& put in &$domain$& during the testing
RCPT command, the recipient's domain (which is in &$domain$&) can be used to
influence the sender checking.
-.new
&*Warning*&: It is a bad idea to use this condition on its own as a control on
relaying, because sender addresses are easily, and commonly, forged.
-.wen
.vitem &*senders&~=&~*&<&'address&~list'&>
-.cindex "&%senders%&" "ACL condition"
+.cindex "&%senders%& ACL condition"
.cindex "sender" "ACL checking"
.cindex "&ACL;" "testing a sender"
This condition tests the sender of the message against the given list. To test
.code
senders = :
.endd
-.new
&*Warning*&: It is a bad idea to use this condition on its own as a control on
relaying, because sender addresses are easily, and commonly, forged.
-.wen
.vitem &*spam&~=&~*&<&'username'&>
-.cindex "&%spam%&" "ACL condition"
+.cindex "&%spam%& ACL condition"
.cindex "&ACL;" "scanning for spam"
This condition is available only when Exim is compiled with the
content-scanning extension. It causes the incoming message to be scanned by
SpamAssassin. For details, see chapter &<<CHAPexiscan>>&.
.vitem &*verify&~=&~certificate*&
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
.cindex "TLS" "client certificate verification"
.cindex "certificate" "verification of client"
.cindex "&ACL;" "certificate verification"
server requests a certificate only if the client matches &%tls_verify_hosts%&
or &%tls_try_verify_hosts%& (see chapter &<<CHAPTLS>>&).
-.new
.vitem &*verify&~=&~csa*&
.cindex "CSA verification"
This condition checks whether the sending host (the client) is authorized to
send email. Details of how this works are given in section
&<<SECTverifyCSA>>&.
-.wen
.vitem &*verify&~=&~header_sender/*&<&'options'&>
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying sender in the header"
.cindex "header lines" "verifying the sender in"
.cindex "sender" "verifying in header"
.endd
.vitem &*verify&~=&~header_syntax*&
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying header syntax"
.cindex "header lines" "verifying syntax"
.cindex "verifying" "header syntax"
common as they used to be.
.vitem &*verify&~=&~helo*&
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying HELO/EHLO"
.cindex "HELO" "verifying"
.cindex "EHLO" "verifying"
.cindex "verifying" "EHLO"
.cindex "verifying" "HELO"
-.new
This condition is true if a HELO or EHLO command has been received from the
-client host, and its contents have been verified. It there has been no previous
-attempt to verify the the HELO/EHLO contents, it is carried out when this
+client host, and its contents have been verified. If there has been no previous
+attempt to verify the HELO/EHLO contents, it is carried out when this
condition is encountered. See the description of the &%helo_verify_hosts%& and
&%helo_try_verify_hosts%& options for details of how to request verification
independently of this condition.
-.wen
-.new
+For SMTP input that does not come over TCP/IP (the &%-bs%& command line
+option), this condition is always true.
+
+
.vitem &*verify&~=&~not_blind*&
.cindex "verifying" "not blind"
-.cindex "bcc recipients" "verifying none"
+.cindex "bcc recipients, verifying none"
This condition checks that there are no blind (bcc) recipients in the message.
Every envelope recipient must appear either in a &'To:'& header line or in a
&'Cc:'& header line for this condition to be true. Local parts are checked
There are, of course, many legitimate messages that make use of blind (bcc)
recipients. This check should not be used on its own for blocking messages.
-.wen
.vitem &*verify&~=&~recipient/*&<&'options'&>
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying recipient"
.cindex "recipient" "verifying"
.cindex "verifying" "recipient"
-.cindex "&$address_data$&"
+.vindex "&$address_data$&"
This condition is relevant only after a RCPT command. It verifies the current
recipient. Details of address verification are given later, starting at section
&<<SECTaddressverification>>&. After a recipient has been verified, the value
value for the child address.
.vitem &*verify&~=&~reverse_host_lookup*&
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying host reverse lookup"
.cindex "host" "verifying reverse lookup"
This condition ensures that a verified host name has been looked up from the IP
is no client host involved), it always succeeds.
.vitem &*verify&~=&~sender/*&<&'options'&>
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying sender"
.cindex "sender" "verifying"
.cindex "verifying" "sender"
the message's sender is empty (that is, this is a bounce message), the
condition is true. Otherwise, the sender address is verified.
-.cindex "&$address_data$&"
-.cindex "&$sender_address_data$&"
+.vindex "&$address_data$&"
+.vindex "&$sender_address_data$&"
If there is data in the &$address_data$& variable at the end of routing, its
value is placed in &$sender_address_data$& at the end of verification. This
value can be used in subsequent conditions and modifiers in the same ACL
to avoid doing it more than once per message.
.vitem &*verify&~=&~sender=*&<&'address'&>&*/*&<&'options'&>
-.cindex "&%verify%&" "ACL condition"
+.cindex "&%verify%& ACL condition"
This is a variation of the previous option, in which a modified address is
verified as a sender.
.endlist
.cindex "&ACL;" "testing a DNS list"
In its simplest form, the &%dnslists%& condition tests whether the calling host
is on at least one of a number of DNS lists by looking up the inverted IP
-address in one or more DNS domains. For example, if the calling host's IP
+address in one or more DNS domains. (Note that DNS list domains are not mail
+domains, so the &`+`& syntax for named lists doesn't work - it is used for
+special options instead.) For example, if the calling host's IP
address is 192.168.62.43, and the ACL statement is
.code
deny dnslists = blackholes.mail-abuse.org : \
-.section "Specifying the IP address for a DNS list lookup"
+.section "Specifying the IP address for a DNS list lookup" "SECID201"
.cindex "DNS list" "keyed by explicit IP address"
By default, the IP address that is used in a DNS list lookup is the IP address
of the calling host. However, you can specify another IP address by listing it
-.section "DNS lists keyed on domain names"
+.section "DNS lists keyed on domain names" "SECID202"
.cindex "DNS list" "keyed by domain name"
There are some lists that are keyed on domain names rather than inverted IP
addresses (see for example the &'domain based zones'& link at
Thus, this example checks whether or not the IP addresses of the sender
domain's mail servers are on the Spamhaus black list.
+The key that was used for a successful DNS list lookup is put into the variable
+&$dnslist_matched$& (see section &<<SECID204>>&).
-.section "Data returned by DNS lists"
+.section "Data returned by DNS lists" "SECID203"
.cindex "DNS list" "data returned from"
DNS lists are constructed using address records in the DNS. The original RBL
just used the address 127.0.0.1 on the right hand side of each record, but the
127.1.0.6 RSS and DUL
127.1.0.7 RSS and DUL and RBL
.endd
-Some DNS lists may return more than one address record.
+Section &<<SECTaddmatcon>>& below describes how you can distinguish between
+different values. Some DNS lists may return more than one address record;
+see section &<<SECThanmuldnsrec>>& for details of how they are checked.
-.section "Variables set from DNS lists"
+.section "Variables set from DNS lists" "SECID204"
+.cindex "expansion" "variables, set from DNS list"
.cindex "DNS list" "variables set from"
-.cindex "&$dnslist_domain$&"
-.cindex "&$dnslist_text$&"
-.cindex "&$dnslist_value$&"
-When an entry is found in a DNS list, the variable &$dnslist_domain$&
-contains the name of the domain that matched, &$dnslist_value$& contains the
-data from the entry, and &$dnslist_text$& contains the contents of any
-associated TXT record. If more than one address record is returned by the DNS
-lookup, all the IP addresses are included in &$dnslist_value$&, separated by
-commas and spaces.
-
-You can use these variables in &%message%& or &%log_message%& modifiers &--
-although these appear before the condition in the ACL, they are not expanded
-until after it has failed. For example:
+.vindex "&$dnslist_domain$&"
+.vindex "&$dnslist_matched$&"
+.vindex "&$dnslist_text$&"
+.vindex "&$dnslist_value$&"
+When an entry is found in a DNS list, the variable &$dnslist_domain$& contains
+the name of the overall domain that matched (for example,
+&`spamhaus.example`&), &$dnslist_matched$& contains the key within that domain
+(for example, &`192.168.5.3`&), and &$dnslist_value$& contains the data from
+the DNS record. When the key is an IP address, it is not reversed in
+&$dnslist_matched$& (though it is, of course, in the actual lookup). In simple
+cases, for example:
+.code
+deny dnslists = spamhaus.example
+.endd
+the key is also available in another variable (in this case,
+&$sender_host_address$&). In more complicated cases, however, this is not true.
+For example, using a data lookup (as described in section &<<SECTmulkeyfor>>&)
+might generate a dnslists lookup like this:
+.code
+deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
+.endd
+If this condition succeeds, the value in &$dnslist_matched$& might be
+&`192.168.6.7`& (for example).
+
+If more than one address record is returned by the DNS lookup, all the IP
+addresses are included in &$dnslist_value$&, separated by commas and spaces.
+The variable &$dnslist_text$& contains the contents of any associated TXT
+record. For lists such as RBL+ the TXT record for a merged entry is often not
+very meaningful. See section &<<SECTmordetinf>>& for a way of obtaining more
+information.
+
+You can use the DNS list variables in &%message%& or &%log_message%& modifiers
+&-- although these appear before the condition in the ACL, they are not
+expanded until after it has failed. For example:
.code
deny hosts = !+local_networks
message = $sender_host_address is listed \
deny dnslists = rblplus.mail-abuse.org=127.0.0.2
.endd
rejects only those hosts that yield 127.0.0.2. Without this additional data,
-any address record is considered to be a match. If more than one address record
-is found on the list, they are all checked for a matching right-hand side.
+any address record is considered to be a match. For the moment, we assume
+that the DNS lookup returns just one record. Section &<<SECThanmuldnsrec>>&
+describes how multiple records are handled.
More than one IP address may be given for checking, using a comma as a
separator. These are alternatives &-- if any one of them matches, the
-.section "Negated DNS matching conditions"
+.section "Negated DNS matching conditions" "SECID205"
You can supply a negative list of IP addresses as part of a &%dnslists%&
condition. Whereas
.code
+.section "Handling multiple DNS records from a DNS list" "SECThanmuldnsrec"
+A DNS lookup for a &%dnslists%& condition may return more than one DNS record,
+thereby providing more than one IP address. When an item in a &%dnslists%& list
+is followed by &`=`& or &`&&`& and a list of IP addresses, in order to restrict
+the match to specific results from the DNS lookup, there are two ways in which
+the checking can be handled. For example, consider the condition:
+.code
+dnslists = a.b.c=127.0.0.1
+.endd
+What happens if the DNS lookup for the incoming IP address yields both
+127.0.0.1 and 127.0.0.2 by means of two separate DNS records? Is the
+condition true because at least one given value was found, or is it false
+because at least one of the found values was not listed? And how does this
+affect negated conditions? Both possibilities are provided for with the help of
+additional separators &`==`& and &`=&&`&.
+
+.ilist
+If &`=`& or &`&&`& is used, the condition is true if any one of the looked up
+IP addresses matches one of the listed addresses. For the example above, the
+condition is true because 127.0.0.1 matches.
+.next
+If &`==`& or &`=&&`& is used, the condition is true only if every one of the
+looked up IP addresses matches one of the listed addresses. If the condition is
+changed to:
+.code
+dnslists = a.b.c==127.0.0.1
+.endd
+and the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+false because 127.0.0.2 is not listed. You would need to have:
+.code
+dnslists = a.b.c==127.0.0.1,127.0.0.2
+.endd
+for the condition to be true.
+.endlist
+
+When &`!`& is used to negate IP address matching, it inverts the result, giving
+the precise opposite of the behaviour above. Thus:
+.ilist
+If &`!=`& or &`!&&`& is used, the condition is true if none of the looked up IP
+addresses matches one of the listed addresses. Consider:
+.code
+dnslists = a.b.c!&0.0.0.1
+.endd
+If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+false because 127.0.0.1 matches.
+.next
+If &`!==`& or &`!=&&`& is used, the condition is true there is at least one
+looked up IP address that does not match. Consider:
+.code
+dnslists = a.b.c!=&0.0.0.1
+.endd
+If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+true, because 127.0.0.2 does not match. You would need to have:
+.code
+dnslists = a.b.c!=&0.0.0.1,0.0.0.2
+.endd
+for the condition to be false.
+.endlist
+When the DNS lookup yields only a single IP address, there is no difference
+between &`=`& and &`==`& and between &`&&`& and &`=&&`&.
+
+
+
+
+.section "Detailed information from merged DNS lists" "SECTmordetinf"
+.cindex "DNS list" "information from merged"
+When the facility for restricting the matching IP values in a DNS list is used,
+the text from the TXT record that is set in &$dnslist_text$& may not reflect
+the true reason for rejection. This happens when lists are merged and the IP
+address in the A record is used to distinguish them; unfortunately there is
+only one TXT record. One way round this is not to use merged lists, but that
+can be inefficient because it requires multiple DNS lookups where one would do
+in the vast majority of cases when the host of interest is not on any of the
+lists.
+
+A less inefficient way of solving this problem is available. If
+two domain names, comma-separated, are given, the second is used first to
+do an initial check, making use of any IP value restrictions that are set.
+If there is a match, the first domain is used, without any IP value
+restrictions, to get the TXT record. As a byproduct of this, there is also
+a check that the IP being tested is indeed on the first list. The first
+domain is the one that is put in &$dnslist_domain$&. For example:
+.code
+reject message = \
+ rejected because $sender_host_address is blacklisted \
+ at $dnslist_domain\n$dnslist_text
+ dnslists = \
+ sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \
+ dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
+.endd
+For the first blacklist item, this starts by doing a lookup in
+&'sbl-xbl.spamhaus.org'& and testing for a 127.0.0.2 return. If there is a
+match, it then looks in &'sbl.spamhaus.org'&, without checking the return
+value, and as long as something is found, it looks for the corresponding TXT
+record. If there is no match in &'sbl-xbl.spamhaus.org'&, nothing more is done.
+The second blacklist item is processed similarly.
+
+If you are interested in more than one merged list, the same list must be
+given several times, but because the results of the DNS lookups are cached,
+the DNS calls themselves are not repeated. For example:
+.code
+reject dnslists = \
+ http.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.2 : \
+ socks.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.3 : \
+ misc.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.4 : \
+ dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
+.endd
+In this case there is one lookup in &'dnsbl.sorbs.net'&, and if none of the IP
+values matches (or if no record is found), this is the only lookup that is
+done. Only if there is a match is one of the more specific lists consulted.
+
+
+
.section "DNS lists and IPv6" "SECTmorednslistslast"
.cindex "IPv6" "DNS black lists"
.cindex "DNS list" "IPv6 usage"
dnslists = some.list.example
.endd
-.new
-.section "Rate limiting senders" "SECTratelimiting"
+.section "Rate limiting incoming messages" "SECTratelimiting"
.cindex "rate limiting" "client sending"
.cindex "limiting client sending rates"
-.oindex "&%smpt_ratelimit_*%&"
+.oindex "&%smtp_ratelimit_*%&"
The &%ratelimit%& ACL condition can be used to measure and control the rate at
which clients can send email. This is more powerful than the
&%smtp_ratelimit_*%& options, because those options control the rate of
If the average client sending rate is less than &'m'& messages per time
period &'p'& then the condition is false; otherwise it is true.
-.new
As a side-effect, the &%ratelimit%& condition sets the expansion variable
&$sender_rate$& to the client's computed rate, &$sender_rate_limit$& to the
configured value of &'m'&, and &$sender_rate_period$& to the configured value
send in each time interval. It also specifies the number of messages permitted
in a fast burst. By increasing both &'m'& and &'p'& but keeping &'m/p'&
constant, you can allow a client to send more messages in a burst without
-changing its overall sending rate limit. Conversely, if &'m'& and &'p'& are
+changing its long-term sending rate limit. Conversely, if &'m'& and &'p'& are
both small, messages must be sent at an even rate.
There is a script in &_util/ratelimit.pl_& which extracts sending rates from
instructions when it is run with no arguments.
The key is used to look up the data for calculating the client's average
-sending rate. This data is stored in a database maintained by Exim in its spool
-directory, alongside the retry and other hints databases. The default key is
-&$sender_host_address$&, which applies the limit to each client host IP address.
+sending rate. This data is stored in Exim's spool directory, alongside the
+retry and other hints databases. The default key is &$sender_host_address$&,
+which means Exim computes the sending rate of each client host IP address.
By changing the key you can change how Exim identifies clients for the purpose
of ratelimiting. For example, to limit the sending rate of each authenticated
user, independent of the computer they are sending from, set the key to
&$authenticated_id$&. You must ensure that the lookup key is meaningful; for
example, &$authenticated_id$& is only meaningful if the client has
-authenticated, and you can check with with the &%authenticated%& ACL condition.
-.wen
+authenticated (which you can check with the &%authenticated%& ACL condition).
-Internally, Exim includes the smoothing constant &'p'& and the options in the
-lookup key because they alter the meaning of the stored data. This is not true
-for the limit &'m'&, so you can alter the configured maximum rate and Exim will
-still remember clients' past behaviour, but if you alter the other ratelimit
-parameters Exim forgets past behaviour.
+The lookup key does not have to identify clients: If you want to limit the
+rate at which a recipient receives messages, you can use the key
+&`$local_part@$domain`& with the &%per_rcpt%& option (see below) in a RCPT
+ACL.
-Each &%ratelimit%& condition can have up to two options. The first option
-specifies what Exim measures the rate of, and the second specifies how Exim
-handles excessively fast clients. The options are separated by a slash, like
-the other parameters.
+Each &%ratelimit%& condition can have up to four options. A &%per_*%& option
+specifies what Exim measures the rate of, for example messages or recipients
+or bytes. You can adjust the measurement using the &%unique=%& and/or
+&%count=%& options. You can also control when Exim updates the recorded rate
+using a &%strict%&, &%leaky%&, or &%readonly%& option. The options are
+separated by a slash, like the other parameters. They may appear in any order.
-The &%per_conn%& option limits the client's connection rate.
+Internally, Exim appends the smoothing constant &'p'& onto the lookup key with
+any options that alter the meaning of the stored data. The limit &'m'& is not
+stored, so you can alter the configured maximum rate and Exim will still
+remember clients' past behaviour. If you change the &%per_*%& mode or add or
+remove the &%unique=%& option, the lookup key changes so Exim will forget past
+behaviour. The lookup key is not affected by changes to the update mode and
+the &%count=%& option.
-The &%per_mail%& option limits the client's rate of sending messages. This is
-the default if none of the &%per_*%& options is specified.
-The &%per_byte%& option limits the sender's email bandwidth. Note that it is
-best to use this option in the DATA ACL; if it is used in an earlier ACL it
-relies on the SIZE parameter on the MAIL command, which may be inaccurate or
-completely missing. You can follow the limit &'m'& in the configuration with K,
-M, or G to specify limits in kilobytes, megabytes, or gigabytes, respectively.
+.section "Ratelimit options for what is being measured" "ratoptmea"
+.cindex "rate limiting" "per_* options"
+The &%per_conn%& option limits the client's connection rate. It is not
+normally used in the &%acl_not_smtp%&, &%acl_not_smtp_mime%&, or
+&%acl_not_smtp_start%& ACLs.
-The &%per_cmd%& option causes Exim to recompute the rate every time the
-condition is processed. This can be used to limit the SMTP command rate. The
-alias &%per_rcpt%& is provided for use in the RCPT ACL instead of &%per_cmd%&
-to make it clear that the effect is to limit the rate at which recipients are
-accepted. Note that in this case the rate limiting engine will see a message
-with many recipients as a large high-speed burst.
