. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.93"
+.set previousversion "4.98"
.include ./local_params
.set ACL "access control lists (ACLs)"
.set I " "
+.set drivernamemax "64"
+
.macro copyyear
-2020
+2024
.endmacro
. /////////////////////////////////////////////////////////////////////////////
. --- 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.
+. --- Also one for multiple option def headings be grouped in a single
+. --- table (but without the split capability).
+
+.macro otable
+.itable all 0 0 4 8* left 6* center 6* center 6* right
+.endmacro
+
+.macro orow
+.row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&"
+.endmacro
.macro option
.arg 5
.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'&"
+.otable
+.orow "$1" "$2" "$3" "$4"
+.endtable
+.endmacro
+
+.macro options
+.eacharg
+.oindex "&%$+1%&"
+.endeach 4
+.otable
+.eacharg
+.orow "$+1" "$+2" "$+3" "$+4"
+.endeach 4
.endtable
.endmacro
.itable none 0 0 2 $1 left $2 left
.endmacro
+
+. --- A macro for a plain variable, including the .vitem and .vindex
+.macro var
+.vitem $1
+.vindex $1
+.endmacro
+
+. --- A macro for a "tainted" marker, done as a one-element table
+.macro tmark
+.itable none 0 0 1 10pt left
+.row &'Tainted'&
+.endtable
+.endmacro
+
+. --- A macro for a tainted variable, adding a taint-marker
+.macro tvar
+.var $1
+.tmark
+.endmacro
+
+. --- A macro for a cmdline option, including a .oindex
+. --- 1st arg is the option name, undecorated (we do that here).
+. --- 2nd arg, optional, text (decorated as needed) to be appended to the name
+.macro cmdopt
+.vitem &%$1%&$=2+&~$2+
+.oindex &%$1%&
+.endmacro
+
. --- 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.
. --- 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.
+. --- The index entry points to the most-recent chapter head, section or subsection
+. --- head, or list-item.
.macro cindex
&<indexterm role="concept">&
&</indexterm>&
.endmacro
+. --- The index entry points to the most-recent chapter head, section or subsection
+. --- head, or varlist item.
+
.macro vindex
&<indexterm role="variable">&
&<primary>&$1&</primary>&
.macro index
.echo "** Don't use .index; use .cindex or .oindex or .vindex"
.endmacro
+
+
+. use this for a concept-index entry for a header line
+.macro chindex
+.cindex "&'$1'& header line"
+.cindex "header lines" $1
+.endmacro
. ////////////////////////////////////////////////////////////////////////////
</revision></revhistory>
<copyright><year>
.copyyear
- </year><holder>University of Cambridge</holder></copyright>
+ </year><holder>The Exim Maintainers</holder></copyright>
</bookinfo>
.literal off
. /////////////////////////////////////////////////////////////////////////////
-. This chunk of literal XML implements index entries of the form "x, see y" and
-. "x, see also y". However, the DocBook DTD doesn't allow <indexterm> entries
+. These implement index entries of the form "x, see y" and "x, see also y".
+. However, the DocBook DTD doesn't allow <indexterm> entries
. at the top level, so we have to put the .chapter directive first.
. /////////////////////////////////////////////////////////////////////////////
.chapter "Introduction" "CHID1"
-.literal xml
-<indexterm role="variable">
- <primary>$1, $2, etc.</primary>
- <see><emphasis>numerical variables</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>address</primary>
- <secondary>rewriting</secondary>
- <see><emphasis>rewriting</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>Bounce Address Tag Validation</primary>
- <see><emphasis>BATV</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>Client SMTP Authorization</primary>
- <see><emphasis>CSA</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>CR character</primary>
- <see><emphasis>carriage return</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>CRL</primary>
- <see><emphasis>certificate revocation list</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>delivery</primary>
- <secondary>failure report</secondary>
- <see><emphasis>bounce message</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>dialup</primary>
- <see><emphasis>intermittently connected hosts</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>exiscan</primary>
- <see><emphasis>content scanning</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>failover</primary>
- <see><emphasis>fallback</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>fallover</primary>
- <see><emphasis>fallback</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>filter</primary>
- <secondary>Sieve</secondary>
- <see><emphasis>Sieve filter</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>ident</primary>
- <see><emphasis>RFC 1413</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>LF character</primary>
- <see><emphasis>linefeed</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>maximum</primary>
- <seealso><emphasis>limit</emphasis></seealso>
-</indexterm>
-<indexterm role="concept">
- <primary>monitor</primary>
- <see><emphasis>Exim monitor</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>no_<emphasis>xxx</emphasis></primary>
- <see>entry for xxx</see>
-</indexterm>
-<indexterm role="concept">
- <primary>NUL</primary>
- <see><emphasis>binary zero</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>passwd file</primary>
- <see><emphasis>/etc/passwd</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>process id</primary>
- <see><emphasis>pid</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>RBL</primary>
- <see><emphasis>DNS list</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>redirection</primary>
- <see><emphasis>address redirection</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>return path</primary>
- <seealso><emphasis>envelope sender</emphasis></seealso>
-</indexterm>
-<indexterm role="concept">
- <primary>scanning</primary>
- <see><emphasis>content scanning</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>SSL</primary>
- <see><emphasis>TLS</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>string</primary>
- <secondary>expansion</secondary>
- <see><emphasis>expansion</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>top bit</primary>
- <see><emphasis>8-bit characters</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>variables</primary>
- <see><emphasis>expansion, variables</emphasis></see>
-</indexterm>
-<indexterm role="concept">
- <primary>zero, binary</primary>
- <see><emphasis>binary zero</emphasis></see>
+.macro seeother
+.literal xml
+<indexterm role="$2">
+ <primary>$3</primary>
+.arg 5
+ <secondary>$5</secondary>
+.endarg
+ <$1><emphasis>$4</emphasis></$1>
</indexterm>
-
.literal off
+.endmacro
+
+. NB: for the 4-arg variant the ordering is awkward
+.macro see
+.seeother see "$1" "$2" "$3" "$4"
+.endmacro
+.macro seealso
+.seeother seealso "$1" "$2" "$3" "$4"
+.endmacro
+
+.see variable "<emphasis>$1</emphasis>, <emphasis>$2</emphasis>, etc." "numerical variables"
+.see concept address rewriting rewriting
+.see concept "Bounce Address Tag Validation" BATV
+.see concept "Client SMTP Authorization" CSA
+.see concept "CR character" "carriage return"
+.see concept CRL "certificate revocation list"
+.seealso concept de-tainting "tainted data"
+.see concept delivery "bounce message" "failure report"
+.see concept dialup "intermittently connected hosts"
+.see concept exiscan "content scanning"
+.see concept fallover fallback
+.see concept filter "Sieve filter" Sieve
+.see concept headers "header lines"
+.see concept ident "RFC 1413"
+.see concept "LF character" "linefeed"
+.seealso concept maximum limit
+.see concept monitor "Exim monitor"
+.see concept "no_<emphasis>xxx</emphasis>" "entry for xxx"
+.see concept NUL "binary zero"
+.see concept "passwd file" "/etc/passwd"
+.see concept "process id" pid
+.see concept RBL "DNS list"
+.see concept redirection "address redirection"
+.see concept "return path" "envelope sender"
+.see concept scanning "content scanning"
+.see concept SSL TLS
+.see concept string expansion expansion
+.see concept "top bit" "8-bit characters"
+.see concept variables "expansion, variables"
+.see concept "zero, binary" "binary zero"
. /////////////////////////////////////////////////////////////////////////////
.cindex "FAQ"
As well as Exim distribution tar files, the Exim website contains a number of
differently formatted versions of the documentation. A recent addition to the
-online information is the Exim wiki (&url(https://wiki.exim.org)),
+online information is &url(https://wiki.exim.org,the Exim wiki),
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.
The wiki site should always redirect to the correct place, which is currently
The following Exim mailing lists exist:
.table2 140pt
-.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"
+.row &'exim-announce@lists.exim.org'& "Moderated, low volume announcements list"
+.row &'exim-users@lists.exim.org'& "General discussion list"
+.row &'exim-users-de@lists.exim.org'& "General discussion list in German language"
+.row &'exim-dev@lists.exim.org'& "Discussion of bugs, enhancements, etc."
+.row &'exim-cvs@lists.exim.org'& "Automated commit messages from the VCS"
.endtable
You can subscribe to these lists, change your existing subscriptions, and view
.cindex "bug reports"
.cindex "reporting bugs"
Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported
-via the Bugzilla (&url(https://bugs.exim.org)). However, if you are unsure
+via &url(https://bugs.exim.org,the Bugzilla). 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 "limitations of Exim"
.cindex "bang paths" "not handled by Exim"
Exim is designed for use as an Internet MTA, and therefore handles addresses in
-RFC 2822 domain format only. It cannot handle UUCP &"bang paths"&, though
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+domain format only. It cannot handle UUCP &"bang paths"&, though
simple two-component bang paths can be converted by a straightforward rewriting
configuration. This restriction does not prevent Exim from being interfaced to
UUCP as a transport mechanism, provided that domain addresses are used.
.cindex "local part" "definition of"
.cindex "domain" "definition of"
-The term &'local part'&, which is taken from RFC 2822, is used to refer to the
+The term &'local part'&, which is taken from
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822), is used to refer to the
part of an email address that precedes the @ sign. The part that follows the
@ sign is called the &'domain'& or &'mail domain'&.
.chapter "Incorporated code" "CHID2"
.cindex "incorporated code"
.cindex "regular expressions" "library"
-.cindex "PCRE"
+.cindex "PCRE2"
.cindex "OpenDMARC"
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 to PCRE is no longer shipped with
-Exim, so you will need to use the version of PCRE shipped with your system,
+Exim monitor using the freely-distributable PCRE2 library, copyright
+© University of Cambridge. The source to PCRE2 is not longer shipped with
+Exim, so you will need to use the version of PCRE2 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).
+&url(https://github.com/PhilipHazel/pcre2/releases).
.next
.cindex "cdb" "acknowledgment"
Support for the cdb (Constant DataBase) lookup method is provided by code
.ilist
Sieve filters are written in the standard filtering language that is defined
-by RFC 3028.
+by &url(https://www.rfc-editor.org/rfc/rfc3028.html,RFC 3028).
.next
Exim filters are written in a syntax that is unique to Exim, but which is more
powerful than Sieve, which it pre-dates.
.cindex "base36"
.cindex "Darwin"
.cindex "Cygwin"
-Every message handled by Exim is given a &'message id'& which is sixteen
+.cindex "exim_msgdate"
+Every message handled by Exim is given a &'message id'& which is 23
characters long. It is divided into three parts, separated by hyphens, for
-example &`16VDhn-0001bo-D3`&. Each part is a sequence of letters and digits,
+example &`16VDhn-000000001bo-D342`&. Each part is a sequence of letters and digits,
normally encoding numbers in base 62. However, in the Darwin operating
system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36
(avoiding the use of lower case letters) is used instead, because the message
contains the number of seconds since the start of the epoch (the normal Unix
way of representing the date and time of day).
.next
-After the first hyphen, the next six characters are the id of the process that
-received the message.
+After the first hyphen, the next
+eleven
+characters are the id of the process that received the message.
.next
-There are two different possibilities for the final two characters:
+There are two different possibilities for the final four characters:
.olist
.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
+time of reception, normally in units of
+microseconds.
+but for systems
that must use base 36 instead of base 62 (because of case-insensitive file
-systems), the units are 1/1000 of a second.
+systems), the units are
+2 us.
.next
-If &%localhost_number%& is set, it is multiplied by 200 (100) and added to
-the fractional part of the time, which in this case is in units of 1/200
-(1/100) of a second.
+If &%localhost_number%& is set, it is multiplied by
+500000 (250000) and added to
+the fractional part of the time, which in this case is in units of 2 us (4 us).
.endlist
.endlist
pid, it is guaranteed that the time will be different. In most cases, the clock
will already have ticked while the message was being received.
+The exim_msgdate utility (see section &<<SECTexim_msgdate>>&) can be
+used to display the date, and optionally the process id, of an Exim
+Message ID.
+
.section "Receiving mail" "SECID13"
.cindex "receiving mail"
order in which they are tested. The individual configuration options are
described in more detail in chapter &<<CHAProutergeneric>>&.
-.ilist
+.olist
.cindex affix "router precondition"
The &%local_part_prefix%& and &%local_part_suffix%& options can specify that
the local parts handled by the router may or must have certain prefixes and/or
.next
Individual routers can be explicitly skipped when running the routers to
check an address given in the SMTP EXPN command (see the &%expn%& option).
+
.next
If the &%domains%& option is set, the domain of the address must be in the set
of domains that it defines.
+.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using router domains option"
+A match verifies the variable &$domain$& (which carries tainted data)
+and assigns an untainted value to the &$domain_data$& variable.
+Such an untainted value is often needed in the transport.
+For specifics of the matching operation and the resulting untainted value,
+refer to section &<<SECTdomainlist>>&.
+
+When an untainted value is wanted, use this option
+rather than the generic &%condition%& option.
+
.next
.vindex "&$local_part_prefix$&"
.vindex "&$local_part_prefix_v$&"
.vindex "&$local_part_suffix_v$&"
.cindex affix "router precondition"
If the &%local_parts%& option is set, the local part of the address must be in
-the set of local parts that it defines. If &%local_part_prefix%& or
+the set of local parts that it defines.
+A match verifies the variable &$local_part$& (which carries tainted data)
+and assigns an untainted value to the &$local_part_data$& variable.
+Such an untainted value is often needed in the transport.
+For specifics of the matching operation and the resulting untainted value,
+refer to section &<<SECTlocparlis>>&.
+
+When an untainted value is wanted, use this option
+rather than the generic &%condition%& option.
+
+If &%local_part_prefix%& or
&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
part before this check. If you want to do precondition tests on local parts
that include affixes, you can do so by using a &%condition%& option (see below)
-.new
that uses the variables &$local_part$&, &$local_part_prefix$&,
&$local_part_prefix_v$&, &$local_part_suffix$&
and &$local_part_suffix_v$& as necessary.
-.wen
+
.next
.vindex "&$local_user_uid$&"
.vindex "&$local_user_gid$&"
local user are placed in &$local_user_uid$& and &$local_user_gid$& and the
user's home directory is placed in &$home$&; these values can be used in the
remaining preconditions.
+
.next
If the &%router_home_directory%& option is set, it is expanded at this point,
because it overrides the value of &$home$&. If this expansion were left till
later, the value of &$home$& as set by &%check_local_user%& would be used in
subsequent tests. Having two different values of &$home$& in the same router
could lead to confusion.
+
.next
If the &%senders%& option is set, the envelope sender address must be in the
set of addresses that it defines.
+
.next
If the &%require_files%& option is set, the existence or non-existence of
specified files is tested.
+
.next
.cindex "customizing" "precondition"
If the &%condition%& option is set, it is evaluated and tested. This option
uses an expanded string to allow you to set up your own custom preconditions.
Expanded strings are described in chapter &<<CHAPexpand>>&.
+
+Note that while using
+this option for address matching technically works,
+it does not set any de-tainted values.
+Such values are often needed, either for router-specific options or
+for transport options.
+Using the &%domains%& and &%local_parts%& options is usually the most
+convenient way to obtain them.
.endlist
.cindex "delivery" "in detail"
When a message is to be delivered, the sequence of events is as follows:
-.ilist
+.olist
If a system-wide filter file is specified, the message is passed to it. The
filter may add recipients to the message, replace the recipients, discard the
message, cause a new message to be generated, or cause the message delivery to
-.section "Temporary delivery failure" "SECID20"
+.subsection "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
-.section "Permanent delivery failure" "SECID21"
+.subsection "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" "SECID22"
+.subsection "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 in the queue,
A C99-capable compiler will be required for the build.
-.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 package or the PCRE development package for your operating
-system. If your system has a normal PCRE installation the Exim build
+.section "PCRE2 library" "SECTpcre"
+.cindex "PCRE2 library"
+Exim no longer has an embedded regular-expression library as the vast majority of
+modern systems include PCRE2 as a system library, although you may need to
+install the PCRE2 package or the PCRE2 development package for your operating
+system. If your system has a normal PCRE2 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
+headers are in an unusual location you will need to either set the PCRE2_LIBS
and INCLUDE directives appropriately,
-or set PCRE_CONFIG=yes to use the installed &(pcre-config)& command.
+or set PCRE2_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(https://www.pcre.org/).
+PCRE2 support then you will need to obtain and build the current PCRE2
+from &url(https://github.com/PhilipHazel/pcre2/releases).
+More information on PCRE2 is available at &url(https://www.pcre.org/).
.section "DBM libraries" "SECTdb"
.cindex "DBM libraries" "discussion of"
versions. However, the more recent releases seem to have standardized on the
Berkeley DB library.
+.new
+Ownership of the Berkeley DB library has moved to a major corporation;
+development seems to have stalled and documentation is not freely available.
+This is probably not tenable for the long term use by Exim.
+.wen
+
Different DBM libraries have different conventions for naming the files they
use. When a program opens a file called &_dbmfile_&, there are several
possibilities:
.next
To complicate things further, there are several very different versions of the
Berkeley DB package. Version 1.85 was stable for a very long time, releases
-2.&'x'& and 3.&'x'& were current for a while, but the latest versions when Exim last revamped support were numbered 4.&'x'&.
-Maintenance of some of the earlier releases has ceased. All versions of
-Berkeley DB could be obtained from
+2.&'x'& and 3.&'x'& were current for a while,
+but the latest versions when Exim last revamped support were numbered 5.&'x'&.
+Maintenance of some of the earlier releases has ceased,
+and Exim no longer supports versions before 3.&'x'&.
+All versions of Berkeley DB could be obtained from
&url(http://www.sleepycat.com/), which is now a redirect to their new owner's
page with far newer versions listed.
It is probably wise to plan to move your storage configurations away from
Yet another DBM library, called &'tdb'&, is available from
&url(https://sourceforge.net/projects/tdb/files/). It has its own interface, and also
operates on a single file.
+.next
+It is possible to use &url(https://www.sqlite.org/index.html,sqlite3)
+for the DBM library.
.endlist
.cindex "USE_DB"
.code
USE_DB=yes
.endd
-Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An
-error is diagnosed if you set more than one of these.
+Similarly, for gdbm you set USE_GDBM, for tdb you set USE_TDB,
+and for sqlite3 you set USE_SQLITE.
+An error is diagnosed if you set more than one of these.
+You can set USE_NDBM if needed to override an operating system default.
At the lowest level, the build-time configuration sets none of these options,
thereby assuming an interface of type (1). However, some operating system
.code
DBMLIB = -ldb
DBMLIB = -ltdb
+DBMLIB = -lsqlite3
+DBMLIB = -lgdbm -lgdbm_compat
.endd
+The last of those was for a Linux having GDBM provide emulated NDBM facilities.
Settings like that will work if the DBM library is installed in the standard
place. Sometimes it is not, and the library's header file may also not be in
the default path. You may need to set INCLUDE to specify where the header
There is further detailed discussion about the various DBM libraries in the
file &_doc/dbm.discuss.txt_& in the Exim distribution.
+.new
+When moving from one DBM library to another,
+for the hints databases it suffices to just remove all the files in the
+directory named &"db/"& under the spool directory.
+This is because hints are only for optimisation and will be rebuilt
+during normal operations.
+Non-hints DBM databases (used by &"dbm"& lookups in the configuration)
+will need individual rebuilds for the new DBM library.
+This is not done automatically
+.wen
+
.section "Pre-building configuration" "SECID25"
.cindex "&[iconv()]& support"
.cindex "RFC 2047"
The contents of header lines in messages may be encoded according to the rules
-described RFC 2047. This makes it possible to transmit characters that are not
+described in &url(https://www.rfc-editor.org/rfc/rfc2047,RFC 2047).
+This makes it possible to transmit characters that are not
in the ASCII character set, and to label them as being in a particular
character set. When Exim is inspecting header lines by means of the &%$h_%&
mechanism, it decodes them, and translates them into a specified character set
.cindex "OpenSSL" "building Exim with"
.cindex "GnuTLS" "building Exim with"
Exim is usually built to support encrypted SMTP connections, using the STARTTLS
-command as per RFC 2487. It can also support clients that expect to
+command as per &url(https://www.rfc-editor.org/rfc/rfc2487,RFC 2487).
+It can also support clients that expect to
start a TLS session immediately on connection to a non-standard port (see the
&%tls_on_connect_ports%& runtime option and the &%-tls-on-connect%& command
line option).
-.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
+.section "Dynamically loaded module support" "SECTdynamicmodules"
.cindex "lookup modules"
+.cindex "router modules"
+.cindex "transport modules"
+.cindex "authenticator 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
+library dependencies without requiring all systems to install all of those
dependencies.
-Most, but not all, lookup types can be built this way.
+.new
+Any combination of lookup types can be built this way.
+Lookup types that provide several variants will be loaded as
+Exim starts.
+Types that provide only one method are not loaded until used by
+the runtime configuration.
+.wen
-Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
+For building
+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.
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:
+only if each is installed:
.code
LOOKUP_LSEARCH=yes
LOOKUP_SQLITE=2
LOOKUP_MYSQL=2
.endd
+Set also &`LOOKUP_`&<&'lookup_type'&>&` INCLUDE`& and
+&`LOOKUP_`&<&'lookup_type'&>`_LIBS if needed for each lookup type,
+ensuring that duplicates are not present in more global values.
+
+.new
+Similarly, authenticator, router and transport drivers can be built
+as external modules.
+Modules will be searched for as demanded by the runtime configuration,
+permitting a smaller Exim binary.
+
+For building, as above but using
+&`AUTH_*`&, &`ROUTER_*`& and &`TRANSPORT_*`& instead of &`LOOKUP_*`&,
+.wen
.section "The building process" "SECID29"
+.section "Running the daemon" SECTdaemonLaunch
+The most common command line for launching the Exim daemon looks like
+.code
+exim -bd -q5m
+.endd
+This starts a daemon which
+.ilist
+listens for incoming smtp connections, launching handler processes for
+each new one
+.next
+starts a queue-runner process every five minutes, to inspect queued messages
+and run delivery attempts on any that have arrived at their retry time
+.endlist
+Should a queue run take longer than the time between queue-runner starts,
+they will run in parallel.
+Numbers of jobs of the various types are subject to policy controls
+defined in the configuration.
+
+
.section "Upgrading Exim" "SECID36"
.cindex "upgrading Exim"
If you are already running Exim on your host, building and installing a new
See the &%untrusted_set_sender%& option for a way of permitting non-trusted
users to set envelope senders.
-.cindex "&'From:'& header line"
-.cindex "&'Sender:'& header line"
-.cindex "header lines" "From:"
-.cindex "header lines" "Sender:"
+.chindex From:
+.chindex Sender:
For a trusted user, there is never any check on the contents of the &'From:'&
header line, and a &'Sender:'& line is never added. Furthermore, any existing
&'Sender:'& line in incoming local (non-TCP/IP) messages is not removed.
.vlist
-.vitem &%--%&
-.oindex "--"
+.cmdopt "--" "--"
.cindex "options" "command line; terminating"
This is a pseudo-option whose only purpose is to terminate the options and
therefore to cause subsequent command line items to be treated as arguments
rather than options, even if they begin with hyphens.
-.vitem &%--help%&
-.oindex "&%--help%&"
+.cmdopt --help
This option causes Exim to output a few sentences stating what it is.
The same output is generated if the Exim binary is called with no options and
no arguments.
-.vitem &%--version%&
-.oindex "&%--version%&"
+.cmdopt --version
This option is an alias for &%-bV%& and causes version information to be
displayed.
These options are used by Sendmail for selecting configuration files and are
ignored by Exim.
-.vitem &%-B%&<&'type'&>
+.cmdopt -B <&'type'&>
.oindex "&%-B%&"
.cindex "8-bit characters"
.cindex "Sendmail compatibility" "8-bit characters"
This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit
clean; it ignores this option.
-.vitem &%-bd%&
-.oindex "&%-bd%&"
+.cmdopt -bd
.cindex "daemon"
.cindex "SMTP" "listener"
.cindex "queue runner"
referenced from the configuration (for example, alias files) are changed,
because these are reread each time they are used.
-.vitem &%-bdf%&
-.oindex "&%-bdf%&"
+Either a SIGTERM or a SIGINT signal should be used to cause the daemon
+to cleanly shut down.
+Subprocesses handling recceiving or delivering messages,
+or for scanning the queue,
+will not be affected by the termination of the daemon process.
+
+.cmdopt -bdf
This option has the same effect as &%-bd%& except that it never disconnects
from the controlling terminal, even when no debugging is specified.
-.vitem &%-be%&
-.oindex "&%-be%&"
+.cmdopt -be
.cindex "testing" "string expansion"
.cindex "expansion" "testing"
Run Exim in expansion testing mode. Exim discards its root privilege, to
Because macros in the config file are often used for secrets, those are only
available to admin users.
-.vitem &%-bem%&&~<&'filename'&>
-.oindex "&%-bem%&"
+The word &"set"& at the start of a line, followed by a single space,
+is recognised specially as defining a value for a variable.
+.cindex "tainted data" "expansion testing"
+If the sequence &",t"& is inserted before the space,
+the value is marked as tainted.
+The syntax is otherwise the same as the ACL modifier &"set ="&.
+
+.cmdopt -bem <&'filename'&>
.cindex "testing" "string expansion"
.cindex "expansion" "testing"
This option operates like &%-be%& except that it must be followed by the name
line, because further arguments are taken as strings to expand (just like
&%-be%&).
-.vitem &%-bF%&&~<&'filename'&>
-.oindex "&%-bF%&"
+.cmdopt -bF <&'filename'&>
.cindex "system filter" "testing"
.cindex "testing" "system filter"
This option is the same as &%-bf%& except that it assumes that the filter being
tested is a system filter. The additional commands that are available only in
system filters are recognized.
-.vitem &%-bf%&&~<&'filename'&>
-.oindex "&%-bf%&"
+.cmdopt -bf <&'filename'&>
.cindex "filter" "testing"
.cindex "testing" "filter file"
.cindex "forward file" "testing"
can be set by means of additional command line options (see the next four
options).
-.vitem &%-bfd%&&~<&'domain'&>
-.oindex "&%-bfd%&"
+.cmdopt -bfd <&'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
&$qualify_domain$&.
-.vitem &%-bfl%&&~<&'local&~part'&>
-.oindex "&%-bfl%&"
+.cmdopt -bfl <&'local&~part'&>
This sets the local part of the recipient address when a filter file is being
tested by means of the &%-bf%& option. The default is the username of the
process that calls Exim. A local part should be specified with any prefix or
suffix stripped, because that is how it appears to the filter when a message is
actually being delivered.
-.vitem &%-bfp%&&~<&'prefix'&>
-.oindex "&%-bfp%&"
+.cmdopt -bfp <&'prefix'&>
.cindex affix "filter testing"
This sets the prefix of the local part of the recipient address when a filter
file is being tested by means of the &%-bf%& option. The default is an empty
prefix.
-.vitem &%-bfs%&&~<&'suffix'&>
-.oindex "&%-bfs%&"
+.cmdopt -bfs <&'suffix'&>
.cindex affix "filter testing"
This sets the suffix of the local part of the recipient address when a filter
file is being tested by means of the &%-bf%& option. The default is an empty
suffix.
-.vitem &%-bh%&&~<&'IP&~address'&>
-.oindex "&%-bh%&"
+.cmdopt -bh <&'IP&~address'&>
.cindex "testing" "incoming SMTP"
.cindex "SMTP" "testing incoming"
.cindex "testing" "relay control"
&*Warning 1*&:
.cindex "RFC 1413"
-You can test features of the configuration that rely on ident (RFC 1413)
+You can test features of the configuration that rely on ident
+(&url(https://www.rfc-editor.org/rfc/rfc2487,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.
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(https://www.jetmore.org/john/code/swaks/,swaks).
+&url(https://www.jetmore.org/john/code/swaks/,swaks,swaks).
-.vitem &%-bhc%&&~<&'IP&~address'&>
-.oindex "&%-bhc%&"
+.cmdopt -bhc <&'IP&~address'&>
This option operates in the same way as &%-bh%&, except that address
verification callouts are performed if required. This includes consulting and
updating the callout cache database.
-.vitem &%-bi%&
-.oindex "&%-bi%&"
+.cmdopt -bi
.cindex "alias file" "building"
.cindex "building alias file"
.cindex "Sendmail compatibility" "&%-bi%& option"
&%-bi%& is a no-op.
. // Keep :help first, then the rest in alphabetical order
-.vitem &%-bI:help%&
-.oindex "&%-bI:help%&"
+.cmdopt -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
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%&"
+.cmdopt -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%&"
+.cmdopt -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
+useful for ManageSieve
+(&url(https://datatracker.ietf.org/doc/html/rfc5804.html,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.
-.vitem &%-bm%&
-.oindex "&%-bm%&"
+.cmdopt -bm
.cindex "local message reception"
This option runs an Exim receiving process that accepts an incoming,
locally-generated message on the standard input. The recipients are given as the
command arguments (except when &%-t%& is also present &-- see below). Each
-argument can be a comma-separated list of RFC 2822 addresses. This is the
+argument can be a comma-separated list of
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822) addresses.
+This is the
default option for selecting the overall action of an Exim call; it is assumed
if no other conflicting option is present.
suppressing this for special cases.
Policy checks on the contents of local messages can be enforced by means of
-the non-SMTP ACL. See chapter &<<CHAPACL>>& for details.
+the non-SMTP ACL. See section &<<SECnonSMTP>>& for details.
.cindex "return code" "for &%-bm%&"
The return code is zero if the message is successfully accepted. Otherwise, the
.cindex "&""From""& line"
.cindex "UUCP" "&""From""& line"
.cindex "Sendmail compatibility" "&""From""& line"
-of the message must be as defined in RFC 2822, except that, for
+of the message must be as defined in
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822),
+except that, for
compatibility with Sendmail and Smail, a line in one of the forms
.code
From sender Fri Jan 5 12:55 GMT 1997
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%&"
+.cmdopt -bmalware <&'filename'&>
.cindex "testing", "malware"
.cindex "malware scan test"
This debugging option causes Exim to scan the given file or directory
there are better tools for file-scanning. This option exists to help
administrators verify their Exim and AV scanner configuration.
-.vitem &%-bnq%&
-.oindex "&%-bnq%&"
+.cmdopt -bnq
.cindex "address qualification, suppressing"
By default, Exim automatically qualifies unqualified addresses (those
without domains) that appear in messages that are submitted locally (that
unqualified addresses in header lines are left alone.
-.vitem &%-bP%&
-.oindex "&%-bP%&"
+.cmdopt -bP
.cindex "configuration options" "extracting"
.cindex "options" "configuration &-- extracting"
If this option is given with no arguments, it causes the values of all Exim's
For the "-bP macro <name>" form, if no such macro is found
the exit status will be nonzero.