+The &%per_mail%& option limits the client's rate of sending messages. This is
+the default if none of the &%per_*%& options is specified. It can be used in
+&%acl_smtp_mail%&, &%acl_smtp_rcpt%&, &%acl_smtp_predata%&, &%acl_smtp_mime%&,
+&%acl_smtp_data%&, or &%acl_not_smtp%&.
+
+The &%per_byte%& option limits the sender's email bandwidth. It can be used in
+the same ACLs as the &%per_mail%& option, though it is best to use this option
+in the &%acl_smtp_mime%&, &%acl_smtp_data%& or &%acl_not_smtp%& ACLs; if it is
+used in an earlier ACL, Exim relies on the SIZE parameter given by the client
+in its MAIL command, which may be inaccurate or completely missing. You can
+follow the limit &'m'& in the configuration with K, M, or G to specify limits
+in kilobytes, megabytes, or gigabytes, respectively.
+
+The &%per_rcpt%& option causes Exim to limit the rate at which recipients are
+accepted. It can be used in the &%acl_smtp_rcpt%&, &%acl_smtp_predata%&,
+&%acl_smtp_mime%&, &%acl_smtp_data%&, or &%acl_smtp_rcpt%& ACLs. In
+&%acl_smtp_rcpt%& the rate is updated one recipient at a time; in the other
+ACLs the rate is updated with the total recipient count in one go. Note that
+in either case the rate limiting engine will see a message with many
+recipients as a large high-speed burst.
+
+The &%per_addr%& option is like the &%per_rcpt%& option, except it counts the
+number of different recipients that the client has sent messages to in the
+last time period. That is, if the client repeatedly sends messages to the same
+recipient, its measured rate is not increased. This option can only be used in
+&%acl_smtp_rcpt%&.
+The &%per_cmd%& option causes Exim to recompute the rate every time the
+condition is processed. This can be used to limit the rate of any SMTP
+command. If it is used in multiple ACLs it can limit the aggregate rate of
+multiple different commands.
+
+The &%count=%& option can be used to alter how much Exim adds to the client's
+measured rate. For example, the &%per_byte%& option is equivalent to
+&`per_mail/count=$message_size`&. If there is no &%count=%& option, Exim
+increases the measured rate by one (except for the &%per_rcpt%& option in ACLs
+other than &%acl_smtp_rcpt%&). The count does not have to be an integer.
+
+The &%unique=%& option is described in section &<<ratoptuniq>>& below.
+
+
+.section "Ratelimit update modes" "ratoptupd"
+.cindex "rate limiting" "reading data without updating"
+You can specify one of three options with the &%ratelimit%& condition to
+control when its database is updated. This section describes the &%readonly%&
+mode, and the next section describes the &%strict%& and &%leaky%& modes.
+
+If the &%ratelimit%& condition is used in &%readonly%& mode, Exim looks up a
+previously-computed rate to check against the limit.
+
+For example, you can test the client's sending rate and deny it access (when
+it is too fast) in the connect ACL. If the client passes this check then it
+can go on to send a message, in which case its recorded rate will be updated
+in the MAIL ACL. Subsequent connections from the same client will check this
+new rate.
+.code
+acl_check_connect:
+ deny ratelimit = 100 / 5m / readonly
+ log_message = RATE CHECK: $sender_rate/$sender_rate_period \
+ (max $sender_rate_limit)
+# ...
+acl_check_mail:
+ warn ratelimit = 100 / 5m / strict
+ log_message = RATE UPDATE: $sender_rate/$sender_rate_period \
+ (max $sender_rate_limit)
+.endd
+
+If Exim encounters multiple &%ratelimit%& conditions with the same key when
+processing a message then it may increase the client's measured rate more than
+it should. For example, this will happen if you check the &%per_rcpt%& option
+in both &%acl_smtp_rcpt%& and &%acl_smtp_data%&. However it's OK to check the
+same &%ratelimit%& condition multiple times in the same ACL. You can avoid any
+multiple update problems by using the &%readonly%& option on later ratelimit
+checks.
+
+The &%per_*%& options described above do not make sense in some ACLs. If you
+use a &%per_*%& option in an ACL where it is not normally permitted then the
+update mode defaults to &%readonly%& and you cannot specify the &%strict%& or
+&%leaky%& modes. In other ACLs the default update mode is &%leaky%& (see the
+next section) so you must specify the &%readonly%& option explicitly.
+
+
+.section "Ratelimit options for handling fast clients" "ratoptfast"
+.cindex "rate limiting" "strict and leaky modes"
If a client's average rate is greater than the maximum, the rate limiting
engine can react in two possible ways, depending on the presence of the
-&%strict%& or &%leaky%& options. This is independent of the other
+&%strict%& or &%leaky%& update modes. This is independent of the other
counter-measures (such as rejecting the message) that may be specified by the
-rest of the ACL. The default mode is leaky, which avoids a sender's
-over-aggressive retry rate preventing it from getting any email through.
-
-The &%strict%& option means that the client's recorded rate is always updated.
-The effect of this is that Exim measures the client's average rate of attempts
-to send email, which can be much higher than the maximum. If the client is over
-the limit it will be subjected to counter-measures until it slows down below
-the maximum rate. The smoothing period determines the time it takes for a high
-sending rate to decay exponentially to 37% of its peak value, which means that
-you can work out the time (the number of smoothing periods) that a client is
-subjected to counter-measures after an over-limit burst with this formula:
-.code
-ln(peakrate/maxrate)
-.endd
-The &%leaky%& option means that the client's recorded rate is not updated if it
-is above the limit. The effect of this is that Exim measures the client's
-average rate of successfully sent email, which cannot be greater than the
-maximum. If the client is over the limit it will suffer some counter-measures,
-but it will still be able to send email at the configured maximum rate,
-whatever the rate of its attempts. This is generally the better choice if you
-have clients that retry automatically.
-
+rest of the ACL.
+
+The &%leaky%& (default) option means that the client's recorded rate is not
+updated if it is above the limit. The effect of this is that Exim measures the
+client's average rate of successfully sent email, which cannot be greater than
+the maximum allowed. If the client is over the limit it may suffer some
+counter-measures (as specified in the ACL), but it will still be able to send
+email at the configured maximum rate, whatever the rate of its attempts. This
+is generally the better choice if you have clients that retry automatically.
+For example, it does not prevent a sender with an over-aggressive retry rate
+from getting any email through.
+
+The &%strict%& option means that the client's recorded rate is always
+updated. The effect of this is that Exim measures the client's average rate
+of attempts to send email, which can be much higher than the maximum it is
+actually allowed. If the client is over the limit it may be subjected to
+counter-measures by the ACL. It must slow down and allow sufficient time to
+pass that its computed rate falls below the maximum before it can send email
+again. The time (the number of smoothing periods) it must wait and not
+attempt to send mail can be calculated with this formula:
+.code
+ ln(peakrate/maxrate)
+.endd
+
+
+.section "Limiting the rate of different events" "ratoptuniq"
+.cindex "rate limiting" "counting unique events"
+The &%ratelimit%& &%unique=%& option controls a mechanism for counting the
+rate of different events. For example, the &%per_addr%& option uses this
+mechanism to count the number of different recipients that the client has
+sent messages to in the last time period; it is equivalent to
+&`per_rcpt/unique=$local_part@$domain`&. You could use this feature to
+measure the rate that a client uses different sender addresses with the
+options &`per_mail/unique=$sender_address`&.
+
+For each &%ratelimit%& key Exim stores the set of &%unique=%& values that it
+has seen for that key. The whole set is thrown away when it is older than the
+rate smoothing period &'p'&, so each different event is counted at most once
+per period. In the &%leaky%& update mode, an event that causes the client to
+go over the limit is not added to the set, in the same way that the client's
+recorded rate is not updated in the same situation.
+
+When you combine the &%unique=%& and &%readonly%& options, the specific
+&%unique=%& value is ignored, and Exim just retrieves the client's stored
+rate.
+
+The &%unique=%& mechanism needs more space in the ratelimit database than the
+other &%ratelimit%& options in order to store the event set. The number of
+unique values is potentially as large as the rate limit, so the extra space
+required increases with larger limits.
+
+The uniqueification is not perfect: there is a small probability that Exim
+will think a new event has happened before. If the sender's rate is less than
+the limit, Exim should be more than 99.9% correct. However in &%strict%& mode
+the measured rate can go above the limit, in which case Exim may under-count
+events by a significant margin. Fortunately, if the rate is high enough (2.7
+times the limit) that the false positive rate goes above 9%, then Exim will
+throw away the over-full event set before the measured rate falls below the
+limit. Therefore the only harm should be that exceptionally high sending rates
+are logged incorrectly; any countermeasures you configure will be as effective
+as intended.
+
+
+.section "Using rate limiting" "useratlim"
Exim's other ACL facilities are used to define what counter-measures are taken
when the rate limit is exceeded. This might be anything from logging a warning
(for example, while measuring existing sending rates in order to define
message. For example:
.code
# Log all senders' rates
-warn
- ratelimit = 0 / 1h / strict
- log_message = Sender rate $sender_rate / $sender_rate_period
+warn ratelimit = 0 / 1h / strict
+ log_message = Sender rate $sender_rate / $sender_rate_period
-# Slow down fast senders; note the need to truncate $sender_rate at the
-# decimal point.
-warn
- ratelimit = 100 / 1h / per_rcpt / strict
- delay = ${eval: ${sg{$sender_rate}{[.].*}{}} - \
- $sender_rate_limit }s
+# Slow down fast senders; note the need to truncate $sender_rate
+# at the decimal point.
+warn ratelimit = 100 / 1h / per_rcpt / strict
+ delay = ${eval: ${sg{$sender_rate}{[.].*}{}} - \
+ $sender_rate_limit }s
# Keep authenticated users under control
-deny
- authenticated = *
- ratelimit = 100 / 1d / strict / $authenticated_id
+deny authenticated = *
+ ratelimit = 100 / 1d / strict / $authenticated_id
# System-wide rate limit
-defer
- message = Sorry, too busy. Try again later.
- ratelimit = 10 / 1s / $primary_hostname
+defer message = Sorry, too busy. Try again later.
+ ratelimit = 10 / 1s / $primary_hostname
# Restrict incoming rate from each host, with a default
# set using a macro and special cases looked up in a table.
-defer
- message = Sender rate exceeds $sender_rate_limit \
- messages per $sender_rate_period
- ratelimit = ${lookup {$sender_host_address} \
- cdb {DB/ratelimits.cdb} \
- {$value} {RATELIMIT} }
+defer message = Sender rate exceeds $sender_rate_limit \
+ messages per $sender_rate_period
+ ratelimit = ${lookup {$sender_host_address} \
+ cdb {DB/ratelimits.cdb} \
+ {$value} {RATELIMIT} }
.endd
&*Warning*&: If you have a busy server with a lot of &%ratelimit%& tests,
especially with the &%per_rcpt%& option, you may suffer from a performance
RAM disk for Exim's hints directory (usually &_/var/spool/exim/db/_&). However
this means that Exim will lose its hints data after a reboot (including retry
hints, the callout cache, and ratelimit data).
-.wen
+
.section "Address verification" "SECTaddressverification"
.cindex "verifying address" "options for"
.cindex "policy control" "address verification"
Several of the &%verify%& conditions described in section
-&<<SECTaclconditions>>& cause addresses to be verified. These conditions can be
-followed by options that modify the verification process. The options are
-separated from the keyword and from each other by slashes, and some of them
-contain parameters. For example:
+&<<SECTaclconditions>>& cause addresses to be verified. Section
+&<<SECTsenaddver>>& discusses the reporting of sender verification failures.
+The verification conditions can be followed by options that modify the
+verification process. The options are separated from the keyword and from each
+other by slashes, and some of them contain parameters. For example:
.code
verify = sender/callout
verify = recipient/defer_ok/callout=10s,defer_ok
The &%no_details%& option is covered in section &<<SECTsenaddver>>&, which
discusses the reporting of sender address verification failures.
.next
-.new
The &%success_on_redirect%& option causes verification always to succeed
immediately after a successful redirection. By default, if a redirection
generates just one address, that address is also verified. See further
.endlist
.cindex "verifying address" "differentiating failures"
-.cindex "&$recipient_verify_failure$&"
-.cindex "&$sender_verify_failure$&"
-.cindex "&$acl_verify_message$&"
+.vindex "&$recipient_verify_failure$&"
+.vindex "&$sender_verify_failure$&"
+.vindex "&$acl_verify_message$&"
After an address verification failure, &$acl_verify_message$& contains the
error message that is associated with the failure. It can be preserved by
coding like this:
If you are writing your own custom rejection message or log message when
denying access, you can use this variable to include information about the
verification failure.
-.wen
In addition, &$sender_verify_failure$& or &$recipient_verify_failure$& (as
appropriate) contains one of the following words:
.cindex "verifying address" "by callout"
.cindex "callout" "verification"
.cindex "SMTP" "callout verification"
-.new
For non-local addresses, routing verifies the domain, but is unable to do any
checking of the local part. There are situations where some means of verifying
the local part is desirable. One way this can be done is to make an SMTP
lot of resource usage to the cost of verifying an address. However, Exim does
cache the results of callouts, which helps to reduce the cost. Details of
caching are in section &<<SECTcallvercache>>&.
-.wen
Recipient callouts are usually used only between hosts that are controlled by
the same administration. For example, a corporate gateway host could use
remote transport. (For routers that do verification only, no transport need be
specified.) Otherwise, the default SMTP port is used. If a remote transport
specifies an outgoing interface, this is used; otherwise the interface is not
-specified.
+specified. Likewise, the text that is used for the HELO command is taken from
+the transport's &%helo_data%& option; if there is no transport, the value of
+&$smtp_active_hostname$& is used.
For a sender callout check, Exim makes SMTP connections to the remote hosts, to
test whether a bounce message could be delivered to the sender address. The
following SMTP commands are sent:
.display
-&`HELO `&<&'smtp active host name'&>
+&`HELO `&<&'local host name'&>
&`MAIL FROM:<>`&
&`RCPT TO:`&<&'the address to be tested'&>
&`QUIT`&
hosts, the ACL yields &"defer"&, unless the &%defer_ok%& parameter of the
&%callout%& option is given, in which case the condition is forced to succeed.
+.cindex "SMTP" "output flushing, disabling for callout"
+A callout may take a little time. For this reason, Exim normally flushes SMTP
+output before performing a callout in an ACL, to avoid unexpected timeouts in
+clients when the SMTP PIPELINING extension is in use. The flushing can be
+disabled by using a &%control%& modifier to set &%no_callout_flush%&.
.vlist
.vitem <&'a&~time&~interval'&>
-.cindex "callout timeout" "specifying"
+.cindex "callout" "timeout, specifying"
This specifies the timeout that applies for the callout attempt to each host.
For example:
.code
verify = sender/callout=5s
.endd
The default is 30 seconds. The timeout is used for each response from the
-remote host. It is also used for the intial connection, unless overridden by
+remote host. It is also used for the initial connection, unless overridden by
the &%connect%& parameter.
.vitem &*connect&~=&~*&<&'time&~interval'&>
-.cindex "callout connection timeout" "specifying"
+.cindex "callout" "connection timeout, specifying"
This parameter makes it possible to set a different (usually smaller) timeout
for making the SMTP connection. For example:
.code
If not specified, this timeout defaults to the general timeout value.
.vitem &*defer_ok*&
-.cindex "callout defer" "action on"
+.cindex "callout" "defer, action on"
When this parameter is present, failure to contact any host, or any other kind
of temporary error, is treated as success by the ACL. However, the cache is not
updated in this circumstance.
-.new
.vitem &*fullpostmaster*&
.cindex "callout" "full postmaster check"
This operates like the &%postmaster%& option (see below), but if the check for
&'postmaster@domain'& fails, it tries just &'postmaster'&, without a domain, in
accordance with the specification in RFC 2821. The RFC states that the
unqualified address &'postmaster'& should be accepted.
-.wen
.vitem &*mailfrom&~=&~*&<&'email&~address'&>
.vitem &*maxwait&~=&~*&<&'time&~interval'&>
-.cindex "callout overall timeout" "specifying"
+.cindex "callout" "overall timeout, specifying"
This parameter sets an overall timeout for performing a callout verification.
For example:
.code
.vitem &*no_cache*&
-.cindex "callout cache" "suppressing"
-.cindex "caching callout" "suppressing"
+.cindex "callout" "cache, suppressing"
+.cindex "caching callout, suppressing"
When this parameter is given, the callout cache is neither read nor updated.
.vitem &*postmaster*&
.cindex "callout" "postmaster; checking"
-When this parameter is set, a sucessful callout check is followed by a similar
+When this parameter is set, a successful callout check is followed by a similar
check for the local part &'postmaster'& at the same domain. If this address is
rejected, the callout fails (but see &%fullpostmaster%& above). The result of
the postmaster check is recorded in a cache record; if it is a failure, this is
really random &-- it is defined by the expansion of the option
&%callout_random_local_part%&, which defaults to
.code
-$primary_host_name-$tod_epoch-testing
+$primary_hostname-$tod_epoch-testing
.endd
The idea here is to try to determine whether the remote host accepts all local
parts without checking. If it does, there is no point in doing callouts for
.code
deny !verify = recipient/callout=use_postmaster
.endd
-.new
-.cindex "&$qualify_domain$&"
+.vindex "&$qualify_domain$&"
It causes a non-empty postmaster address to be used in the MAIL command when
performing the callout for the recipient, and also for a &"random"& check if
that is configured. The local part of the address is &`postmaster`& and the
domain is the contents of &$qualify_domain$&.
-.wen
.vitem &*use_sender*&
This option applies to recipient callouts only. For example:
.section "Callout caching" "SECTcallvercache"
.cindex "hints database" "callout cache"
-.cindex "callout" "caching"
+.cindex "callout" "cache, description of"
.cindex "caching" "callout"
Exim caches the results of callouts in order to reduce the amount of resources
used, unless you specify the &%no_cache%& parameter with the &%callout%&
.section "Sender address verification reporting" "SECTsenaddver"
.cindex "verifying" "suppressing error details"
-When sender verification fails in an ACL, the details of the failure are
-given as additional output lines before the 550 response to the relevant
-SMTP command (RCPT or DATA). For example, if sender callout is in use,
+See section &<<SECTaddressverification>>& for a general discussion of
+verification. When sender verification fails in an ACL, the details of the
+failure are given as additional output lines before the 550 response to the
+relevant SMTP command (RCPT or DATA). For example, if sender callout is in use,
you might see:
.code
MAIL FROM:<xyz@abc.example>
If more than one RCPT command fails in the same way, the details are given
only for the first of them. However, some administrators do not want to send
out this much information. You can suppress the details by adding
-&"/no_details"& to the ACL statement that requests sender verification. For
+&`/no_details`& to the ACL statement that requests sender verification. For
example:
.code
verify = sender/no_details
mailing list, where the existence of the alias itself is sufficient for
verification to succeed.
-.new
It is possible, however, to change the default behaviour so that all successful
redirections count as successful verifications, however many new addresses are
generated. This is specified by the &%success_on_redirect%& verification
.endd
In this example, verification succeeds if a router generates a new address, and
the callout does not occur, because no address was routed to a remote host.
-.wen
+When verification is being tested via the &%-bv%& option, the treatment of
+redirections is as just described, unless the &%-v%& or any debugging option is
+also specified. In that case, full verification is done for every generated
+address and a report is output for each of them.