-.vitem &%-bp%&
-.oindex "&%-bp%&"
+.cmdopt -bp
.cindex "queue" "listing messages in"
.cindex "listing" "messages in the queue"
This option requests a listing of the contents of the mail queue on the
complete.
-.vitem &%-bpa%&
-.oindex "&%-bpa%&"
+.cmdopt -bpa
This option operates like &%-bp%&, but in addition it shows delivered addresses
that were generated from the original top level address(es) in each message by
alias or forwarding operations. These addresses are flagged with &"+D"& instead
of just &"D"&.
-.vitem &%-bpc%&
-.oindex "&%-bpc%&"
+.cmdopt -bpc
.cindex "queue" "count of messages on"
This option counts the number of messages in the queue, and writes the total
to the standard output. It is restricted to admin users, unless
&%queue_list_requires_admin%& is set false.
-.vitem &%-bpr%&
-.oindex "&%-bpr%&"
+.cmdopt -bpi
+.cindex queue "list of message IDs"
+This option operates like &%-bp%&, but only outputs message ids
+(one per line).
+
+
+.cmdopt -bpr
This option operates like &%-bp%&, but the output is not sorted into
chronological order of message arrival. This can speed it up when there are
lots of messages in the queue, and is particularly useful if the output is
going to be post-processed in a way that doesn't need the sorting.
-.vitem &%-bpra%&
-.oindex "&%-bpra%&"
+.cmdopt -bpra
This option is a combination of &%-bpr%& and &%-bpa%&.
-.vitem &%-bpru%&
-.oindex "&%-bpru%&"
+.cmdopt -bpri
+This option is a combination of &%-bpr%& and &%-bpi%&.
+
+.cmdopt -bpru
This option is a combination of &%-bpr%& and &%-bpu%&.
-.vitem &%-bpu%&
-.oindex "&%-bpu%&"
+.cmdopt -bpu
This option operates like &%-bp%& but shows only undelivered top-level
addresses for each message displayed. Addresses generated by aliasing or
forwarding are not shown, unless the message was deferred after processing by a
router with the &%one_time%& option set.
-.vitem &%-brt%&
-.oindex "&%-brt%&"
+.cmdopt -brt
.cindex "testing" "retry configuration"
.cindex "retry" "configuration testing"
This option is for testing retry rules, and it must be followed by up to three
Retry rule: *@haydn.comp.mus.example quota_3d F,1h,15m
.endd
-.vitem &%-brw%&
-.oindex "&%-brw%&"
+.cmdopt -brw
.cindex "testing" "rewriting"
.cindex "rewriting" "testing"
This option is for testing address rewriting rules, and it must be followed by
would be rewritten for each possible place it might appear. See chapter
&<<CHAPrewrite>>& for further details.
-.vitem &%-bS%&
-.oindex "&%-bS%&"
+.cmdopt -bS
.cindex "SMTP" "batched incoming"
.cindex "batched SMTP input"
This option is used for batched SMTP input, which is an alternative interface
provoked if the terminating dot is missing. A further message may then follow.
As for other local message submissions, the contents of incoming batch SMTP
-messages can be checked using the non-SMTP ACL (see chapter &<<CHAPACL>>&).
+messages can be checked using the non-SMTP ACL (see section &<<SECnonSMTP>>&).
Unqualified addresses are automatically qualified using &%qualify_domain%& and
&%qualify_recipient%&, as appropriate, unless the &%-bnq%& option is used.
Some other SMTP commands are recognized in the input. HELO and EHLO act
-as RSET; VRFY, EXPN, ETRN, and HELP act as NOOP;
+as RSET; VRFY, EXPN, ETRN, ATRN, and HELP act as NOOP;
QUIT quits, ignoring the rest of the standard input.
.cindex "return code" "for &%-bS%&"
More details of input using batched SMTP are given in section
&<<SECTincomingbatchedSMTP>>&.
-.vitem &%-bs%&
-.oindex "&%-bs%&"
+.cmdopt -bs
.cindex "SMTP" "local input"
.cindex "local SMTP input"
This option causes Exim to accept one or more messages by reading SMTP commands
Exim behaves in exactly the same way as it does when receiving a message via
the listening daemon.
-.vitem &%-bt%&
-.oindex "&%-bt%&"
+.cmdopt -bt
.cindex "testing" "addresses"
.cindex "address" "testing"
This option runs Exim in address testing mode, in which each argument is taken
those conditions using &%-bt%&. The &%-N%& option provides a possible way of
doing such tests.
-.vitem &%-bV%&
-.oindex "&%-bV%&"
+.cmdopt -bV
.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.
realistic testing is needed. The &%-bh%& and &%-N%& options provide more
dynamic testing facilities.
-.vitem &%-bv%&
-.oindex "&%-bv%&"
+.cmdopt -bv
.cindex "verifying address" "using &%-bv%&"
.cindex "address" "verification"
This option runs Exim in address verification mode, in which each argument is
sender when running &%-bv%& tests. Without it, the sender is assumed to be the
calling user at the default qualifying domain.
-.vitem &%-bvs%&
-.oindex "&%-bvs%&"
+.cmdopt -bvs
This option acts like &%-bv%&, but verifies the address as a sender rather
than a recipient address. This affects any rewriting and qualification that
might happen.
-.vitem &%-bw%&
-.oindex "&%-bw%&"
+.cmdopt -bw
.cindex "daemon"
.cindex "inetd"
.cindex "inetd" "wait mode"
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%&"
+.cmdopt -C <&'filelist'&>
.cindex "configuration file" "alternate"
.cindex "CONFIGURE_FILE"
.cindex "alternate configuration file"
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
-&`deliver `& general delivery logic
-&`dns `& DNS lookups (see also resolver)
-&`dnsbl `& DNS black list (aka RBL) code
-&`exec `& arguments for &[execv()]& calls
-&`expand `& detailed debugging for string expansions
-&`filter `& filter handling
-&`hints_lookup `& hints data lookups
-&`host_lookup `& all types of name-to-IP address handling
-&`ident `& ident lookup
-&`interface `& lists of local interfaces
-&`lists `& matching things in lists
-&`load `& system load checks
-&`local_scan `& can be used by &[local_scan()]& (see chapter &&&
- &<<CHAPlocalscan>>&)
-&`lookup `& general lookup code and all lookups
-&`memory `& memory handling
-&`noutf8 `& modifier: avoid UTF-8 line-drawing
-&`pid `& modifier: add pid to debug output lines
-&`process_info `& setting info for the process log
-&`queue_run `& queue runs
-&`receive `& general message reception logic
-&`resolver `& turn on the DNS resolver's debugging output
-&`retry `& retry handling
-&`rewrite `& address rewriting
-&`route `& address routing
-&`timestamp `& modifier: add timestamp to debug output lines
-&`tls `& TLS logic
-&`transport `& transports
-&`uid `& changes of uid/gid and looking up uid/gid
-&`verify `& address verification logic
-&`all `& almost all of the above (see below), and also &%-v%&
-.endd
+.itable none 0 0 2 20* left 80* left
+.irow acl "ACL interpretation"
+.irow auth "authenticators"
+.irow deliver "general delivery logic"
+.irow dns "DNS lookups (see also resolver)"
+.irow dnsbl "DNS black list (aka RBL) code"
+.irow exec "arguments for &[execv()]& calls"
+.irow expand "detailed debugging for string expansions"
+.irow filter "filter handling"
+.irow hints_lookup "hints data lookups"
+.irow host_lookup "all types of name-to-IP address handling"
+.irow ident "ident lookup"
+.irow interface "lists of local interfaces"
+.irow lists "matching things in lists"
+.irow load "system load checks"
+.irow local_scan "can be used by &[local_scan()]& (see chapter &&&
+ &<<CHAPlocalscan>>&)"
+.irow lookup "general lookup code and all lookups"
+.irow memory "memory handling"
+.irow noutf8 "modifier: avoid UTF-8 line-drawing"
+.irow pid "modifier: add pid to debug output lines"
+.irow process_info "setting info for the process log"
+.irow queue_run "queue runs"
+.irow receive "general message reception logic"
+.irow resolver "turn on the DNS resolver's debugging output"
+.irow retry "retry handling"
+.irow rewrite "address rewriting""
+.irow route "address routing"
+.irow timestamp "modifier: add timestamp to debug output lines"
+.irow tls "TLS logic"
+.irow transport "transports"
+.irow uid "changes of uid/gid and looking up uid/gid"
+.irow verify "address verification logic"
+.irow all "almost all of the above (see below), and also &%-v%&"
+.endtable
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`&
subprocesses that the daemon creates. Thus, it is useful for monitoring the
behaviour of the daemon without creating as much output as full debugging does.
-.vitem &%-dropcr%&
-.oindex "&%-dropcr%&"
+.cmdopt -dropcr
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>>&.
-.vitem &%-E%&
-.oindex "&%-E%&"
+.cmdopt -E
.cindex "bounce message" "generating"
This option specifies that an incoming message is a locally-generated delivery
failure report. It is used internally by Exim when handling delivery failures
example, the &%vacation%& program uses &%-eq%&. Exim treats all options of the
form &%-e%&&'x'& as synonymous with the corresponding &%-oe%&&'x'& options.
-.vitem &%-F%&&~<&'string'&>
-.oindex "&%-F%&"
+.cmdopt -F <&'string'&>
.cindex "sender" "name"
.cindex "name" "of sender"
This option sets the sender's full name for use when a locally-generated
their &'gecos'& entries, no security considerations are involved. White space
between &%-F%& and the <&'string'&> is optional.
-.vitem &%-f%&&~<&'address'&>
-.oindex "&%-f%&"
+.cmdopt -f <&'address'&>
.cindex "sender" "address"
.cindex "address" "sender"
.cindex "trusted users"
&"From&~"& line in the message &-- see the description of &%-bm%& above &-- but
if &%-f%& is also present, it overrides &"From&~"&.
-.vitem &%-G%&
-.oindex "&%-G%&"
+.cmdopt -G
.cindex "submission fixups, suppressing (command-line)"
This option is equivalent to an ACL applying:
.code
As this affects audit information, the caller must be a trusted user to use
this option.
-.vitem &%-h%&&~<&'number'&>
-.oindex "&%-h%&"
+.cmdopt -h <&'number'&>
.cindex "Sendmail compatibility" "&%-h%& option ignored"
This option is accepted for compatibility with Sendmail, but has no effect. (In
Sendmail it overrides the &"hop count"& obtained by counting &'Received:'&
headers.)
-.vitem &%-i%&
-.oindex "&%-i%&"
+.cmdopt -i
.cindex "Solaris" "&'mail'& command"
.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'&
-command in Solaris 2.4 uses it. See also &%-ti%&.
+line by itself should not terminate an incoming, non-SMTP message.
+Solaris 2.4 (SunOS 5.4) Sendmail has a similar &%-i%& processing option
+&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf),
+p. 1M-529), and therefore a &%-oi%& command line option, which both are used
+by its &'mailx'& command.
-.vitem &%-L%&&~<&'tag'&>
-.oindex "&%-L%&"
+.cmdopt -L <&'tag'&>
.cindex "syslog" "process name; set with flag"
This option is equivalent to setting &%syslog_processname%& in the config
file and setting &%log_file_path%& to &`syslog`&.
The tag should not be longer than 32 characters.
-.vitem &%-M%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
-.oindex "&%-M%&"
+.cmdopt -M <&'message&~id'&>&~<&'message&~id'&>&~...
.cindex "forcing delivery"
.cindex "delivery" "forcing attempt"
.cindex "frozen messages" "forcing delivery"
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.
-.vitem &%-Mar%&&~<&'message&~id'&>&~<&'address'&>&~<&'address'&>&~...
-.oindex "&%-Mar%&"
+.cmdopt -Mar <&'message&~id'&>&~<&'address'&>&~<&'address'&>&~...
.cindex "message" "adding recipients"
.cindex "recipient" "adding"
This option requests Exim to add the addresses to the list of recipients of the
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'&>&&&
+ &~<&'host&~IP'&>&&&
+ &~<&'sequence&~number'&>&&&
&~<&'message&~id'&>"
.oindex "&%-MC%&"
.cindex "SMTP" "passed connection"
given in chapter &<<CHAPSMTP>>&. This must be the final option, and the caller
must be root or the Exim user in order to use it.
-.vitem &%-MCA%&
-.oindex "&%-MCA%&"
+.cmdopt -MCA
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option. It signifies that the
connection to the remote host has been authenticated.
-.vitem &%-MCD%&
-.oindex "&%-MCD%&"
+.cmdopt -MCD
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option. It signifies that the
remote host supports the ESMTP &_DSN_& extension.
-.new
-.vitem &%-MCd%&
-.oindex "&%-MCd%&"
+.cmdopt -MCd
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-d%& option
to pass on an information string on the purpose of the process.
-.wen
-.vitem &%-MCG%&&~<&'queue&~name'&>
-.oindex "&%-MCG%&"
+.cmdopt -MCG <&'queue&~name'&>
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option. It signifies that an
alternate queue is used, named by the following argument.
-.vitem &%-MCK%&
-.oindex "&%-MCK%&"
+.cmdopt -MCK
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option. It signifies that a
remote host supports the ESMTP &_CHUNKING_& extension.
-.vitem &%-MCP%&
-.oindex "&%-MCP%&"
+.cmdopt -MCL
+This option is not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MC%& option. It signifies that the server to
+which Exim is connected advertised limits on numbers of mails, recipients or
+recipient domains.
+The limits are given by the following three arguments.
+
+.cmdopt -MCP
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option. It signifies that the server to
which Exim is connected supports pipelining.
-.vitem &%-MCQ%&&~<&'process&~id'&>&~<&'pipe&~fd'&>
-.oindex "&%-MCQ%&"
+.cmdopt -MCp
+This option is not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MC%& option. It signifies that the connection
+t a remote server is via a SOCKS proxy, using addresses and ports given by
+the following four arguments.
+
+.cmdopt -MCQ <&'process&~id'&>&~<&'pipe&~fd'&>
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option when the original delivery was
started by a queue runner. It passes on the process id of the queue runner,
signals the final completion of the sequence of processes that are passing
messages through the same SMTP connection.
-.vitem &%-MCS%&
-.oindex "&%-MCS%&"
+.cmdopt -MCq <&'recipient&~address'&>&~<&'size'&>
+This option is not intended for use by external callers. It is used internally
+by Exim to implement quota checking for local users.
+
+.cmdopt -MCS
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
ESMTP SIZE option should be used on messages delivered down the existing
connection.
-.vitem &%-MCT%&
-.oindex "&%-MCT%&"
+.cmdopt -MCT
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
host to which Exim is connected supports TLS encryption.
-.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
-.oindex "&%-MCt%&"
+.vitem &%-MCr%&&~<&'SNI'&> &&&
+ &%-MCs%&&~<&'SNI'&>
+.oindex "&%-MCs%&"
+.oindex "&%-MCr%&"
+These options are not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MCt%& option, and passes on the fact that
+a TLS Server Name Indication was sent as part of the channel establishment.
+The argument gives the SNI string.
+The "r" variant indicates a DANE-verified connection.
+
+.cmdopt -MCt <&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
connection is being proxied by a parent process for handling TLS encryption.
The arguments give the local address and port being proxied, and the TLS cipher.
-.vitem &%-Mc%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
-.oindex "&%-Mc%&"
+.cmdopt -Mc <&'message&~id'&>&~<&'message&~id'&>&~...
.cindex "hints database" "not overridden by &%-Mc%&"
.cindex "delivery" "manually started &-- not forced"
This option requests Exim to run a delivery attempt on each message, in turn,
&%-q%& with a message id argument. A distinction between queue run deliveries
and other deliveries is made in one or two places.
-.vitem &%-Mes%&&~<&'message&~id'&>&~<&'address'&>
-.oindex "&%-Mes%&"
+.cmdopt -Mes <&'message&~id'&>&~<&'address'&>
.cindex "message" "changing sender"
.cindex "sender" "changing"
This option requests Exim to change the sender address in the message to the
is active (in the middle of a delivery attempt), its status is not altered.
This option can be used only by an admin user.
-.vitem &%-Mf%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
-.oindex "&%-Mf%&"
+.cmdopt -Mf <&'message&~id'&>&~<&'message&~id'&>&~...
.cindex "freezing messages"
.cindex "message" "manually freezing"
This option requests Exim to mark each listed message as &"frozen"&. This
attempt), their status is not altered. This option can be used only by an admin
user.
-.vitem &%-Mg%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
-.oindex "&%-Mg%&"
+.cmdopt -Mg <&'message&~id'&>&~<&'message&~id'&>&~...
.cindex "giving up on messages"
.cindex "message" "abandoning delivery attempts"
.cindex "delivery" "abandoning further attempts"
This option requests Exim to give up trying to deliver the listed messages,
including any that are frozen. However, if any of the messages are active,
their status is not altered. For non-bounce messages, a delivery error message
-is sent to the sender, containing the text &"cancelled by administrator"&.
+is sent to the sender.
Bounce messages are just discarded. This option can be used only by an admin
user.
-.vitem &%-MG%&&~<&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~...
-.oindex "&%-MG%&"
+.cmdopt -MG <&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~...
.cindex queue named
.cindex "named queues" "moving messages"
.cindex "queue" "moving messages"
If the messages are not currently located in the default queue,
a &%-qG<name>%& option will be required to define the source queue.
-.vitem &%-Mmad%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
-.oindex "&%-Mmad%&"
+.cmdopt -Mmad <&'message&~id'&>&~<&'message&~id'&>&~...
.cindex "delivery" "cancelling all"
This option requests Exim to mark all the recipient addresses in the messages
as already delivered (&"mad"& for &"mark all delivered"&). However, if any
message is active (in the middle of a delivery attempt), its status is not
altered. This option can be used only by an admin user.
-.vitem &%-Mmd%&&~<&'message&~id'&>&~<&'address'&>&~<&'address'&>&~...
-.oindex "&%-Mmd%&"
+.cmdopt -Mmd <&'message&~id'&>&~<&'address'&>&~<&'address'&>&~...
.cindex "delivery" "cancelling by address"
.cindex "recipient" "removing"
.cindex "removing recipients"
(in the middle of a delivery attempt), its status is not altered. This option
can be used only by an admin user.
-.vitem &%-Mrm%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
-.oindex "&%-Mrm%&"
+.cmdopt -Mrm <&'message&~id'&>&~<&'message&~id'&>&~...
.cindex "removing messages"
.cindex "abandoning mail"
.cindex "message" "manually discarding"
. a bounce message.
. .wen
-.vitem &%-Mset%&&~<&'message&~id'&>
-.oindex "&%-Mset%&"
+.cmdopt -Mset <&'message&~id'&>
.cindex "testing" "string expansion"
.cindex "expansion" "testing"
This option is useful only in conjunction with &%-be%& (that is, when testing
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%&"
+.cmdopt -Mt <&'message&~id'&>&~<&'message&~id'&>&~...
.cindex "thawing messages"
.cindex "unfreezing messages"
.cindex "frozen messages" "thawing"
messages are active, their status is not altered. This option can be used only
by an admin user.
-.vitem &%-Mvb%&&~<&'message&~id'&>
-.oindex "&%-Mvb%&"
+.cmdopt -Mvb <&'message&~id'&>
.cindex "listing" "message body"
.cindex "message" "listing body of"
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%&"
+.cmdopt -Mvc <&'message&~id'&>
.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.
+be written to the standard output in
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+format. This option can be used only by an admin user.
-.vitem &%-Mvh%&&~<&'message&~id'&>
-.oindex "&%-Mvh%&"
+.cmdopt -Mvh <&'message&~id'&>
.cindex "listing" "message headers"
.cindex "header lines" "listing"
.cindex "message" "listing header lines"
This option causes the contents of the message headers (-H) spool file to be
written to the standard output. This option can be used only by an admin user.
-.vitem &%-Mvl%&&~<&'message&~id'&>
-.oindex "&%-Mvl%&"
+.cmdopt -Mvl <&'message&~id'&>
.cindex "listing" "message log"
.cindex "message" "listing message log"
This option causes the contents of the message log spool file to be written to
the standard output. This option can be used only by an admin user.
-.vitem &%-m%&
-.oindex "&%-m%&"
-This is apparently a synonym for &%-om%& that is accepted by Sendmail, so Exim
-treats it that way too.
+.cmdopt -m
+This is a synonym for &%-om%& that is accepted by Sendmail
+(&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf)
+p. 1M-258), so Exim treats it that way too.
-.vitem &%-N%&
-.oindex "&%-N%&"
+.cmdopt -N
.cindex "debugging" "&%-N%& option"
.cindex "debugging" "suppressing delivery"
This is a debugging option that inhibits delivery of a message at the transport
the message, and applies to any subsequent delivery attempts that may happen
for that message.
-.vitem &%-n%&
-.oindex "&%-n%&"
+.cmdopt -n
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 makes the output more terse (suppresses
option names, environment values and config pretty printing).
-.vitem &%-O%&&~<&'data'&>
-.oindex "&%-O%&"
+.cmdopt -O <&'data'&>
This option is interpreted by Sendmail to mean &`set option`&. It is ignored by
Exim.
-.vitem &%-oA%&&~<&'file&~name'&>
-.oindex "&%-oA%&"
+.cmdopt -oA <&'file&~name'&>
.cindex "Sendmail compatibility" "&%-oA%& option"
This option is used by Sendmail in conjunction with &%-bi%& to specify an
alternative alias filename. Exim handles &%-bi%& differently; see the
description above.
-.vitem &%-oB%&&~<&'n'&>
-.oindex "&%-oB%&"
+.cmdopt -oB <&'n'&>
.cindex "SMTP" "passed connection"
.cindex "SMTP" "multiple deliveries"
.cindex "multiple SMTP deliveries"
be delivered down one SMTP connection, overriding the value set in any &(smtp)&
transport. If <&'n'&> is omitted, the limit is set to 1.
-.vitem &%-odb%&
-.oindex "&%-odb%&"
+.cmdopt -odb
.cindex "background delivery"
.cindex "delivery" "in the background"
This option applies to all modes in which Exim accepts incoming messages,
overrides it if &%queue_only_override%& is set true, which is the default
setting. If &%queue_only_override%& is set false, &%-odb%& has no effect.
-.vitem &%-odf%&
-.oindex "&%-odf%&"
+.cmdopt -odf
.cindex "foreground delivery"
.cindex "delivery" "in the foreground"
This option requests &"foreground"& (synchronous) delivery when Exim has
restricted configuration that never queues messages.
-.vitem &%-odi%&
-.oindex "&%-odi%&"
+.cmdopt -odi
This option is synonymous with &%-odf%&. It is provided for compatibility with
Sendmail.
-.vitem &%-odq%&
-.oindex "&%-odq%&"
+.cmdopt -odq
.cindex "non-immediate delivery"
.cindex "delivery" "suppressing immediate"
.cindex "queueing incoming messages"
conditions. This option overrides all of them and also &%-odqs%&. It always
forces queueing.
-.vitem &%-odqs%&
-.oindex "&%-odqs%&"
+.cmdopt -odqs
.cindex "SMTP" "delaying delivery"
.cindex "first pass routing"
This option is a hybrid between &%-odb%&/&%-odi%& and &%-odq%&.
configuration option has the same effect for specific domains. See also the
&%-qq%& option.
-.vitem &%-oee%&
-.oindex "&%-oee%&"
+.cmdopt -oee
.cindex "error" "reporting"
If an error is detected while a non-SMTP message is being received (for
example, a malformed address), the error is reported to the sender in a mail
is that the original message has no recipients, or 1 for any other error.
This is the default &%-oe%&&'x'& option if Exim is called as &'rmail'&.
-.vitem &%-oem%&
-.oindex "&%-oem%&"
+.cmdopt -oem
.cindex "error" "reporting"
.cindex "return code" "for &%-oem%&"
This is the same as &%-oee%&, except that Exim always exits with a non-zero
return code, whether or not the error message was successfully sent.
This is the default &%-oe%&&'x'& option, unless Exim is called as &'rmail'&.
-.vitem &%-oep%&
-.oindex "&%-oep%&"
+.cmdopt -oep
.cindex "error" "reporting"
If an error is detected while a non-SMTP message is being received, the
error is reported by writing a message to the standard error file (stderr).
.cindex "return code" "for &%-oep%&"
The return code is 1 for all errors.
-.vitem &%-oeq%&
-.oindex "&%-oeq%&"
+.cmdopt -oeq
.cindex "error" "reporting"
This option is supported for compatibility with Sendmail, but has the same
effect as &%-oep%&.
-.vitem &%-oew%&
-.oindex "&%-oew%&"
+.cmdopt -oew
.cindex "error" "reporting"
This option is supported for compatibility with Sendmail, but has the same
effect as &%-oem%&.
-.vitem &%-oi%&
-.oindex "&%-oi%&"
+.cmdopt -oi
.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
lines that start with a dot. This option is set by default if Exim is called as
&'rmail'&. See also &%-ti%&.
-.vitem &%-oitrue%&
-.oindex "&%-oitrue%&"
+.cmdopt -oitrue
This option is treated as synonymous with &%-oi%&.
-.vitem &%-oMa%&&~<&'host&~address'&>
-.oindex "&%-oMa%&"
+.cmdopt -oMa <&'host&~address'&>
.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
are present on the command line, the sender host IP address is taken from
whichever one is last.
-.vitem &%-oMaa%&&~<&'name'&>
-.oindex "&%-oMaa%&"
+.cmdopt -oMaa <&'name'&>
.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
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%&"
+.cmdopt -oMai <&'string'&>
.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).
where there is no default) for messages from local sources. See chapter
&<<CHAPSMTPAUTH>>& for a discussion of authenticated ids.
-.vitem &%-oMas%&&~<&'address'&>
-.oindex "&%-oMas%&"
+.cmdopt -oMas <&'address'&>
.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
specified on a MAIL command overrides this value. See chapter
&<<CHAPSMTPAUTH>>& for a discussion of authenticated senders.
-.vitem &%-oMi%&&~<&'interface&~address'&>
-.oindex "&%-oMi%&"
+.cmdopt -oMi <&'interface&~address'&>
.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
&$received_ip_address$& and the port number, if present, in &$received_port$&.
-.vitem &%-oMm%&&~<&'message&~reference'&>
-.oindex "&%-oMm%&"
+.cmdopt -oMm <&'message&~reference'&>
.cindex "message reference" "message reference, specifying for local message"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMm%&
option sets the message reference, e.g. message-id, and is logged during
The message reference is the message-id of the original message for which Exim
is sending the bounce.
-.vitem &%-oMr%&&~<&'protocol&~name'&>
-.oindex "&%-oMr%&"
+.cmdopt -oMr <&'protocol&~name'&>
.cindex "protocol, specifying for local message"
.vindex "&$received_protocol$&"
See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMr%&
one of those same names. For &%-bS%& (batched SMTP) however, the protocol can
be set by &%-oMr%&. Repeated use of this option is not supported.
-.vitem &%-oMs%&&~<&'host&~name'&>
-.oindex "&%-oMs%&"
+.cmdopt -oMs <&'host&~name'&>
.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
uses the name it is given.
-.vitem &%-oMt%&&~<&'ident&~string'&>
-.oindex "&%-oMt%&"
+.cmdopt -oMt <&'ident&~string'&>
.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, except when &%-bh%& is
used, when there is no default.
-.vitem &%-om%&
-.oindex "&%-om%&"
+.cmdopt -om
.cindex "Sendmail compatibility" "&%-om%& option ignored"
In Sendmail, this option means &"me too"&, indicating that the sender of a
message should receive a copy of the message if the sender appears in an alias
expansion. Exim always does this, so the option does nothing.
-.vitem &%-oo%&
-.oindex "&%-oo%&"
+.cmdopt -oo
.cindex "Sendmail compatibility" "&%-oo%& option ignored"
This option is ignored. In Sendmail it specifies &"old style headers"&,
whatever that means.
-.vitem &%-oP%&&~<&'path'&>
-.oindex "&%-oP%&"
+.cmdopt -oP <&'path'&>
.cindex "pid (process id)" "of daemon"
.cindex "daemon" "process id (pid)"
This option is useful only in conjunction with &%-bd%& or &%-q%& with a time
without &%-bd%&, this is the only way of causing Exim to write a pid file,
because in those cases, the normal pid file is not used.
-.new
-.vitem &%-oPX%&
-.oindex "&%-oPX%&"
+.cmdopt -oPX
.cindex "pid (process id)" "of daemon"
.cindex "daemon" "process id (pid)"
This option is not intended for general use.
The daemon uses it when terminating due to a SIGTEM, possibly in
combination with &%-oP%&&~<&'path'&>.
It causes the pid file to be removed.
-.wen
-.vitem &%-or%&&~<&'time'&>
-.oindex "&%-or%&"
+.cmdopt -or <&'time'&>
.cindex "timeout" "for non-SMTP input"
This option sets a timeout value for incoming non-SMTP messages. If it is not
set, Exim will wait forever for the standard input. The value can also be set
by the &%receive_timeout%& option. The format used for specifying times is
described in section &<<SECTtimeformat>>&.
-.vitem &%-os%&&~<&'time'&>
-.oindex "&%-os%&"
+.cmdopt -os <&'time'&>
.cindex "timeout" "for SMTP input"
.cindex "SMTP" "input timeout"
This option sets a timeout value for incoming SMTP messages. The timeout
the &%smtp_receive_timeout%& option; it defaults to 5 minutes. The format used
for specifying times is described in section &<<SECTtimeformat>>&.
-.vitem &%-ov%&
-.oindex "&%-ov%&"
+.cmdopt -ov
This option has exactly the same effect as &%-v%&.
-.vitem &%-oX%&&~<&'number&~or&~string'&>
-.oindex "&%-oX%&"
+.cmdopt -oX <&'number&~or&~string'&>
.cindex "TCP/IP" "setting listening ports"
.cindex "TCP/IP" "setting listening interfaces"
.cindex "port" "receiving TCP/IP"
in chapter &<<CHAPinterfaces>>&. When &%-oX%& is used to start a daemon, no pid
file is written unless &%-oP%& is also present to specify a pid filename.
-.vitem &%-pd%&
-.oindex "&%-pd%&"
+.cmdopt -oY
+.cindex "daemon notifier socket"
+This option controls the creation of an inter-process communications endpoint
+by the Exim daemon.
+It is only relevant when the &%-bd%& (start listening daemon) option is also
+given.
+Normally the daemon creates this socket, unless a &%-oX%& and &*no*& &%-oP%&
+option is also present.
+If this option is given then the socket will not be created. This is required
+if the system is running multiple daemons, in which case it should
+be used on all.
+The features supported by the socket will not be available in such cases.