-.new
.section "Client SMTP authorization (CSA)" "SECTverifyCSA"
.cindex "CSA" "verifying"
Client SMTP Authorization is a system that allows a site to advertise
.section "Bounce address tag validation" "SECTverifyPRVS"
-.cindex "BATV" "verifying"
+.cindex "BATV, verifying"
Bounce address tag validation (BATV) is a scheme whereby the envelope senders
of outgoing messages have a cryptographic, timestamped &"tag"& added to them.
Genuine incoming bounce messages should therefore always be addressed to
recipients that have a valid tag. This scheme is a way of detecting unwanted
bounce messages caused by sender address forgeries (often called &"collateral
-spam"&), because the recipients of such messages will not include valid tags.
+spam"&), because the recipients of such messages do not include valid tags.
There are two expansion items to help with the implementation of the BATV
&"prvs"& (private signature) scheme in an Exim configuration. This scheme signs
-the original envelope sender address by using a simple shared key to add a hash
-of the address and some time-based randomizing information. The &%prvs%&
-expansion item creates a signed address, and the &%prvscheck%& expansion item
-checks one. The syntax of these expansion items is described in section
+the original envelope sender address by using a simple key to add a hash of the
+address and some time-based randomizing information. The &%prvs%& expansion
+item creates a signed address, and the &%prvscheck%& expansion item checks one.
+The syntax of these expansion items is described in section
&<<SECTexpansionitems>>&.
As an example, suppose the secret per-address keys are stored in an MySQL
use this:
.code
# Bounces: drop unsigned addresses for BATV senders
-deny message = This address does not send an unsigned reverse path.
+deny message = This address does not send an unsigned reverse path
senders = :
recipients = +batv_senders
timeout checks succeed. The &$prvscheck_result$& variable contains the result
of the checks (empty for failure, &"1"& for success).
-Of course, when you accept a prvs-signed address, you have to ensure that the
-routers accept it and deliver it correctly. The easiest way to handle this is
-to use a &(redirect)& router to remove the signature with a configuration along
-these lines:
+There is one more issue you must consider when implementing prvs-signing:
+you have to ensure that the routers accept prvs-signed addresses and
+deliver them correctly. The easiest way to handle this is to use a &(redirect)&
+router to remove the signature with a configuration along these lines:
.code
batv_redirect:
driver = redirect
{$value}fail}}}
.endd
If no key can be found for the existing return path, no signing takes place.
-.wen
patient. The remote host is making an SMTP connection back to your host, and
trying a number of common probes to test for open relay vulnerability. The
results of the tests will eventually appear on your terminal.
-
+.ecindex IIDacl
. ////////////////////////////////////////////////////////////////////////////
.chapter "Content scanning at ACL time" "CHAPexiscan"
-.cindex "content scanning" "at ACL time"
+.scindex IIDcosca "content scanning" "at ACL time"
The extension of Exim to include content scanning at ACL time, formerly known
as &"exiscan"&, was originally implemented as a patch by Tom Kistner. The code
was integrated into the main source for Exim release 4.50, and Tom continues to
maintain it. Most of the wording of this chapter is taken from Tom's
specification.
-.new
It is also possible to scan the content of messages at other times. The
&[local_scan()]& function (see chapter &<<CHAPlocalscan>>&) allows for content
scanning after all the ACLs have run. A transport filter can be used to scan
messages at delivery time (see the &%transport_filter%& option, described in
chapter &<<CHAPtransportgeneric>>&).
-.wen
If you want to include the ACL-time content-scanning features when you compile
Exim, you need to arrange for WITH_CONTENT_SCAN to be defined in your
&_Local/Makefile_&. When you do that, the Exim binary is built with:
.ilist
-.new
Two additional ACLs (&%acl_smtp_mime%& and &%acl_not_smtp_mime%&) that are run
for all MIME parts for SMTP and non-SMTP messages, respectively.
-.wen
.next
Additional ACL conditions and modifiers: &%decode%&, &%malware%&,
&%mime_regex%&, &%regex%&, and &%spam%&. These can be used in the ACL that is
this manual. You can find out about them by reading the file called
&_doc/experimental.txt_&.
-All the content-scanning facilites work on a MBOX copy of the message that is
+All the content-scanning facilities work on a MBOX copy of the message that is
temporarily created in a file called:
.display
<&'spool_directory'&>&`/scan/`&<&'message_id'&>/<&'message_id'&>&`.eml`&
specialized interfaces for &"daemon"& type virus scanners, which are resident
in memory and thus are much faster.
-.cindex "&%av_scanner%&"
+
+.oindex "&%av_scanner%&"
You can set the &%av_scanner%& option in first part of the Exim configuration
file to specify which scanner to use, together with any additional options that
are needed. The basic syntax is as follows:
.code
av_scanner = sophie:/var/run/sophie
.endd
-If the value of &%av_scanner%& starts with dollar character, it is expanded
+If the value of &%av_scanner%& starts with a dollar character, it is expanded
before use. The following scanner types are supported in this release:
.vlist
av_scanner = aveserver:/var/run/aveserver
.endd
+
.vitem &%clamd%&
.cindex "virus scanners" "clamd"
This daemon-type scanner is GPL and free. You can get it at
number, and a port, separated by space, as in the second of these examples:
.code
av_scanner = clamd:/opt/clamd/socket
-av_scanner = clamd:192.168.2.100 1234
-.endd
+av_scanner = clamd:192.0.2.3 1234
+av_scanner = clamd:192.0.2.3 1234:local
+.endd
+If the value of av_scanner points to a UNIX socket file or contains the local
+keyword, then the ClamAV interface will pass a filename containing the data
+to be scanned, which will should normally result in less I/O happening and be
+more efficient. Normally in the TCP case, the data is streamed to ClamAV as
+Exim does not assume that there is a common filesystem with the remote host.
+There is an option WITH_OLD_CLAMAV_STREAM in &_src/EDITME_& available, should
+you be running a version of ClamAV prior to 0.95.
If the option is unset, the default is &_/tmp/clamd_&. Thanks to David Saez for
contributing the code for this scanner.
.code
Virus 'W32/Magistr-B' found in file ./those.bat
.endd
-For the trigger expression, we can just match the word &"found"&. For the name
-expression, we want to extract the W32/Magistr-B string, so we can match for
-the single quotes left and right of it. Altogether, this makes the
+For the trigger expression, we can match the phrase &"found in file"&. For the
+name expression, we want to extract the W32/Magistr-B string, so we can match
+for the single quotes left and right of it. Altogether, this makes the
configuration setting:
.code
av_scanner = cmdline:\
- /path/to/sweep -all -rec -archive %s:\
- found:'(.+)'
+ /path/to/sweep -ss -all -rec -archive %s:\
+ found in file:'(.+)'
.endd
.vitem &%drweb%&
.cindex "virus scanners" "DrWeb"
.vitem &%sophie%&
.cindex "virus scanners" "Sophos and Sophie"
Sophie is a daemon that uses Sophos' &%libsavi%& library to scan for viruses.
-You can get Sophie at &url(http://www.vanja.com/tools/sophie/). The only
-option for this scanner type is the path to the UNIX socket that Sophie uses
-for client communication. For example:
+You can get Sophie at &url(http://www.clanfield.info/sophie/). The only option
+for this scanner type is the path to the UNIX socket that Sophie uses for
+client communication. For example:
.code
av_scanner = sophie:/tmp/sophie
.endd
the option.
.endlist
-.new
When &%av_scanner%& is correctly set, you can use the &%malware%& condition in
the DATA ACL. &*Note*&: You cannot use the &%malware%& condition in the MIME
ACL.
-.wen
The &%av_scanner%& option is expanded each time &%malware%& is called. This
makes it possible to use different scanners. See further below for an example.
The condition succeeds if a virus was found, and fail otherwise. This is the
recommended usage.
.next
-&"false"& or &"0"&, in which case no scanning is done and the condition fails
-immediately.
+&"false"& or &"0"& or an empty string, in which case no scanning is done and
+the condition fails immediately.
.next
A regular expression, in which case the message is scanned for viruses. The
condition succeeds if a virus is found and its name matches the regular
.endlist
You can append &`/defer_ok`& to the &%malware%& condition to accept messages
-even if there is a problem with the virus scanner.
+even if there is a problem with the virus scanner. Otherwise, such a problem
+causes the ACL to defer.
-.cindex "&$malware_name$&"
+.vindex "&$malware_name$&"
When a virus is found, the condition sets up an expansion variable called
&$malware_name$& that contains the name of the virus. You can use it in a
&%message%& modifier that specifies the error returned to the sender, and/or in
use the &%demime%& condition (see section &<<SECTdemimecond>>&) before the
&%malware%& condition.
+Beware the interaction of Exim's &%message_size_limit%& with any size limits
+imposed by your anti-virus scanner.
+
Here is a very simple scanning example:
.code
deny message = This message contains malware ($malware_name)
.section "Scanning with SpamAssassin" "SECTscanspamass"
.cindex "content scanning" "for spam"
.cindex "spam scanning"
-.cindex "SpamAssassin" "scanning with"
+.cindex "SpamAssassin"
The &%spam%& ACL condition calls SpamAssassin's &%spamd%& daemon to get a spam
score and a report for the message. You can get SpamAssassin at
&url(http://www.spamassassin.org), or, if you have a working Perl
documentation to see how you can tweak it. The default installation should work
nicely, however.
-.cindex "&%spamd_address%&"
+.oindex "&%spamd_address%&"
After having installed and configured SpamAssassin, start the &%spamd%& daemon.
By default, it listens on 127.0.0.1, TCP port 783. If you use another host or
port for &%spamd%&, you must set the &%spamd_address%& option in the global
&*Warning*&: It is not possible to use the UNIX socket connection method with
multiple &%spamd%& servers.
+The &%spamd_address%& variable is expanded before use if it starts with
+a dollar sign. In this case, the expansion may return a string that is
+used as the list so that multiple spamd servers can be the result of an
+expansion.
-.section "Calling SpamAssassin from an Exim ACL"
+.section "Calling SpamAssassin from an Exim ACL" "SECID206"
Here is a simple example of the use of the &%spam%& condition in a DATA ACL:
.code
deny message = This message was classified as SPAM
spam = joe
.endd
-The right-hand side of the &%spam%& condition specifies the username that
-SpamAssassin should scan for. If you do not want to scan for a particular user,
-but rather use the SpamAssassin system-wide default profile, you can scan for
-an unknown user, or simply use &"nobody"&. However, you must put something on
-the right-hand side.
+The right-hand side of the &%spam%& condition specifies a name. This is
+relevant if you have set up multiple SpamAssassin profiles. If you do not want
+to scan using a specific profile, but rather use the SpamAssassin system-wide
+default profile, you can scan for an unknown name, or simply use &"nobody"&.
+However, you must put something on the right-hand side.
+
+The name allows you to use per-domain or per-user antispam profiles in
+principle, but this is not straightforward in practice, because a message may
+have multiple recipients, not necessarily all in the same domain. Because the
+&%spam%& condition has to be called from a DATA ACL in order to be able to
+read the contents of the message, the variables &$local_part$& and &$domain$&
+are not set.
+
+The right-hand side of the &%spam%& condition is expanded before being used, so
+you can put lookups or conditions there. When the right-hand side evaluates to
+&"0"& or &"false"&, no scanning is done and the condition fails immediately.
-The username allows you to use per-domain or per-user antispam profiles. The
-right-hand side is expanded before being used, so you can put lookups or
-conditions there. When the right-hand side evaluates to &"0"& or &"false"&, no
-scanning is done and the condition fails immediately.
-.new
Scanning with SpamAssassin uses a lot of resources. If you scan every message,
-large ones may cause significant performance degredation. As most spam messages
+large ones may cause significant performance degradation. As most spam messages
are quite small, it is recommended that you do not scan the big ones. For
example:
.code
condition = ${if < {$message_size}{10K}}
spam = nobody
.endd
-.wen
The &%spam%& condition returns true if the threshold specified in the user's
SpamAssassin profile has been matched or exceeded. If you want to use the
it always return &"true"& by appending &`:true`& to the username.
.cindex "spam scanning" "returned variables"
-When the &%spam%& condition is run, it sets up the following expansion
-variables:
+When the &%spam%& condition is run, it sets up a number of expansion
+variables. These variables are saved with the received message, thus they are
+available for use at delivery time.
.vlist
.vitem &$spam_score$&
.vitem &$spam_score_int$&
The spam score of the message, multiplied by ten, as an integer value. For
-example &"34"& or &"305"&. This is useful for numeric comparisons in
-conditions. This variable is special; it is saved with the message, and written
-to Exim's spool file. This means that it can be used during the whole life of
-the message on your Exim system, in particular, in routers or transports during
-the later delivery phase.
+example &"34"& or &"305"&. It may appear to disagree with &$spam_score$&
+because &$spam_score$& is rounded and &$spam_score_int$& is truncated.
+The integer value is useful for numeric comparisons in conditions.
.vitem &$spam_bar$&
A string consisting of a number of &"+"& or &"-"& characters, representing the
message. Useful for inclusion in headers or reject messages.
.endlist
-The &%spam%& condition caches its results. If you call it again with the same
-user name, it does not scan again, but rather returns the same values as
-before.
+The &%spam%& condition caches its results unless expansion in
+spamd_address was used. If you call it again with the same user name, it
+does not scan again, but rather returns the same values as before.
-The &%spam%& condition returns DEFER if there is any error while running the
-message through SpamAssassin. If you want to treat DEFER as FAIL (to pass on to
-the next ACL statement block), append &`/defer_ok`& to the right-hand side of
-the spam condition, like this:
+The &%spam%& condition returns DEFER if there is any error while running
+the message through SpamAssassin or if the expansion of spamd_address
+failed. If you want to treat DEFER as FAIL (to pass on to the next ACL
+statement block), append &`/defer_ok`& to the right-hand side of the
+spam condition, like this:
.code
deny message = This message was classified as SPAM
spam = joe/defer_ok
condition:
.code
# put headers in all messages (no matter if spam or not)
-warn message = X-Spam-Score: $spam_score ($spam_bar)
- spam = nobody:true
-warn message = X-Spam-Report: $spam_report
- spam = nobody:true
+warn spam = nobody:true
+ add_header = X-Spam-Score: $spam_score ($spam_bar)
+ add_header = X-Spam-Report: $spam_report
# add second subject line with *SPAM* marker when message
# is over threshold
-warn message = Subject: *SPAM* $h_Subject:
- spam = nobody
+warn spam = nobody
+ add_header = Subject: *SPAM* $h_Subject:
# reject spam at high scores (> 12)
deny message = This message scored $spam_score spam points.
.section "Scanning MIME parts" "SECTscanmimepart"
.cindex "content scanning" "MIME parts"
.cindex "MIME content scanning"
-.cindex "&%acl_smtp_mime%&"
-.new
+.oindex "&%acl_smtp_mime%&"
+.oindex "&%acl_not_smtp_mime%&"
The &%acl_smtp_mime%& global option specifies an ACL that is called once for
each MIME part of an SMTP message, including multipart types, in the sequence
of their position in the message. Similarly, the &%acl_not_smtp_mime%& option
cases.
These ACLs are called (possibly many times) just before the &%acl_smtp_data%&
-ACL in the case of an SMTP message, or just before a non-SMTP message is
-accepted. However, a MIME ACL is called only if the message contains a
-&'MIME-Version:'& header line. When a call to a MIME ACL does not yield
-&"accept"&, ACL processing is aborted and the appropriate result code is sent
-to the client. In the case of an SMTP message, the &%acl_smtp_data%& ACL is not
-called when this happens.
+ACL in the case of an SMTP message, or just before the &%acl_not_smtp%& ACL in
+the case of a non-SMTP message. However, a MIME ACL is called only if the
+message contains a &'Content-Type:'& header line. When a call to a MIME
+ACL does not yield &"accept"&, ACL processing is aborted and the appropriate
+result code is sent to the client. In the case of an SMTP message, the
+&%acl_smtp_data%& ACL is not called when this happens.
You cannot use the &%malware%& or &%spam%& conditions in a MIME ACL; these can
only be used in the DATA or non-SMTP ACLs. However, you can use the &%regex%&
condition to match against the raw MIME part. You can also use the
&%mime_regex%& condition to match against the decoded MIME part (see section
&<<SECTscanregex>>&).
-.wen
At the start of a MIME ACL, a number of variables are set from the header
information for the relevant MIME part. These are described below. The contents
of the MIME part are not by default decoded into a disk file except for MIME
parts whose content-type is &"message/rfc822"&. If you want to decode a MIME
-part into a disk file, you can use the &%decode%& modifier. The general syntax
-is:
+part into a disk file, you can use the &%decode%& condition. The general
+syntax is:
.display
&`decode = [/`&<&'path'&>&`/]`&<&'filename'&>
.endd
If the string does not start with a slash, it is used as the
filename, and the default path is then used.
.endlist
-
-You can easily decode a file with its original, proposed filename using
+The &%decode%& condition normally succeeds. It is only false for syntax
+errors or unusual circumstances such as memory shortages. You can easily decode
+a file with its original, proposed filename using
.code
decode = $mime_filename
.endd
.vitem &$mime_is_coverletter$&
This variable attempts to differentiate the &"cover letter"& of an e-mail from
-attached data. It can be used to clamp down on flashy or unneccessarily encoded
+attached data. It can be used to clamp down on flashy or unnecessarily encoded
content in the cover letter, while not restricting attachments at all.
The variable contains 1 (true) for a MIME part believed to be part of the
errors in MIME containers and can match file extensions found in the message
against a list. Using this facility produces files containing the unpacked MIME
parts of the message in the temporary scan directory. If you do antivirus
-scanning, it is recommened that you use the &%demime%& condition before the
+scanning, it is recommended that you use the &%demime%& condition before the
antivirus (&%malware%&) condition.
On the right-hand side of the &%demime%& condition you can pass a
.vlist
.vitem &$demime_errorlevel$&
-.cindex "&$demime_errorlevel$&"
+.vindex "&$demime_errorlevel$&"
When an error is detected in a MIME container, this variable contains the
severity of the error, as an integer number. The higher the value, the more
severe the error (the current maximum value is 3). If this variable is unset or
zero, no error occurred.
.vitem &$demime_reason$&
-.cindex "&$demime_reason$&"
+.vindex "&$demime_reason$&"
When &$demime_errorlevel$& is greater than zero, this variable contains a
human-readable text string describing the MIME error that occurred.
.endlist
.vlist
.vitem &$found_extension$&
-.cindex "&$found_extension$&"
+.vindex "&$found_extension$&"
When the &%demime%& condition is true, this variable contains the file
extension it found.
.endlist
demime = exe:doc
control = freeze
.endd
+.ecindex IIDcosca
.chapter "Adding a local scan function to Exim" "CHAPlocalscan" &&&
"Local scan function"
-.cindex "&[local_scan()]& function" "description of"
+.scindex IIDlosca "&[local_scan()]& function" "description of"
.cindex "customizing" "input scan using C function"
.cindex "policy control" "by local scan function"
In these days of email worms, viruses, and ever-increasing spam, some sites
-.section "Building Exim to use a local scan function"
+.section "Building Exim to use a local scan function" "SECID207"
.cindex "&[local_scan()]& function" "building Exim to use"
To make use of the local scan function feature, you must tell Exim where your
function is before building Exim, by setting LOCAL_SCAN_SOURCE in your
.vlist
.vitem &`LOCAL_SCAN_ACCEPT`&
-.cindex "&$local_scan_data$&"
+.vindex "&$local_scan_data$&"
The message is accepted. If you pass back a string of text, it is saved with
the message, and made available in the variable &$local_scan_data$&. No
newlines are permitted (if there are any, they are turned into spaces) and the
printed with the suffix K or M.
.vitem &*opt_octint*&
-This also specifies an integer, but the value is always interpeted as an
+This also specifies an integer, but the value is always interpreted as an
octal integer, whether or not it starts with the digit zero, and it is
always output in octal.
-.section "Available Exim variables"
+.section "Available Exim variables" "SECID208"
.cindex "&[local_scan()]& function" "available Exim variables"
The header &_local_scan.h_& gives you access to a number of C variables. These
are the only ones that are guaranteed to be maintained from release to release.
-Note, however, that you can obtain the value of any Exim variable by calling
-&'expand_string()'&. The exported variables are as follows:
+Note, however, that you can obtain the value of any Exim expansion variable,
+including &$recipients$&, by calling &'expand_string()'&. The exported
+C variables are as follows:
.vlist
+.vitem &*int&~body_linecount*&
+This variable contains the number of lines in the message's body.
+
+.vitem &*int&~body_zerocount*&
+This variable contains the number of binary zero bytes in the message's body.
+
.vitem &*unsigned&~int&~debug_selector*&
This variable is set to zero when no debugging is taking place. Otherwise, it
is a bitmap of debugging selectors. Two bits are identified for use in
is NULL for locally submitted messages.
.vitem &*int&~interface_port*&
-The port on which this message was received.
+The port on which this message was received. When testing with the &%-bh%&
+command line option, the value of this variable is -1 unless a port has been
+specified via the &%-oMi%& option.
.vitem &*uschar&~*message_id*&
This variable contains Exim's message id for the incoming message (the value of
The list of accepted recipients, held in a vector of length
&%recipients_count%&. The &%recipient_item%& structure is discussed below. You
can add additional recipients by calling &'receive_add_recipient()'& (see
-below). You can delete recipients by removing them from the vector and adusting
-the value in &%recipients_count%&. In particular, by setting
+below). You can delete recipients by removing them from the vector and
+adjusting the value in &%recipients_count%&. In particular, by setting
&%recipients_count%& to zero you remove all recipients. If you then return the
value &`LOCAL_SCAN_ACCEPT`&, the message is accepted, but immediately
blackholed. To replace the recipients, you can set &%recipients_count%& to zero
.endlist
-.section "Structure of header lines"
+.section "Structure of header lines" "SECID209"
The &%header_line%& structure contains the members listed below.
You can add additional header lines by calling the &'header_add()'& function
(see below). You can cause header lines to be ignored (deleted) by setting
-.section "Structure of recipient items"
+.section "Structure of recipient items" "SECID210"
The &%recipient_item%& structure contains these members:
.vlist
-.section "Available Exim functions"
+.section "Available Exim functions" "SECID211"
.cindex "&[local_scan()]& function" "available Exim functions"
The header &_local_scan.h_& gives you access to a number of Exim functions.
These are the only ones that are guaranteed to be maintained from release to
fine in this circumstance. Unless you have made a mistake with the recipient
addresses, you should get a return code of zero.
+
+.vitem &*pid_t&~child_open_exim2(int&~*fd,&~uschar&~*sender,&~uschar&~&&&
+ *sender_authentication)*&
+This function is a more sophisticated version of &'child_open()'&. The command
+that it runs is:
+.display
+&`exim -t -oem -oi -f `&&'sender'&&` -oMas `&&'sender_authentication'&
+.endd
+The third argument may be NULL, in which case the &%-oMas%& option is omitted.
+
+
.vitem &*void&~debug_printf(char&~*,&~...)*&
This is Exim's debugging function, with arguments as for &'(printf()'&. The
output is written to the standard error stream. If no debugging is selected,
if ((debug_selector & D_local_scan) != 0)
debug_printf("xxx", ...);
.endd
+
.vitem &*uschar&~*expand_string(uschar&~*string)*&
This is an interface to Exim's string expansion code. The return value is the
expanded string, or NULL if there was an expansion failure.
.code
lss_match_host(sender_host_name, sender_host_address, ...)
.endd
-.cindex "&$sender_host_address$&"
+.vindex "&$sender_host_address$&"
An empty address field matches an empty item in the host list. If the host name
is NULL, the name corresponding to &$sender_host_address$& is automatically
looked up if a host name is required to match an item in the list. The return
the addition of that field to the structure. However, it is easy to add such a
value afterwards. For example:
.code
-receive_add_recipient(US"monitor@mydom.example", -1);
-recipients_list[recipients_count-1].errors_to =
-US"postmaster@mydom.example";
+ receive_add_recipient(US"monitor@mydom.example", -1);
+ recipients_list[recipients_count-1].errors_to =
+ US"postmaster@mydom.example";
.endd
.vitem &*BOOL&~receive_remove_recipient(uschar&~*recipient)*&
There is also a convenience function called &'store_get_perm()'& that gets a
block of memory from the permanent pool while preserving the value of
&%store_pool%&.
-
+.ecindex IIDlosca
. ////////////////////////////////////////////////////////////////////////////
.chapter "System-wide message filtering" "CHAPsystemfilter"
-.cindex "filter" "system filter"
-.cindex "filtering all mail"
-.cindex "system filter"
+.scindex IIDsysfil1 "filter" "system filter"
+.scindex IIDsysfil2 "filtering all mail"
+.scindex IIDsysfil3 "system filter"
The previous chapters (on ACLs and the local scan function) describe checks
that can be applied to messages before they are accepted by a host. There is
also a mechanism for checking messages once they have been received, but before
of the &%first_delivery%& condition in an &%if%& command in the filter to
prevent it happening on retries.
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
&*Warning*&: Because the system filter runs just once, variables that are
specific to individual recipient addresses, such as &$local_part$& and
&$domain$&, are not set, and the &"personal"& condition is not meaningful. If
described in section &<<SECTperaddfil>>& below.
-.section "Specifying a system filter"
+.section "Specifying a system filter" "SECID212"
.cindex "uid (user id)" "system filter"
.cindex "gid (group id)" "system filter"
The name of the file that contains the system filter must be specified by
by the &%reply%& command.
-.section "Testing a system filter"
+.section "Testing a system filter" "SECID213"
You can run simple tests of a system filter in the same way as for a user
filter, but you should use &%-bF%& rather than &%-bf%&, so that features that
are permitted only in system filters are recognized.
-.section "Contents of a system filter"
+.section "Contents of a system filter" "SECID214"
The language used to specify system filters is the same as for users' filter
files. It is described in the separate end-user document &'Exim's interface to
mail filtering'&. However, there are some additional features that are
-.section "Additional variable for system filters"
-.cindex "&$recipients$&"
+.section "Additional variable for system filters" "SECID215"
+.vindex "&$recipients$&"
The expansion variable &$recipients$&, containing a list of all the recipients
of the message (separated by commas and white space), is available in system
filters. It is not available in users' filters for privacy reasons.
-.section "Defer, freeze, and fail commands for system filters"
+.section "Defer, freeze, and fail commands for system filters" "SECID216"
.cindex "freezing messages"
.cindex "message" "freezing"
.cindex "message" "forced failure"
-.section "Setting an errors address in a system filter"
+.section "Setting an errors address in a system filter" "SECID217"
.cindex "envelope sender"
In a system filter, if a &%deliver%& command is followed by
.code
.section "Per-address filtering" "SECTperaddfil"
-.cindex "&$domain$&"
-.cindex "&$local_part$&"
+.vindex "&$domain$&"
+.vindex "&$local_part$&"
In contrast to the system filter, which is run just once per message for each
delivery attempt, it is also possible to set up a system-wide filtering
operation that runs once for each recipient address. In this case, variables
its intended recipient. The router will not then claim to have dealt with the
address, so it will be passed on to subsequent routers to be delivered in the
normal way.
+.ecindex IIDsysfil1
+.ecindex IIDsysfil2
+.ecindex IIDsysfil3
. ////////////////////////////////////////////////////////////////////////////
.chapter "Message processing" "CHAPmsgproc"
-.cindex "message" "general processing"
+.scindex IIDmesproc "message" "general processing"
Exim performs various transformations on the sender and recipient addresses of
all messages that it handles, and also on the messages' header lines. Some of
these are optional and configurable, while others always take place. All of
.section "Submission mode for non-local messages" "SECTsubmodnon"
.cindex "message" "submission"
.cindex "submission mode"
-.new
Processing that happens automatically for locally-originated messages (unless
&%suppress_local_fixups%& is set) can also be requested for messages that are
received over TCP/IP. The term &"submission mode"& is used to describe this
-state. Submisssion mode is set by the modifier
-.wen
+state. Submission mode is set by the modifier
.code
control = submission
.endd
warn hosts = 127.0.0.1
control = submission
.endd
-.cindex "&%sender_retain%&"
+.cindex "&%sender_retain%& submission option"
There are some options that can be used when setting submission mode. A slash
is used to separate options. For example:
.code
.code
control = submission/domain=some.domain
.endd
-.new
The domain may be empty. How this value is used is described in sections
&<<SECTthefrohea>>& and &<<SECTthesenhea>>&. There is also a &%name%& option
that allows you to specify the user's full name for inclusion in a created
specified by submission mode. Although this might be slightly unexpected, it
does mean that you can configure ACL checks to spot that a user is trying to
spoof another's address.
-.wen
.section "Line endings" "SECTlineendings"
.cindex "line endings"
-.section "Unqualified addresses"
+.section "Unqualified addresses" "SECID218"
.cindex "unqualified addresses"
.cindex "address" "qualification"
By default, Exim expects every envelope address it receives from an external
requirement to accept unqualified addresses from specific hosts or IP networks.
Exim has two options that separately control which hosts may send unqualified
-sender or receipient addresses in SMTP commands, namely
+sender or recipient addresses in SMTP commands, namely
&%sender_unqualified_hosts%& and &%recipient_unqualified_hosts%&. In both
cases, if an unqualified address is accepted, it is qualified by adding the
value of &%qualify_domain%& or &%qualify_recipient%&, as appropriate.
-.cindex "&%qualify_domain%&"
-.cindex "&%qualify_recipient%&"
+.oindex "&%qualify_domain%&"
+.oindex "&%qualify_recipient%&"
Unqualified addresses in header lines are automatically qualified for messages
that are locally originated, unless the &%-bnq%& option is given on the command
line. For messages received over SMTP, unqualified addresses in header lines
-.section "The UUCP From line"
+.section "The UUCP From line" "SECID219"
.cindex "&""From""& line"
.cindex "UUCP" "&""From""& line"
.cindex "sender" "address"
-.cindex "&%uucp_from_pattern%&"
-.cindex "&%uucp_from_sender%&"
+.oindex "&%uucp_from_pattern%&"
+.oindex "&%uucp_from_sender%&"
.cindex "envelope sender"
.cindex "Sendmail compatibility" "&""From""& line"
Messages that have come from UUCP (and some other applications) often begin
-.section "Resent- header lines"
+.section "Resent- header lines" "SECID220"
.cindex "&%Resent-%& header lines"
RFC 2822 makes provision for sets of header lines starting with the string
&`Resent-`& to be added to a message when it is resent by the original
-.section "The Auto-Submitted: header line"
-Whenever Exim generates a bounce or a delay warning message, it includes the
-header line:
-.new
+.section "The Auto-Submitted: header line" "SECID221"
+Whenever Exim generates an autoreply, a bounce, or a delay warning message, it
+includes the header line:
.code
Auto-Submitted: auto-replied
.endd
-.wen
-.section "The Bcc: header line"
+.section "The Bcc: header line" "SECID222"
.cindex "&'Bcc:'& header line"
If Exim is called with the &%-t%& option, to take recipient addresses from a
message's header, it removes any &'Bcc:'& header line that may exist (after
existing &'Bcc:'& is not removed.
-.section "The Date: header line"
+.section "The Date: header line" "SECID223"
.cindex "&'Date:'& header line"
-.new
If a locally-generated or submission-mode message has no &'Date:'& header line,
Exim adds one, using the current date and time, unless the
&%suppress_local_fixups%& control has been specified.
-.wen
-.section "The Delivery-date: header line"
+.section "The Delivery-date: header line" "SECID224"
.cindex "&'Delivery-date:'& header line"
-.cindex "&%delivery_date_remove%&"
+.oindex "&%delivery_date_remove%&"
&'Delivery-date:'& header lines are not part of the standard RFC 2822 header
set. Exim can be configured to add them to the final delivery of messages. (See
the generic &%delivery_date_add%& transport option.) They should not be present
messages.
-.section "The Envelope-to: header line"
+.section "The Envelope-to: header line" "SECID225"
.cindex "&'Envelope-to:'& header line"
-.cindex "&%envelope_to_remove%&"
+.oindex "&%envelope_to_remove%&"
&'Envelope-to:'& header lines are not part of the standard RFC 2822 header set.
Exim can be configured to add them to the final delivery of messages. (See the
generic &%envelope_to_add%& transport option.) They should not be present in
The envelope sender address is not empty (that is, this is not a bounce
message). The added header line copies the envelope sender address.
.next
-.cindex "&$authenticated_id$&"
+.vindex "&$authenticated_id$&"
The SMTP session is authenticated and &$authenticated_id$& is not empty.
.olist
-.cindex "&$qualify_domain$&"
+.vindex "&$qualify_domain$&"
If no domain is specified by the submission control, the local part is
&$authenticated_id$& and the domain is &$qualify_domain$&.
.next
If a non-empty domain is specified by the submission control, the local
-part is &$authenticated_id$&, and the the domain is the specified domain.
+part is &$authenticated_id$&, and the domain is the specified domain.
.next
If an empty domain is specified by the submission control,
&$authenticated_id$& is assumed to be the complete address.
A non-empty envelope sender takes precedence.
-.new
If a locally-generated incoming message does not contain a &'From:'& header
line, and the &%suppress_local_fixups%& control is not set, Exim adds one
containing the sender's address. The calling user's login name and full name
They are obtained from the password data by calling &[getpwuid()]& (but see the
&%unknown_login%& configuration option). The address is qualified with
&%qualify_domain%&.
-.wen
For compatibility with Sendmail, if an incoming, non-SMTP message has a
&'From:'& header line containing just the unqualified login name of the calling
name as described in section &<<SECTconstr>>&.
-.section "The Message-ID: header line"
+.section "The Message-ID: header line" "SECID226"
.cindex "&'Message-ID:'& header line"
.cindex "message" "submission"
-.cindex "&%message_id_header_text%&"
-.new
+.oindex "&%message_id_header_text%&"
If a locally-generated or submission-mode incoming message does not contain a
&'Message-ID:'& or &'Resent-Message-ID:'& header line, and the
&%suppress_local_fixups%& control is not set, Exim adds a suitable header line
followed by @ and the primary host name. Additional information can be included
in this header line by setting the &%message_id_header_text%& and/or
&%message_id_header_domain%& options.
-.wen
-.section "The Received: header line"
+.section "The Received: header line" "SECID227"
.cindex "&'Received:'& header line"
A &'Received:'& header line is added at the start of every message. The
contents are defined by the &%received_header_text%& configuration option, and
-H spool file is written) the earliest time at which delivery could start.
+.section "The References: header line" "SECID228"
+.cindex "&'References:'& header line"
+Messages created by the &(autoreply)& transport include a &'References:'&
+header line. This is constructed according to the rules that are described in
+section 3.64 of RFC 2822 (which states that replies should contain such a
+header line), and section 3.14 of RFC 3834 (which states that automatic
+responses are not different in this respect). However, because some mail
+processing software does not cope well with very long header lines, no more
+than 12 message IDs are copied from the &'References:'& header line in the
+incoming message. If there are more than 12, the first one and then the final
+11 are copied, before adding the message ID of the incoming message.
+
-.section "The Return-path: header line"
+
+.section "The Return-path: header line" "SECID229"
.cindex "&'Return-path:'& header line"
-.cindex "&%return_path_remove%&"
+.oindex "&%return_path_remove%&"
&'Return-path:'& header lines are defined as something an MTA may insert when
it does the final delivery of messages. (See the generic &%return_path_add%&
transport option.) Therefore, they should not be present in messages in
.section "The Sender: header line" "SECTthesenhea"
.cindex "&'Sender:'& header line"
.cindex "message" "submission"
-.new
For a locally-originated message from an untrusted user, Exim may remove an
existing &'Sender:'& header line, and it may add a new one. You can modify
these actions by setting the &%local_sender_retain%& option true, the
be permitted by setting &%local_from_prefix%& and &%local_from_suffix%&
appropriately. If &'From:'& does not contain the correct sender, a &'Sender:'&
line is added to the message.
-.wen
If you set &%local_from_check%& false, this checking does not occur. However,
the removal of an existing &'Sender:'& line still happens, unless you also set
a message is received over TCP/IP in submission mode, and &%sender_retain%& is
not specified on the submission control, the following processing takes place:
-.cindex "&$authenticated_id$&"
+.vindex "&$authenticated_id$&"
First, any existing &'Sender:'& lines are removed. Then, if the SMTP session is
authenticated, and &$authenticated_id$& is not empty, a sender address is
created as follows:
.ilist
-.cindex "&$qualify_domain$&"
+.vindex "&$qualify_domain$&"
If no domain is specified by the submission control, the local part is
&$authenticated_id$& and the domain is &$qualify_domain$&.
.next
If a non-empty domain is specified by the submission control, the local part
-is &$authenticated_id$&, and the the domain is the specified domain.
+is &$authenticated_id$&, and the domain is the specified domain.
.next
If an empty domain is specified by the submission control,
&$authenticated_id$& is assumed to be the complete address.
added. Prefixes and suffixes for the local part in &'From:'& can be permitted
by setting &%local_from_prefix%& and &%local_from_suffix%& appropriately.
-.new
.cindex "return path" "created from &'Sender:'&"
&*Note*&: Whenever a &'Sender:'& header line is created, the return path for
the message (the envelope sender address) is changed to be the same address,
except in the case of submission mode when &%sender_retain%& is specified.
-.wen
"SECTheadersaddrem"
.cindex "header lines" "adding; in router or transport"
.cindex "header lines" "removing; in router or transport"
-.new
When a message is delivered, the addition and removal of header lines can be
specified in a system filter, or on any of the routers and transports that
process the message. Section &<<SECTaddremheasys>>& contains details about
modifying headers in a system filter. Header lines can also be added in an ACL
-as a message is received (see section &<<SECTaddheadwarn>>&).
-.wen
+as a message is received (see section &<<SECTaddheadacl>>&).
In contrast to what happens in a system filter, header modifications that are
specified on routers and transports apply only to the particular recipient
transported. Therefore, they do not affect the basic set of header lines, and
they do not affect the values of the variables that refer to header lines.
-.new
&*Note*&: In particular, this means that any expansions in the configuration of
the transport cannot refer to the modified header lines, because such
expansions all occur before the message is actually transported.
-.wen
For both routers and transports, the result of expanding a &%headers_add%&
option must be in the form of one or more RFC 2822 header lines, separated by
an address passes through several routers as a result of aliasing or
forwarding, the changes are cumulative.
-.cindex "&%unseen%& option"
+.oindex "&%unseen%&"
However, this does not apply to multiple routers that result from the use of
the &%unseen%& option. Any header modifications that were specified by the
&"unseen"& router or its predecessors apply only to the &"unseen"& delivery.