+
+The socket is currently used for
+.ilist
+fast ramp-up of queue runner processes
+.next
+caching compiled regexes
+.next
+obtaining a current queue size
+.endlist
+
+.cmdopt -pd
.cindex "Perl" "starting the interpreter"
This option applies when an embedded Perl interpreter is linked with Exim (see
chapter &<<CHAPperl>>&). It overrides the setting of the &%perl_at_start%&
option, forcing the starting of the interpreter to be delayed until it is
needed.
-.vitem &%-ps%&
-.oindex "&%-ps%&"
+.cmdopt -ps
.cindex "Perl" "starting the interpreter"
This option applies when an embedded Perl interpreter is linked with Exim (see
chapter &<<CHAPperl>>&). It overrides the setting of the &%perl_at_start%&
or &`s`& using this option (but that does not seem a real limitation).
Repeated use of this option is not supported.
-.vitem &%-q%&
-.oindex "&%-q%&"
+.cmdopt -q
.cindex "queue runner" "starting manually"
This option is normally restricted to admin users. However, there is a
configuration option called &%prod_requires_admin%& which can be set false to
.cindex "queue" "routing"
.cindex "routing" "whole queue before delivery"
.cindex "first pass routing"
+.cindex "queue runner" "two phase"
An option starting with &%-qq%& requests a two-stage queue run. In the first
stage, the queue is scanned as if the &%queue_smtp_domains%& option matched
every domain. Addresses are routed, local deliveries happen, but no remote
transports are run.
-.new
Performance will be best if the &%queue_run_in_order%& option is false.
-.wen
+If that is so and
+the &%queue_fast_ramp%& option is true
+and a daemon-notifier socket is available
+then in the first phase of the run,
+once a threshold number of messages are routed for a given host,
+a delivery process is forked in parallel with the rest of the scan.
.cindex "hints database" "remembering routing"
The hints database that remembers which messages are waiting for specific hosts
-is updated, as if delivery to those hosts had been deferred. After this is
-complete, a second, normal queue scan happens, with routing and delivery taking
-place as normal. Messages that are routed to the same host should mostly be
+is updated, as if delivery to those hosts had been deferred.
+
+After the first queue scan complete,
+a second, normal queue scan is done, with routing and delivery taking
+place as normal.
+Messages that are routed to the same host should mostly be
delivered down a single SMTP
.cindex "SMTP" "passed connection"
.cindex "SMTP" "multiple deliveries"
.cindex "multiple SMTP deliveries"
connection because of the hints that were set up during the first queue scan.
-This option may be useful for hosts that are connected to the Internet
+
+Two-phase queue runs should be used on systems which, even intermittently,
+have a large queue (such as mailing-list operators).
+They may also be useful for hosts that are connected to the Internet
intermittently.
.vitem &%-q[q]i...%&
Such a daemon listens for incoming SMTP calls, and also starts a queue runner
process every 30 minutes.
+.cindex "named queues" "queue runners"
+It is possible to set up runners for multiple named queues within one daemon,
+For example:
+.code
+exim -qGhipri/2m -q10m -qqGmailinglist/1h
+.endd
+
When a daemon is started by &%-q%& with a time value, but without &%-bd%&, no
pid file is written unless one is explicitly requested by the &%-oP%& option.
The &%-R%& option makes it straightforward to initiate delivery of all messages
to a given domain after a host has been down for some time. When the SMTP
-command ETRN is accepted by its ACL (see chapter &<<CHAPACL>>&), its default
+command ETRN is accepted by its ACL (see section &<<SECTETRN>>&), its default
effect is to run Exim with the &%-R%& option, but it can be configured to run
an arbitrary command instead.
-.vitem &%-r%&
-.oindex "&%-r%&"
+.cmdopt -r
This is a documented (for Sendmail) obsolete alternative name for &%-f%&.
.vitem &%-S%&<&'rsflags'&>&~<&'string'&>
conditions must be met for a message to be selected. If either of the options
has &'f'& or &'ff'& in its flags, the associated action is taken.
-.vitem &%-Tqt%&&~<&'times'&>
-.oindex "&%-Tqt%&"
+.cmdopt -Tqt <&'times'&>
This is an option that is exclusively for use by the Exim testing suite. It is not
recognized when Exim is run normally. It allows for the setting up of explicit
&"queue times"& so that various warning/retry features can be tested.
-.vitem &%-t%&
-.oindex "&%-t%&"
+.cmdopt -t
.cindex "recipient" "extracting from header lines"
-.cindex "&'Bcc:'& header line"
-.cindex "&'Cc:'& header line"
-.cindex "&'To:'& header line"
+.chindex Bcc:
+.chindex Cc:
+.chindex To:
When Exim is receiving a locally-generated, non-SMTP message on its standard
input, the &%-t%& option causes the recipients of the message to be obtained
from the &'To:'&, &'Cc:'&, and &'Bcc:'& header lines in the message instead of
with Sendmail and other MTAs. (Prior to release 4.20, Exim gave an error if
&%-t%& was used in conjunction with &%Resent-%& header lines.)
-RFC 2822 talks about different sets of &%Resent-%& header lines (for when a
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+talks about different sets of &%Resent-%& header lines (for when a
message is resent several times). The RFC also specifies that they should be
added at the front of the message, and separated by &'Received:'& lines. It is
not at all clear how &%-t%& should operate in the present of multiple sets,
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%&
-.oindex "&%-ti%&"
+.cmdopt -ti
This option is exactly equivalent to &%-t%& &%-i%&. It is provided for
compatibility with Sendmail.
-.vitem &%-tls-on-connect%&
-.oindex "&%-tls-on-connect%&"
+.cmdopt -tls-on-connect
.cindex "TLS" "use without STARTTLS"
.cindex "TLS" "automatic start"
This option is available when Exim is compiled with TLS support. It forces all
&<<CHAPTLS>>& for further details.
-.vitem &%-U%&
-.oindex "&%-U%&"
+.cmdopt -U
.cindex "Sendmail compatibility" "&%-U%& option ignored"
Sendmail uses this option for &"initial message submission"&, and its
documentation states that in future releases, it may complain about
syntactically invalid messages rather than fixing them when this flag is not
set. Exim ignores this option.
-.vitem &%-v%&
-.oindex "&%-v%&"
+.cmdopt -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
receiving and delivering a message, and if an SMTP connection is made, the SMTP
selectors are shown with each log line. If none are shown, the logging is
unconditional.
-.vitem &%-x%&
-.oindex "&%-x%&"
+.cmdopt -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"&).
It sets &%-x%& when calling the MTA from its &%mail%& command. Exim ignores
this option.
-.vitem &%-X%&&~<&'logfile'&>
-.oindex "&%-X%&"
+.cmdopt -X <&'logfile'&>
This option is interpreted by Sendmail to cause debug information to be sent
to the named file. It is ignored by Exim.
-.vitem &%-z%&&~<&'log-line'&>
-.oindex "&%-z%&"
+.cmdopt -z <&'log-line'&>
This option writes its argument to Exim's logfile.
Use is restricted to administrators; the intent is for operational notes.
Quotes should be used to maintain a multi-word item as a single argument,
&` _DRIVER_ROUTER_* `& router drivers
&` _DRIVER_TRANSPORT_* `& transport drivers
&` _DRIVER_AUTHENTICATOR_* `& authenticator drivers
+&` _EXP_COND_* `& expansion conditions
+&` _EXP_ITEM_* `& expansion items
+&` _EXP_OP_* `& expansion operators
+&` _EXP_VAR_* `& expansion variables
&` _LOG_* `& log_selector values
&` _OPT_MAIN_* `& main config options
&` _OPT_ROUTERS_* `& generic router options
contains two IP addresses, the IPv4 address 127.0.0.1 and the IPv6 address ::1.
&*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
+list items, it is not ignored when parsing the list. The spaces around the first
+colon in the example above are necessary. If they were not there, the list would
be interpreted as the two items 127.0.0.1:: and 1.
-.section "Changing list separators" "SECTlistsepchange"
+.subsection "Changing list separators" "SECTlistsepchange"
.cindex "list separator" "changing"
.cindex "IPv6" "addresses in lists"
Doubling colons in IPv6 addresses is an unwelcome chore, so a mechanism was
-.section "Empty items in lists" "SECTempitelis"
+.subsection "Empty items in lists" "SECTempitelis"
.cindex "list" "empty item in"
An empty item at the end of a list is always ignored. In other words, trailing
separator characters are ignored. Thus, the list in
to your domain (MX delivery) for various good reasons (eg, ability to impose
much saner TLS protocol and ciphersuite requirements without unintended
consequences).
-RFC 6409 (previously 4409) specifies use of port 587 for SMTP Submission,
+&url(https://www.rfc-editor.org/rfc/rfc6409,RFC 6409) (previously 4409)
+specifies use of port 587 for SMTP Submission,
which uses STARTTLS, so this is the &"submission"& port.
-RFC 8314 specifies use of port 465 as the &"submissions"& protocol,
+&url(https://www.rfc-editor.org/rfc/rfc8314,RFC 8314)
+specifies use of port 465 as the &"submissions"& protocol,
which should be used in preference to 587.
You should also consider deploying SRV records to help clients find
these ports.
because not all DNS reverse zones are maintained, and sometimes DNS servers are
unreachable.
-The next two lines are concerned with &'ident'& callbacks, as defined by RFC
-1413 (hence their names):
+The next two lines are concerned with &'ident'& callbacks, as defined by
+&url(https://www.rfc-editor.org/rfc/rfc1413,RFC 1413)
+(hence their names):
.code
rfc1413_hosts = *
rfc1413_query_timeout = 0s
.endd
In an ideal world everybody follows the standards. For non-ASCII
-messages RFC 2047 is a standard, allowing a maximum line length of 76
+messages &url(https://www.rfc-editor.org/rfc/rfc2048,RFC 2047)
+is a standard, allowing a maximum line length of 76
characters. Exim adheres that standard and won't process messages which
violate this standard. (Even ${rfc2047:...} expansions will fail.)
In particular, the Exim maintainers have had multiple reports of
imposes a security risk (e.g. PATH). There are two lists:
&%keep_environment%& for the variables to import as they are, and
&%add_environment%& for variables we want to set to a fixed value.
-Note that TZ is handled separately, by the $%timezone%$ runtime
+Note that TZ is handled separately, by the &%timezone%& runtime
option and by the TIMEZONE_DEFAULT buildtime option.
.code
# keep_environment = ^LDAP
input and output (that is, not using TCP/IP). A number of MUAs operate in this
manner.
.code
-deny message = Restricted characters in address
- domains = +local_domains
+deny domains = +local_domains
local_parts = ^[.] : ^.*[@%!/|]
+ message = Restricted characters in address
-deny message = Restricted characters in address
- domains = !+local_domains
+deny domains = !+local_domains
local_parts = ^[./|] : ^.*[@%!] : ^.*/\\.\\./
+ message = Restricted characters in address
.endd
These statements are concerned with local parts that contain any of the
characters &"@"&, &"%"&, &"!"&, &"/"&, &"|"&, or dots in unusual places.
or &"|"&. If you have local accounts that include these characters, you will
have to modify this rule.
-Empty components (two dots in a row) are not valid in RFC 2822, but Exim
+Empty components (two dots in a row) are not valid in
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822),
+but Exim
allows them because they have been encountered in practice. (Consider the
common convention of local parts constructed as
&"&'first-initial.second-initial.family-name'&"& when applied to someone like
This statement requires the recipient address to be verified; if verification
fails, the address is rejected.
.code
-# deny message = rejected because $sender_host_address \
+# deny dnslists = black.list.example
+# message = rejected because $sender_host_address \
# is in a black list at $dnslist_domain\n\
# $dnslist_text
-# dnslists = black.list.example
#
# warn dnslists = black.list.example
# add_header = X-Warning: $sender_host_address is in \
# request with your smarthost provider to get things fixed:
hosts_require_tls = *
tls_verify_hosts = *
- # As long as tls_verify_hosts is enabled, this won't matter, but if you
- # have to comment it out then this will at least log whether you succeed
- # or not:
+ # As long as tls_verify_hosts is enabled, this this will have no effect,
+ # but if you have to comment it out then this will at least log whether
+ # you succeed or not:
tls_try_verify_hosts = *
#
# The SNI name should match the name which we'll expect to verify;
This &(appendfile)& transport is used for local delivery to user mailboxes in
traditional BSD mailbox format.
-.new
We prefer to avoid using &$local_part$& directly to define the mailbox filename,
as it is provided by a potential bad actor.
Instead we use &$local_part_data$&,
the result of looking up &$local_part$& in the user database
(done by using &%check_local_user%& in the the router).
-.wen
By default &(appendfile)& runs under the uid and gid of the
local user, which requires the sticky bit to be set on the &_/var/mail_&
.chapter "Regular expressions" "CHAPregexp"
.cindex "regular expressions" "library"
-.cindex "PCRE"
+.cindex "PCRE2"
Exim supports the use of regular expressions in many of its options. It
-uses the PCRE regular expression library; this provides regular expression
+uses the PCRE2 regular expression library; this provides regular expression
matching that is compatible with Perl 5. The syntax and semantics of
regular expressions is discussed in
online Perl manpages, in
. --- to the old URL for now. 2018-09-07.
The documentation for the syntax and semantics of the regular expressions that
-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
+are supported by PCRE2 is included in the PCRE2 distribution, and no further
+description is included here. The PCRE2 functions are called from Exim using
+the default option settings (that is, with no PCRE2 options set), except that
+the PCRE2_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,
lookup. Lookups of this type are conditional expansion items. Different results
can be defined for the cases of lookup success and failure. See chapter
&<<CHAPexpand>>&, where string expansions are described in detail.
-The key for the lookup is specified as part of the string expansion.
+The key for the lookup is &*specified*& as part of the string to be expanded.
.next
Lists of domains, hosts, and email addresses can contain lookup requests as a
way of avoiding excessively long linear lists. In this case, the data that is
returned by the lookup is often (but not always) discarded; whether the lookup
succeeds or fails is what really counts. These kinds of list are described in
chapter &<<CHAPdomhosaddlists>>&.
-The key for the lookup is given by the context in which the list is expanded.
+Depending on the lookup type (see below)
+the key for the lookup may need to be &*specified*& as above
+or may be &*implicit*&,
+given by the context in which the list is being checked.
.endlist
String expansions, lists, and lookups interact with each other in such a way
domains = ${lookup{$sender_host_address}lsearch{/some/file}}
domains = lsearch;/some/file
.endd
+.ilist
The first uses a string expansion, the result of which must be a domain list.
+The key for an expansion-style lookup must be given explicitly.
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
When the lookup succeeds, the result of the expansion is a list of domains (and
possibly other types of item that are allowed in domain lists).
.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using a lookup expansion"
The result of the expansion is not tainted.
+.next
In the second example, the lookup is a single item in a domain list. It causes
Exim to use a lookup to see if the domain that is being processed can be found
-in the file. The file could contains lines like this:
+in the file.
+The file could contains lines like this:
.code
domain1:
domain2:
Any data that follows the keys is not relevant when checking that the domain
matches the list item.
+The key for a list-style lookup is implicit, from the lookup context, if
+the lookup is a single-key type (see below).
+For query-style lookup types the query must be given explicitly.
+.endlist
+
It is possible, though no doubt confusing, to use both kinds of lookup at once.
Consider a file containing lines like this:
.code
first &%domains%& setting above generates the second setting, which therefore
causes a second lookup to occur.
+The lookup type may optionally be followed by a comma
+and a comma-separated list of options.
+Each option is a &"name=value"& pair.
+Whether an option is meaningful depends on the lookup type.
+
+All lookups support the option &"cache=no_rd"&.
+If this is given then the cache that Exim manages for lookup results
+is not checked before doing the lookup.
+The result of the lookup is still written to the cache.
+
The rest of this chapter describes the different lookup types that are
available. Any of them can be used in any part of the configuration where a
lookup is permitted.
The &'single-key'& type requires the specification of a file in which to look,
and a single key to search for. The key must be a non-empty string for the
lookup to succeed. The lookup type determines how the file is searched.
-.new
.cindex "tainted data" "single-key lookups"
-The file string may not be tainted
-.wen
+The file string may not be tainted.
+
+.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using a single-key lookup"
+All single-key lookups support the option &"ret=key"&.
+If this is given and the lookup
+(either underlying implementation or cached value)
+returns data, the result is replaced with a non-tainted
+version of the lookup key.
+
.next
.cindex "query-style lookup" "definition of"
The &'query-style'& type accepts a generalized database query. No particular
key value is assumed by Exim for query-style lookups. You can use whichever
Exim variables you need to construct the database query.
+
+For the string-expansion kind of lookups, the query is given in the first
+bracketed argument of the &${lookup ...}$& expansion.
+For the list-argument kind of lookup the query is given by the remainder of the
+list item after the first semicolon.
+
+.cindex "tainted data" "quoting for lookups"
+If tainted data is used in the query then it should be quoted by
+using the &*${quote_*&<&'lookup-type'&>&*:*&<&'string'&>&*}*& expansion operator
+appropriate for the lookup.
.endlist
The code for each lookup type is in a separate source file that is included in
.cindex "single-key lookup" "list of types"
The following single-key lookup types are implemented:
-.ilist
+.subsection cdb
.cindex "cdb" "description of"
.cindex "lookup" "cdb"
.cindex "binary zero" "in lookup key"
-&(cdb)&: The given file is searched as a Constant DataBase file, using the key
+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 particularly suitable for large files containing
because the code for reading cdb files is included directly in Exim itself.
However, no means of building or testing cdb files is provided with Exim, so
you need to obtain a cdb distribution in order to do this.
-.next
+
+.subsection dbm
.cindex "DBM" "lookup type"
.cindex "lookup" "dbm"
.cindex "binary zero" "in lookup key"
-&(dbm)&: Calls to DBM library functions are used to extract data from the given
+Calls to DBM library functions are used to extract data from the given
DBM file by looking up the record with the given key. A terminating binary
zero is included in the key that is passed to the DBM library. See section
&<<SECTdb>>& for a discussion of DBM libraries.
the DB_UNKNOWN option. This enables it to handle any of the types of database
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
+
+.subsection dbmjz
.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
+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
+
+.subsection dbmnz
.cindex "lookup" "dbmnz"
.cindex "lookup" "dbm &-- terminating zero"
.cindex "binary zero" "in lookup key"
.cindex "Courier"
.cindex "&_/etc/userdbshadow.dat_&"
.cindex "dbmnz lookup type"
-&(dbmnz)&: This is the same as &(dbm)&, except that a terminating binary zero
+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
other application that does not use terminating zeros. For example, you need to
calls using the passwords from Courier's &_/etc/userdbshadow.dat_& file. Exim's
utility program for creating DBM files (&'exim_dbmbuild'&) includes the zeros
by default, but has an option to omit them (see section &<<SECTdbmbuild>>&).
-.next
+
+.subsection dsearch
.cindex "lookup" "dsearch"
.cindex "dsearch lookup type"
-&(dsearch)&: The given file must be an
-.new
-absolute
-.wen
-directory path; this is searched for an entry
+The given file must be an absolute directory path; 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.
+Unless the options (below) permit a path,
+the key may not contain any forward slash characters.
If &[lstat()]& succeeds then so does the lookup.
-.new
.cindex "tainted data" "dsearch result"
The result is regarded as untainted.
separated by a comma. Options, if present, are a comma-separated list having
each element starting with a tag name and an equals.
-Two options are supported, for the return value and for filtering match
+Three options are supported, for the return value and for filtering match
candidates.
The "ret" option requests an alternate result value of
the entire path for the entry. Example:
${lookup {passwd} dsearch,ret=full {/etc}}
.endd
The default result is just the requested entry.
+
The "filter" option requests that only directory entries of a given type
are matched. The match value is one of "file", "dir" or "subdir" (the latter
not matching "." or ".."). Example:
.endd
The default matching is for any entry type, including directories
and symlinks.
-.wen
+
+The "key" option relaxes the restriction that only a simple path component can
+be searched for, to permit a sequence of path components. Example:
+.code
+${lookup {foo/bar} dsearch,key=path {/etc}}
+.endd
+If this option is used, a ".." component in the key is specifically disallowed.
+The default operation is that the key may only be a single path component.
An example of how this
lookup can be used to support virtual domains is given in section
&<<SECTvirtualdomains>>&.
-.next
+
+.subsection iplsearch
.cindex "lookup" "iplsearch"
.cindex "iplsearch lookup type"
-&(iplsearch)&: The given file is a text file containing keys and data. A key is
+The given file is a text file containing keys and data. A key is
terminated by a colon or white space or the end of the line. The keys in the
file must be IP addresses, or IP addresses with CIDR masks. Keys that involve
IPv6 addresses must be enclosed in quotes to prevent the first internal colon
lookup types support only literal keys.
&*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>>&).
+the implicit key is the host's IP address rather than its name
+(see section &<<SECThoslispatsikey>>&).
&*Warning 3*&: Do not use an IPv4-mapped IPv6 address for a key; use the
IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this
notation before executing the lookup.)
-.next
+
+One option is supported, "ret=full", to request the return of the entire line
+rather than omitting the key portion.
+Note however that the key portion will have been de-quoted.
+
+.subsection json
.cindex lookup json
.cindex json "lookup type"
.cindex JSON expansions
-&(json)&: The given file is a text file with a JSON structure.
+The given file is a text file with a JSON structure.
An element of the structure is extracted, defined by the search key.
The key is a list of subelement selectors
(colon-separated by default but changeable in the usual way)
or array; for the latter two a string-representation of the JSON
is returned.
For elements of type string, the returned value is de-quoted.
-.next
+
+
+.subsection lmdb
+.cindex LMDB
+.cindex lookup lmdb
+.cindex database lmdb
+The given file is an LMDB database.
+LMDB is a memory-mapped key-value store,
+with API modeled loosely on that of BerkeleyDB.
+See &url(https://symas.com/products/lightning-memory-mapped-database/,LMDB)
+for the feature set and operation modes.
+
+Exim provides read-only access via the LMDB C library.
+The library can be obtained from &url(https://github.com/LMDB/lmdb)
+or your operating system package repository.
+To enable LMDB support in Exim set LOOKUP_LMDB=yes in &_Local/Makefile_&.
+
+You will need to separately create the LMDB database file,
+possibly using the &"mdb_load"& utility.
+
+
+.subsection lsearch
.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
+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 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
quoted keys (exactly as for unquoted keys). There is no special handling of
quotes for the data part of an &(lsearch)& line.
-.next
+.subsection nis
.cindex "NIS lookup type"
.cindex "lookup" "NIS"
.cindex "binary zero" "in lookup key"
-&(nis)&: The given file is the name of a NIS map, and a NIS lookup is done with
+The given file is the name of a NIS map, and a NIS lookup is done with
the given key, without a terminating binary zero. There is a variant called
&(nis0)& which does include the terminating binary zero in the key. This is
reportedly needed for Sun-style alias files. Exim does not recognize NIS
aliases; the full map names must be used.
-.next
+.subsection (n)wildlsearch
.cindex "wildlsearch lookup type"
.cindex "lookup" "wildlsearch"
.cindex "nwildlsearch lookup type"
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.
-
.olist
The string may begin with an asterisk to mean &"ends with"&. For example:
.code
- *.a.b.c data for anything.a.b.c
- *fish data for anythingfish
+*.a.b.c data for anything.a.b.c
+*fish data for anythingfish
.endd
.next
The string may begin with a circumflex to indicate a regular expression. For
example, for &(wildlsearch)&:
.code
- ^\N\d+\.a\.b\N data for <digits>.a.b
+^\N\d+\.a\.b\N data for <digits>.a.b
.endd
Note the use of &`\N`& to disable expansion of the contents of the regular
expression. If you are using &(nwildlsearch)&, where the keys are not
string-expanded, the equivalent entry is:
.code
- ^\d+\.a\.b data for <digits>.a.b
+^\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
+^(?-i)\d+\.a\.b data for <digits>.a.b
.endd
If the regular expression contains white space or colon characters, you must
lookup name terminated by a semicolon, and followed by lookup data. For
example:
.code
- cdb;/some/file data for keys that match the file
+cdb;/some/file data for keys that match the file
.endd
The data that is obtained from the nested lookup is discarded.
.endlist olist
&((n)wildlsearch)& can &'not'& be turned into a DBM or cdb file, because those
lookup types support only literal keys.
-.next
+.subsection spf
.cindex "spf lookup type"
.cindex "lookup" "spf"
-&(spf)&: If Exim is built with SPF support, manual lookups can be done
+If Exim is built with SPF support, manual lookups can be done
(as opposed to the standard ACL condition method).
For details see section &<<SECSPF>>&.
-.endlist ilist
.section "Query-style lookup types" "SECTquerystylelookups"
The supported query-style lookup types are listed below. Further details about
many of them are given in later sections.
-.ilist
+.subsection dnsdb
.cindex "DNS" "as a lookup type"
.cindex "lookup" "DNS"
-&(dnsdb)&: This does a DNS search for one or more records whose domain names
+This does a DNS search for one or more records whose domain names
are given in the supplied query. The resulting data is the contents of the
records. See section &<<SECTdnsdb>>&.
-.next
+
+.subsection ibase
.cindex "InterBase lookup type"
.cindex "lookup" "InterBase"
-&(ibase)&: This does a lookup in an InterBase database.
-.next
+This does a lookup in an InterBase database.
+
+.subsection ldap
.cindex "LDAP" "lookup type"
.cindex "lookup" "LDAP"
-&(ldap)&: This does an LDAP lookup using a query in the form of a URL, and
+This does an LDAP lookup using a query in the form of a URL, and
returns attributes from a single entry. There is a variant called &(ldapm)&
that permits values from multiple entries to be returned. A third variant
called &(ldapdn)& returns the Distinguished Name of a single entry instead of
any attribute values. See section &<<SECTldap>>&.
-.next
+
+.subsection mysql
.cindex "MySQL" "lookup type"
.cindex "lookup" "MySQL"
-&(mysql)&: The format of the query is an SQL statement that is passed to a
+The format of the query is an SQL statement that is passed to a
MySQL database. See section &<<SECTsql>>&.
-.next
+
+.subsection nisplus
.cindex "NIS+ lookup type"
.cindex "lookup" "NIS+"
-&(nisplus)&: This does a NIS+ lookup using a query that can specify the name of
+This does a NIS+ lookup using a query that can specify the name of
the field to be returned. See section &<<SECTnisplus>>&.
-.next
+
+.subsection oracle
.cindex "Oracle" "lookup type"
.cindex "lookup" "Oracle"
-&(oracle)&: The format of the query is an SQL statement that is passed to an
+The format of the query is an SQL statement that is passed to an
Oracle database. See section &<<SECTsql>>&.
-.next
+
+.subsection passwd
.cindex "lookup" "passwd"
.cindex "passwd lookup type"
.cindex "&_/etc/passwd_&"
-&(passwd)& is a query-style lookup with queries that are just user names. The
+This is a query-style lookup with queries that are just user names. The
lookup calls &[getpwnam()]& to interrogate the system password data, and on
success, the result string is the same as you would get from an &(lsearch)&
lookup on a traditional &_/etc/passwd file_&, though with &`*`& for the
.code
*:42:42:King Rat:/home/kr:/bin/bash
.endd
-.next
+
+.subsection pgsql
.cindex "PostgreSQL lookup type"
.cindex "lookup" "PostgreSQL"
-&(pgsql)&: The format of the query is an SQL statement that is passed to a
+The format of the query is an SQL statement that is passed to a
PostgreSQL database. See section &<<SECTsql>>&.
-.next
+.subsection redis
.cindex "Redis lookup type"
.cindex lookup Redis
-&(redis)&: The format of the query is either a simple get or simple set,
+The format of the query is either a simple get or simple set,
passed to a Redis database. See section &<<SECTsql>>&.
-.next
+.subsection sqlite
.cindex "sqlite lookup type"
.cindex "lookup" "sqlite"
-&(sqlite)&: The format of the query is
-new
-an optional filename
-.wen
-followed by an SQL statement
-that is passed to an SQLite database. See section &<<SECTsqlite>>&.
+The format of the query is
+an SQL statement that is passed to an SQLite database. See section &<<SECTsqlite>>&.
-.next
-&(testdb)&: This is a lookup type that is used for testing Exim. It is
+.subsection testdb
+This is a lookup type that is used for testing Exim. It is
not likely to be useful in normal operation.
-.next
+
+.subsection whoson
.cindex "whoson lookup type"
.cindex "lookup" "whoson"
-. --- still http:-only, 2018-09-07
-&(whoson)&: &'Whoson'& (&url(http://whoson.sourceforge.net)) is a protocol that
+&'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
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"&.
-.endlist
in a database file is useless, because the asterisk in a partial matching
subject key is always followed by a dot.
+When the lookup is done from a string-expansion,
+the variables &$1$& and &$2$& contain the wild and non-wild parts of the key
+during the expansion of the replacement text.
+They return to their previous values at the end of the lookup item.
+
of independent, short-lived processes, this caching applies only within a
single Exim process. There is no inter-process lookup caching facility.
+If an option &"cache=no_rd"& is used on the lookup then
+the cache is only written to, cached data is not used for the operation
+and a real lookup is done.
+
For single-key lookups, Exim keeps the relevant files open in case there is
another lookup that needs them. In some types of configuration this can lead to
many files being kept open for messages with many recipients. To avoid hitting
.code
${quote_<lookup-type>:<string>}
.endd
-For example, the safest way to write the NIS+ query is
+For example, the way to write the NIS+ query is
.code
[name="${quote_nisplus:$local_part}"]
.endd
+.cindex "tainted data" "in lookups"
+&*All*& tainted data used in a query-style lookup must be quoted
+using a mechanism appropriate for the lookup type.
See chapter &<<CHAPexpand>>& for full coverage of string expansions. The quote
operator can be used for all lookup types, but has no effect for single-key
lookups, since no quoting is ever needed in their key strings.
${lookup dnsdb{>:,; soa=a.b.example.com}}
.endd
-.section "Dnsdb lookup modifiers" "SECTdnsdb_mod"
+.subsection "Dnsdb lookup modifiers" SECTdnsdb_mod
.cindex "dnsdb modifiers"
.cindex "modifiers" "dnsdb"
.cindex "options" "dnsdb"
value of the set of returned DNS records.
-.section "Pseudo dnsdb record types" "SECID66"
+.subsection "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
.endd
-.section "Multiple dnsdb lookups" "SECID67"
+.subsection "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
First we explain how LDAP queries are coded.
-.section "Format of LDAP queries" "SECTforldaque"
+.subsection "Format of LDAP queries" SECTforldaque
.cindex "LDAP" "query format"
-An LDAP query takes the form of a URL as defined in RFC 2255. For example, in
+An LDAP query takes the form of a URL as defined in
+&url(https://www.rfc-editor.org/rfc/rfc2255,RFC 2255). For example, in
the configuration of a &(redirect)& router one might have this setting:
.code
data = ${lookup ldap \
&_exim.conf_&.