-.section "Case of local parts"
+.section "Case of local parts" "SECID230"
.cindex "case of local parts"
.cindex "local part" "case of"
RFC 2822 states that the case of letters in the local parts of addresses cannot
-.section "Dots in local parts"
+.section "Dots in local parts" "SECID231"
.cindex "dot" "in local part"
.cindex "local part" "dots in"
RFC 2822 forbids empty components in local parts. That is, an unquoted local
-.section "Rewriting addresses"
+.section "Rewriting addresses" "SECID232"
.cindex "rewriting" "addresses"
Rewriting of sender and recipient addresses, and addresses in headers, can
happen automatically, or as the result of configuration options, as described
deliveries for unreasonable amounts of time, just because one address could not
immediately be routed. Exim therefore does not delay other deliveries when
routing of one or more addresses is deferred.
+.ecindex IIDmesproc
+
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
.chapter "SMTP processing" "CHAPSMTP"
-.cindex "SMTP" "processing details"
-.cindex "LMTP" "processing details"
+.scindex IIDsmtpproc1 "SMTP" "processing details"
+.scindex IIDsmtpproc2 "LMTP" "processing details"
Exim supports a number of different ways of using the SMTP protocol, and its
LMTP variant, which is an interactive protocol for transferring messages into a
closed mail store application. This chapter contains details of how SMTP is
characteristics (for example, the same envelope sender) that resolve to the
same set of hosts, in the same order, are sent in a single SMTP transaction,
even if they are for different domains, unless there are more than the setting
-of the &%max_rcpts%& option in the &(smtp)& transport allows, in which case
-they are split into groups containing no more than &%max_rcpts%& addresses
+of the &%max_rcpt%&s option in the &(smtp)& transport allows, in which case
+they are split into groups containing no more than &%max_rcpt%&s addresses
each. If &%remote_max_parallel%& is greater than one, such groups may be sent
in parallel sessions. The order of hosts with identical MX values is not
significant when checking whether addresses can be batched in this way.
-
-.section "Variable Envelope Return Paths (VERP)"
-.cindex "VERP"
-.cindex "Variable Envelope Return Paths"
-.cindex "envelope sender"
-Variable Envelope Return Paths &-- see
-&*ftp://koobera.math.uic.edu/www/proto/verp.txt*& &-- can be supported in Exim
-by using the &%return_path%& generic transport option to rewrite the return
-path at transport time. For example, the following could be used on an &(smtp)&
-transport:
-.code
-return_path = \
- ${if match {$return_path}{^(.+?)-request@your.dom.example\$}\
- {$1-request=$local_part%$domain@your.dom.example}fail}
-.endd
-This has the effect of rewriting the return path (envelope sender) on all
-outgoing SMTP messages, if the local part of the original return path ends in
-&"-request"&, and the domain is &'your.dom.example'&. The rewriting inserts the
-local part and domain of the recipient into the return path. Suppose, for
-example, that a message whose return path has been set to
-&'somelist-request@your.dom.example'& is sent to
-&'subscriber@other.dom.example'&. In the transport, the return path is
-rewritten as
-.code
-somelist-request=subscriber%other.dom.example@your.dom.example
-.endd
-For this to work, you must arrange for outgoing messages that have &"-request"&
-in their return paths to have just a single recipient. This can be done by
-setting
-.code
-max_rcpt = 1
-.endd
-.cindex "&$local_part$&"
-in the &(smtp)& transport. Otherwise a single copy of a message might be
-addressed to several different recipients in the same domain, in which case
-&$local_part$& is not available (because it is not unique). Of course, if you
-do start sending out messages with this kind of return path, you must also
-configure Exim to accept the bounce messages that come back to those paths.
-Typically this would be done by setting an &%local_part_suffix%& option for a
-suitable router.
-
-The overhead incurred in using VERP depends very much on the size of the
-message, the number of recipient addresses that resolve to the same remote
-host, and the speed of the connection over which the message is being sent. If
-a lot of addresses resolve to the same host and the connection is slow, sending
-a separate copy of the message for each address may take substantially longer
-than sending a single copy with many recipients (for which VERP cannot be
-used).
-
-
-
-.section "Incoming SMTP messages over TCP/IP"
+.section "Incoming SMTP messages over TCP/IP" "SECID233"
.cindex "SMTP" "incoming over TCP/IP"
.cindex "incoming SMTP over TCP/IP"
.cindex "inetd"
-.section "Unrecognized SMTP commands"
+.section "Unrecognized SMTP commands" "SECID234"
.cindex "SMTP" "unrecognized commands"
If Exim receives more than &%smtp_max_unknown_commands%& unrecognized SMTP
commands during a single SMTP connection, it drops the connection after sending
circumstances, a number of non-SMTP lines are sent first.
-.section "Syntax and protocol errors in SMTP commands"
+.section "Syntax and protocol errors in SMTP commands" "SECID235"
.cindex "SMTP" "syntax errors"
.cindex "SMTP" "protocol errors"
A syntax error is detected if an SMTP command is recognized, but there is
-.section "Use of non-mail SMTP commands"
+.section "Use of non-mail SMTP commands" "SECID236"
.cindex "SMTP" "non-mail commands"
The &"non-mail"& SMTP commands are those other than MAIL, RCPT, and
DATA. Exim counts such commands, and drops the connection if there are too
When a new message is expected, one occurrence of RSET is not counted. This
allows a client to send one RSET between messages (this is not necessary,
-but some clients do it). Exim also allows one uncounted occurence of HELO
+but some clients do it). Exim also allows one uncounted occurrence of HELO
or EHLO, and one occurrence of STARTTLS between messages. After
starting up a TLS session, another EHLO is expected, and so it too is not
counted.
-.section "The VRFY and EXPN commands"
+.section "The VRFY and EXPN commands" "SECID237"
When Exim receives a VRFY or EXPN command on a TCP/IP connection, it
runs the ACL specified by &%acl_smtp_vrfy%& or &%acl_smtp_expn%& (as
appropriate) in order to decide whether the command should be accepted or not.
left lying around if there is a system or program crash. To guard against this,
Exim ignores any records that are more than six hours old.
-.cindex "&%smtp_etrn_command%&"
+.oindex "&%smtp_etrn_command%&"
For more control over what ETRN does, the &%smtp_etrn_command%& option can
used. This specifies a command that is run whenever ETRN is received,
whatever the form of its argument. For
smtp_etrn_command = /etc/etrn_command $domain \
$sender_host_address
.endd
-.cindex "&$domain$&"
+.vindex "&$domain$&"
The string is split up into arguments which are independently expanded. The
expansion variable &$domain$& is set to the argument of the ETRN command,
and no syntax checking is done on the contents of this argument. Exim does not
-.section "Incoming local SMTP"
+.section "Incoming local SMTP" "SECID238"
.cindex "SMTP" "local incoming"
Some user agents use SMTP to pass messages to their local MTA using the
standard input and output, as opposed to passing the envelope on the command
this is done for BSMTP, messages may contain multiple RCPT commands. See
chapter &<<CHAPbatching>>& for more details.
-.cindex "&$host$&"
+.vindex "&$host$&"
When one or more addresses are routed to a BSMTP transport by a router that
sets up a host list, the name of the first host on the list is available to the
transport in the variable &$host$&. Here is an example of such a transport and
and EHLO act as RSET; VRFY, EXPN, ETRN and HELP, act
as NOOP; QUIT quits.
-No policy checking is done for BSMTP input. That is, no ACL is run at anytime.
-In this respect it is like non-SMTP local input.
+Minimal policy checking is done for BSMTP input. Only the non-SMTP
+ACL is run in the same way as for non-SMTP local input.
If an error is detected while reading a message, including a missing &"."& at
the end, Exim gives up immediately. It writes details of the error to the
The return code from Exim is zero only if there were no errors. It is 1 if some
messages were accepted before an error was detected, and 2 if no messages were
accepted.
+.ecindex IIDsmtpproc1
+.ecindex IIDsmtpproc2
to all warning and bounce messages,
-.section "Customizing bounce messages"
+.section "Customizing bounce messages" "SECID239"
.cindex "customizing" "bounce message"
.cindex "bounce message" "customizing"
If &%bounce_message_text%& is set, its contents are included in the default
logs. If any text item in the file is empty, default text is used for that
item.
-.cindex "&$bounce_recipient$&"
-.cindex "&$bounce_return_size_limit$&"
+.vindex "&$bounce_recipient$&"
+.vindex "&$bounce_return_size_limit$&"
Each item of text that is read from the file is expanded, and there are two
expansion variables which can be of use here: &$bounce_recipient$& is set to
the recipient of an error message while it is being created, and
<$sender_address>
}}could not be delivered to all of its recipients.
-The following address(es) failed:
+This is a permanent error. The following address(es) failed:
****
The following text was generated during the delivery attempt(s):
****
mail delivery software will give up, and when that happens,
the message will be returned to you.
.endd
-.cindex "&$warn_message_delay$&"
-.cindex "&$warn_message_recipients$&"
+.vindex "&$warn_message_delay$&"
+.vindex "&$warn_message_recipients$&"
However, in the default state the subject and date lines are omitted if no
appropriate headers exist. During the expansion of this file,
&$warn_message_delay$& is set to the delay time in one of the forms &"<&'n'&>
-.section "Sending mail to a smart host"
+.section "Sending mail to a smart host" "SECID240"
.cindex "smart host" "example router"
If you want to send all mail for non-local domains to a &"smart host"&, you
should replace the default &(dnslookup)& router with a router which does the
expanded into a file name or a pipe delivery, which is usually inappropriate in
a mailing list.
-.cindex "&%errors_to%&"
+.oindex "&%errors_to%&"
The &%errors_to%& option specifies that any delivery errors caused by addresses
taken from a mailing list are to be sent to the given address rather than the
original sender of the message. However, before acting on this, Exim verifies
-.section "Syntax errors in mailing lists"
+.section "Syntax errors in mailing lists" "SECID241"
.cindex "mailing lists" "syntax errors in"
If an entry in redirection data contains a syntax error, Exim normally defers
delivery of the original address. That means that a syntax error in a mailing
-.section "Re-expansion of mailing lists"
+.section "Re-expansion of mailing lists" "SECID242"
.cindex "mailing lists" "re-expansion of"
Exim remembers every individual address to which a message has been delivered,
in order to avoid duplication, but it normally stores only the original
-.section "Closed mailing lists"
+.section "Closed mailing lists" "SECID243"
.cindex "mailing lists" "closed"
The examples so far have assumed open mailing lists, to which anybody may
send mail. It is also possible to set up closed lists, where mail is accepted
+.section "Variable Envelope Return Paths (VERP)" "SECTverp"
+.cindex "VERP"
+.cindex "Variable Envelope Return Paths"
+.cindex "envelope sender"
+Variable Envelope Return Paths &-- see &url(http://cr.yp.to/proto/verp.txt) &--
+are a way of helping mailing list administrators discover which subscription
+address is the cause of a particular delivery failure. The idea is to encode
+the original recipient address in the outgoing envelope sender address, so that
+if the message is forwarded by another host and then subsequently bounces, the
+original recipient can be extracted from the recipient address of the bounce.
+
+.oindex &%errors_to%&
+.oindex &%return_path%&
+Envelope sender addresses can be modified by Exim using two different
+facilities: the &%errors_to%& option on a router (as shown in previous mailing
+list examples), or the &%return_path%& option on a transport. The second of
+these is effective only if the message is successfully delivered to another
+host; it is not used for errors detected on the local host (see the description
+of &%return_path%& in chapter &<<CHAPtransportgeneric>>&). Here is an example
+of the use of &%return_path%& to implement VERP on an &(smtp)& transport:
+.code
+verp_smtp:
+ driver = smtp
+ max_rcpt = 1
+ return_path = \
+ ${if match {$return_path}{^(.+?)-request@your.dom.example\$}\
+ {$1-request+$local_part=$domain@your.dom.example}fail}
+.endd
+This has the effect of rewriting the return path (envelope sender) on outgoing
+SMTP messages, if the local part of the original return path ends in
+&"-request"&, and the domain is &'your.dom.example'&. The rewriting inserts the
+local part and domain of the recipient into the return path. Suppose, for
+example, that a message whose return path has been set to
+&'somelist-request@your.dom.example'& is sent to
+&'subscriber@other.dom.example'&. In the transport, the return path is
+rewritten as
+.code
+somelist-request+subscriber=other.dom.example@your.dom.example
+.endd
+.vindex "&$local_part$&"
+For this to work, you must tell Exim to send multiple copies of messages that
+have more than one recipient, so that each copy has just one recipient. This is
+achieved by setting &%max_rcpt%& to 1. Without this, a single copy of a message
+might be sent to several different recipients in the same domain, in which case
+&$local_part$& is not available in the transport, because it is not unique.
+
+Unless your host is doing nothing but mailing list deliveries, you should
+probably use a separate transport for the VERP deliveries, so as not to use
+extra resources in making one-per-recipient copies for other deliveries. This
+can easily be done by expanding the &%transport%& option in the router:
+.code
+dnslookup:
+ driver = dnslookup
+ domains = ! +local_domains
+ transport = \
+ ${if match {$return_path}{^(.+?)-request@your.dom.example\$}\
+ {verp_smtp}{remote_smtp}}
+ no_more
+.endd
+If you want to change the return path using &%errors_to%& in a router instead
+of using &%return_path%& in the transport, you need to set &%errors_to%& on all
+routers that handle mailing list addresses. This will ensure that all delivery
+errors, including those detected on the local host, are sent to the VERP
+address.
+
+On a host that does no local deliveries and has no manual routing, only the
+&(dnslookup)& router needs to be changed. A special transport is not needed for
+SMTP deliveries. Every mailing list recipient has its own return path value,
+and so Exim must hand them to the transport one at a time. Here is an example
+of a &(dnslookup)& router that implements VERP:
+.code
+verp_dnslookup:
+ driver = dnslookup
+ domains = ! +local_domains
+ transport = remote_smtp
+ errors_to = \
+ ${if match {$return_path}{^(.+?)-request@your.dom.example\$}}
+ {$1-request+$local_part=$domain@your.dom.example}fail}
+ no_more
+.endd
+Before you start sending out messages with VERPed return paths, you must also
+configure Exim to accept the bounce messages that come back to those paths.
+Typically this is done by setting a &%local_part_suffix%& option for a
+router, and using this to route the messages to wherever you want to handle
+them.
+
+The overhead incurred in using VERP depends very much on the size of the
+message, the number of recipient addresses that resolve to the same remote
+host, and the speed of the connection over which the message is being sent. If
+a lot of addresses resolve to the same host and the connection is slow, sending
+a separate copy of the message for each address may take substantially longer
+than sending a single copy with many recipients (for which VERP cannot be
+used).
+
+
+
+
+
+
.section "Virtual domains" "SECTvirtualdomains"
.cindex "virtual domains"
.cindex "domain" "virtual"
local_part_suffix_optional
allow_filter
.endd
-.cindex "&$local_part_suffix$&"
+.vindex "&$local_part_suffix$&"
It runs a user's &_.forward_& file for all local parts of the form
&'username-*'&. Within the filter file the user can distinguish different
cases by testing the variable &$local_part_suffix$&. For example:
-.section "Simplified vacation processing"
+.section "Simplified vacation processing" "SECID244"
.cindex "vacation processing"
The traditional way of running the &'vacation'& program is for a user to set up
a pipe command in a &_.forward_& file
-.section "Taking copies of mail"
+.section "Taking copies of mail" "SECID245"
.cindex "message" "copying every"
Some installations have policies that require archive copies of all messages to
be made. A single copy of each message can easily be taken by an appropriate
-.section "Intermittently connected hosts"
+.section "Intermittently connected hosts" "SECID246"
.cindex "intermittently connected hosts"
It has become quite common (because it is cheaper) for hosts to connect to the
Internet periodically rather than remain connected all the time. The normal
Nevertheless there are some features that can be used.
-.section "Exim on the upstream server host"
+.section "Exim on the upstream server host" "SECID247"
It is tempting to arrange for incoming mail for the intermittently connected
host to remain on Exim's queue until the client connects. However, this
approach does not scale very well. Two different kinds of waiting message are
-.section "Exim on the intermittently connected client host"
+.section "Exim on the intermittently connected client host" "SECID248"
The value of &%smtp_accept_queue_per_connection%& should probably be
increased, or even set to zero (that is, disabled) on the intermittently
connected host, so that all incoming messages down a single connection get
.chapter "Using Exim as a non-queueing client" "CHAPnonqueueing" &&&
"Exim as a non-queueing client"
-.cindex "client" "non-queueing"
-.cindex "smart host" "queueing; suppressing"
+.cindex "client, non-queueing"
+.cindex "smart host" "suppressing queueing"
On a personal computer, it is a common requirement for all
email to be sent to a &"smart host"&. There are plenty of MUAs that can be
configured to operate that way, for all the popular operating systems.
tweaks were needed to make it behave as required, though it is somewhat of an
overkill to use a fully-featured MTA for this purpose.
-.cindex "&%mua_wrapper%&"
+.oindex "&%mua_wrapper%&"
There is a Boolean global option called &%mua_wrapper%&, defaulting false.
Setting &%mua_wrapper%& true causes Exim to run in a special mode where it
assumes that it is being used to &"wrap"& a command-line MUA in the manner
A daemon cannot be run, nor will Exim accept incoming messages from &'inetd'&.
In other words, the only way to submit messages is via the command line.
.next
-Each message is synchonously delivered as soon as it is received (&%-odi%& is
+Each message is synchronously delivered as soon as it is received (&%-odi%& is
assumed). All queueing options (&%queue_only%&, &%queue_smtp_domains%&,
&%control%& in an ACL, etc.) are quietly ignored. The Exim reception process
does not finish until the delivery attempt is complete. If the delivery is
No retry data is maintained, and any retry rules are ignored.
.next
A number of Exim options are overridden: &%deliver_drop_privilege%& is forced
-true, &%max_rcpt%& in the smtp transport is forced to &"unlimited"&,
+true, &%max_rcpt%& in the &(smtp)& transport is forced to &"unlimited"&,
&%remote_max_parallel%& is forced to one, and fallback hosts are ignored.
.endlist
. ////////////////////////////////////////////////////////////////////////////
.chapter "Log files" "CHAPlog"
+.scindex IIDloggen "log" "general description"
.cindex "log" "types of"
-.cindex "log" "general description"
Exim writes three different logs, referred to as the main log, the reject log,
and the panic log:
.endd
.endlist
+.cindex "log" "process ids in"
+.cindex "pid (process id)" "in log lines"
+Exim does not include its process id in log lines by default, but you can
+request that it does so by specifying the &`pid`& log selector (see section
+&<<SECTlogselector>>&). When this is set, the process id is output, in square
+brackets, immediately after the time and date.
+
If you do not specify anything at build time or run time, that is where the
logs are written.
-A log file path may also contain &`%D`& if datestamped log file names are in
-use &-- see section &<<SECTdatlogfil>>& below.
+A log file path may also contain &`%D`& or &`%M`& if datestamped log file names
+are in use &-- see section &<<SECTdatlogfil>>& below.
Here are some examples of possible settings:
.display
-.section "Logging to local files that are periodically &""cycled""&"
+.section "Logging to local files that are periodically &""cycled""&" "SECID285"
.cindex "log" "cycling local files"
.cindex "cycling logs"
.cindex "&'exicyclog'&"
.cindex "log" "local files; writing to"
-Some operating systems provide centralized and standardised methods for cycling
+Some operating systems provide centralized and standardized methods for cycling
log files. For those that do not, a utility script called &'exicyclog'& is
provided (see section &<<SECTcyclogfil>>&). This renames and compresses the
main and reject logs each time it is called. The maximum number of old logs to
.cindex "log" "datestamped files"
Instead of cycling the main and reject log files by renaming them
periodically, some sites like to use files whose names contain a datestamp,
-for example, &_mainlog-20031225_&. The datestamp is in the form &_yyyymmdd_&.