-.section "LDAP quoting" "SECID68"
+.subsection "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,
) => \29
\ => \5C
.endd
-in accordance with RFC 2254. The resulting string is then quoted according
+in accordance with
+&url(https://www.rfc-editor.org/rfc/rfc2254,RFC 2254).
+The resulting string is then quoted according
to the rules for URLs, that is, all non-alphanumeric characters except
.code
! $ ' - . _ ( ) * +
, + " \ < > ;
.endd
It also inserts a backslash before any leading spaces or # characters, and
-before any trailing spaces. (These rules are in RFC 2253.) The resulting string
-is then quoted according to the rules for URLs. For example:
+before any trailing spaces. (These rules are in
+&url(https://www.rfc-editor.org/rfc/rfc2255,RFC 2253).)
+The resulting string is then quoted according to the rules for URLs.
+For example:
.code
${quote_ldap_dn: a(bc)*, a<yz>; }
.endd
authentication below.
-.section "LDAP connections" "SECID69"
+.subsection "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 specifying 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
+(&url(https://www.rfc-editor.org/rfc/rfc1738,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" "SECID70"
+.subsection "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
spaces. If a value contains spaces it must be enclosed in double quotes, and
when double quotes are used, backslash is interpreted in the usual way inside
them. The following names are recognized:
-.display
-&`DEREFERENCE`& set the dereferencing parameter
-&`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
-&`SERVERS `& set alternate server list for this query only
-&`SIZE `& set the limit for the number of entries returned
-&`TIME `& set the maximum waiting time for a query
-.endd
+.itable none 0 0 2 20* left 80* left
+.irow DEREFERENCE "set the dereferencing parameter"
+.irow NETTIME "set a timeout for a network operation"
+.irow USER "set the DN, for authenticating the LDAP bind"
+.irow PASS "set the password, likewise"
+.irow REFERRALS "set the referrals parameter"
+.irow SERVERS "set alternate server list for this query only"
+.irow SIZE "set the limit for the number of entries returned"
+.irow TIME "set the maximum waiting time for a query"
+.endtable
The value of the DEREFERENCE parameter must be one of the words &"never"&,
&"searching"&, &"finding"&, or &"always"&. The value of the REFERRALS parameter
must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP
on the number of entries returned, and no time limit on queries.
When a DN is quoted in the USER= setting for LDAP authentication, Exim
-removes any URL quoting that it may contain before passing it LDAP. Apparently
+removes any URL quoting that it may contain before passing it to the LDAP library.
+Apparently
some libraries do this for themselves, but some do not. Removing the URL
quoting has two advantages:
-.section "Format of data returned by LDAP" "SECID71"
+.subsection "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
with a newline between the data for each row.
-.section "More about MySQL, PostgreSQL, Oracle, InterBase, and Redis" "SECID72"
+.subsection "More about MySQL, PostgreSQL, Oracle, InterBase, and Redis" SECID72
.cindex "MySQL" "lookup type"
.cindex "PostgreSQL lookup type"
.cindex "lookup" "MySQL"
The &%quote_redis%& expansion operator
escapes whitespace and backslash characters with a backslash.
-.section "Specifying the server in the query" "SECTspeserque"
-.new
+.subsection "Specifying the server in the query" SECTspeserque
For MySQL, PostgreSQL and Redis 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 appending a comma-separated option to the query type:
.display
-.endd
&`,servers=`&&'server1:server2:server3:...'&
-.wen
+.endd
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
${lookup pgsql,servers=master/db/name/pw {UPDATE ...} }
.endd
-.new
-An older syntax places the servers speciification before the qury,
+A now-deprecated syntax places the servers specification before the query,
semicolon separated:
.code
${lookup mysql{servers=master; UPDATE ...} }
.endd
-The new version avoids potential issues with tainted
-arguments in the query, for explicit expansion.
+The new version avoids issues with tainted
+arguments explicitly expanded as part of the query.
+The entire string within the braces becomes tainted,
+including the server specification - which is not permissible.
+If the older sytax is used, a warning message will be logged.
+This syntax will be removed in a future release.
+
&*Note*&: server specifications in list-style lookups are still problematic.
-.wen
-.section "Special MySQL features" "SECID73"
+.subsection "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 default value is &"exim"&.
The full syntax of each item in &%mysql_servers%& is:
.display
-<&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&&
- <&'database'&>/<&'user'&>/<&'password'&>
+<&'hostspec'&><&'portspec'&>(<&'socket name'&>)[<&'option group'&>]/&&&
+ <&'database'&>/<&'user'&>/<&'password'&>
.endd
Any of the four 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"&.
+.new
+A &'hostspec'& can be a hostname, an IPv4 address or an IPv6 address.
+For the latter, a &'portspec'& is a dot followed by a port number;
+for the other two a &'portspec'& is a colon followed by a port number.
+.wen
+
+Note that the default list-separator for the list of servers is a colon so
+(unless that is changed) all colons in list items must be doubled.
+
No database need be supplied &-- but if it is absent here, it must be given in
the queries.
anything (for example, setting a field to the value it already has), the result
is zero because no rows are affected.
+To get an encryted connection, use a Mysql option file with the required
+parameters for the connection.
+
+
+.subsection "Special PostgreSQL features" SECID74
+.new
+The &'hostspec'& for PostgreSQL follows the same rules as for MySQL above.
+.wen
-.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.
-.section "More about SQLite" "SECTsqlite"
+.subsection "More about SQLite" SECTsqlite
.cindex "lookup" "SQLite"
.cindex "sqlite lookup type"
SQLite is different to the other SQL lookups because a filename 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.
-.new
.oindex &%sqlite_dbfile%&
-The preferred way of specifying the file is by using the
-&%sqlite_dbfile%& option, set to
-an absolute path.
-.wen
+There are two ways of
+specifying the file.
+The first is by using the &%sqlite_dbfile%& main option.
+The second, which allows separate files for each query,
+is to use an option appended, comma-separated, to the &"sqlite"&
+lookup type word. The option is the word &"file"&, then an equals,
+then the filename.
+The filename in this case cannot contain whitespace or open-brace charachters.
+
A deprecated method is available, prefixing the query with the filename
separated by white space.
-This means that the path name cannot contain white space.
+This means that
.cindex "tainted data" "sqlite file"
-It also means that the query cannot use any tainted values, as that taints
+the query cannot use any tainted values, as that taints
the entire query including the filename - resulting in a refusal to open
the file.
-.new
+In all the above cases the filename must be an absolute path.
+
Here is a lookup expansion example:
.code
sqlite_dbfile = /some/thing/sqlitedb
domainlist relay_to_domains = sqlite;\
select * from relays where ip='$sender_host_address';
.endd
-.wen
The only character affected by the &%quote_sqlite%& operator is a single
quote, which it doubles.
to 5 seconds, but it can be changed by means of the &%sqlite_lock_timeout%&
option.
-.section "More about Redis" "SECTredis"
+.subsection "More about Redis" SECTredis
.cindex "lookup" "Redis"
.cindex "redis lookup type"
Redis is a non-SQL database. Commands are simple get and set.
+.section "Results of list checking" SECTlistresults
+The primary result of doing a list check is a truth value.
+In some contexts additional information is stored
+about the list element that matched:
+.vlist
+.vitem hosts
+A &%hosts%& ACL condition
+will store a result in the &$host_data$& variable.
+.vitem local_parts
+A &%local_parts%& router option or &%local_parts%& ACL condition
+will store a result in the &$local_part_data$& variable.
+.vitem domains
+A &%domains%& router option or &%domains%& ACL condition
+will store a result in the &$domain_data$& variable.
+.vitem senders
+A &%senders%& router option or &%senders%& ACL condition
+will store a result in the &$sender_data$& variable.
+.vitem recipients
+A &%recipients%& ACL condition
+will store a result in the &$recipient_data$& variable.
+.endlist
+
+The detail of the additional information depends on the
+type of match and is given below as the &*value*& information.
+
+
+
+
.section "Expansion of lists" "SECTlistexpand"
.cindex "expansion" "of lists"
-Each list is expanded as a single string before it is used.
+.new
+Each list, after any leading change-of-separator specification
+(see &<<SECTlistsepchange>>&) is expanded as a single string,
+.cindex "tainted data" tracking
+&*Note*&: As a result, if any component was tainted then the
+entire expansion result string becomes tainted.
+
+Splitting out a leading explicit change-of-separator permits
+one being safely used on a list that has tainted components
+while still detecting the use of a tainted setting.
+The latter is not permitted.
+.wen
&'Exception: the router headers_remove option, where list-item
splitting is done before string-expansion.'&
-.section "Negated items in lists" "SECID76"
+.subsection "Negated items in lists" SECID76
.cindex "list" "negation"
.cindex "negation" "in lists"
Items in a list may be positive or negative. Negative items are indicated by a
-.section "File names in lists" "SECTfilnamlis"
+.subsection "File names in lists" SECTfilnamlis
.cindex "list" "filename in"
If an item in a domain, host, address, or local part list is an absolute
filename (beginning with a slash character), each line of the file is read and
-.section "An lsearch file is not an out-of-line list" "SECID77"
+.subsection "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
-.new
-.section "Results of list checking" SECTlistresults
-The primary result of doing a list check is a truth value.
-In some contexts additional information is stored
-about the list element that matched:
-.vlist
-.vitem hosts
-A &%hosts%& ACL condition
-will store a result in the &$host_data$& variable.
-.vitem local_parts
-A &%local_parts%& router option or &%local_parts%& ACL condition
-will store a result in the &$local_part_data$& variable.
-.vitem domains
-A &%domains%& router option or &%domains%& ACL condition
-.vitem senders
-A &%senders%& router option or &%senders%& ACL condition
-will store a result in the &$sender_data$& variable.
-.vitem recipients
-A &%recipients%& ACL condition
-will store a result in the &$recipient_data$& variable.
-.endlist
-
-The detail of the additional information depends on the
-type of match and is given below as the &*value*& information.
-.wen
-
-
-
-
-.section "Named lists" "SECTnamedlists"
+.subsection "Named lists" SECTnamedlists
.cindex "named lists"
.cindex "list" "named"
A list of domains, hosts, email addresses, or local parts can be given a name
referenced lists if you can.
.new
+The list item which references a named list (&"+<listname>"&)
+may not be tainted.
+.wen
+
.cindex "hiding named list values"
.cindex "named lists" "hiding value of"
Some named list definitions may contain sensitive data, for example, passwords for
.code
hide domainlist filter_for_domains = ldap;PASS=secret ldap::/// ...
.endd
-.wen
Named lists may have a performance advantage. When Exim is routing an
-.section "Named lists compared with macros" "SECID78"
+.subsection "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" "SECID79"
+.subsection "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
possible to use the same configuration file on several different hosts that
differ only in their names.
-.new
The value for a match will be the primary host name.
+.new
+The pattern may not be tainted.
.wen
In today's Internet, the use of domain literals is controversial;
see the &%allow_domain_literals%& main option.
-.new
The value for a match will be the string &`@[]`&.
+.new
+The pattern may not be tainted.
.wen
but a secondary MX target is. &"Primary"& means an MX record with the lowest
preference value &-- there may of course be more than one of them.
+.new
+The pattern may not be tainted.
+.wen
+
The MX lookup that takes place when matching a pattern of this type is
performed with the resolver options for widening names turned off. Thus, for
example, a single-component domain will &'not'& be expanded by adding the
domains = <? @mx_any/ignore=<;127.0.0.1;::1 ? \
an.other.domain ? ...
.endd
-.new
The value for a match will be the list element string (starting &`@mx_`&).
-.wen
.next
list item such as &`*key.ex`& matches &'donkey.ex'& as well as
&'cipher.key.ex'&.
-.new
The value for a match will be the list element string (starting with the asterisk).
Additionally, &$0$& will be set to the matched string
and &$1$& to the variable portion which the asterisk matched.
-.wen
.next
.cindex "regular expressions" "in domain list"
it is not to be expanded (unless you really do want to build a regular
expression by expansion, of course).
-.new
The value for a match will be the list element string (starting with the circumflex).
Additionally, &$0$& will be set to the string matching the regular expression,
and &$1$& (onwards) to any submatches identified by parentheses.
-.wen
&$domain_data$& variable and can be referred to in other router options or
other statements in the same ACL.
.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using ACL domains condition"
The value will be untainted.
+&*Note*&: If the data result of the lookup (as opposed to the key)
+is empty, then this empty value is stored in &$domain_data$&.
+The option to return the key for the lookup, as the value,
+may be what is wanted.
+
.next
Any of the single-key lookup type names may be preceded by
&%domains%& option on a router, the value is preserved in the &$domain_data$&
variable and can be referred to in other options.
.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using router domains option"
The value will be untainted.
.next
-.new
If the pattern starts with the name of a lookup type
of either kind (single-key or query-style) it may be
followed by a comma and options,
The options are lookup-type specific and consist of a comma-separated list.
-Each item starts with a tag and and equals "=".
-.wen
+Each item starts with a tag and and equals "=" sign.
.next
.cindex "domain list" "matching literal domain name"
.cindex "tainted data" "de-tainting"
Note that this is commonly untainted
(depending on the way the list was created).
+Specifically, explicit text in the configuration file in not tainted.
This is a useful way of obtaining an untainted equivalent to
the domain, for later operations.
+
+However if the list (including one-element lists)
+is created by expanding a variable containing tainted data,
+it is tainted and so will the match value be.
.endlist
involved, to ensure that the right value is being used as the key.
-.section "Special host list patterns" "SECID80"
+.subsection "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
-.section "Host list patterns that match by IP address" "SECThoslispatip"
+.subsection "Host list patterns that match by IP address" SECThoslispatip
.cindex "host list" "matching IP addresses"
If an IPv4 host calls an IPv6 host and the call is accepted on an IPv6 socket,
the incoming address actually appears in the IPv6 host as
.endd
.next
.cindex "CIDR notation"
-If the pattern is an IP address followed by a slash and a mask length (for
-example 10.11.42.0/24), it is matched against the IP address of the subject
-host under the given mask. This allows, an entire network of hosts to be
+If the pattern is an IP address followed by a slash and a mask length, for
+example
+.code
+10.11.42.0/24
+.endd
+, it is matched against the IP address of the subject
+host under the given mask. This allows an entire network of hosts to be
included (or excluded) by a single item. The mask uses CIDR notation; it
specifies the number of address bits that must match, starting from the most
significant end of the address.
-.section "Host list patterns for single-key lookups by host address" &&&
- "SECThoslispatsikey"
+.subsection "Host list patterns for single-key lookups by host address" &&&
+ SECThoslispatsikey
.cindex "host list" "lookup of IP address"
When a host is to be identified by a single-key lookup of its complete IP
address, the pattern takes this form:
-.section "Host list patterns that match by host name" "SECThoslispatnam"
+.subsection "Host list patterns that match by host name" SECThoslispatnam
.cindex "host" "lookup failures"
.cindex "unknown host name"
.cindex "host list" "matching host name"
-.section "Behaviour when an IP address or name cannot be found" "SECTbehipnot"
+.subsection "Behaviour when an IP address or name cannot be found" SECTbehipnot
.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
list. The effect of each one lasts until the next, or until the end of the
list.
-.section "Mixing wildcarded host names and addresses in host lists" &&&
- "SECTmixwilhos"
+.subsection "Mixing wildcarded host names and addresses in host lists" &&&
+ SECTmixwilhos
.cindex "host list" "mixing names and addresses in"
This section explains the host/ip processing logic with the same concepts
.endlist
-.section "Temporary DNS errors when looking up host information" &&&
- "SECTtemdnserr"
+.subsection "Temporary DNS errors when looking up host information" &&&
+ SECTtemdnserr
.cindex "host" "lookup failures, temporary"
.cindex "&`+include_defer`&"
.cindex "&`+ignore_defer`&"
-.section "Host list patterns for single-key lookups by host name" &&&
- "SECThoslispatnamsk"
+.subsection "Host list patterns for single-key lookups by host name" &&&
+ SECThoslispatnamsk
.cindex "unknown host name"
.cindex "host list" "matching host name"
If a pattern is of the form
&*Reminder*&: With this kind of pattern, you must have host &'names'& as
keys in the file, not IP addresses. If you want to do lookups based on IP
-addresses, you must precede the search type with &"net-"& (see section
-&<<SECThoslispatsikey>>&). There is, however, no reason why you could not use
+addresses, you must precede the search type with &"net-"&
+(see section &<<SECThoslispatsikey>>&).
+There is, however, no reason why you could not use
two items in the same list, one doing an address lookup and one doing a name
lookup, both using the same file.
-.section "Host list patterns for query-style lookups" "SECID81"
+.subsection "Host list patterns for query-style lookups" SECID81
If a pattern is of the form
.display
<&'query-style-search-type'&>;<&'query'&>
-.section "Case of letters in address lists" "SECTcasletadd"
+.subsection "Case of letters in address lists" SECTcasletadd
.cindex "case of local parts"
.cindex "address list" "case forcing"
.cindex "case forcing in address lists"
Domains in email addresses are always handled caselessly, but for local parts
case may be significant on some systems (see &%caseful_local_part%& for how
-Exim deals with this when routing addresses). However, RFC 2505 (&'Anti-Spam
+Exim deals with this when routing addresses). However,
+&url(https://www.rfc-editor.org/rfc/rfc2505,RFC 2505) (&'Anti-Spam
Recommendations for SMTP MTAs'&) suggests that matching of addresses to
blocking lists should be done in a case-independent manner. Since most address
lists in Exim are used for this kind of control, Exim attempts to do this by
performed caselessly, regular expressions that match against an entire address
become case-sensitive after &"+caseful"& has been seen.
+.new
+This string may not be tainted.
+To do caseful matching on list elements whic are tainted,
+place them in a named list.
+.wen
+
.section "Local part lists" "SECTlocparlis"
.cindex "list" "local part list"
.cindex "local part" "list"
+These behave in the same way as domain and host lists, with the following
+changes:
+
Case-sensitivity in local part lists is handled in the same way as for address
lists, as just described. The &"+caseful"& item can be used if required. In a
setting of the &%local_parts%& option in a router with &%caseful_local_part%&
&%caseful_local_part%& is set true in a router, matching in the &%local_parts%&
option is case-sensitive from the start.
+.new
+This string may not be tainted.
+To do caseful matching on list elements whic are tainted,
+place them in a named list.
+.wen
+
If a local part list is indirected to a file (see section &<<SECTfilnamlis>>&),
comments are handled in the same way as address lists &-- they are recognized
only if the # is preceded by white space or the start of the line.
below in section &<<SECTexpansionitems>>& onwards. Backslash is used as an
escape character, as described in the following section.
+.cindex "tainted data" tracking
+If any porttion of the result string is tainted, the entire result is.
+
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
conditions do not expand some of the brace-delimited branches, for security
reasons,
.cindex "tainted data" expansion
+.cindex "tainted data" definition
.cindex expansion "tainted data"
and expansion of data deriving from the sender (&"tainted data"&)
-is not permitted.
+is not permitted (including acessing a file using a tainted name).
+
+Common ways of obtaining untainted equivalents of variables with
+tainted values
+.cindex "tainted data" "de-tainting"
+come down to using the tainted value as a lookup key in a trusted database.
+This database could be the filesystem structure,
+or the password file,
+or accessed via a DBMS.
+Specific methods are indexed under &"de-tainting"&.
database lookups, and the use of expansion operators such as &%sg%&, &%substr%&
and &%nhash%&.
+When reading lines from the standard input,
+macros can be defined and ACL variables can be set.
+For example:
+.code
+MY_MACRO = foo
+set acl_m_myvar = bar
+.endd
+Such macros and variables can then be used in later input lines.
+
Exim gives up its root privilege when it is called with the &%-be%& option, and
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.
.vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&"
.cindex authentication "results header"
-.cindex headers "authentication-results:"
+.chindex Authentication-Results:
.cindex authentication "expansion item"
This item returns a string suitable for insertion as an
&'Authentication-Results:'&
.code
add_header = :at_start:${authresults {$primary_hostname}}
.endd
-This is safe even if no authentication results are available.
+This is safe even if no authentication results are available
+and would generally be placed in the DATA ACL.
.vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&&
.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 (&<<SECTlistsepchange>>&).
-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
+.new
+<&'string1'&> first has the part after any change-of-list-separator
+(see &<<SECTlistsepchange>>&) expanded,
+then the whole is taken as a list.
+.wen
+The default separator for the list is a colon.
+
+For each item in this list,
+its value is placed in &$item$&, and then the condition is evaluated.
+Any modification of &$value$& by this evaluation is discarded.
+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:
${filter{a:b:c}{!eq{$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.
+to what it was before.
+See also the &%map%& and &%reduce%& expansion items.
.vitem &*${hash{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&
value of HEADERS_CHARSET in &_Local/Makefile_&. The ultimate default is
ISO-8859-1.
-Header names follow the syntax of RFC 2822, which states that they may contain
+Header names follow the syntax of
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822),
+which states that they may contain
any printing characters except space and colon. Consequently, curly brackets
&'do not'& terminate header names, and should not be used to enclose them as
if they were variables. Attempting to do so causes a syntax error.
Header lines that are added in a RCPT ACL (for example)
are saved until the message's incoming header lines are available, at which
point they are added.
-When any of the above ACLs ar
+When any of the above ACLs are
running, however, header lines added by earlier ACLs are visible.
Upper case and lower case letters are synonymous in header names. If the
those headers that contain lists of addresses, a comma is also inserted at the
junctions between headers. This does not happen for the &%rheader%& expansion.
-.new
-.cindex "tainted data"
+.cindex "tainted data" "message headers"
When the headers are from an incoming message,
the result of expanding any of these variables is tainted.
-.wen
.vitem &*${hmac{*&<&'hashname'&>&*}{*&<&'secret'&>&*}{*&<&'string'&>&*}}*&
.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 &`${md5:secret_text...}`& or
+&url(https://www.rfc-editor.org/rfc/rfc2104.RFC 2104).
+This differs from &`${md5:secret_text...}`& or
&`${sha1:secret_text...}`& in that the hmac step adds a signature to the
cryptographic hash, allowing for authentication that is not possible with MD5
or SHA-1 alone. The hash name must expand to either &`md5`& or &`sha1`& at
apart from an optional leading minus,
and leading and trailing white space (which is ignored).
-After expansion, <&'string1'&> is interpreted as a list, colon-separated by
-default, but the separator can be changed in the usual way (&<<SECTlistsepchange>>&).
+.new
+The <&'string1'&> argument, after any leading change-of-separator
+(see &<<SECTlistsepchange>>&),
+is expanded and the whole forms the list.
+.wen
+By default, the list separator is a colon.
The first field of the list is numbered one.
If the number is negative, the fields are
You can use &`fail`& instead of {<&'string3'&>} as in a string extract.
-.vitem "&*${lookup{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&&
- {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&"
-This is the first of one of two different types of lookup item, which are both
-described in the next item.
+.vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*&
+.cindex quoting "for list"
+.cindex list quoting
+This item doubles any occurrence of the separator character
+in the given string.
+An empty string is replaced with a single space.
+This converts the string into a safe form for use as a list element,
+in a list using the given separator.
+
-.vitem "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&&
+.vitem "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&&
+ {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" &&&
+ "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&&
{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&"
.cindex "expansion" "lookup in"
.cindex "file" "lookups"
.vitem &*${map{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&
.cindex "expansion" "list creation"
.vindex "&$item$&"
-After expansion, <&'string1'&> is interpreted as a list, colon-separated by
-default, but the separator can be changed in the usual way (&<<SECTlistsepchange>>&).
-For each item
-in this list, its value is place in &$item$&, and then <&'string2'&> is
+.new
+<&'string1'&> first has the part after any change-of-list-separator
+(see &<<SECTlistsepchange>>&) expanded,
+then the whole is taken as a list.
+.wen
+The default separator for the list is a colon.
+
+For each item in this list,
+its value is place in &$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:
name of the subroutine, is nine.
The return value of the subroutine is inserted into the expanded string, unless
-the return value is &%undef%&. In that case, the expansion fails in the same
-way as an explicit &"fail"& on a lookup item. The return value is a scalar.
-Whatever you return is evaluated in a scalar context. For example, if you
-return the name of a Perl vector, the return value is the size of the vector,
+the return value is &%undef%&. In that case, the entire expansion is
+forced to fail, in the same way as an explicit &"fail"& on a lookup item
+does (see section &<<SECTforexpfai>>&). Whatever you return is evaluated
+in a scalar context, thus the return value is a scalar. For example, if you
+return a Perl vector, the return value is the size of the vector,
not its contents.
If the subroutine exits by calling Perl's &%die%& function, the expansion fails
.cindex "expansion" "inserting an entire file"
.cindex "file" "inserting into expansion"
.cindex "&%readfile%& expansion item"
-The filename and end-of-line string are first expanded separately. The file is
+The filename and end-of-line (eol) 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,
newlines are left in the string.
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 no terminating NUL is ever sent)
+(unless it is an empty string; no terminating NUL is ever sent)
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:
${readsocket{/socket/name}{request string}{3s:shutdown=no}}
.endd
-.new
The following option names are recognised:
.ilist
&*cache*&
sending the request. Values are &"yes"& (the default) or &"no"&
(preferred, eg. by some webservers).
+.next
+&*sni*&
+Controls the use of Server Name Identification on the connection.
+Any nonempty value will be the SNI sent; TLS will be forced.
+
.next
&*tls*&
Controls the use of TLS on the connection.
Values are &"yes"& or &"no"& (the default).
-If it is enabled, a shutdown as descripbed above is never done.
+If it is enabled, a shutdown as described above is never done.
.endlist
-.wen
A fourth argument allows you to change any newlines that are in the data
.cindex "list" "reducing to a scalar"
.vindex "&$value$&"
.vindex "&$item$&"
-This operation reduces a list to a single, scalar string. After expansion,
-<&'string1'&> is interpreted as a list, colon-separated by default, but the
-separator can be changed in the usual way (&<<SECTlistsepchange>>&).
+This operation reduces a list to a single, scalar string.
+
+.new
+<&'string1'&> first has the part after any change-of-list-separator
+(see &<<SECTlistsepchange>>&) expanded,
+then the whole is taken as a list.
+.wen
+The default separator for the list is a colon.
+
Then <&'string2'&> is expanded and
assigned to the &$value$& variable. After this, each item in the <&'string1'&>
list is assigned to &$item$&, in turn, and <&'string3'&> is expanded for each of
restored to what they were before. See also the &%filter%& and &%map%&
expansion items.
+. A bit of a special-case logic error in writing an expansion;
+. probably not worth including in the mainline of documentation.
+. If only we had footnotes (the html output variant is the problem).
+.
+. .new
+. &*Note*&: if an &'expansion condition'& is used in <&'string3'&>
+. and that condition modifies &$value$&,
+. then the string expansions dependent on the condition cannot use
+. the &$value$& of the reduce iteration.
+. .wen
+
.vitem &*$rheader_*&<&'header&~name'&>&*:*&&~or&~&*$rh_*&<&'header&~name'&>&*:*&
This item inserts &"raw"& header lines. It is described with the &%header%&
expansion item in section &<<SECTexpansionitems>>& above.
-.vitem "&*${run{*&<&'command'&>&*&~*&<&'args'&>&*}{*&<&'string1'&>&*}&&&
+.vitem "&*${run<&'options'&> {*&<&'command&~string'&>&*}{*&<&'string1'&>&*}&&&
{*&<&'string2'&>&*}}*&"
.cindex "expansion" "running a command"
.cindex "&%run%& expansion item"
-The command and its arguments are first expanded as one string. The string is
-split apart into individual arguments by spaces, and then the command is run
+This item runs an external command, as a subprocess.
+One option is supported after the word &'run'&, comma-separated
+and without whitespace.
+
+If the option &'preexpand'& is not used,
+the command string before expansion is split into individual arguments by spaces
+and then each argument is separately expanded.
+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 the command requires
a shell, you must explicitly code it.
+The command name may not be tainted, but the remaining arguments can be.
+&*Note*&: if tainted arguments are used, they are supplied by a
+potential attacker;
+a careful assessment for security vulnerabilities should be done.
+
+If the option &'preexpand'& is used,
+the command string is first expanded as a whole.
+The expansion result is split apart into individual arguments by spaces,
+and then the command is run as above.
Since the arguments are split by spaces, when there is a variable expansion
which has an empty result, it will cause the situation that the argument will
simply be omitted when the program is actually executed by Exim. If the
around the command arguments. A possible guard against this is to wrap the
variable in the &%sg%& operator to change any quote marks to some other
character.
+Neither the command nor any argument may be tainted.
The standard input for the command exists, but is empty. The standard output
and standard error are set to the same file descriptor.
.code
${run{/bin/bash -c "/usr/bin/id >/tmp/id"}{yes}{yes}}
.endd
+Note that &$value$& will not persist beyond the reception of a single message.
.vindex "&$runrc$&"
The return code from the command is put in the variable &$runrc$&, and this
.cindex sorting "a list"
.cindex list sorting
.cindex expansion "list sorting"
-After expansion, <&'string'&> is interpreted as a list, colon-separated by
-default, but the separator can be changed in the usual way (&<<SECTlistsepchange>>&).
+.new
+<&'string'&> first has the part after any change-of-list-separator
+(see &<<SECTlistsepchange>>&) expanded,
+then the whole is taken as a list.
+.wen
+The default separator for the list is a colon.
+
The <&'comparator'&> argument is interpreted as the operator
of a two-argument expansion condition.
The numeric operators plus ge, gt, le, lt (and ~i variants) are supported.
-.new
.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*&
-SRS encoding. See SECT &<<SECTSRS>>& for details.
-.wen
+SRS encoding. See section &<<SECTSRS>>& for details.
-.vitem &*${substr{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&
+.vitem &*${substr{*&<&'start'&>&*}{*&<&'len'&>&*}{*&<&'subject'&>&*}}*&
.cindex "&%substr%& expansion item"
.cindex "substring extraction"
.cindex "expansion" "substring extraction"
The three strings are expanded; the first two must yield numbers. Call them
<&'n'&> and <&'m'&>. If you are using fixed values for these numbers, that is,
-if <&'string1'&> and <&'string2'&> do not change when they are expanded, you
+if <&'start'&> and <&'len'&> do not change when they are expanded, you
can use the simpler operator notation that avoids some of the braces:
.code
-${substr_<n>_<m>:<string>}
+${substr_<n>_<m>:<subject>}
.endd
The second number is optional (in both notations).
If it is absent in the simpler format, the preceding underscore must also be
.vitem &*${address:*&<&'string'&>&*}*&
.cindex "expansion" "RFC 2822 address handling"
.cindex "&%address%& expansion item"
-The string is interpreted as an RFC 2822 address, as it might appear in a
+The string is interpreted as an
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address, as it might appear in a
header line, and the effective address is extracted from it. If the string does
not parse successfully, the result is empty.
.vitem &*${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
+The string (after expansion) is interpreted as a list of addresses in
+&url(https://www.rfc-editor.org/rfc/rfc2822,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.
.vitem &*${domain:*&<&'string'&>&*}*&
.cindex "domain" "extraction"
.cindex "expansion" "domain extraction"
-The string is interpreted as an RFC 2822 address and the domain is extracted
-from it. If the string does not parse successfully, the result is empty.
+The string is interpreted as an
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address and the domain is extracted from it.
+If the string does not parse successfully, the result is empty.
.vitem &*${escape:*&<&'string'&>&*}*&
.vitem &*${escape8bit:*&<&'string'&>&*}*&
.cindex "expansion" "escaping 8-bit characters"
.cindex "&%escape8bit%& expansion item"
-If the string contains and characters with the most significant bit set,
+If the string contains any characters with the most significant bit set,
they are converted to escape sequences starting with a backslash.
Backslashes and DEL characters are also converted.
As a more realistic example, in an ACL you might have
.code
-deny message = Too many bad recipients
- condition = \
+deny condition = \
${if and { \
{>{$rcpt_count}{10}} \
{ \
{${eval:$rcpt_count/2}} \
} \
}{yes}{no}}
+ message = Too many bad recipients
.endd
The condition is true if there have been more than 10 RCPT commands and
fewer than half of them have resulted in a valid recipient.
+.vitem &*${headerwrap_*&<&'cols'&>&*_*&<&'limit'&>&*:*&<&'string'&>&*}*&
+.cindex header "wrapping operator"
+.cindex expansion "header wrapping"
+This operator line-wraps its argument in a way useful for headers.
+The &'cols'& value gives the column number to wrap after,
+the &'limit'& gives a limit number of result characters to truncate at.
+Either just the &'limit'& and the preceding underbar, or both, can be omitted;
+the defaults are 80 and 998.
+Wrapping will be inserted at a space if possible before the
+column number is reached.
+Whitespace at a chosen wrap point is removed.
+A line-wrap consists of a newline followed by a tab,
+and the tab is counted as 8 columns.
+
+
+
.vitem &*${hex2b64:*&<&'hexstring'&>&*}*&
.cindex "base64 encoding" "conversion from hex"
.cindex "expansion" "hex to base64"
.cindex "list" "item count"
.cindex "list" "count of items"
.cindex "&%listcount%& expansion item"
-The string is interpreted as a list and the number of items is returned.
+The part of the string after any leading change-of-separator is expanded,
+then the whole is interpreted as a list and the number of items is returned.
.vitem &*${listnamed:*&<&'name'&>&*}*&&~and&~&*${listnamed_*&<&'type'&>&*:*&<&'name'&>&*}*&
and selects address-, domain-, host- or localpart- lists to search among respectively.
Otherwise all types are searched in an undefined order and the first
matching list is returned.
+&*Note*&: Neither string-expansion of lists referenced by named-list syntax elements,
+nor expansion of lookup elements, is done by the &%listnamed%& operator.
.vitem &*${local_part:*&<&'string'&>&*}*&
.cindex "expansion" "local part extraction"
.cindex "&%local_part%& expansion item"
-The string is interpreted as an RFC 2822 address and the local part is
-extracted from it. If the string does not parse successfully, the result is
-empty.
+The string is interpreted as an
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address and the local part is extracted from it.
+If the string does not parse successfully, the result is empty.
The parsing correctly handles SMTPUTF8 Unicode in the string.
-.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*&
+.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& &&&
+ &*${mask_n:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*&
.cindex "masked IP address"
.cindex "IP address" "masking"
.cindex "CIDR notation"
.code
${mask:10.111.131.206/28}
.endd
-returns the string &"10.111.131.192/28"&. Since this operation is expected to
-be mostly used for looking up masked addresses in files, the result for an IPv6
+returns the string &"10.111.131.192/28"&.
+
+Since this operation is expected to
+be mostly used for looking up masked addresses in files, the
+normal
+result for an IPv6
address uses dots to separate components instead of colons, because colon
terminates a key string in lsearch files. So, for example,
.code
.code
3ffe.ffff.836f.0a00.000a.0800.2000.0000/99
.endd
+If the optional form &*mask_n*& is used, IPv6 address result are instead
+returned in normailsed form, using colons and with zero-compression.
Letters in IPv6 addresses are always output in lower case.
.vitem &*${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%&).
+required to do so by the rules of
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+for quoting local parts. For example,
+a plus sign would not cause quoting (but it would for &%quote%&).
If you are creating a new email address from the contents of &$local_part$&
(or any other unknown data), you should always use this operator.
.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
+This operator encodes text according to the rules of
+&url(https://www.rfc-editor.org/rfc/rfc2047,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
&%headers_charset%& option, which gets its default at build time. If the 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
+This operator decodes strings that are encoded as per
+&url(https://www.rfc-editor.org/rfc/rfc2047,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.
.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
+The item is replaced by the length of the expanded string, expressed as a
decimal number. &*Note*&: Do not confuse &%strlen%& with &%length%&.
All measurement is done in bytes and is not UTF-8 aware.
.cindex "&%utf8_localpart_from_alabel%& expansion item"
These convert EAI mail name components between UTF-8 and a-label forms.
For information on internationalisation support see &<<SECTi18nMTA>>&.
+
+
+.vitem &*${xtextd:*&<&'string'&>&*}*&
+.cindex "text forcing in strings"
+.cindex "string" "xtext decoding"
+.cindex "xtext"
+.cindex "&%xtextd%& expansion item"
+This performs xtext decoding of the string (per
+&url(https://www.rfc-editor.org/rfc/rfc3461,RFC 3461) section 4).
+
+
+
.endlist
.cindex "expansion" "numeric comparison"
There are a number of symbolic operators for doing numeric comparisons. They
are:
-.display
-&`= `& equal
-&`== `& equal
-&`> `& greater
-&`>= `& greater or equal
-&`< `& less
-&`<= `& less or equal
-.endd
+.itable none 0 0 2 10* left 90* left
+.irow "= " "equal"
+.irow "== " "equal"
+.irow "> " "greater"
+.irow ">= " "greater or equal"
+.irow "< " "less"
+.irow "<= " "less or equal"
+.endtable
For example:
.code
${if >{$message_size}{10M} ...
is done by calling the &[stat()]& function. The use of the &%exists%& test in
users' filter files may be locked out by the system administrator.
+&*Note:*& Testing a path using this condition is not a sufficient way of
+de-tainting it.
+Consider using a dsearch lookup.
+
.vitem &*first_delivery*&
.cindex "delivery" "first"
.cindex "first delivery"
.cindex "expansion" "first delivery test"
.cindex "&%first_delivery%& expansion condition"
+.cindex retry condition
This condition, which has no data, is true during a message's first delivery
attempt. It is false during any subsequent delivery attempts.
.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 (&<<SECTlistsepchange>>&).
+These conditions iterate over a list.
+.new
+The first argument, after any leading change-of-separator
+(see &<<SECTlistsepchange>>&),
+is expanded and the whole forms the list.
+.wen
+By default, the list separator is a colon.
+
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 &$item$&.
.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:
+that the condition must be false for at least one item.
+
+Example:
.code
-${if forany{<, $recipients}{match{$item}{^user3@}}{yes}{no}}
+${if forany{$recipients_list}{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.
Case and collation order are defined per the system C locale.
-.new
.vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*&
SRS decode. See SECT &<<SECTSRS>>& for details.
-.wen
-.vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
- &*inlisti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
+.vitem &*inlist&~{*&<&'subject'&>&*}{*&<&'list'&>&*}*& &&&
+ &*inlisti&~{*&<&'subject'&>&*}{*&<&'list'&>&*}*&
.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.
+The <&'subject'&> string is expanded.
+.new
+The <&'list'&> first has any change-of-list-separator
++(see &<<SECTlistsepchange>>&) retained verbatim,
++then the remainder is expanded.
++.wen
+The whole is treated as a list of simple strings;
+if the subject string is a member of that list, then the condition is true.
For the case-independent &%inlisti%& condition, case is defined per the system C locale.
These are simpler to use versions of the more powerful &*forany*& condition.
${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}}
.endd
+The variable &$value$& will be set for a successful match and can be
+used in the success clause of an &%if%& expansion item using the condition.
+.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using an inlist expansion condition"
+It will have the same taint status as the list; expansions such as
+.code
+${if inlist {$h_mycode:} {0 : 1 : 42} {$value}}
+.endd
+can be used for de-tainting.
+Any previous &$value$& is restored after the if.
+
+
.vitem &*isip&~{*&<&'string'&>&*}*& &&&
&*isip4&~{*&<&'string'&>&*}*& &&&
&*isip6&~{*&<&'string'&>&*}*&
.next
The item @[] matches any of the local host's interface addresses.
.next
-Single-key lookups are assumed to be like &"net-"& style lookups in host lists,
+Single-key lookups are assumed to be like &"net-"& style lookups in host lists
+(see section &<<SECThoslispatsikey>>&),
even if &`net-`& is not specified. There is never any attempt to turn the IP
address into a host name. The most common type of linear search for
&*match_ip*& is likely to be &*iplsearch*&, in which the file can contain CIDR
Note that <&'string2'&> is not itself subject to string expansion, unless
Exim was built with the EXPAND_LISTMATCH_RHS option.
+.new
+For the latter case, only the part after any leading
+change-of-separator specification is expanded.
+.wen
Consult section &<<SECThoslispatip>>& for further details of these patterns.
+The variable &$value$& will be set for a successful match and can be
+used in the success clause of an &%if%& expansion item using the condition.
+Any previous &$value$& is restored after the if.
+
.vitem &*match_local_part&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*&
.cindex "domain list" "in expansion condition"
.cindex "address list" "in expansion condition"
.endd
.cindex "&`+caseful`&"
For address lists, the matching starts off caselessly, but the &`+caseful`&
-item can be used, as in all address lists, to cause subsequent items to
-have their local parts matched casefully. Domains are always matched
-caselessly.
+item can be used, as in all address lists, to cause subsequent items
+(including those of referenced named lists)
+to have their local parts matched casefully.
+Domains are always matched caselessly.
+
+The variable &$value$& will be set for a successful match and can be
+used in the success clause of an &%if%& expansion item using the condition.
+.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using a match_local_part expansion condition"
+It will have the same taint status as the list; expansions such as
+.code
+${if match_local_part {$local_part} {alice : bill : charlotte : dave} {$value}}
+.endd
+can be used for de-tainting.
+Any previous &$value$& is restored after the if.
Note that <&'string2'&> is not itself subject to string expansion, unless
Exim was built with the EXPAND_LISTMATCH_RHS option.
+.new
+For the latter case, only the part after any leading
+change-of-separator specification is expanded.
+.wen
&*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
.cindex "&%pam%& expansion condition"
&'Pluggable Authentication Modules'&
(&url(https://mirrors.edge.kernel.org/pub/linux/libs/pam/)) are a facility that is
-available in the latest releases of Solaris and in some GNU/Linux
-distributions. The Exim support, which is intended for use in conjunction with
+available in Solaris
+and in some GNU/Linux distributions.
+The Exim support, which is intended for use in conjunction with
the SMTP AUTH command, is available only if Exim is compiled with
.code
SUPPORT_PAM=yes
There can be problems if any of the strings are permitted to contain colon
characters. In the usual way, these have to be doubled to avoid being taken as
-separators. If the data is being inserted from a variable, the &%sg%& expansion
-item can be used to double any existing colons. For example, the configuration
+separators.
+The &%listquote%& expansion item can be used for this.
+For example, the configuration
of a LOGIN authenticator might contain this setting:
.code
-server_condition = ${if pam{$auth1:${sg{$auth2}{:}{::}}}}
-.endd
-For a PLAIN authenticator you could use:
-.code
-server_condition = ${if pam{$auth2:${sg{$auth3}{:}{::}}}}
+server_condition = ${if pam{$auth1:${listquote{:}{$auth2}}}}
.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 "Radius"
.cindex "expansion" "Radius authentication"
.cindex "&%radius%& expansion condition"
-Radius authentication (RFC 2865) is supported in a similar way to PAM. You must
+Radius authentication
+(&url(https://www.rfc-editor.org/rfc/rfc2865,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.
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 "tainted data"
+Variables marked as &'tainted'& are likely to carry data supplied by
+a potential attacker.
+Variables without such marking may also, depending on how their
+values are created.
+Such variables should not be further expanded,
+used as filenames
+or used as command-line arguments for external commands.
.vlist
.vitem "&$0$&, &$1$&, etc"
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.
+If the subject string was tainted then any captured substring will also be.
.vitem "&$acl_arg1$&, &$acl_arg2$&, etc"
Within an acl condition, expansion condition or expansion item
.vitem &$acl_verify_message$&
.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:
+message. It retains its value for use in subsequent modifiers of the verb.
+The message can be preserved by coding like this:
.code
warn !verify = sender
set acl_m0 = $acl_verify_message
You can use &$acl_verify_message$& during the expansion of the &%message%& or
&%log_message%& modifiers, to include information about the verification
failure.
+&*Note*&: The variable is cleared at the end of processing the ACL verb.
.vitem &$address_data$&
.vindex "&$address_data$&"
When, as a result of aliasing or forwarding, a message is directed to a pipe,
this variable holds the pipe command when the transport is running.
-.vitem "&$auth1$& &-- &$auth3$&"
+.new
+.vitem &$atrn_host$&
+.vindex ATRN "data for routing"
+When an ATRN command is accepted, this variable is filled in with the client
+IP and port, for use in a manualroute router.
+.wen
+
+.vitem "&$auth1$& &-- &$auth4$&"
.vindex "&$auth1$&, &$auth2$&, etc"
These variables are used in SMTP authenticators (see chapters
&<<CHAPplaintext>>&&--&<<CHAPtlsauth>>&). Elsewhere, they are empty.
the ACL's as well.
-.vitem &$authenticated_sender$&
+.tvar &$authenticated_sender$&
.cindex "sender" "authenticated"
.cindex "authentication" "sender"
.cindex "AUTH" "on MAIL command"
-.vindex "&$authenticated_sender$&"
When acting as a server, Exim takes note of the AUTH= parameter on an incoming
SMTP MAIL command if it believes the sender is sufficiently trusted, as
described in section &<<SECTauthparamail>>&. Unless the data is the string
possible to distinguish between &"did not try to authenticate"&
(&$sender_host_authenticated$& is empty and &$authentication_failed$& is set to
&"0"&) and &"tried to authenticate but failed"& (&$sender_host_authenticated$&
-is empty and &$authentication_failed$& is set to &"1"&). Failure includes any
-negative response to an AUTH command, including (for example) an attempt to use
-an undefined mechanism.
+is empty and &$authentication_failed$& is set to &"1"&).
+Failure includes cancellation of a authentication attempt,
+and any negative response to an AUTH command,
+(including, for example, an attempt to use an undefined mechanism).
.vitem &$av_failed$&
.cindex "content scanning" "AV scanner failure"
.vindex "&$config_file$&"
The name of the main configuration file Exim is using.
-.vitem &$dmarc_domain_policy$& &&&
- &$dmarc_status$& &&&
- &$dmarc_status_text$& &&&
- &$dmarc_used_domains$&
-Results of DMARC verification.
-For details see section &<<SECDMARC>>&.
+.vitem &$connection_id$&
+.vindex "&$connection_id$&"
+.cindex connection "identifier logging"
+An identifier for the accepted connection, for use in custom logging.
.vitem &$dkim_verify_status$&
Results of DKIM verification.
a colon-separated list of signer domains and identities for the message.
For details see section &<<SECDKIMVFY>>&.
+.vitem &$dmarc_alignment_spf$& &&&
+ &$dmarc_alignment_dkim$& &&&
+ &$dmarc_domain_policy$& &&&
+ &$dmarc_status$& &&&
+ &$dmarc_status_text$& &&&
+ &$dmarc_used_domains$&
+Results of DMARC verification.
+For details see section &<<SECDMARC>>&.
+
.vitem &$dnslist_domain$& &&&
&$dnslist_matched$& &&&
&$dnslist_text$& &&&
looked up, the contents of any associated TXT record, and the value from the
main A record. See section &<<SECID204>>& for more details.
-.vitem &$domain$&
-.vindex "&$domain$&"
+.tvar &$domain$&
When an address is being routed, or delivered on its own, this variable
contains the domain. Uppercase letters in the domain are converted into lower
case for &$domain$&.
the complete argument of the ETRN command (see section &<<SECTETRN>>&).
.endlist
-.new
.cindex "tainted data"
If the origin of the data is an incoming message,
-the result of expanding this variable is tainted.
-When un untainted version is needed, one should be obtained from
+the result of expanding this variable is tainted and may not
+be further expanded or used as a filename.
+When an untainted version is needed, one should be obtained from
looking up the value in a local (therefore trusted) database.
Often &$domain_data$& is usable in this role.
-.wen
.vitem &$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$&. In addition, if the driver routes the
+When the &%domains%& condition on a router
+or an ACL
+matches a domain
+against a list, the match value is copied to &$domain_data$&.
+This is an enhancement over previous versions of Exim, when it only
+applied to the data read by a lookup.
+For details on match values see section &<<SECTlistresults>>& et. al.
+
+If the router routes the
address to a transport, the value is available in that transport. If the
transport is handling multiple addresses, the value from the first address is
used.
-&$domain_data$& is also set when the &%domains%& condition in an ACL matches a
-domain by means of a lookup. The data read by the lookup is available during
-the rest of the ACL statement. In all other situations, this variable expands
-to nothing.
+&$domain_data$& set in an ACL is available during
+the rest of the ACL statement.
.vitem &$exim_gid$&
.vindex "&$exim_gid$&"
This value may be overridden by the &%exim_version%& main config option.
.vitem &$header_$&<&'name'&>
+.tmark
This is not strictly an expansion variable. It is expansion syntax for
inserting the message header line with the given name. Note that the name must
be terminated by colon or white space, because it may contain a wide variety of
allows you, for example, to do things like this:
.code
deny hosts = net-lsearch;/some/file
-message = $host_data
+ message = $host_data
.endd
+
.vitem &$host_lookup_deferred$&
.cindex "host name" "lookup, failure of"
.vindex "&$host_lookup_deferred$&"
of the temporary file which is about to be renamed. It can be used to construct
a unique name for the file.
-.vitem &$interface_address$&
+.vitem &$interface_address$& &&&
+ &$interface_port$&
.vindex "&$interface_address$&"
-This is an obsolete name for &$received_ip_address$&.
-
-.vitem &$interface_port$&
.vindex "&$interface_port$&"
-This is an obsolete name for &$received_port$&.
+These are obsolete names for &$received_ip_address$& and &$received_port$&.
.vitem &$item$&
.vindex "&$item$&"
is an integer. For example, if the load average is 0.21, the value of the
variable is 210. The value is recomputed every time the variable is referenced.
-.vitem &$local_part$&
-.vindex "&$local_part$&"
+.tvar &$local_part$&
When an address is being routed, or delivered on its own, this
variable contains the local part. When a number of addresses are being
delivered together (for example, multiple RCPT commands in an SMTP
because a message may have many recipients and the system filter is called just
once.
-.new
.cindex "tainted data"
If the origin of the data is an incoming message,
-the result of expanding this variable is tainted.
+the result of expanding this variable is tainted and
+may not be further expanded or used as a filename.
&*Warning*&: the content of this variable is usually provided by a potential
attacker.
Often &$local_part_data$& is usable in this role.
If needed, use a router &%address_data%& or &%set%& option for
the retrieved data.
-.wen
When a message is being delivered to a file, pipe, or autoreply transport as a
result of aliasing or forwarding, &$local_part$& is set to the local part of
.vitem &$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$&. In addition, if the driver routes the address
-to a transport, the value is available in that transport. If the transport is
-handling multiple addresses, the value from the first address is used.
+When the &%local_parts%& condition on a router or ACL
+matches a local part list
+the match value is copied to &$local_part_data$&.
+This is an enhancement over previous versions of Exim, when it only
+applied to the data read by a lookup.
+For details on match values see section &<<SECTlistresults>>& et. al.
-.new
The &%check_local_user%& router option also sets this variable.
-.wen
-
-&$local_part_data$& is also set when the &%local_parts%& condition in an ACL
-matches a local part by means of a lookup. The data read by the lookup is
-available during the rest of the ACL statement. In all other situations, this
-variable expands to nothing.
.vindex &$local_part_prefix$& &&&
&$local_part_prefix_v$& &&&
value of &$local_part$& during routing and subsequent delivery. The values of
any prefix or suffix are in &$local_part_prefix$& and
&$local_part_suffix$&, respectively.
-.new
.cindex "tainted data"
If the specification did not include a wildcard then
the affix variable value is not tainted.
the affix matched by the wildcard is in
&$local_part_prefix_v$& or &$local_part_suffix_v$& as appropriate,
and both the whole and varying values are tainted.
-.wen
.vitem &$local_scan_data$&
.vindex "&$local_scan_data$&"
This variable contains the number of bytes in the longest line that was
received as part of the message, not counting the line termination
character(s).
-It is not valid if the &%spool_files_wireformat%& option is used.
+It is not valid if the &%spool_wireformat%& option is used.
.vitem &$message_age$&
.cindex "message" "age of"
of seconds since the message was received. It does not change during a single
delivery attempt.
-.vitem &$message_body$&
+.tvar &$message_body$&
.cindex "body of message" "expansion variable"
.cindex "message body" "in expansion"
.cindex "binary zero" "in message body"
-.vindex "&$message_body$&"
.oindex "&%message_body_visible%&"
This variable contains the initial portion of a message's body while it is
being delivered, and is intended mainly for use in filter files. The maximum
this can be disabled by setting &%message_body_newlines%& to be true. Binary
zeros are always converted into spaces.
-.vitem &$message_body_end$&
+.tvar &$message_body_end$&
.cindex "body of message" "expansion variable"
.cindex "message body" "in expansion"
-.vindex "&$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$&.
also &$message_size$&, &$body_linecount$&, and &$body_zerocount$&.
If the spool file is wireformat
-(see the &%spool_files_wireformat%& main option)
+(see the &%spool_wireformat%& main option)
the CRLF line-terminators are included in the count.
.vitem &$message_exim_id$&
line; it is the local id that Exim assigns to the message, for example:
&`1BXTIK-0001yO-VA`&.
-.vitem &$message_headers$&
-.vindex &$message_headers$&
+.tvar &$message_headers$&
This variable contains a concatenation of all the header lines when a message
is being processed, except for lines added by routers or transports. The header
lines are separated by newline characters. Their contents are decoded in the
same way as a header line that is inserted by &%bheader%&.
-.vitem &$message_headers_raw$&
-.vindex &$message_headers_raw$&
+.tvar &$message_headers_raw$&
This variable is like &$message_headers$& except that no processing of the
contents of header lines is done.
Here is an example of the use of this variable in a DATA ACL:
.code
-deny message = Too many lines in message header
- condition = \
+deny condition = \
${if <{250}{${eval:$message_linecount - $body_linecount}}}
+ message = Too many lines in message header
.endd
In the MAIL and RCPT ACLs, the value is zero because at that stage the
message has not yet been received.
-This variable is not valid if the &%spool_files_wireformat%& option is used.
+This variable is not valid if the &%spool_wireformat%& option is used.
.vitem &$message_size$&
.cindex "size" "of message"
contains the size supplied on the MAIL command, or -1 if no size was given. The
value may not, of course, be truthful.
-.vitem &$mime_$&&'xxx'&
+.vitem &$mime_anomaly_level$& &&&
+ &$mime_anomaly_text$& &&&
+ &$mime_boundary$& &&&
+ &$mime_charset$& &&&
+ &$mime_content_description$& &&&
+ &$mime_content_disposition$& &&&
+ &$mime_content_id$& &&&
+ &$mime_content_size$& &&&
+ &$mime_content_transfer_encoding$& &&&
+ &$mime_content_type$& &&&
+ &$mime_decoded_filename$& &&&
+ &$mime_filename$& &&&
+ &$mime_is_coverletter$& &&&
+ &$mime_is_multipart$& &&&
+ &$mime_is_rfc822$& &&&
+ &$mime_part_count$&
A number of variables whose names start with &$mime$& are
available when Exim is compiled with the content-scanning extension. For
details, see section &<<SECTscanmimepart>>&.
These variables are counters that can be incremented by means
of the &%add%& command in filter files.
-.vitem &$original_domain$&
+.tvar &$original_domain$&
.vindex "&$domain$&"
-.vindex "&$original_domain$&"
When a top-level address is being processed for delivery, this contains the
same value as &$domain$&. However, if a &"child"& address (for example,
generated by an alias, forward, or filter file) is being processed, this
filter, it is set up with an artificial &"parent"& address. This has the local
part &'system-filter'& and the default qualify domain.
-.vitem &$original_local_part$&
+.tvar &$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$& always contains the full local
For messages received by SMTP over TCP/IP, this is normally the uid of the Exim
user.
-.vitem &$parent_domain$&
-.vindex "&$parent_domain$&"
+.tvar &$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$&
-.vindex "&$parent_local_part$&"
+.tvar &$parent_local_part$&
This variable is similar to &$original_local_part$&
(see above), except that it refers to the immediately preceding parent address.
(described under &%transport_filter%& in chapter &<<CHAPtransportgeneric>>&).
It cannot be used in general expansion strings, and provokes an &"unknown
variable"& error if encountered.
+&*Note*&: This value permits data supplied by a potential attacker to
+be used in the command for a &(pipe)& transport.
+Such configurations should be carefully assessed for security vulnerbilities.
.vitem &$primary_hostname$&
.vindex "&$primary_hostname$&"
This variable is set to &"yes"& if PRDR was requested by the client for the
current message, otherwise &"no"&.
-.vitem &$prvscheck_address$&
-This variable is used in conjunction with the &%prvscheck%& expansion item,
-which is described in sections &<<SECTexpansionitems>>& and
-&<<SECTverifyPRVS>>&.
-
-.vitem &$prvscheck_keynum$&
-This variable is used in conjunction with the &%prvscheck%& expansion item,
-which is described in sections &<<SECTexpansionitems>>& and
-&<<SECTverifyPRVS>>&.
-
-.vitem &$prvscheck_result$&
-This variable is used in conjunction with the &%prvscheck%& expansion item,
+.vitem &$prvscheck_address$& &&&
+ &$prvscheck_keynum$& &&&
+ &$prvscheck_result$&
+These variables are used in conjunction with the &%prvscheck%& expansion item,
which is described in sections &<<SECTexpansionitems>>& and
&<<SECTverifyPRVS>>&.
.cindex "spool" "number of messages"
This variable contains the number of messages queued.
It is evaluated on demand, but no more often than once every minute.
+If there is no daemon notifier socket open, the value will be
+an empty string.
.vitem &$r_...$&
.vindex &$r_...$&
is available in the DATA ACL, the non-SMTP ACL, and while routing and
delivering.
-.vitem &$received_for$&
-.vindex "&$received_for$&"
+.tvar &$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$&
+.vitem &$received_ip_address$& &&&
+ &$received_port$&
.vindex "&$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$&
-is set to the local port number. (The remote IP address and port are in
+.vindex "&$received_port$&"
+As soon as an Exim server starts processing an incoming TCP/IP connection, these
+variables are set to the address and port on the local IP interface.
+(The remote IP address and port are in
&$sender_host_address$& and &$sender_host_port$&.) When testing with &%-bh%&,
the port value is -1 unless it has been set using the &%-oMi%& command line
option.
time.
For outbound connections see &$sending_ip_address$&.
-.vitem &$received_port$&
-.vindex "&$received_port$&"
-See &$received_ip_address$&.
-
.vitem &$received_protocol$&
.vindex "&$received_protocol$&"
When a message is being processed, this variable contains the name of the
The main use of this variable is expected to be to distinguish between
rejections of MAIL and rejections of RCPT.
-.vitem &$recipients$&
-.vindex "&$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$& only in these
+.tvar &$recipients$&
+.tvar &$recipients_list$&
+These variables both contain the envelope recipients for a message.
+
+The first uses a comma and a space separate the addresses in the replacement text.
+&*Note*&: an address can legitimately contain a comma;
+this variable is not intended for further processing.
+
+The second is a proper Exim list; colon-separated.
+
+However, the variables
+are not generally available, to prevent exposure of Bcc recipients in
+unprivileged users' filter files. You can use either of them only in these
cases:
.olist
When a &%regex%& or &%mime_regex%& ACL condition succeeds,
these variables contain the
captured substrings identified by the regular expression.
+If the subject string was tainted then so will any captured substring.
-.vitem &$reply_address$&
-.vindex "&$reply_address$&"
+.tvar &$reply_address$&
When a message is being processed, this variable contains the contents of the
&'Reply-To:'& header line if one exists and it is not empty, or otherwise the
contents of the &'From:'& header line. Apart from the removal of leading
.cindex "router" "name"
.cindex "name" "of router"
.vindex "&$router_name$&"
-During the running of a router this variable contains its name.
+During the running of a router, or a transport called,
+this variable contains the router name.
.vitem &$runrc$&
.cindex "return code" "from &%run%& expansion"
happens, &$self_hostname$& is set to the name of the local host that the
original router encountered. In other circumstances its contents are null.
-.vitem &$sender_address$&
-.vindex "&$sender_address$&"
+.tvar &$sender_address$&
When a message is being processed, this variable contains the sender's address
that was received in the message's envelope. The case of letters in the address
is retained, in both the local part and the domain. For bounce messages, the
after the end of the current ACL statement. If you want to preserve it for
longer, you can save it in an ACL variable.
-.vitem &$sender_address_domain$&
-.vindex "&$sender_address_domain$&"
+.tvar &$sender_address_domain$&
The domain portion of &$sender_address$&.
-.vitem &$sender_address_local_part$&
-.vindex "&$sender_address_local_part$&"
+.tvar &$sender_address_local_part$&
The local part portion of &$sender_address$&.
.vitem &$sender_data$&
.cindex "DNS" "DNSSEC"
done using DNS information the resolver library stated was authenticated data.
-.vitem &$sender_helo_name$&
-.vindex "&$sender_helo_name$&"
+.tvar &$sender_helo_name$&
When a message is received from a remote host that has issued a HELO or EHLO
command, the argument of that command is placed in this variable. It is also
set if HELO or EHLO is used when a message is received using SMTP locally via
dns_dnssec_ok = 1
.endd
-.new
In addition, on Linux with glibc 2.31 or newer the resolver library will
default to stripping out a successful validation status.
This will break a previously working Exim installation.
.code
options trust-ad
.endd
-.wen
Exim does not perform DNSSEC validation itself, instead leaving that to a
validating resolver (e.g. unbound, or bind with suitable configuration).
is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3).