-Exim has support for this way of working. It is enabled by setting the
-&%log_file_path%& option to a path that includes &`%D`& at the point where the
-datestamp is required. For example:
+for example, &_mainlog-20031225_&. The datestamp is in the form &_yyyymmdd_& or
+&_yyyymm_&. Exim has support for this way of working. It is enabled by setting
+the &%log_file_path%& option to a path that includes &`%D`& or &`%M`& at the
+point where the datestamp is required. For example:
.code
log_file_path = /var/spool/exim/log/%slog-%D
log_file_path = /var/log/exim-%s-%D.log
log_file_path = /var/spool/exim/log/%D-%slog
+log_file_path = /var/log/exim/%s.%M
.endd
As before, &`%s`& is replaced by &"main"& or &"reject"&; the following are
examples of names generated by the above examples:
/var/spool/exim/log/mainlog-20021225
/var/log/exim-reject-20021225.log
/var/spool/exim/log/20021225-mainlog
+/var/log/exim/main.200212
.endd
When this form of log file is specified, Exim automatically switches to new
files at midnight. It does not make any attempt to compress old logs; you
The location of the panic log is also determined by &%log_file_path%&, but it
is not datestamped, because rotation of the panic log does not make sense.
-When generating the name of the panic log, &`%D`& is removed from the string.
-In addition, if it immediately follows a slash, a following non-alphanumeric
-character is removed; otherwise a preceding non-alphanumeric character is
-removed. Thus, the three examples above would give these panic log names:
+When generating the name of the panic log, &`%D`& or &`%M`& are removed from
+the string. In addition, if it immediately follows a slash, a following
+non-alphanumeric character is removed; otherwise a preceding non-alphanumeric
+character is removed. Thus, the four examples above would give these panic
+log names:
.code
/var/spool/exim/log/paniclog
/var/log/exim-panic.log
/var/spool/exim/log/paniclog
+/var/log/exim/panic
.endd
-.section "Logging to syslog"
+.section "Logging to syslog" "SECID249"
.cindex "log" "syslog; writing to"
The use of syslog does not change what Exim logs or the format of its messages,
except in one respect. If &%syslog_timestamp%& is set false, the timestamps on
-.section "Log line flags"
+.section "Log line flags" "SECID250"
One line is written to the main log for each message received, and for each
successful, unsuccessful, and delayed delivery. These lines can readily be
picked out by the distinctive two-character flags that immediately follow the
.endd
-.section "Logging message reception"
+.section "Logging message reception" "SECID251"
.cindex "log" "reception line"
The format of the single-line entry in the main log that is written for every
message received is shown in the basic example below, which is split over
.cindex "authentication" "logging"
.cindex "AUTH" "logging"
-.new
For all messages, the P field specifies the protocol used to receive the
message. This is the value that is stored in &$received_protocol$&. In the case
of incoming SMTP messages, the value indicates whether or not any SMTP
session was encrypted, there is an additional X field that records the cipher
suite that was used.
-The protocol is set to &"esmptsa"& or &"esmtpa"& for messages received from
+The protocol is set to &"esmtpsa"& or &"esmtpa"& for messages received from
hosts that have authenticated themselves using the SMTP AUTH command. The first
value is used when the SMTP connection was encrypted (&"secure"&). In this case
there is an additional item A= followed by the name of the authenticator that
was used. If an authenticated identification was set up by the authenticator's
&%server_set_id%& option, this is logged too, separated by a colon from the
authenticator name.
-.wen
.cindex "size" "of message"
The id field records the existing message id, if present. The size of the
-.section "Logging deliveries"
+.section "Logging deliveries" "SECID252"
.cindex "log" "delivery line"
The format of the single-line entry in the main log that is written for every
delivery is shown in one of the examples below, for local and remote
data when a message is delivered. See section &<<SECTlogselector>>& below.
-.section "Discarded deliveries"
+.section "Discarded deliveries" "SECID253"
.cindex "discarded messages"
.cindex "message" "discarded"
.cindex "delivery" "discarded; logging"
.endd
-.section "Deferred deliveries"
+.section "Deferred deliveries" "SECID254"
When a delivery is deferred, a line of the following form is logged:
.code
2002-12-19 16:20:23 16aiQz-0002Q5-00 == marvin@endrest.example
-.section "Delivery failures"
+.section "Delivery failures" "SECID255"
.cindex "delivery" "failure; logging"
If a delivery fails because an address cannot be routed, a line of the
following form is logged:
-.section "Fake deliveries"
+.section "Fake deliveries" "SECID256"
.cindex "delivery" "fake; logging"
If a delivery does not actually take place because the &%-N%& option has been
used to suppress it, a normal delivery line is written to the log, except that
-.section "Completion"
+.section "Completion" "SECID257"
A line of the form
.code
2002-10-31 09:00:11 16ZCW1-0005MB-00 Completed
-.section "Summary of Fields in Log Lines"
+.section "Summary of Fields in Log Lines" "SECID258"
.cindex "log" "summary of fields"
A summary of the field identifiers that are used in log lines is shown in
the following table:
.display
&`A `& authenticator name (and optional id)
&`C `& SMTP confirmation on delivery
+&` `& command list for &"no mail in SMTP session"&
&`CV `& certificate verification status
+&`D `& duration of &"no mail in SMTP session"&
&`DN `& distinguished name from peer certificate
&`DT `& on &`=>`& lines: time taken for a delivery
&`F `& sender address (on delivery lines)
.endd
-.section "Other log entries"
+.section "Other log entries" "SECID259"
Various other types of log entry are written from time to time. Most should be
self-explanatory. Among the more common are:
&`*queue_run `& start and end queue runs
&` queue_time `& time on queue for one recipient
&` queue_time_overall `& time on queue for whole message
+&` pid `& Exim process id
&` received_recipients `& recipients on <= lines
&` received_sender `& sender on <= lines
&`*rejected_header `& header contents on reject log
&`*retry_defer `& &"retry time not reached"&
-&` return_path_on_delivery `& put return path on => and *\ lines
+&` return_path_on_delivery `& put return path on => and ** lines
&` sender_on_delivery `& add sender to => lines
+&`*sender_verify_fail `& sender verification failures
&`*size_reject `& rejection because too big
&`*skip_delivery `& delivery skipped in a queue run
&` smtp_confirmation `& SMTP confirmation on => lines
&` smtp_connection `& SMTP connections
&` smtp_incomplete_transaction`& incomplete SMTP transactions
+&` smtp_no_mail `& session with no MAIL commands
&` smtp_protocol_error `& SMTP protocol errors
&` smtp_syntax_error `& SMTP syntax errors
&` subject `& contents of &'Subject:'& on <= lines
&` tls_certificate_verified `& certificate verification status
&`*tls_cipher `& TLS cipher suite on <= and => lines
&` tls_peerdn `& TLS peer DN on <= and => lines
+&` tls_sni `& TLS SNI on <= lines
&` unknown_in_list `& DNS lookup failed in list match
&` all `& all of the above
More details on each of these items follows:
.ilist
-.cindex "&%warn%& statement" "log when skipping"
-.new
+.cindex "&%warn%& ACL verb" "log when skipping"
&%acl_warn_skipped%&: When an ACL &%warn%& statement is skipped because one of
its conditions cannot be evaluated, a log line to this effect is written if
this log selector is set.
-.wen
.next
.cindex "log" "rewriting"
.cindex "rewriting" "logging"
parentheses between them.
.next
.cindex "log" "Exim arguments"
-.cindex "Exim arguments" "logging"
+.cindex "Exim arguments, logging"
&%arguments%&: This causes Exim to write the arguments with which it was called
to the main log, preceded by the current working directory. This is a debugging
feature, added to make it easier to find out how certain MUAs call
connection is rejected, for whatever reason.
.next
.cindex "log" "delayed delivery"
-.cindex "delayed delivery" "logging"
+.cindex "delayed delivery, logging"
&%delay_delivery%&: A log entry is written whenever a delivery process is not
started for an incoming message because the load is too high or too many
messages were received on one connection. Logging does not occur if no delivery
.next
.cindex "log" "ETRN commands"
.cindex "ETRN" "logging"
-&%etrn%&: Every legal ETRN command that is received is logged, before the ACL
+&%etrn%&: Every valid ETRN command that is received is logged, before the ACL
is run to determine whether or not it is actually accepted. An invalid ETRN
command, or one received within a message transaction is not logged by this
selector (see &%smtp_syntax_error%& and &%smtp_protocol_error%&).
.cindex "log" "incoming remote port"
.cindex "port" "logging remote"
.cindex "TCP/IP" "logging incoming remote port"
-.cindex "&$sender_fullhost$&"
-.cindex "&$sender_rcvhost$&"
+.vindex "&$sender_fullhost$&"
+.vindex "&$sender_rcvhost$&"
&%incoming_port%&: The remote port number from which a message was received is
added to log entries and &'Received:'& header lines, following the IP address
in square brackets, and separated from it by a colon. This is implemented by
the default setting, because for most ordinary configurations, the remote port
number is always 25 (the SMTP port).
.next
+.cindex "log" "process ids in"
+.cindex "pid (process id)" "in log lines"
+&%pid%&: The current process id is added to every log line, in square brackets,
+immediately after the time and date.
+.next
.cindex "log" "queue run"
.cindex "queue runner" "logging"
&%queue_run%&: The start and end of every queue run are logged.
This is the original sender that was received with the message; it is not
necessarily the same as the outgoing return path.
.next
+.cindex "log" "sender verify failure"
+&%sender_verify_fail%&: If this selector is unset, the separate log line that
+gives details of a sender verification failure is not written. Log lines for
+the rejection of SMTP commands contain just &"sender verify failed"&, so some
+detail is lost.
+.next
.cindex "log" "size rejection"
&%size_reject%&: A log line is written whenever a message is rejected because
it is too big.
and the message sender plus any accepted recipients are included in the log
line. This can provide evidence of dictionary attacks.
.next
+.cindex "log" "non-MAIL SMTP sessions"
+.cindex "MAIL" "logging session without"
+&%smtp_no_mail%&: A line is written to the main log whenever an accepted SMTP
+connection terminates without having issued a MAIL command. This includes both
+the case when the connection is dropped, and the case when QUIT is used. It
+does not include cases where the connection is rejected right at the start (by
+an ACL, or because there are too many connections, or whatever). These cases
+already have their own log lines.
+
+The log line that is written contains the identity of the client in the usual
+way, followed by D= and a time, which records the duration of the connection.
+If the connection was authenticated, this fact is logged exactly as it is for
+an incoming message, with an A= item. If the connection was encrypted, CV=,
+DN=, and X= items may appear as they do for an incoming message, controlled by
+the same logging options.
+
+Finally, if any SMTP commands were issued during the connection, a C= item
+is added to the line, listing the commands that were used. For example,
+.code
+C=EHLO,QUIT
+.endd
+shows that the client issued QUIT straight after EHLO. If there were fewer
+than 20 commands, they are all listed. If there were more than 20 commands,
+the last 20 are listed, preceded by &"..."&. However, with the default
+setting of 10 for &%smtp_accep_max_nonmail%&, the connection will in any case
+have been aborted before 20 non-mail commands are processed.
+.next
.cindex "log" "SMTP protocol error"
.cindex "SMTP" "logging protocol error"
&%smtp_protocol_error%&: A log line is written for every SMTP protocol error
using &%-bs%& the sender identification (normally the calling user) is given.
.next
.cindex "log" "subject"
-.cindex "subject" "logging"
+.cindex "subject, logging"
&%subject%&: The subject of the message is added to the arrival log line,
preceded by &"T="& (T for &"topic"&, since S is already used for &"size"&).
Any MIME &"words"& in the subject are decoded. The &%print_topbitchars%& option
connection, and a certificate is supplied by the remote host, the peer DN is
added to the log line, preceded by DN=.
.next
-.new
+.cindex "log" "TLS SNI"
+.cindex "TLS" "logging SNI"
+&%tls_sni%&: When a message is received over an encrypted connection, and
+the remote host provided the Server Name Indication extension, the SNI is
+added to the log line, preceded by SNI=.
+.next
.cindex "log" "DNS failure in list"
&%unknown_in_list%&: This setting causes a log entry to be written when the
result of a list match is failure because a DNS lookup failed.
-.wen
.endlist
-.section "Message log"
+.section "Message log" "SECID260"
.cindex "message" "log file for"
.cindex "log" "message log; description of"
.cindex "&_msglog_& directory"
-.cindex "&%preserve_message_logs%&"
+.oindex "&%preserve_message_logs%&"
In addition to the general log files, Exim writes a log file for each message
that it handles. The names of these per-message logs are the message ids, and
they are kept in the &_msglog_& sub-directory of the spool directory. Each
On a heavily loaded system, it may be desirable to disable the use of
per-message logs, in order to reduce disk I/O. This can be done by setting the
&%message_logs%& option false.
+.ecindex IIDloggen
+
. ////////////////////////////////////////////////////////////////////////////
.chapter "Exim utilities" "CHAPutils"
-.cindex "utilities"
+.scindex IIDutils "utilities"
A number of utility scripts and programs are supplied with Exim and are
described in this chapter. There is also the Exim Monitor, which is covered in
the next chapter. The utilities described here are:
-.itable none 0 0 4 2* left 8* left 30* left 40* left
-.row "" &<<SECTfinoutwha>>& &'exiwhat'& &&&
+.itable none 0 0 3 7* left 15* left 40* left
+.irow &<<SECTfinoutwha>>& &'exiwhat'& &&&
"list what Exim processes are doing"
-.row "" &<<SECTgreptheque>>& &'exiqgrep'& "grep the queue"
-.row "" &<<SECTsumtheque>>& &'exiqsumm'& "summarize the queue"
-.row "" &<<SECTextspeinf>>& &'exigrep'& "search the main log"
-.row "" &<<SECTexipick>>& &'exipick'& "select messages on &&&
- various criteria"
-.row "" &<<SECTcyclogfil>>& &'exicyclog'& "cycle (rotate) log files"
-.row "" &<<SECTmailstat>>& &'eximstats'& &&&
+.irow &<<SECTgreptheque>>& &'exiqgrep'& "grep the queue"
+.irow &<<SECTsumtheque>>& &'exiqsumm'& "summarize the queue"
+.irow &<<SECTextspeinf>>& &'exigrep'& "search the main log"
+.irow &<<SECTexipick>>& &'exipick'& "select messages on &&&
+ various criteria"
+.irow &<<SECTcyclogfil>>& &'exicyclog'& "cycle (rotate) log files"
+.irow &<<SECTmailstat>>& &'eximstats'& &&&
"extract statistics from the log"
-.row "" &<<SECTcheckaccess>>& &'exim_checkaccess'& &&&
+.irow &<<SECTcheckaccess>>& &'exim_checkaccess'& &&&
"check address acceptance from given IP"
-.row "" &<<SECTdbmbuild>>& &'exim_dbmbuild'& "build a DBM file"
-.row "" &<<SECTfinindret>>& &'exinext'& "extract retry information"
-.row "" &<<SECThindatmai>>& &'exim_dumpdb'& "dump a hints database"
-.row "" &<<SECThindatmai>>& &'exim_tidydb'& "clean up a hints database"
-.row "" &<<SECThindatmai>>& &'exim_fixdb'& "patch a hints database"
-.row "" &<<SECTmailboxmaint>>& &'exim_lock'& "lock a mailbox file"
+.irow &<<SECTdbmbuild>>& &'exim_dbmbuild'& "build a DBM file"
+.irow &<<SECTfinindret>>& &'exinext'& "extract retry information"
+.irow &<<SECThindatmai>>& &'exim_dumpdb'& "dump a hints database"
+.irow &<<SECThindatmai>>& &'exim_tidydb'& "clean up a hints database"
+.irow &<<SECThindatmai>>& &'exim_fixdb'& "patch a hints database"
+.irow &<<SECTmailboxmaint>>& &'exim_lock'& "lock a mailbox file"
.endtable
-.new
Another utility that might be of use to sites with many MTAs is Tom Kistner's
&'exilog'&. It provides log visualizations across multiple Exim servers. See
&url(http://duncanthrax.net/exilog/) for details.
-.wen
.section "Finding out what Exim processes are doing (exiwhat)" "SECTfinoutwha"
.cindex "&'exiwhat'&"
-.cindex "process" "querying"
+.cindex "process, querying"
.cindex "SIGUSR1"
On operating systems that can restart a system call after receiving a signal
(most modern OS), an Exim process responds to the SIGUSR1 signal by writing
-.section "Summarising the queue (exiqsumm)" "SECTsumtheque"
+.section "Summarizing the queue (exiqsumm)" "SECTsumtheque"
.cindex "&'exiqsumm'&"
.cindex "queue" "summary"
The &'exiqsumm'& utility is a Perl script which reads the output of &`exim
.code
3 2322 74m 66m msn.com.example
.endd
-Each line lists the number of
-pending deliveries for a domain, their total volume, and the length of time
-that the oldest and the newest messages have been waiting. Note that the number
-of pending deliveries is greater than the number of messages when messages
-have more than one recipient.
+Each line lists the number of pending deliveries for a domain, their total
+volume, and the length of time that the oldest and the newest messages have
+been waiting. Note that the number of pending deliveries is greater than the
+number of messages when messages have more than one recipient.
A summary line is output at the end. By default the output is sorted on the
domain name, but &'exiqsumm'& has the options &%-a%& and &%-c%&, which cause
the output to be sorted by oldest message and by count of messages,
-respectively.
+respectively. There are also three options that split the messages for each
+domain into two or more subcounts: &%-b%& separates bounce messages, &%-f%&
+separates frozen messages, and &%-s%& separates messages according to their
+sender.
The output of &'exim -bp'& contains the original addresses in the message, so
this also applies to the output from &'exiqsumm'&. No domains from addresses
"SECTextspeinf"
.cindex "&'exigrep'&"
.cindex "log" "extracts; grepping for"
-.new
The &'exigrep'& utility is a Perl script that searches one or more main log
files for entries that match a given pattern. When it finds a match, it
extracts all the log entries for the relevant message, not just those that
match the pattern. Thus, &'exigrep'& can extract complete log entries for a
given message, or all mail for a given user, or for a given host, for example.
The input files can be in Exim log format or syslog format.
-.wen
-
-If a matching log line is not associated with a specific message, it is always
-included in &'exigrep'&'s output. The usage is:
+If a matching log line is not associated with a specific message, it is
+included in &'exigrep'&'s output without any additional lines. The usage is:
.display
-&`exigrep [-l] [-t<`&&'n'&&`>] <`&&'pattern'&&`> [<`&&'log file'&&`>] ...`&
+&`exigrep [-t<`&&'n'&&`>] [-I] [-l] [-v] <`&&'pattern'&&`> [<`&&'log file'&&`>] ...`&
.endd
+If no log file names are given on the command line, the standard input is read.
+
The &%-t%& argument specifies a number of seconds. It adds an additional
condition for message selection. Messages that are complete are shown only if
they spent more than <&'n'&> seconds on the queue.
-The &%-l%& flag means &"literal"&, that is, treat all characters in the
+By default, &'exigrep'& does case-insensitive matching. The &%-I%& option
+makes it case-sensitive. This may give a performance improvement when searching
+large log files. Without &%-I%&, the Perl pattern matches use Perl's &`/i`&
+option; with &%-I%& they do not. In both cases it is possible to change the
+case sensitivity within the pattern by using &`(?i)`& or &`(?-i)`&.
+
+The &%-l%& option means &"literal"&, that is, treat all characters in the
pattern as standing for themselves. Otherwise the pattern must be a Perl
-regular expression. The pattern match is case-insensitive. If no file names are
-given on the command line, the standard input is read.
+regular expression.
+
+The &%-v%& option inverts the matching condition. That is, a line is selected
+if it does &'not'& match the pattern.
If the location of a &'zcat'& command is known from the definition of
ZCAT_COMMAND in &_Local/Makefile_&, &'exigrep'& automatically passes any file
.section "Selecting messages by various criteria (exipick)" "SECTexipick"
.cindex "&'exipick'&"
John Jetmore's &'exipick'& utility is included in the Exim distribution. It
-lists messages from the queue according to a variety of criteria. For details,
-run:
-.code
-exipick --help
-.endd
+lists messages from the queue according to a variety of criteria. For details
+of &'exipick'&'s facilities, visit the web page at
+&url(http://www.exim.org/eximwiki/ToolExipickManPage) or run &'exipick'& with
+the &%--help%& option.
.section "Cycling log files (exicyclog)" "SECTcyclogfil"
you are using log files with datestamps in their names (see section
&<<SECTdatlogfil>>&). Some operating systems have their own standard mechanisms
for log cycling, and these can be used instead of &'exicyclog'& if preferred.
+There are two command line options for &'exicyclog'&:
+.ilist
+&%-k%& <&'count'&> specifies the number of log files to keep, overriding the
+default that is set when Exim is built. The default default is 10.
+.next
+&%-l%& <&'path'&> specifies the log file path, in the same format as Exim's
+&%log_file_path%& option (for example, &`/var/log/exim_%slog`&), again
+overriding the script's default, which is to find the setting from Exim's
+configuration.
+.endlist
Each time &'exicyclog'& is run the file names get &"shuffled down"& by one. If
the main log file name is &_mainlog_& (the default) then when &'exicyclog'& is
run &_mainlog_& becomes &_mainlog.01_&, the previous &_mainlog.01_& becomes
-&_mainlog.02_& and so on, up to a limit which is set in the script, and which
-defaults to 10. Log files whose numbers exceed the limit are discarded. Reject
+&_mainlog.02_& and so on, up to the limit that is set in the script or by the
+&%-k%& option. Log files whose numbers exceed the limit are discarded. Reject
logs are handled similarly.
If the limit is greater than 99, the script uses 3-digit numbers such as
to one that is greater, or &'vice versa'&, you will have to fix the names of
any existing log files.
-
If no &_mainlog_& file exists, the script does nothing. Files that &"drop off"&
the end are deleted. All files with numbers greater than 01 are compressed,
using a compression command which is configured by the COMPRESS_COMMAND
.cindex "&'eximstats'&"
A Perl script called &'eximstats'& is provided for extracting statistical
information from log files. The output is either plain text, or HTML.
-Exim log files are also suported by the &'Lire'& system produced by the
+Exim log files are also supported by the &'Lire'& system produced by the
LogReport Foundation &url(http://www.logreport.org).
The &'eximstats'& script has been hacked about quite a bit over time. The
for remote hosts
.next
&'callout'&: the callout cache
-.new
.next
&'ratelimit'&: the data for implementing the ratelimit ACL condition
-.wen
.next
&'misc'&: other hints data
.endlist
-.section "exim_dumpdb"
+.section "exim_dumpdb" "SECID261"
.cindex "&'exim_dumpdb'&"
The entire contents of a database are written to the standard output by the
&'exim_dumpdb'& program, which has no options or arguments other than the
of the letters R, or T, depending on whether it refers to a routing or
transport retry. For a local delivery, the next part is the local address; for
a remote delivery it is the name of the remote host, followed by its failing IP
-address (unless &%no_retry_include_ip_address%& is set on the &(smtp)&
+address (unless &%retry_include_ip_address%& is set false on the &(smtp)&
transport). If the remote port is not the standard one (port 25), it is added
to the IP address. Then there follows an error code, an additional error code,
and a textual description of the error.
-.section "exim_tidydb"
+.section "exim_tidydb" "SECID262"
.cindex "&'exim_tidydb'&"
-.new
The &'exim_tidydb'& utility program is used to tidy up the contents of a hints
database. If run with no options, it removes all records that are more than 30
days old. The age is calculated from the date and time that the record was last
since the first delivery failure. Information about a host that has been down
for more than 30 days will remain in the database, provided that the record is
updated sufficiently often.
-.wen
The cutoff date can be altered by means of the &%-t%& option, which must be
followed by a time. For example, to remove all records older than a week from
-.section "exim_fixdb"
+.section "exim_fixdb" "SECID263"
.cindex "&'exim_fixdb'&"
The &'exim_fixdb'& program is a utility for interactively modifying databases.
Its main use is for testing Exim, but it might also be occasionally useful for
.endd
Note that if a command is supplied, it must be entirely contained within the
second argument &-- hence the quotes.
-
+.ecindex IIDutils
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
.chapter "The Exim monitor" "CHAPeximon"
-.cindex "Exim monitor" "description"
+.scindex IIDeximon "Exim monitor" "description"
.cindex "X-windows"
.cindex "&'eximon'&"
.cindex "Local/eximon.conf"
-.cindex "_exim_monitor/EDITME_"
+.cindex "&_exim_monitor/EDITME_&"
The Exim monitor is an application which displays in an X window information
about the state of Exim's queue and what Exim is doing. An admin user can
perform certain operations on messages from this GUI interface; however all
-.section "Running the monitor"
+.section "Running the monitor" "SECID264"
The monitor is started by running the script called &'eximon'&. This is a shell
script that sets up a number of environment variables, and then runs the
binary called &_eximon.bin_&. The default appearance of the monitor window can
In order to see the contents of messages on the queue, and to operate on them,
&'eximon'& must either be run as root or by an admin user.
+The command-line parameters of &'eximon'& are passed to &_eximon.bin_& and may
+contain X11 resource parameters interpreted by the X11 library. In addition,
+if the first parameter starts with the string "gdb" then it is removed and the
+binary is invoked under gdb (the parameter is used as the gdb command-name, so
+versioned variants of gdb can be invoked).
+
The monitor's window is divided into three parts. The first contains one or
more stripcharts and two action buttons, the second contains a &"tail"& of the
main log file, and the third is a display of the queue of messages awaiting
-.section "The stripcharts"
+.section "The stripcharts" "SECID265"
.cindex "stripchart"
The first stripchart is always a count of messages on the queue. Its name can
be configured by setting QUEUE_STRIPCHART_NAME in the
-.section "Main action buttons"
+.section "Main action buttons" "SECID266"
.cindex "size" "of monitor window"
.cindex "Exim monitor" "window size"
.cindex "window size"
-.section "The log display"
+.section "The log display" "SECID267"
.cindex "log" "tail of; in monitor"
The second section of the window is an area in which a display of the tail of
the main log is maintained.
-.section "The queue display"
+.section "The queue display" "SECID268"
.cindex "queue" "display in monitor"
The bottom section of the monitor window contains a list of all messages that
are on the queue, which includes those currently being received or delivered,
-.section "The queue menu"
+.section "The queue menu" "SECID269"
.cindex "queue" "menu in monitor"
If the &%shift%& key is held down and the left button is clicked when the mouse
pointer is over the text for any message, an action menu pops up, and the first
In any text window that is displayed as result of a menu action, the normal
cut-and-paste facility is available, and searching can be carried out using ^R
and ^S, as described above for the log tail window.
-
+.ecindex IIDeximon
. ////////////////////////////////////////////////////////////////////////////
.chapter "Security considerations" "CHAPsecurity"
-.cindex "security"
+.scindex IIDsecurcon "security" "discussion of"
This chapter discusses a number of issues concerned with security, some of
which are also covered in other parts of this manual.
as soon as possible.
-.section "Building a more &""hardened""& Exim"
+.section "Building a more &""hardened""& Exim" "SECID286"
.cindex "security" "build-time features"
There are a number of build-time options that can be set in &_Local/Makefile_&
to create Exim binaries that are &"harder"& to attack, in particular by a rogue
into the Exim account from running a privileged Exim with an arbitrary
configuration file, and using it to break into other accounts.
.next
-If ALT_CONFIG_ROOT_ONLY is defined, root privilege is retained for &%-C%&
-and &%-D%& only if the caller of Exim is root. Without it, the Exim user may
-also use &%-C%& and &%-D%& and retain privilege. Setting this option locks out
-the possibility of testing a configuration using &%-C%& right through message
-reception and delivery, even if the caller is root. The reception works, but by
-that time, Exim is running as the Exim user, so when it re-execs to regain
-privilege for the delivery, the use of &%-C%& causes privilege to be lost.
-However, root can test reception and delivery using two separate commands.
-ALT_CONFIG_ROOT_ONLY is not set by default.
+
+If a non-trusted configuration file (i.e. not the default configuration file
+or one which is trusted by virtue of being listed in the TRUSTED_CONFIG_LIST
+file) is specified with &%-C%&, or if macros are given with &%-D%& (but see
+the next item), then root privilege is retained only if the caller of Exim is
+root. This locks out the possibility of testing a configuration using &%-C%&
+right through message reception and delivery, even if the caller is root. The
+reception works, but by that time, Exim is running as the Exim user, so when
+it re-execs to regain privilege for the delivery, the use of &%-C%& causes
+privilege to be lost. However, root can test reception and delivery using two
+separate commands.
+
+.next
+The WHITELIST_D_MACROS build option declares some macros to be safe to override
+with &%-D%& if the real uid is one of root, the Exim run-time user or the
+CONFIGURE_OWNER, if defined. The potential impact of this option is limited by
+requiring the run-time value supplied to &%-D%& to match a regex that errs on
+the restrictive side. Requiring build-time selection of safe macros is onerous
+but this option is intended solely as a transition mechanism to permit
+previously-working configurations to continue to work after release 4.73.
.next
If DISABLE_D_OPTION is defined, the use of the &%-D%& command line option
is disabled.
-
-.section "Root privilege"
+.section "Root privilege" "SECID270"
.cindex "setuid"
.cindex "root privilege"
The Exim binary is normally setuid to root, which means that it gains root
uid and gid in the following cases:
.ilist
-.cindex "&%-C%& option"
-.cindex "&%-D%& option"
+.oindex "&%-C%&"
+.oindex "&%-D%&"
If the &%-C%& option is used to specify an alternate configuration file, or if
the &%-D%& option is used to define macro values for the configuration, and the
-calling process is not running as root or the Exim user, the uid and gid are
-changed to those of the calling process.
-However, if ALT_CONFIG_ROOT_ONLY is defined in &_Local/Makefile_&, only
-root callers may use &%-C%& and &%-D%& without losing privilege, and if
-DISABLE_D_OPTION is set, the &%-D%& option may not be used at all.
-.next
-.cindex "&%-be%& option"
-.cindex "&%-bf%& option"
-.cindex "&%-bF%& option"
+calling process is not running as root, the uid and gid are changed to those of
+the calling process.
+However, if DISABLE_D_OPTION is defined in &_Local/Makefile_&, the &%-D%&
+option may not be used at all.
+If WHITELIST_D_MACROS is defined in &_Local/Makefile_&, then some macro values
+can be supplied if the calling process is running as root, the Exim run-time
+user or CONFIGURE_OWNER, if defined.
+.next
+.oindex "&%-be%&"
+.oindex "&%-bf%&"
+.oindex "&%-bF%&"
If the expansion test option (&%-be%&) or one of the filter testing options
(&%-bf%& or &%-bF%&) are used, the uid and gid are changed to those of the
calling process.
uid and gid are changed to the Exim user and group. This means that Exim always
runs under its own uid and gid when receiving messages. This also applies when
testing address verification
-.cindex "&%-bv%& option"
-.cindex "&%-bh%& option"
+.oindex "&%-bv%&"
+.oindex "&%-bh%&"
(the &%-bv%& option) and testing incoming message policy controls (the &%-bh%&
option).
.next
.section "Running Exim without privilege" "SECTrunexiwitpri"
-.cindex "privilege" "running without"
+.cindex "privilege, running without"
.cindex "unprivileged running"
.cindex "root privilege" "running without"
Some installations like to run Exim in an unprivileged state for more of its
routing is no longer run as root, and the deliveries themselves cannot change
to any other uid.
+.cindex SIGHUP
+.cindex "daemon" "restarting"
Leaving the binary setuid to root, but setting &%deliver_drop_privilege%& means
that the daemon can still be started in the usual way, and it can respond
correctly to SIGHUP because the re-invocation regains root privilege.
An alternative approach is to make Exim setuid to the Exim user and also setgid
-to the Exim group.
-If you do this, the daemon must be started from a root process. (Calling
-Exim from a root process makes it behave in the way it does when it is setuid
-root.) However, the daemon cannot restart itself after a SIGHUP signal because
-it cannot regain privilege.
+to the Exim group. If you do this, the daemon must be started from a root
+process. (Calling Exim from a root process makes it behave in the way it does
+when it is setuid root.) However, the daemon cannot restart itself after a
+SIGHUP signal because it cannot regain privilege.
It is still useful to set &%deliver_drop_privilege%& in this case, because it
stops Exim from trying to re-invoke itself to do a delivery after a message has
some POP3 or IMAP-only environments):
.olist
-They must be owned by the Exim group and be writable by that group. This
+They must be owned by the Exim group and be writeable by that group. This
implies you must set &%mode%& in the appendfile configuration, as well as the
mode of the mailbox files themselves.
.next
-.section "Delivering to local files"
+.section "Delivering to local files" "SECID271"
Full details of the checks applied by &(appendfile)& before it writes to a file
are given in chapter &<<CHAPappendfile>>&.
-.section "IPv4 source routing"
+.section "IPv4 source routing" "SECID272"
.cindex "source routing" "in IP packets"
.cindex "IP source routing"
Many operating systems suppress IP source-routed packets in the kernel, but
-.section "The VRFY, EXPN, and ETRN commands in SMTP"
+.section "The VRFY, EXPN, and ETRN commands in SMTP" "SECID273"
Support for these SMTP commands is disabled by default. If required, they can
be enabled by defining suitable ACLs.
-.section "Privileged users"
-.cindex "trusted user"
+.section "Privileged users" "SECID274"
+.cindex "trusted users"
.cindex "admin user"
.cindex "privileged user"
.cindex "user" "trusted"
.cindex "user" "admin"
-Exim recognises two sets of users with special privileges. Trusted users are
+Exim recognizes two sets of users with special privileges. Trusted users are
able to submit new messages to Exim locally, but supply their own sender
addresses and information about a sending host. For other users submitting
local messages, Exim sets up the sender address from the uid, and doesn't
permit a remote host to be specified.
-.cindex "&%-f%& option"
+.oindex "&%-f%&"
However, an untrusted user is permitted to use the &%-f%& command line option
in the special form &%-f <>%& to indicate that a delivery failure for the
message should not cause an error report. This affects the message's envelope,
the Exim monitor and see all the information it is capable of providing, which
includes the contents of files on the spool.
-.cindex "&%-M%& option"
-.cindex "&%-q%& option"
+.oindex "&%-M%&"
+.oindex "&%-q%&"
By default, the use of the &%-M%& and &%-q%& options to cause Exim to attempt
delivery of messages on its queue is restricted to admin users. This
restriction can be relaxed by setting the &%no_prod_requires_admin%& option.
queue is also restricted to admin users. This restriction can be relaxed by
setting &%no_queue_list_requires_admin%&.
-Exim recognises an admin user if the calling process is running as root or as
+Exim recognizes an admin user if the calling process is running as root or as
the Exim user or if any of the groups associated with the calling process is
the Exim group. It is not necessary actually to be running under the Exim
group. However, if admin users who are not root or the Exim user are to access
-.section "Spool files"
+.section "Spool files" "SECID275"
.cindex "spool directory" "files"
Exim's spool directory and everything it contains is owned by the Exim user and
set to the Exim group. The mode for spool files is defined in the
-.section "Use of argv[0]"
+.section "Use of argv[0]" "SECID276"
Exim examines the last component of &%argv[0]%&, and if it matches one of a set
of specific strings, Exim assumes certain options. For example, calling Exim
with the last component of &%argv[0]%& set to &"rsmtp"& is exactly equivalent
-.section "Use of %f formatting"
+.section "Use of %f formatting" "SECID277"
The only use made of &"%f"& by Exim is in formatting load average values. These
are actually stored in integer variables as 1000 times the load average.
Consequently, their range is limited and so therefore is the length of the
-.section "Embedded Exim path"
+.section "Embedded Exim path" "SECID278"
Exim uses its own path name, which is embedded in the code, only when it needs
to re-exec in order to regain root privilege. Therefore, it is not root when it
does so. If some bug allowed the path to get overwritten, it would lead to an
-.section "Use of sprintf()"
+.section "Dynamic module directory" "SECTdynmoddir"
+Any dynamically loadable modules must be installed into the directory
+defined in &`LOOKUP_MODULE_DIR`& in &_Local/Makefile_& for Exim to permit
+loading it.
+
+
+.section "Use of sprintf()" "SECID279"
.cindex "&[sprintf()]&"
A large number of occurrences of &"sprintf"& in the code are actually calls to
&'string_sprintf()'&, a function that returns the result in malloc'd store.
-.section "Use of debug_printf() and log_write()"
+.section "Use of debug_printf() and log_write()" "SECID280"
Arbitrary strings are passed to both these functions, but they do their
formatting by calling the function &'string_vformat()'&, which runs through
the format string itself, and checks the length of each conversion.
-.section "Use of strcat() and strcpy()"
+.section "Use of strcat() and strcpy()" "SECID281"
These are used only in cases where the output buffer is known to be large
enough to hold the result.
+.ecindex IIDsecurcon
. ////////////////////////////////////////////////////////////////////////////
.chapter "Format of spool files" "CHAPspool"
-.cindex "format" "spool files"
-.cindex "spool directory" "format of files"
-.cindex "spool files" "format of"
+.scindex IIDforspo1 "format" "spool files"
+.scindex IIDforspo2 "spool directory" "format of files"
+.scindex IIDforspo3 "spool files" "format of"
.cindex "spool files" "editing"
A message on Exim's queue consists of two files, whose names are the message id
followed by -D and -H, respectively. The data portion of the message is kept in
on your own if you do it. Here are some of the pitfalls:
.ilist
-.new
You must ensure that Exim does not try to deliver the message while you are
fiddling with it. The safest way is to take out a write lock on the -D file,
which is what Exim itself does, using &[fcntl()]&. If you update the file in
place, the lock will be retained. If you write a new file and rename it, the
lock will be lost at the instant of rename.
.next
-.cindex "&$body_linecount$&"
+.vindex "&$body_linecount$&"
If you change the number of lines in the file, the value of
&$body_linecount$&, which is stored in the -H file, will be incorrect. At
present, this value is not used by Exim, but there is no guarantee that this
will always be the case.
-.wen
.next
If the message is in MIME format, you must take care not to break it.
.next
If the message is cryptographically signed, any change will invalidate the
signature.
.endlist
-
+All in all, modifying -D files is fraught with danger.
Files whose names end with -J may also be seen in the &_input_& directory (or
its subdirectories when &%split_spool_directory%& is set). These are journal
files, used to record addresses to which the message has been delivered during
-the course of a delivery run. At the end of the run, the -H file is updated,
-and the -J file is deleted.