-.vitem &$sender_host_name$&
-.vindex "&$sender_host_name$&"
+.tvar &$sender_host_name$&
When a message is received from a remote host, this variable contains the
host's name as obtained by looking up its IP address. For messages received by
other means, this variable is empty.
&$smtp_active_hostname$& is saved with any message that is received, so its
value can be consulted during routing and delivery.
-.vitem &$smtp_command$&
-.vindex "&$smtp_command$&"
+.tvar &$smtp_command$&
During the processing of an incoming SMTP command, this variable contains the
entire command. This makes it possible to distinguish between HELO and EHLO in
the HELO ACL, and also to distinguish between commands such as these:
rewriting, whereas the values in &$local_part$& and &$domain$& are taken from
the address after SMTP-time rewriting.
-.vitem &$smtp_command_argument$&
+.tvar &$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$&, this variable is
single connection is being processed. When a child process terminates, the
daemon decrements its copy of the variable.
+.vitem &$smtp_notquit_reason$&
+.vindex "&$smtp_notquit_reason$&"
+When the not-QUIT ACL is running, this variable is set to a string
+that indicates the reason for the termination of the SMTP connection.
+
.vitem "&$sn0$& &-- &$sn9$&"
These variables are copies of the values of the &$n0$& &-- &$n9$& accumulators
that were current at the end of the system filter file. This allows a system
example, a system filter could set a value indicating how likely it is that a
message is junk mail.
-.vitem &$spam_$&&'xxx'&
+.vitem &$spam_score$& &&&
+ &$spam_score_int$& &&&
+ &$spam_bar$& &&&
+ &$spam_report$& &&&
+ &$spam_action$&
A number of variables whose names start with &$spam$& are available when Exim
is compiled with the content-scanning extension. For details, see section
&<<SECTscanspamass>>&.
If certificate verification fails it may refer to a failing chain element
which is not the leaf.
-.vitem &$tls_in_sni$&
-.vindex "&$tls_in_sni$&"
+
+.vitem &$tls_in_resumption$& &&&
+ &$tls_out_resumption$&
+.vindex &$tls_in_resumption$&
+.vindex &$tls_out_resumption$&
+.cindex TLS resumption
+Observability for TLS session resumption. See &<<SECTresumption>>& for details.
+
+
+.tvar &$tls_in_sni$&
.vindex "&$tls_sni$&"
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI "observability on server"
When a TLS session is being established, if the client sends the Server
Name Indication extension, the value will be placed in this variable.
If the variable appears in &%tls_certificate%& then this option and
.vitem &$tls_out_sni$&
.vindex "&$tls_out_sni$&"
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI "observability in client"
During outbound
SMTP deliveries, this variable reflects the value of the &%tls_sni%& option on
the transport.
option to a true value. To avoid breaking existing installations, it
defaults to false.
+&*Note*&: This is entirely separate from Exim's tainted-data tracking.
+
.section "Calling Perl subroutines" "SECID86"
When the configuration file includes a &%perl_startup%& option you can make use
.code
tls_on_connect_ports = 465
.endd
-per RFC 8314.
+per &url(https://www.rfc-editor.org/rfc/rfc8314,RFC 8314).
There is also a command line option &%-tls-on-connect%&, which forces all ports
to behave in this way when a daemon is started.
.section "Miscellaneous" "SECID96"
.table2
+.row &%add_environment%& "environment variables"
.row &%bi_command%& "to run for &%-bi%& command line option"
.row &%debug_store%& "do extra internal checks"
.row &%disable_ipv6%& "do no IPv6 processing"
+.row &%keep_environment%& "environment variables"
.row &%keep_malformed%& "for broken files &-- should not happen"
.row &%localhost_number%& "for unique message ids in clusters"
.row &%message_body_newlines%& "retain newlines in &$message_body$&"
.row &%log_timezone%& "add timezone to log lines"
.row &%message_logs%& "create per-message logs"
.row &%preserve_message_logs%& "after message completion"
+.row &%panic_coredump%& "request coredump on fatal errors"
.row &%process_log_path%& "for SIGUSR1 and &'exiwhat'&"
.row &%slow_lookup_log%& "control logging of slow DNS lookups"
.row &%syslog_duplication%& "controls duplicate log lines on syslog"
.row &%notifier_socket%& "override compiled-in value"
.row &%pid_file_path%& "override compiled-in value"
.row &%queue_run_max%& "maximum simultaneous queue runners"
+.row &%smtp_backlog_monitor%& "level to log listen backlog"
.endtable
.row &%acl_not_smtp%& "ACL for non-SMTP messages"
.row &%acl_not_smtp_mime%& "ACL for non-SMTP MIME parts"
.row &%acl_not_smtp_start%& "ACL for start of non-SMTP message"
+.row &%acl_smtp_atrn%& "ACL for ATRN"
.row &%acl_smtp_auth%& "ACL for AUTH"
.row &%acl_smtp_connect%& "ACL for connection"
.row &%acl_smtp_data%& "ACL for DATA"
.row &%acl_smtp_rcpt%& "ACL for RCPT"
.row &%acl_smtp_starttls%& "ACL for STARTTLS"
.row &%acl_smtp_vrfy%& "ACL for VRFY"
+.row &%acl_smtp_wellknown%& "ACL for WELLKNOWN"
.row &%av_scanner%& "specify virus scanner"
.row &%check_rfc2047_length%& "check length of RFC 2047 &""encoded &&&
words""&"
.row &%local_scan_timeout%& "timeout for &[local_scan()]&"
.row &%message_size_limit%& "for all messages"
.row &%percent_hack_domains%& "recognize %-hack for these domains"
+.row &%proxy_protocol_timeout%& "timeout for proxy protocol negotiation"
.row &%spamd_address%& "set interface to SpamAssassin"
.row &%strict_acl_vars%& "object to unset ACL variables"
+.row &%spf_smtp_comment_template%& "template for &$spf_smtp_comment$&"
.endtable
.table2
.row &%gnutls_compat_mode%& "use GnuTLS compatibility mode"
.row &%gnutls_allow_auto_pkcs11%& "allow GnuTLS to autoload PKCS11 modules"
+.row &%hosts_require_alpn%& "mandatory ALPN"
+.row &%hosts_require_helo%& "mandatory HELO/EHLO"
.row &%openssl_options%& "adjust OpenSSL compatibility options"
.row &%tls_advertise_hosts%& "advertise TLS to these hosts"
+.row &%tls_alpn%& "acceptable protocol names"
.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 &%dkim_verify_keytypes%& "DKIM key types accepted for signatures"
.row &%dkim_verify_min_keysizes%& "DKIM key sizes accepted for signatures"
.row &%dkim_verify_signers%& "DKIM domains for which DKIM ACL is run"
+.row &%dmarc_forensic_sender%& "DMARC sender for report messages"
+.row &%dmarc_history_file%& "DMARC results log"
+.row &%dmarc_tld_file%& "DMARC toplevel domains file"
.row &%host_lookup%& "host name looked up for these hosts"
.row &%host_lookup_order%& "order of DNS and local name lookups"
.row &%recipient_unqualified_hosts%& "may send unqualified recipients"
.row &%dsn_advertise_hosts%& "advertise DSN extensions to these hosts"
.row &%ignore_fromline_hosts%& "allow &""From ""& from these hosts"
.row &%ignore_fromline_local%& "allow &""From ""& from local SMTP"
+.row &%limits_advertise_hosts%& "advertise LIMITS to these hosts"
.row &%pipelining_advertise_hosts%& "advertise pipelining to these hosts"
.row &%pipelining_connect_advertise_hosts%& "advertise pipelining to these hosts"
.row &%prdr_enable%& "advertise PRDR to all hosts"
.row &%smtputf8_advertise_hosts%& "advertise SMTPUTF8 to these hosts"
.row &%tls_advertise_hosts%& "advertise TLS to these hosts"
+.row &%wellknown_advertise_hosts%& "advertise WELLKNOWN to these hosts"
.endtable
.row &%hold_domains%& "hold delivery for these domains"
.row &%local_interfaces%& "for routing checks"
.row &%queue_domains%& "no immediate delivery for these"
+.row &%queue_fast_ramp%& "parallel delivery with 2-phase queue run"
.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"
.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 has been
-read and is on the point of being accepted. See chapter &<<CHAPACL>>& for
+read and is on the point of being accepted. See section &<<SECnonSMTP>>& for
further details.
.option acl_not_smtp_mime 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.
+non-SMTP message. See section &<<SECnonSMTP>>& for further details.
+
+.new
+.option acl_smtp_atrn main string&!! unset
+.cindex ATRN "ACL for"
+.cindex ATRN advertisement
+.cindex "ESMTP extensions" ATRN
+This option defines the ACL that is run when an SMTP ATRN command is
+received.
+If no value is set, or the result after expansion is an empty string,
+then the ATRN facility is not advertised.
+See chapter &<<CHAPACL>>& for general information on ACLs,
+and section &<<SECTATRN>>& for description of ATRN.
+.wen
.option acl_smtp_auth main string&!! unset
.cindex "&ACL;" "setting up for SMTP commands"
.cindex "AUTH" "ACL for"
This option defines the ACL that is run when an SMTP AUTH command is
-received. See chapter &<<CHAPACL>>& for further details.
+received.
+See chapter &<<CHAPACL>>& for general information on ACLs, and chapter
+&<<CHAPSMTPAUTH>>& for details of authentication.
.option acl_smtp_connect main string&!! unset
.cindex "&ACL;" "on SMTP connection"
This option defines the ACL that is run when an SMTP connection is received.
-See chapter &<<CHAPACL>>& for further details.
+See section &<<SECconnectACL>>& for further details.
.option acl_smtp_data main string&!! unset
.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
-acknowledgment is sent. See chapter &<<CHAPACL>>& for further details.
+acknowledgment is sent. See section &<<SECdataACLS>>& for further details.
.option acl_smtp_data_prdr main string&!! accept
.cindex "PRDR" "ACL for"
if the PRDR feature has been negotiated,
is run for each recipient after an SMTP DATA command has been
processed and the message itself has been received, but before the
-acknowledgment is sent. See chapter &<<CHAPACL>>& for further details.
+acknowledgment is sent. See section &<<SECTPRDRACL>>& for further details.
.option acl_smtp_dkim main string&!! unset
.cindex DKIM "ACL for"
.option acl_smtp_etrn main string&!! unset
.cindex "ETRN" "ACL for"
+.cindex "ETRN" advertisement
This option defines the ACL that is run when an SMTP ETRN command is
-received. See chapter &<<CHAPACL>>& for further details.
+received.
+If no value is set then the ETRN facility is not advertised.
+See chapter &<<CHAPACL>>& for general information on ACLs,
+and section &<<SECTETRN>>& for description of ETRN.
.option acl_smtp_expn main string&!! unset
.cindex "EXPN" "ACL for"
.cindex "EHLO" "ACL for"
.cindex "HELO" "ACL for"
This option defines the ACL that is run when an SMTP EHLO or HELO
-command is received. See chapter &<<CHAPACL>>& for further details.
+command is received. See section &<<SECheloACL>>& for further details.
.option acl_smtp_mail main string&!! unset
.option acl_smtp_mailauth main string&!! unset
.cindex "AUTH" "on MAIL command"
This option defines the ACL that is run when there is an AUTH parameter on
-a MAIL command. See chapter &<<CHAPACL>>& for details of ACLs, and chapter
+a MAIL command.
+See chapter &<<CHAPACL>>& for general information on ACLs, and chapter
&<<CHAPSMTPAUTH>>& for details of authentication.
.option acl_smtp_mime main string&!! unset
.cindex "not-QUIT, ACL for"
This option defines the ACL that is run when an SMTP session
ends without a QUIT command being received.
-See chapter &<<CHAPACL>>& for further details.
+See section &<<SECTNOTQUITACL>>& for further details.
.option acl_smtp_predata main string&!! unset
This option defines the ACL that is run when an SMTP DATA command is
.option acl_smtp_rcpt main string&!! unset
.cindex "RCPT" "ACL for"
This option defines the ACL that is run when an SMTP RCPT command is
-received. See chapter &<<CHAPACL>>& for further details.
+received. See section &<<SECTQUITACL>>& for further details.
.option acl_smtp_starttls main string&!! unset
.cindex "STARTTLS, ACL for"
This option defines the ACL that is run when an SMTP VRFY command is
received. See chapter &<<CHAPACL>>& for further details.
+.option acl_smtp_wellknown main string&!! unset
+.cindex "WELLKNOWN, ACL for"
+This option defines the ACL that is run when an SMTP WELLKNOWN command is
+received. See section &<<SECTWELLKNOWNACL>>& for further details.
+
.option add_environment main "string list" empty
.cindex "environment" "set values"
This option adds individual environment variables that the
.option allow_domain_literals main boolean false
.cindex "domain literal"
-If this option is set, the RFC 2822 domain literal format is permitted in
+If this option is set, the
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+domain literal format is permitted in
email addresses. The option is not set by default, because the domain literal
format is not normally required these days, and few people know about it. It
has, however, been exploited by mail abusers.
configuration). This &"magic string"& matches the domain literal form of all
the local host's IP addresses.
-
.option allow_mx_to_ip main boolean false
.cindex "MX record" "pointing to IP address"
It appears that more and more DNS zone administrators are breaking the rules
This option defines a template file containing paragraphs of text to be used
for constructing bounce messages. Details of the file's contents are given in
chapter &<<CHAPemsgcust>>&.
-.new
.cindex bounce_message_file "tainted data"
The option is expanded to give the file path, which must be
absolute and untainted.
-.wen
See also &%warn_message_file%&.
See section &<<CALLaddparcall>>& for details of how this value is used.
-.option check_log_inodes main integer 100
-See &%check_spool_space%& below.
-
-
-.option check_log_space main integer 10M
+.options check_log_inodes main integer 100 &&&
+ check_log_space main integer 10M
See &%check_spool_space%& below.
.oindex "&%check_rfc2047_length%&"
.cindex "RFC 2047" "disabling length check"
.option check_rfc2047_length main boolean true
-RFC 2047 defines a way of encoding non-ASCII characters in headers using a
+&url(https://www.rfc-editor.org/rfc/rfc2047,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
multiple encoded words. By default, Exim does not recognize encoded words that
set false, Exim recognizes encoded words of any length.
-.option check_spool_inodes main integer 100
-See &%check_spool_space%& below.
-
-
-.option check_spool_space main integer 10M
+.options check_spool_inodes main integer 100 &&&
+ check_spool_space main integer 10M
.cindex "checking disk space"
.cindex "disk space, checking"
.cindex "spool directory" "checking space"
.cindex CHUNKING advertisement
.cindex "RFC 3030" "CHUNKING"
.cindex "ESMTP extensions" CHUNKING
-The CHUNKING extension (RFC3030) will be advertised in the EHLO message to
-these hosts.
+The CHUNKING extension
+(&url(https://www.rfc-editor.org/rfc/rfc3030.html,RFC 3030))
+will be advertised in the EHLO message to these hosts.
Hosts may use the BDAT command as an alternate to DATA.
.option commandline_checks_require_admin main boolean &`false`&
listens. See chapter &<<CHAPinterfaces>>& for details of how it is used. For
backward compatibility, &%daemon_smtp_port%& (singular) is a synonym.
-.option daemon_startup_retries main integer 9
+.options daemon_startup_retries main integer 9 &&&
+ daemon_startup_sleep main time 30s
.cindex "daemon startup, retrying"
-This option, along with &%daemon_startup_sleep%&, controls the retrying done by
+These options control 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%&
defines the number of retries after the first failure, and
&%daemon_startup_sleep%& defines the length of time to wait between retries.
-.option daemon_startup_sleep main time 30s
-See &%daemon_startup_retries%&.
-
.option delay_warning main "time list" 24h
.cindex "warning of delay"
.cindex "delay warning, specifying"
to handle IPv6 literal addresses.
-.new
.option dkim_verify_hashes main "string list" "sha256 : sha512"
.cindex DKIM "selecting signature algorithms"
This option gives a list of hash types which are acceptable in signatures,
-.wen
and an order of processing.
Signatures with algorithms not in the list will be ignored.
sha512
.endd
-Note that the acceptance of sha1 violates RFC 8301.
+Note that the acceptance of sha1 violates
+&url(https://www.rfc-editor.org/rfc/rfc8301,RFC 8301).
.option dkim_verify_keytypes main "string list" "ed25519 : rsa"
This option gives a list of key types which are acceptable in signatures,
Signatures with algorithms not in the list will be ignored.
-.new
.option dkim_verify_min_keysizes main "string list" "rsa=1024 ed25519=250"
This option gives a list of key sizes which are acceptable in signatures.
The list is keyed by the algorithm type for the key; the values are in bits.
Signatures with keys smaller than given by this option will fail verification.
-The default enforces the RFC 8301 minimum key size for RSA signatures.
-.wen
+The default enforces the
+&url(https://www.rfc-editor.org/rfc/rfc8301,RFC 8301)
+minimum key size for RSA signatures.
.option dkim_verify_minimal main boolean false
If set to true, verification of signatures will terminate after the
See section &<<SECDKIMVFY>>&.
+.options dmarc_forensic_sender main string&!! unset &&&
+ dmarc_history_file main string unset &&&
+ dmarc_tld_file main string unset
+.cindex DMARC "main section options"
+These options control DMARC processing.
+See section &<<SECDMARC>>& for details.
+
+
.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. It also applies when the
+This option applies to all DNS lookups that Exim does,
+except for TLSA lookups (where knowing about such failures
+is security-relevant).
+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
If the resolver library does not support DNSSEC then this option has no effect.
-.new
On Linux with glibc 2.31 or newer this is insufficient, the resolver library
will default to stripping out a successful validation status.
This will break a previously working Exim installation.
.code
options trust-ad
.endd
-.wen
.option dns_ipv4_lookup main "domain list&!!" unset
.cindex "DSN" "success"
.cindex "Delivery Status Notification" "success"
.cindex "ESMTP extensions" DSN
-DSN extensions (RFC3461) will be advertised in the EHLO message to,
+DSN extensions (&url(https://www.rfc-editor.org/rfc/rfc3461,RFC 3461))
+will be advertised in the EHLO message to,
and accepted from, these hosts.
-Hosts may use the NOTIFY and ENVID options on RCPT TO commands,
-and RET and ORCPT options on MAIL FROM commands.
+Hosts may use the NOTIFY and ORCPT options on RCPT TO commands,
+and RET and ENVID options on MAIL FROM commands.
A NOTIFY=SUCCESS option requests success-DSN messages.
A NOTIFY= option with no argument requests that no delay or failure DSNs
are sent.
-.new
&*Note*&: Supplying success-DSN messages has been criticised
on privacy grounds; it can leak details of internal forwarding.
-.wen
.option dsn_from main "string&!!" "see below"
.cindex "&'From:'& header line" "in bounces"
.code
errors_reply_to = postmaster@my.domain.example
.endd
-The value of the option is not expanded. It must specify a valid RFC 2822
+The value of the option is not expanded. It must specify a valid
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
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
. Allow this long option name to split; give it unsplit as a fifth argument
. for the automatic .oindex that is generated by .option.
+. WAS:
+. .option "extract_addresses_remove_ &~&~arguments"
+. but apparently this results in searchability problems; bug 1197
-.option "extract_addresses_remove_arguments" main boolean true &&&
- extract_addresses_remove_arguments
+.option extract_addresses_remove_arguments main boolean true
.oindex "&%-t%&"
.cindex "command line" "addresses with &%-t%&"
.cindex "Sendmail compatibility" "&%-t%& option"
.option freeze_tell main "string list, comma separated" unset
.cindex "freezing messages" "sending a message when freezing"
+.cindex "frozen messages" "sending a message when freezing"
On encountering certain errors, or when configured to do so in a system filter,
ACL, or special router, Exim freezes a message. This means that no further
delivery attempts take place until an administrator thaws the message, or the
logging that you require.
-.option gecos_name main string&!! unset
+.options gecos_name main string&!! unset &&&
+ gecos_pattern main string unset
.cindex "HP-UX"
.cindex "&""gecos""& field, parsing"
Some operating systems, notably HP-UX, use the &"gecos"& field in the system
gecos_name = $1
.endd
-.option gecos_pattern main string unset
-See &%gecos_name%& above.
-
.option gnutls_compat_mode main boolean unset
This option controls whether GnuTLS is used in compatibility mode in an Exim
.cindex "EHLO" "underscores in"
.cindex "underscore in EHLO/HELO"
This option can be set to a string of rogue characters that are permitted in
-all EHLO and HELO names in addition to the standard letters, digits,
-hyphens, and dots. If you really must allow underscores, you can set
+non-ip-literal EHLO and HELO names in addition to the standard letters, digits,
+hyphens, and dots. For example if you really must allow underscores,
+you can set
.code
helo_allow_chars = _
.endd
+This option does not apply to names that look like ip-literals.
Note that the value is one string, not a list.
nowadays the ACL specified by &%acl_smtp_connect%& can also reject incoming
connections immediately.
+If the connection is on a TLS-on-connect port then the TCP connection is
+just dropped. Otherwise, an SMTP error is sent first.
+
The ability to give an immediate rejection (either by this option or using an
ACL) is provided for use in unusual cases. Many hosts will just try again,
sometimes without much delay. Normally, it is better to use an ACL to reject
.code
hosts_connection_nolog = :
.endd
-If the &%smtp_connection%& log selector is not set, this option has no effect.
+The hosts affected by this option also do not log "no MAIL in SMTP connection"
+lines, as may commonly be produced by a monitoring system.
+
+
+.option hosts_require_alpn main "host list&!!" unset
+.cindex ALPN "require negotiation in server"
+.cindex TLS ALPN
+.cindex TLS "Application Layer Protocol Names"
+If the TLS library supports ALPN
+then a successful negotiation of ALPN will be required for any client
+matching the list, for TLS to be used.
+See also the &%tls_alpn%& option.
+
+&*Note*&: prevention of fallback to in-clear connection is not
+managed by this option, and should be done separately.
+
+.option hosts_require_helo main "host list&!!" *
+.cindex "HELO/EHLO" requiring
+Exim will require an accepted HELO or EHLO command from a host matching
+this list, before accepting a MAIL command.
.option hosts_proxy main "host list&!!" unset
&%timeout_frozen_after%&.
-.option ignore_fromline_hosts main "host list&!!" unset
+.options ignore_fromline_hosts main "host list&!!" unset &&&
+ ignore_fromline_local main boolean false
.cindex "&""From""& line"
.cindex "UUCP" "&""From""& line"
Some broken SMTP clients insist on sending a UUCP-like &"From&~"& line before
&%ignore_fromline_local%& must be set to achieve this effect.
-.option ignore_fromline_local main boolean false
-See &%ignore_fromline_hosts%& above.
.option keep_environment main "string list" unset
.cindex "environment" "values from"
+.option limits_advertise_hosts main "host list&!!" *
+.cindex LIMITS "suppressing advertising"
+.cindex "ESMTP extensions" LIMITS
+This option can be used to suppress the advertisement of the SMTP
+LIMITS extension (&url(https://www.ietf.org/rfc/rfc9422.html,RFC 9422))
+to specific hosts.
+If permitted, Exim as a server will advertise in the EHLO response
+the limit for RCPT commands set by the &%recipients_max%& option (if it is set)
+and the limit for MAIL commands set by the &%smtp_accept_max_per_connection%&
+option.
+
.option local_from_check main boolean true
.cindex "&'Sender:'& header line" "disabling addition of"
.cindex "&'From:'& header line" "disabling checking of"
-.option local_from_prefix main string unset
+.options local_from_prefix main string unset &&&
+ local_from_suffix main string unset
When Exim checks the &'From:'& header line of locally submitted messages for
matching the login id (see &%local_from_check%& above), it can be configured to
ignore certain prefixes and suffixes in the local part of the address. This is
qualify domain.
-.option local_from_suffix main string unset
-See &%local_from_prefix%& above.
-
-
.option local_interfaces main "string list" "see below"
This option controls which network interfaces are used by the daemon for
listening; they are also used to identify the local host when routing. Chapter
.option localhost_number main string&!! unset
.cindex "host" "locally unique number for"
.cindex "message ids" "with multiple hosts"
+.cindex multiple "systems sharing a spool"
+.cindex "multiple hosts" "sharing a spool"
+.cindex "shared spool directory"
+.cindex "spool directory" sharing
.vindex "&$localhost_number$&"
Exim's message ids are normally unique only within the local host. If
-uniqueness among a set of hosts is required, each host must set a different
+uniqueness among a set of hosts is required
+(eg. because they share a spool directory),
+each host must set a different
value for the &%localhost_number%& option. The string is expanded immediately
after reading the configuration file (so that a number can be computed from the
host name, for example) and the result of the expansion must be a number in the
range 0&--16 (or 0&--10 on operating systems with case-insensitive file
systems). This is available in subsequent string expansions via the variable
-&$localhost_number$&. When &%localhost_number is set%&, the final two
+&$localhost_number$&. When &%localhost_number%& is set, the final four
characters of the message id, instead of just being a fractional part of the
time, are computed from the time and the local host number as described in
section &<<SECTmessiden>>&.
.option message_id_header_text main string&!! unset
If this variable is set, the string is expanded and used to augment the text of
the &'Message-id:'& header that Exim creates if a locally-originated incoming
-message does not have one. The text of this header is required by RFC 2822 to
-take the form of an address. By default, Exim uses its internal message id as
+message does not have one. The text of this header is required by
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+to take the form of an address. By default, Exim uses its internal message id as
the local part, and the primary host name as the domain. If this option is set,
it is expanded, and provided the expansion is not forced to fail, and does not
yield an empty string, the result is inserted into the header immediately
transport driver.
-.new
.option notifier_socket main string "$spool_directory/exim_daemon_notify"
This option gives the name for a unix-domain socket on which the daemon
listens for work and information-requests.
The option is expanded before use.
If the platform supports Linux-style abstract socket names, the result
is used with a nul byte prefixed.
-Otherwise, it should be a full path name and use a directory accessible
+Otherwise,
+it should be a full path name and use a directory accessible
to Exim.
-If the Exim command line uses a &%-oX%& option and does not use &%-oP%&
+If this option is set as empty,
+or the command line &%-oY%& option is used, or
+the command line uses a &%-oX%& option and does not use &%-oP%&,
then a notifier socket is not created.
-.wen
.option openssl_options main "string list" "+no_sslv2 +no_sslv3 +single_dh_use +no_ticket +no_renegotiation"
The option is available only if Exim has been built with Oracle support.
+.option panic_coredump main boolean false
+This option is rarely needed but can help for some debugging investigations.
+If set, when an internal error is detected by Exim which is sufficient
+to terminate the process
+(all such are logged in the paniclog)
+then a coredump is requested.
+
+Note that most systems require additional administrative configuration
+to permit write a core file for a setuid program, which is Exim's
+common installed configuration.
+
.option percent_hack_domains main "domain list&!!" unset
.cindex "&""percent hack""&"
.cindex "source routing" "in email address"
The &"percent hack"& is the convention whereby a local part containing a
percent sign is re-interpreted as a new email address, with the percent
replaced by @. This is sometimes called &"source routing"&, though that term is
-also applied to RFC 2822 addresses that begin with an @ character. If this
+also applied to
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+addresses that begin with an @ character. If this
option is set, Exim implements the percent facility for those domains listed,
but no others. This happens before an incoming SMTP address is tested against
an ACL.
local parts. Exim's default configuration does this.
-.option perl_at_start main boolean false
-.cindex "Perl"
-This option is available only when Exim is built with an embedded Perl
-interpreter. See chapter &<<CHAPperl>>& for details of its use.
-
-
-.option perl_startup main string unset
+.options perl_at_start main boolean false &&&
+ perl_startup main string unset
.cindex "Perl"
-This option is available only when Exim is built with an embedded Perl
-interpreter. See chapter &<<CHAPperl>>& for details of its use.
+These options are available only when Exim is built with an embedded Perl
+interpreter. See chapter &<<CHAPperl>>& for details of their use.
.option perl_taintmode main boolean false
.cindex "Perl"
.option pipelining_connect_advertise_hosts main "host list&!!" *
.cindex "pipelining" "early connection"
-.cindex "pipelining" PIPE_CONNECT
-.cindex "ESMTP extensions" X_PIPE_CONNECT
-If Exim is built with the SUPPORT_PIPE_CONNECT build option
+.cindex "pipelining" PIPECONNECT
+.cindex "ESMTP extensions" PIPECONNECT
+If Exim is built without the DISABLE_PIPE_CONNECT build option
this option controls which hosts the facility is advertised to
and from which pipeline early-connection (before MAIL) SMTP
commands are acceptable.
See also the &%hosts_pipe_connect%& smtp transport option.
-Currently the option name &"X_PIPE_CONNECT"& is used.
+The SMTP service extension keyword advertised is &"PIPECONNECT"&;
+it permits the client to pipeline
+TCP connection and hello command (cleatext phase),
+or TLS-establishment and hello command (encrypted phase),
+on later connections to the same host.
.option prdr_enable main boolean false
characters.
This option also affects the header syntax checks performed by the
-&(autoreply)& transport, and whether Exim uses RFC 2047 encoding of
+&(autoreply)& transport, and whether Exim uses
+&url(https://www.rfc-editor.org/rfc/rfc2047,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
&%queue_list_requires_admin%& and &%commandline_checks_require_admin%&.
+.option proxy_protocol_timeout main time 3s
+.cindex proxy "proxy protocol"
+This option sets the timeout for proxy protocol negotiation.
+For details see section &<<SECTproxyInbound>>&.
+
+
.option qualify_domain main string "see below"
.cindex "domain" "for qualifying addresses"
.cindex "address" "qualification"
next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&.
+.option queue_fast_ramp main boolean true
+.cindex "queue runner" "two phase"
+.cindex "queue" "double scanning"
+If set to true, two-phase queue runs, initiated using &%-qq%& on the
+command line, may start parallel delivery processes during their first
+phase. This will be done when a threshold number of messages have been
+routed for a single host.
+
+
.option queue_list_requires_admin main boolean true
.cindex "restricting access to features"
.oindex "&%-bp%&"
&%queue_only_load%&, and &%smtp_accept_queue%&.
-.option queue_only_file main string unset
+.option queue_only_file main "string list" unset
.cindex "queueing incoming messages"
.cindex "message" "queueing by file existence"
This option can be set to a colon-separated list of absolute path names, each
on at the end (preceded by a semicolon). The string is expanded each time it is
used. If the expansion yields an empty string, no &'Received:'& header line is
added to the message. Otherwise, the string should start with the text
-&"Received:"& and conform to the RFC 2822 specification for &'Received:'&
-header lines.
+&"Received:"& and conform to the
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+specification for &'Received:'& header lines.
The default setting is:
.code
option was not set.
-.option recipients_max main integer 0
+.option recipients_max main integer&!! 50000
.cindex "limit" "number of recipients"
.cindex "recipient" "maximum number"
-If this option is set greater than zero, it specifies the maximum number of
+If the value resulting from expanding this option
+is set greater than zero, it specifies the maximum number of
original recipients for any message. Additional recipients that are generated
by aliasing or forwarding do not count. SMTP messages get a 452 response for
all recipients over the limit; earlier recipients are delivered as normal.
Non-SMTP messages with too many recipients are failed, and no deliveries are
done.
+For SMTP message the expansion is done after the connection is
+accepted (but before any SMTP conversation) and may depend on
+the IP addresses and port numbers of the connection.
+&*Note*&: If an expansion is used for the option,
+care should be taken that a resonable value results for
+non-SMTP messages.
+
.cindex "RCPT" "maximum number of incoming"
&*Note*&: The RFCs specify that an SMTP server should accept at least 100
RCPT commands in a single message.
for the remaining recipients at a later time.
-.option remote_max_parallel main integer 2
+.option remote_max_parallel main integer 4
.cindex "delivery" "parallelism for remote"
This option controls parallel delivery of one message to a number of remote
hosts. If the value is less than 2, parallel delivery is disabled, and Exim
deliveries if the configuration allows a delivery attempt as soon as a message
is received.
+See also the &%max_parallel%& generic transport option,
+and the &%serialize_hosts%& smtp transport option.
+
.cindex "number of deliveries"
.cindex "delivery" "maximum number of"
If you want to control the total number of deliveries on the system, you
.option return_path_remove main boolean true
.cindex "&'Return-path:'& header line" "removing"
-RFC 2821, section 4.4, states that an SMTP server must insert a
+&url(https://www.rfc-editor.org/rfc/rfc2821,RFC 2821), section 4.4,
+states that an SMTP server must insert a
&'Return-path:'& header line into a message when it makes a &"final delivery"&.
The &'Return-path:'& header preserves the sender address as received in the
MAIL command. This description implies that this header should not be present
.option rfc1413_hosts main "host list&!!" @[]
.cindex "RFC 1413"
.cindex "host" "for RFC 1413 calls"
-RFC 1413 identification calls are made to any client host which matches
+&url(https://www.rfc-editor.org/rfc/rfc1413,RFC 1413)
+identification calls are made to any client host which matches
an item in the list.
The default value specifies just this host, being any local interface
for the system.
.option rfc1413_query_timeout main time 0s
.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 sets the timeout on
+&url(https://www.rfc-editor.org/rfc/rfc1413,RFC 1413)
+identification calls. If it is set to zero,
no RFC 1413 calls are ever made.
. searchable. NM changed this occurrence for bug 1197 to no longer allow
. the option name to split.
-.option "smtp_accept_max_per_connection" main integer 1000 &&&
- smtp_accept_max_per_connection
+.option smtp_accept_max_per_connection main integer&!! 1000
.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
response is given to subsequent MAIL commands. This limit is a safety
precaution against a client that goes mad (incidents of this type have been
seen).
+The option is expanded after the HELO or EHLO is received
+and may depend on values available at that time.
+An empty or zero value after expansion removes the limit.
.option smtp_accept_max_per_host main string&!! unset
. See the comment on smtp_accept_max_per_connection
-.option "smtp_accept_queue_per_connection" main integer 10 &&&
- smtp_accept_queue_per_connection
+.option smtp_accept_queue_per_connection main integer 10
.cindex "queueing incoming messages"
.cindex "message" "queueing by message count"
This option limits the number of delivery processes that Exim starts
verification if there is no remote transport from which to obtain a
&%helo_data%& value.
+.option smtp_backlog_monitor main integer 0
+.cindex "connection backlog" monitoring
+If this option is set to greater than zero, and the backlog of available
+TCP connections on a socket listening for SMTP is larger than it, a line
+is logged giving the value and the socket address and port.
+The value is retrived jsut before an accept call.
+This facility is only available on Linux.
+
.option smtp_banner main string&!! "see below"
.cindex "SMTP" "welcome banner"
.cindex "banner for SMTP"
.cindex "welcome banner for SMTP"
.cindex "customizing" "SMTP banner"
-This string, which is expanded every time it is used, is output as the initial
+If a connect ACL does not supply a message,
+this string (which is expanded every time it is used) is output as the initial
positive response to an SMTP connection. The default setting is:
.code
smtp_banner = $smtp_active_hostname ESMTP Exim \
$version_number $tod_full
.endd
-Failure to expand the string causes a panic error. If you want to create a
+Failure to expand the string causes a panic error;
+a forced fail just closes the connection.
+If you want to create a
multiline response to the initial SMTP connection, use &"\n"& in the string at
appropriate points, but not at the end. Note that the 220 code is not included
in this string. Exim adds it automatically (several times in the case of a
.option smtp_connect_backlog main integer 20
-.cindex "connection backlog"
+.cindex "connection backlog" "set maximum"
.cindex "SMTP" "connection backlog"
.cindex "backlog of connections"
This option specifies a maximum number of waiting SMTP connections. Exim passes
.option smtp_etrn_command main string&!! unset
-.cindex "ETRN" "command to be run"
+.cindex ETRN "command to be run"
.cindex "ESMTP extensions" ETRN
.vindex "&$domain$&"
If this option is set, the given command is run whenever an SMTP ETRN
smtp_etrn_command = /etc/etrn_command $domain \
$sender_host_address
.endd
-.new
If the option is not set, the argument for the ETRN command must
be a &'#'& followed by an address string.
In this case an &'exim -R <string>'& command is used;
if the ETRN ACL has set up a named-queue then &'-MCG <queue>'& is appended.
-.wen
A new process is created to run the command, but Exim does not wait for it to
complete. Consequently, its status cannot be checked. If the command cannot be
.option smtp_etrn_serialize main boolean true
-.cindex "ETRN" "serializing"
+.cindex ETRN serializing
When this option is set, it prevents the simultaneous execution of more than
one identical command as a result of ETRN in an SMTP connection. See
section &<<SECTETRN>>& for details.
-.option smtp_ratelimit_hosts main "host list&!!" unset
+.options smtp_ratelimit_hosts main "host list&!!" unset &&&
+ smtp_ratelimit_mail main string unset &&&
+ smtp_ratelimit_rcpt main string unset
.cindex "SMTP" "rate limiting"
.cindex "limit" "rate of message arrival"
.cindex "RCPT" "rate limiting"
delays to RCPT commands when more than four occur in a single message.
-.option smtp_ratelimit_mail main string unset
-See &%smtp_ratelimit_hosts%& above.
-
-
-.option smtp_ratelimit_rcpt main string unset
-See &%smtp_ratelimit_hosts%& above.
-
.option smtp_receive_timeout main time&!! 5m
.cindex "timeout" "for SMTP input"
This option is available when Exim is compiled with SPF support.
See section &<<SECSPF>>& for more details.
+.option spf_smtp_comment_template main string&!! "Please%_see%_http://www.open-spf.org/Why"
+This option is available when Exim is compiled with SPF support. It
+allows the customisation of the SMTP comment that the SPF library
+generates. You are strongly encouraged to link to your own explanative
+site. The template must not contain spaces. If you need spaces in the
+output, use the proper placeholder. If libspf2 can not parse the
+template, it uses a built-in default broken link. The following placeholders
+(along with Exim variables (but see below)) are allowed in the template:
+.ilist
+&*%_*&: A space.
+.next
+&*%{L}*&: Envelope sender's local part.
+.next
+&*%{S}*&: Envelope sender.
+.next
+&*%{O}*&: Envelope sender's domain.
+.next
+&*%{D}*&: Current(?) domain.
+.next
+&*%{I}*&: SMTP client Ip.
+.next
+&*%{C}*&: SMTP client pretty IP.
+.next
+&*%{T}*&: Epoch time (UTC).
+.next
+&*%{P}*&: SMTP client domain name.
+.next
+&*%{V}*&: IP version.
+.next
+&*%{H}*&: EHLO/HELO domain.
+.next
+&*%{R}*&: Receiving domain.
+.endlist
+The capitalized placeholders do proper URL encoding, if you use them
+lowercased, no encoding takes place. This list was compiled from the
+libspf2 sources.
+
+A note on using Exim variables: As
+currently the SPF library is initialized before the SMTP EHLO phase,
+the variables useful for expansion are quite limited.
.option split_spool_directory main boolean false
.option syslog_timestamp main boolean true
.cindex "syslog" "timestamps"
+.cindex timestamps syslog
If &%syslog_timestamp%& is set false, the timestamps on Exim's log lines are
omitted when these lines are sent to syslog. See chapter &<<CHAPlog>>& for
details of Exim's logging.
is not required the &%tls_advertise_hosts%& option should be set empty.
-.option tls_certificate main string list&!! unset
+.option tls_alpn main "string list&!!" "smtp : esmtp"
+.cindex TLS "Application Layer Protocol Names"
+.cindex TLS ALPN
+.cindex ALPN "set acceptable names for server"
+If this option is set,
+the TLS library supports ALPN,
+and the client offers either more than one
+ALPN name or a name which does not match the list,
+the TLS connection is declined.
+
+
+.option tls_certificate main "string list&!!" unset
.cindex "TLS" "server certificate; location of"
.cindex "certificate" "server, location of"
The value of this option is expanded, and must then be a list of absolute paths to
file is used, the &$tls_in_ourcert$& variable is unreliable.
The macro "_TLS_BAD_MULTICERT_IN_OURCERT" will be defined for those versions.
+.cindex SNI "selecting server certificate based on"
If the option contains &$tls_out_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.
-If this option is unset or empty a fresh self-signed certificate will be
-generated for every connection.
+If this option is unset or empty a self-signed certificate will be
+used.
+Under Linux this is generated at daemon startup; on other platforms it will be
+generated fresh for every connection.
.option tls_crl main string&!! unset
.cindex "TLS" "server certificate revocation list"
The value of this option is expanded and indicates the source of DH parameters
to be used by Exim.
-This option is ignored for GnuTLS version 3.6.0 and later.
-The library manages parameter negotiation internally.
-
-&*Note: The Exim Maintainers strongly recommend,
-for other TLS library versions,
-using a filename with site-generated
+&*Note: The Exim Maintainers strongly recommend using a filename with site-generated
local DH parameters*&, which has been supported across all versions of Exim. The
other specific constants available are a fallback so that even when
"unconfigured", Exim can offer Perfect Forward Secrecy in older ciphersuites in TLS.
a default DH prime; the default is Exim-specific but lacks verifiable provenance.
In older versions of Exim the default was the 2048 bit prime described in section
-2.2 of RFC 5114, "2048-bit MODP Group with 224-bit Prime Order Subgroup", which
+2.2 of &url(https://www.rfc-editor.org/rfc/rfc5114,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, RFC 5114, RFC 7919, or from other
+of DH primes specified in
+&url(https://www.rfc-editor.org/rfc/rfc2409,RFC 2409),
+&url(https://www.rfc-editor.org/rfc/rfc3526,RFC 3526),
+&url(https://www.rfc-editor.org/rfc/rfc5114,RFC 5114),
+&url(https://www.rfc-editor.org/rfc/rfc7919,RFC 7919), or from other
sources. As names, Exim uses a standard specified name, else "ike" followed by
the number used by IKE, or "default" which corresponds to
&`exim.dev.20160529.3`&.
Some of these will be too small to be accepted by clients.
Some may be too large to be accepted by clients.
The open cryptographic community has suspicions about the integrity of some
-of the later IKE values, which led into RFC7919 providing new fixed constants
-(the "ffdhe" identifiers).
+of the later IKE values, which led into
+&url(https://www.rfc-editor.org/rfc/rfc7919,RFC 7919)
+providing new fixed constants (the "ffdhe" identifiers).
At this point, all of the "ike" values should be considered obsolete;
-they're still in Exim to avoid breaking unusual configurations, but are
+they are still in Exim to avoid breaking unusual configurations, but are
candidates for removal the next time we have backwards-incompatible changes.
+Two of them in particular (&`ike1`& and &`ike22`&) are called out by
+&url(https://www.rfc-editor.org/rfc/rfc8247,RFC 8247)
+as MUST NOT use for IPSEC, and two more (&`ike23`& and &`ike24`&) as
+SHOULD NOT.
+Because of this, Exim regards them as deprecated; if either of the first pair
+are used, warnings will be logged in the paniclog, and if any are used then
+warnings will be logged in the mainlog.
+All four will be removed in a future Exim release.
The TLS protocol does not negotiate an acceptable size for this; clients tend
to hard-drop connections if what is offered by the server is unacceptable,
acceptable bound from 1024 to 2048.
-.option tls_eccurve main string&!! &`auto`&
+.option tls_eccurve main string list&!! &`auto`&
.cindex TLS "EC cryptography"
-This option selects a EC curve for use by Exim when used with OpenSSL.
-It has no effect when Exim is used with GnuTLS.
+This option selects EC curves for use by Exim when used with OpenSSL.
+It has no effect when Exim is used with GnuTLS
+(the equivalent can be done using a priority string for the
+&%tls_require_ciphers%& option).
-After expansion it must contain a valid EC curve parameter, such as
-&`prime256v1`&, &`secp384r1`&, or &`P-512`&. Consult your OpenSSL manual
-for valid selections.
+After expansion it must contain
+one or (only for OpenSSL versiona 1.1.1 onwards) more
+EC curve names, such as &`prime256v1`&, &`secp384r1`&, or &`P-521`&.
+Consult your OpenSSL manual for valid curve names.
For OpenSSL versions before (and not including) 1.0.2, the string
&`auto`& selects &`prime256v1`&. For more recent OpenSSL versions
&`auto`& tells the library to choose.
-If the option expands to an empty string, no EC curves will be enabled.
+If the option expands to an empty string, the effect is undefined.
.option tls_ocsp_file main string&!! unset
-.option tls_privatekey main string list&!! unset
+.option tls_privatekey main "string list&!!" unset
.cindex "TLS" "server private key; location of"
The value of this option is expanded, and must then be a list of absolute paths to
files which contains the server's private keys.
&<<SECTreqciphssl>>& and &<<SECTreqciphgnu>>&.
+.option tls_resumption_hosts main "host list&!!" unset
+.cindex TLS resumption
+This option controls which connections to offer the TLS resumption feature.
+See &<<SECTresumption>>& for details.
+
+
.option tls_try_verify_hosts main "host list&!!" unset
.cindex "TLS" "client certificate verification"
.cindex "certificate" "verification of client"
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 the explicit directory version.
+use the explicit directory version. (If your peer is Exim up to 4.85,
+using GnuTLS, you may need to send the CAs (thus using the file
+variant). Otherwise the peer doesn't send its certificate.)
See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
Any client that matches &%tls_verify_hosts%& is constrained by
&%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
+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.
been in the queue for a specified amount of time, as specified by
&%delay_warning%&. Details of the file's contents are given in chapter
&<<CHAPemsgcust>>&.
-.new
.cindex warn_message_file "tainted data"
The option is expanded to give the file path, which must be
absolute and untainted.
-.wen
See also &%bounce_message_file%&.
+.option wellknown_advertise_hosts main boolean unset
+.cindex WELLKNOWN advertisement
+.cindex "ESMTP extensions" WELLKNOWN
+This option enables the advertising of the SMTP WELLKNOWN extension.
+See also the &%acl_smtp_wellknown%& ACL (&<<SECTWELLKNOWNACL>>&).
+
.option write_rejectlog main boolean true
.cindex "reject log" "disabling"
If this option is set false, Exim no longer writes anything to the reject log.
provide data for a transport is: &%errors_to%&, &%headers_add%&,
&%headers_remove%&, &%transport%&.
+The name of a router is limited to be &drivernamemax; ASCII characters long;
+prior to Exim 4.95 names would be silently truncated at this length, but now
+it is enforced.
.option address_data routers string&!! unset
local system. The check is done by calling the &[getpwnam()]& function rather
than trying to read &_/etc/passwd_& directly. This means that other methods of
holding password data (such as NIS) are supported. If the local part is a local
-user, &$home$& is set from the password data, and can be tested in other
+user,
+.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using router check_local_user option"
+&$local_part_data$& is set to an untainted version of the local part and
+&$home$& is set from the password data. The latter can be tested in other
preconditions that are evaluated after this one (the order of evaluation is
given in section &<<SECTrouprecon>>&). However, the value of &$home$& can be
overridden by &%router_home_directory%&. If the local part is not a local user,
.cindex "security" "MX lookup"
.cindex "DNS" "DNSSEC"
DNS lookups for domains matching &%dnssec_request_domains%& will be done with
-the dnssec request bit set.
+the DNSSEC request bit set.
This applies to all of the SRV, MX, AAAA, A lookup sequence.
.option dnssec_require_domains routers "domain list&!!" unset
.cindex "security" "MX lookup"
.cindex "DNS" "DNSSEC"
DNS lookups for domains matching &%dnssec_require_domains%& will be done with
-the dnssec request bit set. Any returns not having the Authenticated Data bit
+the DNSSEC request bit set. Any returns not having the Authenticated Data bit
(AD bit) set will be ignored and logged as a host-lookup failure.
This applies to all of the SRV, MX, AAAA, A lookup sequence.
.cindex "router" "restricting to specific domains"
.vindex "&$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$& for use in string
-expansions of the driver's private options. See section &<<SECTrouprecon>>& for
+the list.
+The data returned by the list check
+is placed in &$domain_data$& for use in string
+expansions of the driver's private options and in the transport.
+See section &<<SECTrouprecon>>& for
a list of the order in which preconditions are evaluated.
+A complex example, using a file like:
+.code
+alice@dom1
+bill@dom1
+maggie@dom1
+.endd
+and checking both domain and local_part
+.code
+domains = ${domain:${lookup {$local_part@$domain} lseach,ret=key {/path/to/accountsfile}}}
+local_parts = ${local_part:${lookup {$local_part@$domain} lseach,ret=key {/path/to/accountsfile}}}
+.endd
+
.option driver routers string unset
.option dsn_lasthop routers boolean false
.cindex "DSN" "success"
.cindex "Delivery Status Notification" "success"
-If this option is set true, and extended DSN (RFC3461) processing is in effect,
+If this option is set true, and extended DSN
+(&url(https://www.rfc-editor.org/rfc/rfc3461,RFC 3461)) processing is in effect,
Exim will not pass on DSN requests to downstream DSN-aware hosts but will
instead send a success DSN as if the next hop does not support DSN.
Not effective on redirect routers.
that is associated with any addresses that are accepted by the router.
However, the option has no effect when an address is just being verified.
Each list item is separately expanded, at transport time.
-.new
If an item ends in *, it will match any header with the given prefix.
-.wen
The way in which
the text is used to remove header lines at transport time is described in
section &<<SECTheadersaddrem>>&. Header lines are not actually removed until
This behaviour can be overridden by setting &%rcpt_include_affixes%& true on
the relevant transport.
-.new
.vindex &$local_part_prefix_v$&
If wildcarding (above) was used then the part of the prefix matching the
wildcard is available in &$local_part_prefix_v$&.
-.wen
When an address is being verified, &%local_part_prefix%& affects only the
behaviour of the router. If the callout feature of verification is in use, this
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}}
+ condition = ${if match_ip {$sender_host_address} \
+ {<; ; 127.0.0.1 ; ::1}}
.endd
If both &%local_part_prefix%& and &%local_part_suffix%& are set for a router,
string is expanded, it is possible to make it depend on the domain, for
example:
.code
-local_parts = dbm;/usr/local/specials/$domain
+local_parts = dbm;/usr/local/specials/$domain_data
.endd
.vindex "&$local_part_data$&"
-If the match is achieved by a lookup, the data that the lookup returned
+the data returned by the list check
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
+expansions of the router's private options or in the transport.
+You might use this option, for
example, if you have a large number of local virtual domains, and you want to
send all postmaster mail to the same place without having to set up an alias in
each virtual domain:
When a router runs, the strings are evaluated in order,
to create variables which are added to the set associated with
the address.
+This is done immediately after all the preconditions, before the
+evaluation of the &%address_data%& option.
The variable is set with the expansion of the value.
The variables can be used by the router options
(not including any preconditions)
.option check_srv dnslookup string&!! unset
.cindex "SRV record" "enabling use of"
-The &(dnslookup)& router supports the use of SRV records (see RFC 2782) in
-addition to MX and address records. The support is disabled by default. To
+The &(dnslookup)& router supports the use of SRV records
+(see &url(https://www.rfc-editor.org/rfc/rfc2782,RFC 2782))
+in addition to MX and address records. The support is disabled by default. To
enable SRV support, set the &%check_srv%& option to the name of the service
required. For example,
.code
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. For example, the &(ipliteral)&
+takes the form of an
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+domain literal. For example, the &(ipliteral)&
router handles the address
.code
root@[192.168.1.1]
If the file does not exist, or causes no action to be taken (for example, it is
empty or consists only of comments), the router declines. &*Warning*&: This
is not the case when the file contains syntactically valid items that happen to
-yield empty addresses, for example, items containing only RFC 2822 address
-comments.
+yield empty addresses, for example, items containing only
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address comments.
-.new
.cindex "tainted data" "in filenames"
.cindex redirect "tainted data"
Tainted data may not be used for a filename.
In the examples above, &$local_part$& is used for looking up data held locally
on the system, and not used directly (the second example derives &$home$& via
the passsword file or database, using &$local_part$&).
-.wen
it does make a difference if more than one domain is being handled
synonymously.
-If an item begins with &"\"& and the rest of the item parses as a valid RFC
-2822 address that does not include a domain, the item is qualified using the
+If an item begins with &"\"& and the rest of the item parses as a valid
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address that does not include a domain, the item is qualified using the
domain of the incoming address. In the absence of a leading &"\"&, unqualified
addresses are qualified using the value in &%qualify_recipient%&, but you can
force the incoming domain to be used by setting &%qualify_preserve_domain%&.
.cindex "pipe" "in redirection list"
.cindex "address redirection" "to pipe"
An item is treated as a pipe command if it begins with &"|"& and does not parse
-as a valid RFC 2822 address that includes a domain. A transport for running the
+as a valid
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address that includes a domain. A transport for running the
command must be specified by the &%pipe_transport%& option.
Normally, either the router or the transport specifies a user and a group under
which to run the delivery. The default is to use the Exim user and group.
.cindex "file" "in redirection list"
.cindex "address redirection" "to file"
An item is interpreted as a path name if it begins with &"/"& and does not
-parse as a valid RFC 2822 address that includes a domain. For example,
+parse as a valid
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address that includes a domain. For example,
.code
/home/world/minbari
.endd
.code
list1: :include:/opt/lists/list1
.endd
-.new
.cindex "tainted data" "in filenames"
.cindex redirect "tainted data"
Tainted data may not be used for a filename.
-.wen
.next
.cindex "address redirection" "to black hole"
.cindex "delivery" "discard"
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
+By default for verify, 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
and are rewritten according to the global rewriting rules.
+.option sieve_inbox redirect string&!! inbox
+.new
+The value of this option is passed to a Sieve filter to specify the
+name of the mailbox used for "keep" operations (explicit or implicit).
+.wen
+
.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.
.cindex "Sieve filter" "syntax errors in"
Syntax errors in a Sieve filter file cause the &"keep"& action to occur. This
-action is specified by RFC 3028. The values of &%skip_syntax_errors%&,
+action is specified by
+&url(https://www.rfc-editor.org/rfc/rfc3028.html,RFC 3028).
+The values of &%skip_syntax_errors%&,
&%syntax_errors_to%&, and &%syntax_errors_text%& are not used.
&%skip_syntax_errors%& can be used to specify that errors in users' forward
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}}
+ condition = ${if match_ip {$sender_host_address} \
+ {<; ; 127.0.0.1 ; ::1}}
.endd
.scindex IIDgenoptra1 "generic options" "transport"
.scindex IIDgenoptra2 "options" "generic; for transports"
.scindex IIDgenoptra3 "transport" "generic options for"
+The name of a transport is limited to be &drivernamemax; ASCII characters long;
+prior to Exim 4.95 names would be silently truncated at this length, but now
+it is enforced.
+
The following generic options apply to all transports:
its removal from incoming messages, so that delivered messages can safely be
resent to other recipients.
+&*Note:*& If used on a transport handling multiple recipients
+(the smtp transport unless &%max_rcpt%& is 1, the appendfile, pipe or lmtp
+transport if &%batch_max%& is greater than 1)
+then information about Bcc recipients will be leaked.
+Doing so is generally not advised.
+
.option event_action transports string&!! unset
.cindex events
If the result of the expansion is an empty string, or if the expansion
is forced to fail, no action is taken. Other expansion failures are treated as
errors and cause the delivery to be deferred.
-.new
If an item ends in *, it will match any header with the given prefix.
-.wen
Matching headers are omitted from the message as it is transported, as described
in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
.option return_path_add transports boolean false
-.cindex "&'Return-path:'& header line"
+.chindex Return-path:
If this option is true, a &'Return-path:'& header is added to the message.
Although the return path is normally available in the prefix line of BSD
mailboxes, this is commonly not displayed by MUAs, and so the user does not
have easy access to it.
-RFC 2821 states that the &'Return-path:'& header is added to a message &"when
+&url(https://www.rfc-editor.org/rfc/rfc2821,RFC 2821)
+states that the &'Return-path:'& header is added to a message &"when
the delivery SMTP server makes the final delivery"&. This implies that this
header should not be present in incoming messages. Exim has a configuration
option, &%return_path_remove%&, which requests removal of this header from
When the message is about to be written out, the command specified by
&%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.
+input (this in fact is done from a third process, to avoid deadlock).
+The command must be specified as an absolute path.
+
+The process run by the command must use its standard input as the message
+data to be transformed, and write the results on its standard output.
The lines of the message that are written to the transport filter are
terminated by newline (&"\n"&). The message is passed to the filter before any
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. Exim does not check the result, except to
+care not to break
+&url(https://www.rfc-editor.org/rfc/rfc2822,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.
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:
+. used to have $sender_address in this cmdline, but it's tainted
.code
transport_filter = /some/directory/transport-filter.pl \
- $host $host_address $sender_address $pipe_addresses
+ $host $host_address $pipe_addresses
.endd
Two problems arise if you want to use more complicated expansion items to
transport_filter = '/bin/cmd${if eq{$host}{a.b.c}{1}{2}}'
.endd
This runs the command &(/bin/cmd1)& if the host name is &'a.b.c'&, and
-&(/bin/cmd2)& otherwise. If double quotes had been used, they would have been
+&(/bin/cmd2)& otherwise.
+
+Option strings in general have any fully-surrounding double quote wrapping
+removed early in parsing (see &<<SECTstrings>>&).
+Then, for this option, quotes protect against whitespace being
+regarded as a separator while splitting into the command argument vector.
+Either double or single quotes can be used here;
+the former interprets backlash-quoted charachters
+and the latter does not.
+
+If double quotes had been used in this example, they would have been
stripped by Exim when it read the option's value. When the value is used, if
the single quotes were missing, the line would be split into two items,
&`/bin/cmd${if`& and &`eq{$host}{a.b.c}{1}{2}`&, and an error would occur when
used to determine the file or directory name for the delivery. Normally, the
contents of &$address_file$& are used in some way in the string expansion.
.endlist
-.new
+If the &%create_file%& option is set to a path which
+matches (see the option definition below for details)
+a file or directory name
+for the delivery, that name becomes de-tainted.
+
.cindex "tainted data" "in filenames"
.cindex appendfile "tainted data"
Tainted data may not be used for a file or directory name.
This means that, for instance, &$local_part$& cannot be used directly
as a component of a path. It can however be used as the key for a lookup
which returns a path (or component).
-.wen
.cindex "Sieve filter" "configuring &(appendfile)&"
.endd
In this situation, the expansion of &%file%& or &%directory%& in the transport
must transform the relative path into an appropriate absolute filename. In the
-case of Sieve filters, the name &'inbox'& must be handled. It is the name that
+case of Sieve filters, the name &'inbox'& must be handled. It is the
+.new
+default
+.wen
+name that
is used as a result of a &"keep"& action in the filter. This example shows one
way of handling this requirement:
.code
location, absolute paths are used without change, and other folders are in the
&_mail_& directory within the home directory.
+.new
+An alternative for the &"keep"& aspect is to use the &%sieve_inbox%& option
+on the redirect router that calls the Sieve filter,
+to explicitly set the filename used.
+.wen
+
&*Note 1*&: While processing an Exim filter, a relative path such as
&_folder23_& is turned into an absolute path if a home directory is known to
the router. In particular, this is the case if &%check_local_user%& is set. If
&*Note 2*&: An absolute path in &$address_file$& is not treated specially;
the &%file%& or &%directory%& option is still used if it is set.
+.new
+&*Note 3*&: Permitting a user to enable writes to an absolute path
+may be a security issue.
+.wen
beneath.
The option must be set to one of the words &"anywhere"&, &"inhome"&, or
-&"belowhome"&. In the second and third cases, a home directory must have been
-set for the transport. This option is not useful when an explicit filename is
+&"belowhome"&, or to an absolute path.
+
+In the second and third cases, a home directory must have been
+set for the transport, and the file or directory being created must
+reside within it.
+The "belowhome" checking additionally checks for attempts to use "../"
+to evade the testing.
+This option is not useful when an explicit filename is
given for normal mailbox deliveries. It is intended for the case when filenames
are generated from users' &_.forward_& files. These are usually handled
by an &(appendfile)& transport called &%address_file%&. See also
&%file_must_exist%&.
+In the fourth case,
+the value given for this option must be an absolute path for an
+existing directory.
+The value is used for checking instead of a home directory;
+checking is done in "belowhome" mode.
+
+.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using appendfile create_file option"
+If "belowhome" checking is used, the file or directory path
+becomes de-tainted.
+
.option directory appendfile string&!! unset
This option is mutually exclusive with the &%file%& option, but one of &%file%&
(see &%maildir_format%& and &%mailstore_format%&), and see section
&<<SECTopdir>>& for further details of this form of delivery.
+The result of expansion must not be tainted, unless the &%create_file%& option
+specifies a path.
+
.option directory_file appendfile string&!! "see below"
.cindex "base62"
&%use_fcntl_lock%&, &%use_flock_lock%&, or &%use_lockfile%& must be set with
&%file%&.
+The result of expansion must not be tainted, unless the &%create_file%& option
+specifies a path.
+
.cindex "NFS" "lock file"
.cindex "locking files"
.cindex "lock files"
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.
+to the rules in RFCs
+&url(https://www.rfc-editor.org/rfc/rfc2822,2822) and
+&url(https://datatracker.ietf.org/doc/html/rfc3834,3834), 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
.option headers autoreply string&!! unset
-This specifies additional RFC 2822 headers that are to be added to the message
+This specifies additional
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+headers that are to be added to the message
when the message is specified by the transport. Several can be given by using
&"\n"& to separate them. There is no check on the format.