-
+the course of a delivery attempt. If there are still undelivered recipients at
+the end, the -H file is updated, and the -J file is deleted. If, however, there
+is some kind of crash (for example, a power outage) before this happens, the -J
+file remains in existence. When Exim next processes the message, it notices the
+-J file and uses it to update the -H file before starting the next delivery
+attempt.
-.section "Format of the -H file"
+.section "Format of the -H file" "SECID282"
.cindex "uid (user id)" "in spool file"
.cindex "gid (group id)" "in spool file"
The second line of the -H file contains the login name for the uid of the
process that called Exim to read the message, followed by the numerical uid and
gid. For a locally generated message, this is normally the user who sent the
-message. For a message received over TCP/IP, it is normally the Exim user.
+message. For a message received over TCP/IP via the daemon, it is
+normally the Exim user.
The third line of the file contains the address of the message's sender as
transmitted in the envelope, contained in angle brackets. The sender address is
order, and are omitted when not relevant:
.vlist
-.vitem "&%-acl%& <&'number'&> <&'length'&>"
-A line of this form is present for every ACL variable that is not empty. The
-number identifies the variable; the &%acl_c%&&*x*& variables are numbered 0&--9
-and the &%acl_m%&&*x*& variables are numbered 10&--19. The length is the length
-of the data string for the variable. The string itself starts at the beginning
-of the next line, and is followed by a newline character. It may contain
-internal newlines.
-
-.vitem "&%-active_hostname%& <&'hostname'&>"
+.vitem "&%-acl%&&~<&'number'&>&~<&'length'&>"
+This item is obsolete, and is not generated from Exim release 4.61 onwards;
+&%-aclc%& and &%-aclm%& are used instead. However, &%-acl%& is still
+recognized, to provide backward compatibility. In the old format, a line of
+this form is present for every ACL variable that is not empty. The number
+identifies the variable; the &%acl_c%&&*x*& variables are numbered 0&--9 and
+the &%acl_m%&&*x*& variables are numbered 10&--19. The length is the length of
+the data string for the variable. The string itself starts at the beginning of
+the next line, and is followed by a newline character. It may contain internal
+newlines.
+
+.vitem "&%-aclc%&&~<&'rest-of-name'&>&~<&'length'&>"
+A line of this form is present for every ACL connection variable that is
+defined. Note that there is a space between &%-aclc%& and the rest of the name.
+The length is the length of the data string for the variable. The string itself
+starts at the beginning of the next line, and is followed by a newline
+character. It may contain internal newlines.
+
+.vitem "&%-aclm%&&~<&'rest-of-name'&>&~<&'length'&>"
+A line of this form is present for every ACL message variable that is defined.
+Note that there is a space between &%-aclm%& and the rest of the name. The
+length is the length of the data string for the variable. The string itself
+starts at the beginning of the next line, and is followed by a newline
+character. It may contain internal newlines.
+
+.vitem "&%-active_hostname%&&~<&'hostname'&>"
This is present if, when the message was received over SMTP, the value of
&$smtp_active_hostname$& was different to the value of &$primary_hostname$&.
time). Local messages that were input using &%-bnq%& and remote messages from
hosts that match &%sender_unqualified_hosts%& set this flag.
-.vitem "&%-auth_id%& <&'text'&>"
+.vitem "&%-auth_id%&&~<&'text'&>"
The id information for a message received on an authenticated SMTP connection
&-- the value of the &$authenticated_id$& variable.
-.vitem "&%-auth_sender%& <&'address'&>"
+.vitem "&%-auth_sender%&&~<&'address'&>"
The address of an authenticated sender &-- the value of the
&$authenticated_sender$& variable.
-.vitem "&%-body_linecount%& <&'number'&>"
+.vitem "&%-body_linecount%&&~<&'number'&>"
This records the number of lines in the body of the message, and is always
present.
-.vitem "&%-body_zerocount%& <&'number'&>"
+.vitem "&%-body_zerocount%&&~<&'number'&>"
This records the number of binary zero bytes in the body of the message, and is
present if the number is greater than zero.
This is written when a new message is first added to the spool. When the spool
file is updated after a deferral, it is omitted.
-.vitem "&%-frozen%& <&'time'&>"
+.vitem "&%-frozen%&&~<&'time'&>"
.cindex "frozen messages" "spool data"
The message is frozen, and the freezing happened at <&'time'&>.
-.vitem "&%-helo_name%& <&'text'&>"
+.vitem "&%-helo_name%&&~<&'text'&>"
This records the host name as specified by a remote host in a HELO or EHLO
command.
-.vitem "&%-host_address%& <&'address'&>.<&'port'&>"
+.vitem "&%-host_address%&&~<&'address'&>.<&'port'&>"
This records the IP address of the host from which the message was received and
the remote port number that was used. It is omitted for locally generated
messages.
-.vitem "&%-host_auth%& <&'text'&>"
+.vitem "&%-host_auth%&&~<&'text'&>"
If the message was received on an authenticated SMTP connection, this records
the name of the authenticator &-- the value of the
&$sender_host_authenticated$& variable.
This is present if an attempt to look up the sending host's name from its IP
address failed. It corresponds to the &$host_lookup_failed$& variable.
-.vitem "&%-host_name%& <&'text'&>"
+.vitem "&%-host_name%&&~<&'text'&>"
.cindex "reverse DNS lookup"
.cindex "DNS" "reverse lookup"
This records the name of the remote host from which the message was received,
if the host name was looked up from the IP address when the message was being
received. It is not present if no reverse lookup was done.
-.vitem "&%-ident%& <&'text'&>"
+.vitem "&%-ident%&&~<&'text'&>"
For locally submitted messages, this records the login of the originating user,
unless it was a trusted user and the &%-oMt%& option was used to specify an
ident value. For messages received over TCP/IP, this records the ident string
supplied by the remote host, if any.
-.vitem "&%-interface_address%& <&'address'&>.<&'port'&>"
+.vitem "&%-interface_address%&&~<&'address'&>.<&'port'&>"
This records the IP address of the local interface and the port number through
which a message was received from a remote host. It is omitted for locally
generated messages.
.vitem &%-localerror%&
The message is a locally-generated bounce message.
-.vitem "&%-local_scan%& <&'string'&>"
+.vitem "&%-local_scan%&&~<&'string'&>"
This records the data string that was returned by the &[local_scan()]& function
when the message was received &-- the value of the &$local_scan_data$&
variable. It is omitted if no data was returned.
The envelope sender of this message was set by an untrusted local caller (used
to ensure that the caller is displayed in queue listings).
-.vitem "&%-spam_score_int%& <&'number'&>"
+.vitem "&%-spam_score_int%&&~<&'number'&>"
If a message was scanned by SpamAssassin, this is present. It records the value
of &$spam_score_int$&.
A TLS certificate was received from the client that sent this message, and the
certificate was verified by the server.
-.vitem "&%-tls_cipher%& <&'cipher name'&>"
+.vitem "&%-tls_cipher%&&~<&'cipher name'&>"
When the message was received over an encrypted connection, this records the
name of the cipher suite that was used.
-.vitem "&%-tls_peerdn%& <&'peer DN'&>"
+.vitem "&%-tls_peerdn%&&~<&'peer DN'&>"
When the message was received over an encrypted connection, and a certificate
was received from the client, this records the Distinguished Name from that
certificate.
The asterisked headers indicate that the envelope sender, &'From:'& header, and
&'To:'& header have been rewritten, the last one because routing expanded the
unqualified domain &'foundation'&.
+.ecindex IIDforspo1
+.ecindex IIDforspo2
+.ecindex IIDforspo3
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
+.chapter "Support for DKIM (DomainKeys Identified Mail)" "CHID12" &&&
+ "DKIM Support"
+.cindex "DKIM"
+
+DKIM is a mechanism by which messages sent by some entity can be provably
+linked to a domain which that entity controls. It permits reputation to
+be tracked on a per-domain basis, rather than merely upon source IP address.
+DKIM is documented in RFC 4871.
+
+Since version 4.70, DKIM support is compiled into Exim by default. It can be
+disabled by setting DISABLE_DKIM=yes in Local/Makefile.
+
+Exim's DKIM implementation allows to
+.olist
+Sign outgoing messages: This function is implemented in the SMTP transport.
+It can co-exist with all other Exim features, including transport filters.
+.next
+Verify signatures in incoming messages: This is implemented by an additional
+ACL (acl_smtp_dkim), which can be called several times per message, with
+different signature contexts.
+.endlist
+
+In typical Exim style, the verification implementation does not include any
+default "policy". Instead it enables you to build your own policy using
+Exim's standard controls.
+
+Please note that verification of DKIM signatures in incoming mail is turned
+on by default for logging purposes. For each signature in incoming email,
+exim will log a line displaying the most important signature details, and the
+signature status. Here is an example (with line-breaks added for clarity):
+.code
+2009-09-09 10:22:28 1MlIRf-0003LU-U3 DKIM:
+ d=facebookmail.com s=q1-2009b
+ c=relaxed/relaxed a=rsa-sha1
+ i=@facebookmail.com t=1252484542 [verification succeeded]
+.endd
+You might want to turn off DKIM verification processing entirely for internal
+or relay mail sources. To do that, set the &%dkim_disable_verify%& ACL
+control modifier. This should typically be done in the RCPT ACL, at points
+where you accept mail from relay sources (internal hosts or authenticated
+senders).
+
+
+.section "Signing outgoing messages" "SECID513"
+.cindex "DKIM" "signing"
+
+Signing is implemented by setting private options on the SMTP transport.
+These options take (expandable) strings as arguments.
+
+.option dkim_domain smtp string&!! unset
+MANDATORY:
+The domain you want to sign with. The result of this expanded
+option is put into the &%$dkim_domain%& expansion variable.
+
+.option dkim_selector smtp string&!! unset
+MANDATORY:
+This sets the key selector string. You can use the &%$dkim_domain%& expansion
+variable to look up a matching selector. The result is put in the expansion
+variable &%$dkim_selector%& which should be used in the &%dkim_private_key%&
+option along with &%$dkim_domain%&.
+
+.option dkim_private_key smtp string&!! unset
+MANDATORY:
+This sets the private key to use. You can use the &%$dkim_domain%& and
+&%$dkim_selector%& expansion variables to determine the private key to use.
+The result can either
+.ilist
+be a valid RSA private key in ASCII armor, including line breaks.
+.next
+start with a slash, in which case it is treated as a file that contains
+the private key.
+.next
+be "0", "false" or the empty string, in which case the message will not
+be signed. This case will not result in an error, even if &%dkim_strict%&
+is set.
+.endlist
+
+.option dkim_canon smtp string&!! unset
+OPTIONAL:
+This option sets the canonicalization method used when signing a message.
+The DKIM RFC currently supports two methods: "simple" and "relaxed".
+The option defaults to "relaxed" when unset. Note: the current implementation
+only supports using the same canonicalization method for both headers and body.
+
+.option dkim_strict smtp string&!! unset
+OPTIONAL:
+This option defines how Exim behaves when signing a message that
+should be signed fails for some reason. When the expansion evaluates to
+either "1" or "true", Exim will defer. Otherwise Exim will send the message
+unsigned. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion
+variables here.
+
+.option dkim_sign_headers smtp string&!! unset
+OPTIONAL:
+When set, this option must expand to (or be specified as) a colon-separated
+list of header names. Headers with these names will be included in the message
+signature. When unspecified, the header names recommended in RFC4871 will be
+used.
+
+
+.section "Verifying DKIM signatures in incoming mail" "SECID514"
+.cindex "DKIM" "verification"
+
+Verification of DKIM signatures in incoming email is implemented via the
+&%acl_smtp_dkim%& ACL. By default, this ACL is called once for each
+syntactically(!) correct signature in the incoming message.
+
+To evaluate the signature in the ACL a large number of expansion variables
+containing the signature status and its details are set up during the
+runtime of the ACL.
+
+Calling the ACL only for existing signatures is not sufficient to build
+more advanced policies. For that reason, the global option
+&%dkim_verify_signers%&, and a global expansion variable
+&%$dkim_signers%& exist.
+
+The global option &%dkim_verify_signers%& can be set to a colon-separated
+list of DKIM domains or identities for which the ACL &%acl_smtp_dkim%& is
+called. It is expanded when the message has been received. At this point,
+the expansion variable &%$dkim_signers%& already contains a colon-separated
+list of signer domains and identities for the message. When
+&%dkim_verify_signers%& is not specified in the main configuration,
+it defaults as:
+.code
+dkim_verify_signers = $dkim_signers
+.endd
+This leads to the default behaviour of calling &%acl_smtp_dkim%& for each
+DKIM signature in the message. Current DKIM verifiers may want to explicitly
+call the ACL for known domains or identities. This would be achieved as follows:
+.code
+dkim_verify_signers = paypal.com:ebay.com:$dkim_signers
+.endd
+This would result in &%acl_smtp_dkim%& always being called for "paypal.com"
+and "ebay.com", plus all domains and identities that have signatures in the message.
+You can also be more creative in constructing your policy. For example:
+.code
+dkim_verify_signers = $sender_address_domain:$dkim_signers
+.endd
+
+If a domain or identity is listed several times in the (expanded) value of
+&%dkim_verify_signers%&, the ACL is only called once for that domain or identity.
+
+
+Inside the &%acl_smtp_dkim%&, the following expansion variables are
+available (from most to least important):
+
+
+.vlist
+.vitem &%$dkim_cur_signer%&
+The signer that is being evaluated in this ACL run. This can be a domain or
+an identity. This is one of the list items from the expanded main option
+&%dkim_verify_signers%& (see above).
+.vitem &%$dkim_verify_status%&
+A string describing the general status of the signature. One of
+.ilist
+&%none%&: There is no signature in the message for the current domain or
+identity (as reflected by &%$dkim_cur_signer%&).
+.next
+&%invalid%&: The signature could not be verified due to a processing error.
+More detail is available in &%$dkim_verify_reason%&.
+.next
+&%fail%&: Verification of the signature failed. More detail is
+available in &%$dkim_verify_reason%&.
+.next
+&%pass%&: The signature passed verification. It is valid.
+.endlist
+.vitem &%$dkim_verify_reason%&
+A string giving a litte bit more detail when &%$dkim_verify_status%& is either
+"fail" or "invalid". One of
+.ilist
+&%pubkey_unavailable%& (when &%$dkim_verify_status%&="invalid"): The public
+key for the domain could not be retrieved. This may be a temporary problem.
+.next
+&%pubkey_syntax%& (when &%$dkim_verify_status%&="invalid"): The public key
+record for the domain is syntactically invalid.
+.next
+&%bodyhash_mismatch%& (when &%$dkim_verify_status%&="fail"): The calculated
+body hash does not match the one specified in the signature header. This
+means that the message body was modified in transit.
+.next
+&%signature_incorrect%& (when &%$dkim_verify_status%&="fail"): The signature
+could not be verified. This may mean that headers were modified,
+re-written or otherwise changed in a way which is incompatible with
+DKIM verification. It may of course also mean that the signature is forged.
+.endlist
+.vitem &%$dkim_domain%&
+The signing domain. IMPORTANT: This variable is only populated if there is
+an actual signature in the message for the current domain or identity (as
+reflected by &%$dkim_cur_signer%&).
+.vitem &%$dkim_identity%&
+The signing identity, if present. IMPORTANT: This variable is only populated
+if there is an actual signature in the message for the current domain or
+identity (as reflected by &%$dkim_cur_signer%&).
+.vitem &%$dkim_selector%&
+The key record selector string.
+.vitem &%$dkim_algo%&
+The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'.
+.vitem &%$dkim_canon_body%&
+The body canonicalization method. One of 'relaxed' or 'simple'.
+.vitem &%dkim_canon_headers%&
+The header canonicalization method. One of 'relaxed' or 'simple'.
+.vitem &%$dkim_copiedheaders%&
+A transcript of headers and their values which are included in the signature
+(copied from the 'z=' tag of the signature).
+.vitem &%$dkim_bodylength%&
+The number of signed body bytes. If zero ("0"), the body is unsigned. If no
+limit was set by the signer, "9999999999999" is returned. This makes sure
+that this variable always expands to an integer value.
+.vitem &%$dkim_created%&
+UNIX timestamp reflecting the date and time when the signature was created.
+When this was not specified by the signer, "0" is returned.
+.vitem &%$dkim_expires%&
+UNIX timestamp reflecting the date and time when the signer wants the
+signature to be treated as "expired". When this was not specified by the
+signer, "9999999999999" is returned. This makes it possible to do useful
+integer size comparisons against this value.
+.vitem &%$dkim_headernames%&
+A colon-separated list of names of headers included in the signature.
+.vitem &%$dkim_key_testing%&
+"1" if the key record has the "testing" flag set, "0" if not.
+.vitem &%$nosubdomains%&
+"1" if the key record forbids subdomaining, "0" otherwise.
+.vitem &%$dkim_key_srvtype%&
+Service type (tag s=) from the key record. Defaults to "*" if not specified
+in the key record.
+.vitem &%$dkim_key_granularity%&
+Key granularity (tag g=) from the key record. Defaults to "*" if not specified
+in the key record.
+.vitem &%$dkim_key_notes%&
+Notes from the key record (tag n=).
+.endlist
+
+In addition, two ACL conditions are provided:
+
+.vlist
+.vitem &%dkim_signers%&
+ACL condition that checks a colon-separated list of domains or identities
+for a match against the domain or identity that the ACL is currently verifying
+(reflected by &%$dkim_cur_signer%&). This is typically used to restrict an ACL
+verb to a group of domains or identities. For example:
+
+.code
+# Warn when Mail purportedly from GMail has no signature at all
+warn log_message = GMail sender without DKIM signature
+ sender_domains = gmail.com
+ dkim_signers = gmail.com
+ dkim_status = none
+.endd
+.vitem &%dkim_status%&
+ACL condition that checks a colon-separated list of possible DKIM verification
+results agains the actual result of verification. This is typically used
+to restrict an ACL verb to a list of verification outcomes, for example:
+.code
+deny message = Mail from Paypal with invalid/missing signature
+ sender_domains = paypal.com:paypal.de
+ dkim_signers = paypal.com:paypal.de
+ dkim_status = none:invalid:fail
+.endd
+The possible status keywords are: 'none','invalid','fail' and 'pass'. Please
+see the documentation of the &%$dkim_verify_status%& expansion variable above
+for more information of what they mean.
+.endlist
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "Adding new drivers or lookup types" "" &&&
+.chapter "Adding new drivers or lookup types" "CHID13" &&&
"Adding drivers or lookups"
.cindex "adding drivers"
-.cindex "new drivers" "adding"
+.cindex "new drivers, adding"
.cindex "drivers" "adding new"
The following actions have to be taken in order to add a new router, transport,
authenticator, or lookup type to Exim:
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.makeindex "Option index" "option"
+. /////////////////////////////////////////////////////////////////////////////
+. These lines are processing instructions for the Simple DocBook Processor that
+. Philip Hazel has developed as a less cumbersome way of making PostScript and
+. PDFs than using xmlto and fop. They will be ignored by all other XML
+. processors.
+. /////////////////////////////////////////////////////////////////////////////
+
+.literal xml
+<?sdop
+ format="newpage"
+ foot_right_recto="&chaptertitle;"
+ foot_right_verso="&chaptertitle;"
+?>
+.literal off
-.makeindex "Concept index" "concept"
+.makeindex "Options index" "option"
+.makeindex "Variables index" "variable"
+.makeindex "Concept index" "concept"
. /////////////////////////////////////////////////////////////////////////////
git://git.exim.org / exim.git / blobdiff