.cindex "transports" "&(lmtp)&"
.cindex "&(lmtp)& transport"
.cindex "LMTP" "over a pipe"
-.cindex "LMTP" "over a socket"
-The &(lmtp)& transport runs the LMTP protocol (RFC 2033) over a pipe to a
+.cindex "LMTP" "over a unix-domain socket"
+The &(lmtp)& transport runs the LMTP protocol
+(&url(https://www.rfc-editor.org/rfc/rfc2033,RFC 2033)) over a pipe to a
specified command
or by interacting with a Unix domain socket.
This transport is something of a cross between the &(pipe)& and &(smtp)&
details of the local delivery environment and chapter &<<CHAPbatching>>&
for a discussion of local delivery batching.
-.new
.cindex "tainted data" "in pipe command"
.cindex pipe "tainted data"
Tainted data may not be used for the command name.
-.wen
.section "Concurrent delivery" "SECID140"
the &%environment%& option can be used to add additional variables to this
environment. The environment for the &(pipe)& transport is not subject
to the &%add_environment%& and &%keep_environment%& main config options.
+&*Note*&: Using enviroment variables loses track of tainted data.
+Writers of &(pipe)& transport commands should be wary of data supplied
+by potential attackers.
.display
&`DOMAIN `& the domain of the address
&`HOME `& the home directory, if set
Exim, and each argument is separately expanded, as described in section
&<<SECThowcommandrun>>& above.
+.cindex "tainted data"
+No part of the resulting command may be tainted.
+
-.option environment pipe string&!! unset
+.option environment pipe "string list&!!" unset
.cindex "&(pipe)& transport" "environment for command"
.cindex "environment" "&(pipe)& transport"
This option is used to add additional variables to the environment in which the
.cindex "Cyrus"
The next example shows a transport and a router for a system where local
deliveries are handled by the Cyrus IMAP server.
+. Used to have R: local_part_suffix = .* + T: -m $local_part_suffix_v
+. but that suffix is tainted so cannot be used in a command arg
+. Really, you'd want to use a lookup for acceptable suffixes to do real detainting
.code
# transport
local_delivery_cyrus:
driver = pipe
command = /usr/cyrus/bin/deliver \
- -m ${substr_1:$local_part_suffix} -- $local_part
+ -- $local_part_data
user = cyrus
group = mail
return_output
local_user_cyrus:
driver = accept
check_local_user
- local_part_suffix = .*
transport = local_delivery_cyrus
.endd
Note the unsetting of &%message_prefix%& and &%message_suffix%&, and the use of
.option command_timeout smtp time 5m
+.cindex timeout "smtp transport command"
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
remote host. Its value must not be zero.
.option connect_timeout smtp time 5m
+.cindex timeout "smtp transport connect"
This sets a timeout for the &[connect()]& function, which sets up a TCP/IP call
to a remote host. A setting of zero allows the system timeout (typically
several minutes) to act. To have any effect, the value of this option must be
less than the system timeout. However, it has been observed that on some
systems there is no system timeout, which is why the default value for this
-option is 5 minutes, a value recommended by RFC 1123.
+option is 5 minutes, a value recommended by
+&url(https://www.rfc-editor.org/rfc/rfc1123,RFC 1123).
.option connection_max_messages smtp integer 500
For testing purposes, this value can be overridden by the &%-oB%& command line
option.
+.cindex "ESMTP extensions" LIMITS
+If the peer advertises a LIMITS extension with a MAILMAX value,
+and either TLSS is in use or was not advertised,
+that value also constrains the result of this option.
+
.option dane_require_tls_ciphers smtp string&!! unset
.cindex "TLS" "requiring specific ciphers for DANE"
.option data_timeout smtp time 5m
+.cindex timeout "for transmitted SMTP data blocks"
This sets a timeout for the transmission of each block in the data portion of
the message. As a result, the overall timeout for a message depends on the size
of the message. Its value must not be zero. See also &%final_timeout%&.
.option dkim_canon smtp string&!! unset
DKIM signing option. For details see section &<<SECDKIMSIGN>>&.
-.option dkim_domain smtp string list&!! unset
+.option dkim_domain smtp "string list&!!" unset
DKIM signing option. For details see section &<<SECDKIMSIGN>>&.
.option dkim_hash smtp string&!! sha256
DKIM signing option. For details see section &<<SECDKIMSIGN>>&.
.cindex "security" "MX lookup"
.cindex "DNS" "DNSSEC"
DNS lookups for domains matching &%dnssec_request_domains%& will be done with
-the dnssec request bit set. Setting this transport option is only useful if the
+the DNSSEC request bit set. Setting this transport option is only useful if the
transport overrides or sets the host names. See the &%dnssec_request_domains%&
router option.
.cindex "security" "MX lookup"
.cindex "DNS" "DNSSEC"
DNS lookups for domains matching &%dnssec_require_domains%& will be done with
-the dnssec request bit set. Setting this transport option is only
+the DNSSEC request bit set. Setting this transport option is only
useful if the transport overrides or sets the host names. See the
&%dnssec_require_domains%& router option.
.option final_timeout smtp time 10m
+.cindex timeout "for transmitted SMTP data accept"
This is the timeout that applies while waiting for the response to the final
line containing just &"."& that terminates a message. Its value must not be
zero.
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}\
+helo_data = ${lookup dnsdb{ptr=$sending_ip_address} \
+ {${listextract{1}{<\n $value}}} \
{$primary_hostname}}
.endd
The use of &%helo_data%& applies both to sending messages and when doing
callouts.
+.option host_name_extract smtp "string list&!!" "see below"
+.cindex "load balancer" "hosts behind"
+.cindex TLS resumption
+Some mail-accepting sites
+(notably Microsoft)
+operate many servers behind a network load-balancer. When this is done,
+with separated TLS session caches, TLS session resuption becomes problematic.
+It will only succeed when the same server happens to be selected by the
+load-balancer, matching the session stored in the client's cache.
+
+Exim can pull out a server name, if there is one, from the response to the
+client's SMTP EHLO command.
+For normal STARTTLS use, the default value of this option:
+.code
+ ${if and { {match {$host} {.outlook.com\$}} \
+ {match {$item} {\N^250-([\w.]+)\s\N}} \
+ } {$1}}
+.endd
+suffices for one known case.
+
+During the expansion of this option the &$item$& variable will have the
+server's EHLO response.
+
+For TLS-on-connect connections we do not have an EHLO
+response to use. Because of this the default value of this option is
+set to a static string for those cases, meaning that resumption will
+always be attempted if permitted by the &%tls_resumption_hosts%& option.
+
+The result of the option expansion is included in the key used to store and
+retrieve the TLS session, for session resumption.
+
+Operators of high-load sites may wish to evaluate their logs for indications
+of other destination sites operating load-balancers, and develop a suitable
+expression for this option.
+The smtp:ehlo event and the &$tls_out_resumption$& variable
+will be useful for such work.
+
.option hosts smtp "string list&!!" unset
Hosts are associated with an address by a router such as &(dnslookup)&, which
finds the hosts by looking up the address domain in the DNS, or by
.option hosts_pipe_connect smtp "host list&!!" unset
.cindex "pipelining" "early connection"
-.cindex "pipelining" PIPE_CONNECT
+.cindex "pipelining" PIPECONNECT
If Exim is built with the SUPPORT_PIPE_CONNECT build option
this option controls which to hosts the facility watched for
and recorded, and used for subsequent connections.
See also the &%pipelining_connect_advertise_hosts%& main option.
Note:
-When the facility is used, the transport &%helo_data%& option
+When the facility is used, if the transport &%interface%& option is unset
+the &%helo_data%& option
will be expanded before the &$sending_ip_address$& variable
is filled in.
A check is made for the use of that variable, without the
&<<CHAPSMTPAUTH>>& for details of authentication.
-.option hosts_request_ocsp smtp "host list&!!" *
+.option hosts_request_ocsp smtp "host list&!!" "see below"
.cindex "TLS" "requiring for certain servers"
Exim will request a Certificate Status on a
TLS session for any host that matches this list.
&%tls_verify_certificates%& should also be set for the transport.
+The default is &"**"& if DANE is not in use for the connection,
+or if DANE-TA us used.
+It is empty if DANE-EE is used.
+
+.option hosts_require_alpn smtp "host list&!!" unset
+.cindex ALPN "require negotiation in client"
+.cindex TLS ALPN
+.cindex TLS "Application Layer Protocol Names"
+If the TLS library supports ALPN
+then a successful negotiation of ALPN will be required for any host
+matching the list, for TLS to be used.
+See also the &%tls_alpn%& option.
+
+&*Note*&: prevention of fallback to in-clear connection is not
+managed by this option; see &%hosts_require_tls%&.
+
.option hosts_require_dane smtp "host list&!!" unset
.cindex DANE "transport options"
.cindex DANE "requiring for certain servers"
If built with DANE support, Exim will require that a DNSSEC-validated
TLSA record is present for any host matching the list,
-and that a DANE-verified TLS connection is made. See
-the &%dnssec_request_domains%& router and transport options.
+and that a DANE-verified TLS connection is made.
There will be no fallback to in-clear communication.
+See the &%dnssec_request_domains%& router and transport options.
See section &<<SECDANE>>&.
.option hosts_require_ocsp smtp "host list&!!" unset
.cindex "authentication" "optional in client"
This option provides a list of servers to which, provided they announce
authentication support, Exim will attempt to authenticate as a client when it
-connects. If authentication fails, Exim will try to transfer the message
-unauthenticated. See also &%hosts_require_auth%&, and chapter
-&<<CHAPSMTPAUTH>>& for details of authentication.
+connects. If authentication fails
+and &%hosts_require_auth%& permits,
+Exim will try to transfer the message unauthenticated.
+See also chapter &<<CHAPSMTPAUTH>>& for details of authentication.
.option hosts_try_chunking smtp "host list&!!" *
.cindex CHUNKING "enabling, in client"
.cindex "RFC 3030" "CHUNKING"
This option provides a list of servers to which, provided they announce
CHUNKING support, Exim will attempt to use BDAT commands rather than DATA.
-.new
Unless DKIM signing is being done,
-.wen
BDAT will not be used in conjunction with a transport filter.
.option hosts_try_dane smtp "host list&!!" *
.cindex DANE "transport options"
.cindex DANE "attempting for certain servers"
-If built with DANE support, Exim will require that a DNSSEC-validated
-TLSA record is present for any host matching the list,
-and that a DANE-verified TLS connection is made. See
-the &%dnssec_request_domains%& router and transport options.
-There will be no fallback to in-clear communication.
+If built with DANE support, Exim will look up a
+TLSA record for any host matching the list,
+If one is found and that lookup was DNSSEC-validated,
+then Exim requires that a DANE-verified TLS connection is made for that host;
+there will be no fallback to in-clear communication.
+See the &%dnssec_request_domains%& router and transport options.
See section &<<SECDANE>>&.
.option hosts_try_fastopen smtp "host list&!!" *
.cindex "RFC 7413" "TCP Fast Open"
This option provides a list of servers to which, provided
the facility is supported by this system, Exim will attempt to
-perform a TCP Fast Open.
+perform a TCP Fast Open (&url(https://www.rfc-editor.org/rfc/rfc7413,RFC 7413).
No data is sent on the SYN segment but, if the remote server also
supports the facility, it can send its SMTP banner immediately after
the SYN,ACK segment. This can save up to one round-trip time.
string &`IGNOREQUOTA`& is added to RCPT commands, provided that the LMTP server
has advertised support for IGNOREQUOTA in its response to the LHLO command.
-.option max_rcpt smtp integer 100
+.option max_rcpt smtp integer&!! 100
.cindex "RCPT" "maximum number of outgoing"
-This option limits the number of RCPT commands that are sent in a single
-SMTP message transaction. Each set of addresses is treated independently, and
+This option,
+after expansion,
+limits the number of RCPT commands that are sent in a single
+SMTP message transaction.
+A value setting of zero disables the limit.
+
+If a constant is given,
+each set of addresses is treated independently, and
so can cause parallel connections to the same host if &%remote_max_parallel%&
permits this.
+.cindex "ESMTP extensions" LIMITS
+If the peer advertises a LIMITS extension with a RCPTMAX value,
+and either TLSS is in use or was not advertised,
+that value also constrains the result of this option
+and no parallel connections will be caused on meeting the RCPTMAX limit.
+
+
+.option message_linelength_limit smtp integer 998
+.cindex "line length" limit
+This option sets the maximum line length, in bytes, that the transport
+will send. Any messages with lines exceeding the given value
+(before a transport filter, if any)
+will fail and a failure-DSN ("bounce") message will if possible be returned
+to the sender.
+The default value is that defined by the SMTP standards.
+
+It is generally wise to also check in the data ACL so that messages
+received via SMTP can be refused without producing a bounce.
+
.option multi_domain smtp boolean&!! true
.vindex "&$domain$&"
&$address_data$&, &$domain_data$&, &$local_part_data$&,
&$host$&, &$host_address$& and &$host_port$&.
+If the connection is DANE-enabled then this option is ignored;
+only messages having the domain used for the DANE TLSA lookup are
+sent on the connection.
+
+.cindex "ESMTP extensions" LIMITS
+If the peer advertises a LIMITS extension with a RCPTDOMAINMAX value,
+and either TLSS is in use or was not advertised,
+this option is regarded as being false.
+
+
.option port smtp string&!! "see below"
.cindex "port" "sending TCP/IP"
.cindex "TCP/IP" "setting outgoing port"
.vindex "&$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
+protocol
+(&url(https://www.rfc-editor.org/rfc/rfc2033,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>>&.
+&*Note*&: When using LMTP it should be considered whether the default values
+for some other features, such as DANE, are appropriate.
+
If this option is set to &"smtps"&, the default value 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 used to strongly discourage use of this mode,
-but as of RFC 8314 it is perferred over STARTTLS for message submission
+but as of &url(https://www.rfc-editor.org/rfc/rfc8314,RFC 8314) it is preferred
+over STARTTLS for message submission
(as distinct from MTA-MTA communication).
transport. For details see section &<<SECTproxySOCKS>>&.
+.option tls_alpn smtp string&!! unset
+.cindex TLS "Application Layer Protocol Names"
+.cindex TLS ALPN
+.cindex ALPN "set name in client"
+If this option is set
+and the TLS library supports ALPN,
+the value given is used.
+
+As of writing no value has been standardised for email use.
+The authors suggest using &"smtp"&.
+
+
+
.option tls_certificate smtp string&!! unset
.cindex "TLS" "client certificate, location of"
.cindex "certificate" "client, location of"
ciphers is a preference order.
+.option tls_resumption_hosts smtp "host list&!!" unset
+.cindex TLS resumption
+This option controls which connections to use the TLS resumption feature.
+See &<<SECTresumption>>& for details.
+
+
.option tls_sni smtp string&!! unset
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI "setting in client"
.vindex "&$tls_sni$&"
-If this option is set then it sets the $tls_out_sni variable and causes any
+If this option is set
+and the connection is not DANE-validated
+then it sets the $tls_out_sni variable and causes any
TLS session to pass this value as the Server Name Indication extension to
the remote side, which can be used by the remote side to select an appropriate
certificate and private key for the session.
while verifying the server certificate,
checks will be included on the host name
(note that this will generally be the result of a DNS MX lookup)
-versus Subject and Subject-Alternate-Name fields. Wildcard names are permitted
+versus the Subject-Alternate-Name (or, if none, Subject-Name) fields.
+Wildcard names are permitted,
limited to being the initial component of a 3-or-more component FQDN.
There is no equivalent checking on client certificates.
The &%tls_verify_certificates%& option must also be set.
If both this option and &%tls_try_verify_hosts%& are unset
operation is as if this option selected all hosts.
+&*Warning*&: Including a host in &%tls_verify_hosts%& does not require
+that connections use TLS.
+Fallback to in-clear communication will be done unless restricted by
+the &%hosts_require_tls%& option.
.option utf8_downconvert smtp integer&!! -1
.cindex utf8 "address downconversion"
.vindex "&$sender_address$&"
At the start of an ACL for MAIL, the sender address may have been rewritten
-by a special SMTP-time rewrite rule (see section &<<SECTrewriteS>>&), but no
+by a special SMTP-time rewrite rule (see section &<<SSECTrewriteS>>&), but no
ordinary rewrite rules have yet been applied. If, however, the sender address
is verified in the ACL, it is rewritten before verification, and remains
rewritten thereafter. The subsequent value of &$sender_address$& is the
.cindex "testing" "rewriting"
Exim's input rewriting configuration appears in a part of the runtime
configuration file headed by &"begin rewrite"&. It can be tested by the
-&%-brw%& command line option. This takes an address (which can be a full RFC
-2822 address) as its argument. The output is a list of how the address would be
+&%-brw%& command line option. This takes an address (which can be a full
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address) as its argument. The output is a list of how the address would be
transformed by the rewriting rules for each of the different places it might
appear in an incoming message, that is, for each different header and for the
envelope sender and recipient fields. For example,
-.section "Rewriting flags" "SECID153"
+.subsection "Rewriting flags" "SSECID153"
There are three different kinds of flag that may appear on rewriting rules:
.ilist
-.section "Flags specifying which headers and envelope addresses to rewrite" &&&
- "SECID154"
-.cindex "rewriting" "flags"
+.subsection "Flags specifying which headers and envelope addresses to rewrite" &&&
+ "SSECID154"
+.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
+&<<SSECTrewriteS>>&) are present, a main rewriting rule applies to all headers
and to both the sender and recipient fields of the envelope, whereas a
transport-time rewriting rule just applies to all headers. Otherwise, the
rewriting rule is skipped unless the relevant addresses are being processed.
restrict this to special known cases in your own domains.
-.section "The SMTP-time rewriting flag" "SECTrewriteS"
-.cindex "SMTP" "rewriting malformed addresses"
-.cindex "RCPT" "rewriting argument of"
-.cindex "MAIL" "rewriting argument of"
+.subsection "The SMTP-time rewriting flag" SSECTrewriteS
+.cindex SMTP "rewriting malformed addresses"
+.cindex RCPT "rewriting argument of"
+.cindex MAIL "rewriting argument of"
The rewrite flag &"S"& specifies a rewrite of incoming envelope addresses at
SMTP time, as soon as an address is received in a MAIL or RCPT command, and
before any other processing; even before syntax checking. The pattern is
.vindex "&$domain$&"
.vindex "&$local_part$&"
This form of rewrite rule allows for the handling of addresses that are not
-compliant with RFCs 2821 and 2822 (for example, &"bang paths"& in batched SMTP
+compliant with RFCs
+&url(https://www.rfc-editor.org/rfc/rfc2821,2821) and
+&url(https://www.rfc-editor.org/rfc/rfc2822,2822)
+(for example, &"bang paths"& in batched SMTP
input). Because the input is not required to be a syntactically valid address,
the variables &$local_part$& and &$domain$& are not available during the
expansion of the replacement string. The result of rewriting replaces the
original address in the MAIL or RCPT command.
-.section "Flags controlling the rewriting process" "SECID155"
+.subsection "Flags controlling the rewriting process" SSECID155
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:
.next
.cindex "rewriting" "whole addresses"
When an address in a header is rewritten, the rewriting normally applies only
-to the working part of the address, with any comments and RFC 2822 &"phrase"&
-left unchanged. For example, rewriting might change
+to the working part of the address, with any comments and
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+&"phrase"& left unchanged. For example, rewriting might change
.code
From: Ford Prefect <fp42@restaurant.hitch.fict.example>
.endd
Sometimes there is a need to replace the whole address item, and this can be
done by adding the flag letter &"w"& to a rule. If this is set on a rule that
causes an address in a header line to be rewritten, the entire address is
-replaced, not just the working part. The replacement must be a complete RFC
-2822 address, including the angle brackets if necessary. If text outside angle
+replaced, not just the working part. The replacement must be a complete
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address, including the angle brackets if necessary. If text outside angle
brackets contains a character whose value is greater than 126 or less than 32
-(except for tab), the text is encoded according to RFC 2047. The character set
+(except for tab), the text is encoded according to
+&url(https://www.rfc-editor.org/rfc/rfc2047,RFC 2047). The character set
is taken from &%headers_charset%&, which gets its default at build time.
When the &"w"& flag is set on a rule that causes an envelope address to be
.scindex IIDauthconf2 "authentication"
The &"authenticators"& section of Exim's runtime 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
+described in
+&url(https://www.rfc-editor.org/rfc/rfc2554,RFC 2554),
+which allows a client SMTP host to authenticate itself
to a server. This is a common way for a server to recognize clients that are
permitted to use it as a relay. SMTP authentication is not of relevance to the
transfer of mail between servers that have no managerial connection with each
other.
+The name of an authenticator is limited to be &drivernamemax; ASCII characters long;
+prior to Exim 4.95 names would be silently truncated at this length, but now
+it is enforced.
+
.cindex "AUTH" "description of"
.cindex "ESMTP extensions" AUTH
Very briefly, the way SMTP authentication works is as follows:
-.ilist
+.olist
The server advertises a number of authentication &'mechanisms'& in response to
the client's EHLO command.
.next
AUTH_TLS=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.
+authentication mechanism
+(&url(https://www.rfc-editor.org/rfc/rfc2195,RFC 2195)),
+and the second provides an interface to 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 for negotiation of authentication done via non-SMTP means,
-as defined by RFC 4422 Appendix A.
+as defined by &url(https://www.rfc-editor.org/rfc/rfc4422,RFC 4422) Appendix A.
The fifth provides an interface to the GNU SASL authentication library, which
provides mechanisms but typically not data sources.
The sixth provides direct access to Heimdal GSSAPI, geared for Kerberos, but
supporting setting a server keytab.
The seventh can be configured to support
-the PLAIN authentication mechanism (RFC 2595) or the LOGIN mechanism, which is
+the PLAIN authentication mechanism
+(&url(https://www.rfc-editor.org/rfc/rfc2595,RFC 2595))
+or the LOGIN mechanism, which is
not formally documented, but used by several MUAs.
The eighth authenticator
supports Microsoft's &'Secure Password Authentication'& mechanism.
.option public_name authenticators string unset
This option specifies the name of the authentication mechanism that the driver
implements, and by which it is known to the outside world. These names should
-contain only upper case letters, digits, underscores, and hyphens (RFC 2222),
+contain only upper case letters, digits, underscores, and hyphens
+(&url(https://www.rfc-editor.org/rfc/rfc2222,RFC 2222)),
but Exim in fact matches them caselessly. If &%public_name%& is not set, it
defaults to the driver's instance name.
.ilist
The client host must match &%auth_advertise_hosts%& (default *).
.next
-It the &%server_advertise_condition%& option is set, its expansion must not
+If the &%server_advertise_condition%& option is set, its expansion must not
yield the empty string, &"0"&, &"no"&, or &"false"&.
.endlist
Successful authentication sets up information used by the
&%authresults%& expansion item.
+.cindex authentication "failure event, server"
+If an authenticator is run and does not succeed,
+an event of type "auth:fail" is raised.
+While the event is being processed the variables
+&$sender_host_authenticated$& (with the authenticator name)
+and &$authenticated_fail_id$& (as set by the authenticator &%server_set_id%& option)
+will be valid.
+If the event is serviced and a string is returned then the string will be logged
+instead of the default log line.
+See &<<CHAPevents>>& for details on events.
-
-.section "Testing server authentication" "SECID169"
+.subsection "Testing server authentication" "SECID169"
.cindex "authentication" "testing a server"
.cindex "AUTH" "testing a server"
.cindex "base64 encoding" "creating authentication test data"
.endd
gives an incorrect answer because of the unescaped &"@"& and &"$"& characters.
-If you have the &%mimencode%& command installed, another way to do produce
+If you have the &%mimencode%& command installed, another way to produce
base64-encoded strings is to run the command
.code
echo -e -n `\0user\0password' | mimencode
Exim abandons trying to send the message to the host for the moment. It will
try again later. If there are any backup hosts available, they are tried in the
usual way.
+
+.next
+.cindex authentication "failure event, client"
+If the response to authentication is a permanent error (5&'xx'& code),
+an event of type "auth:fail" is raised.
+While the event is being processed the variable
+&$sender_host_authenticated$& (with the authenticator name)
+will be valid.
+If the event is serviced and a string is returned then the string will be logged.
+See &<<CHAPevents>>& for details on events.
+
.next
If the response to authentication is a permanent error (5&'xx'& code), Exim
carries on searching the list of authenticators and tries another one if
-.section "The PLAIN authentication mechanism" "SECID172"
+.subsection "The PLAIN authentication mechanism" "SECID172"
.cindex "PLAIN authentication mechanism"
.cindex authentication PLAIN
.cindex "binary zero" "in &(plaintext)& authenticator"
-The PLAIN authentication mechanism (RFC 2595) specifies that three strings be
+The PLAIN authentication mechanism
+(&url(https://www.rfc-editor.org/rfc/rfc2595,RFC 2595))
+specifies that three strings be
sent as one item of data (that is, one combined string containing two NUL
separators). The data is sent either as part of the AUTH command, or
subsequently in response to an empty prompt from the server.
writing the test makes the logic clearer.
-.section "The LOGIN authentication mechanism" "SECID173"
+.subsection "The LOGIN authentication mechanism" "SECID173"
.cindex "LOGIN authentication mechanism"
.cindex authentication LOGIN
The LOGIN authentication mechanism is not documented in any RFC, but is in use
uninterpreted string.
-.section "Support for different kinds of authentication" "SECID174"
+.subsection "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,
client_send = ^username^mysecret
.endd
The lack of colons means that the entire text is sent with the AUTH
-command, with the circumflex characters converted to NULs. A similar example
+command, with the circumflex characters converted to NULs.
+Note that due to the ambiguity of parsing three consectutive circumflex characters
+there is no way to provide a password having a leading circumflex.
+
+
+A similar example
that uses the LOGIN mechanism is:
.code
fixed_login:
.scindex IIDcramauth2 "authenticators" "&(cram_md5)&"
.cindex "CRAM-MD5 authentication mechanism"
.cindex authentication CRAM-MD5
-The CRAM-MD5 authentication mechanism is described in RFC 2195. The server
+The CRAM-MD5 authentication mechanism is described in
+&url(https://www.rfc-editor.org/rfc/rfc2195,RFC 2195). The server
sends a challenge string to the client, and the response consists of a user
name and the CRAM-MD5 digest of the challenge string combined with a secret
string (password) which is known to both server and client. Thus, the secret
at A L Digital Ltd.
The &(cyrus_sasl)& authenticator provides server support for the Cyrus SASL
-library implementation of the RFC 2222 (&"Simple Authentication and Security
+library implementation of the
+&url(https://www.rfc-editor.org/rfc/rfc2222,RFC 2222)
+(&"Simple Authentication and Security
Layer"&). This library supports a number of authentication mechanisms,
including PLAIN and LOGIN, but also several others that Exim does not support
directly. In particular, there is support for Kerberos authentication.
Note that Dovecot must be configured to use auth-client not auth-userdb.
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:
+authenticator only. There is only one non-generic option:
.option server_socket dovecot string unset
dovecot_plain:
driver = dovecot
public_name = PLAIN
+ server_advertise_condition = ${if def:tls_in_cipher}
server_socket = /var/run/dovecot/auth-client
server_set_id = $auth1
server_socket = /var/run/dovecot/auth-client
server_set_id = $auth1
.endd
+
+&*Note*&: plaintext authentication methods such as PLAIN and LOGIN
+should not be advertised on cleartext SMTP connections.
+See the discussion in section &<<SECTplain_TLS>>&.
+
If the SMTP connection is encrypted, or if &$sender_host_address$& is equal to
&$received_ip_address$& (that is, the connection is local), the &"secured"&
option is passed in the Dovecot authentication command. If, for a TLS
option is passed. When authentication succeeds, the identity of the user
who authenticated is placed in &$auth1$&.
-.new
-The Dovecot configuration to match the above wil look
+The Dovecot configuration to match the above will look
something like:
.code
conf.d/10-master.conf :-
auth_mechanisms = plain login ntlm
.endd
-.wen
.ecindex IIDdcotauth1
.ecindex IIDdcotauth2
made that any particular new authentication mechanism will be supported
without code changes in Exim.
-.new
The library is expected to add support in an upcoming
realease for the SCRAM-SHA-256 method.
The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined
when this happens.
+To see the list of mechanisms supported by the library run Exim with "auth" debug
+enabled and look for a line containing "GNU SASL supports".
+Note however that some may not have been tested from Exim.
+
.option client_authz gsasl string&!! unset
This option can be used to supply an &'authorization id'&
.option client_username gsasl string&!! unset
This option is exapanded before use, and should result in
the account name to be used.
-.wen
-.new
+
.option client_spassword gsasl string&!! unset
+This option is only supported for library versions 1.9.1 and greater.
+The macro _HAVE_AUTH_GSASL_SCRAM_S_KEY will be defined when this is so.
+
If a SCRAM mechanism is being used and this option is set
+and correctly sized
it is used in preference to &%client_password%&.
The value after expansion should be
a 40 (for SHA-1) or 64 (for SHA-256) character string
with the PBKDF2-prepared password, hex-encoded.
+
Note that this value will depend on the salt and iteration-count
supplied by the server.
-.wen
+The option is expanded before use.
+During the expansion &$auth1$& is set with the client username,
+&$auth2$& with the iteration count, and
+&$auth3$& with the salt.
+The intent of this option
+is to support clients that can cache thes salted password
+to save on recalculation costs.
+The cache lookup should return an unusable value
+(eg. an empty string)
+if the salt or iteration count has changed
+If the authentication succeeds then the above variables are set,
+.vindex "&$auth4$&"
+plus the calculated salted password value value in &$auth4$&,
+during the expansion of the &%client_set_id%& option.
+A side-effect of this expansion can be used to prime the cache.
-.option server_channelbinding gsasl boolean false
-Do not set this true and rely on the properties
-without consulting a cryptographic engineer.
+.option server_channelbinding gsasl boolean false
Some authentication mechanisms are able to use external context at both ends
of the session to bind the authentication to that context, and fail the
authentication process if that context differs. Specifically, some TLS
non-issue, as a man-in-the-middle attack will cause the correct client and
server to see different identifiers and authentication will fail.
-.new
This is
only usable by mechanisms which support "channel binding"; at time of
writing, that's the SCRAM family.
When using this feature the "-PLUS" variants of the method names need to be used.
-.wen
This defaults off to ensure smooth upgrade across Exim releases, in case
this option causes some clients to start failing. Some future release
of Exim might have switched the default to be true.
-However, Channel Binding in TLS has proven to be vulnerable in current versions.
-Do not plan to rely upon this feature for security, ever, without consulting
-with a subject matter expert (a cryptographic engineer).
+. However, Channel Binding in TLS has proven to be vulnerable in current versions.
+. Do not plan to rely upon this feature for security, ever, without consulting
+. with a subject matter expert (a cryptographic engineer).
+
+This option was deprecated in previous releases due to doubts over
+the "Triple Handshake" vulnerability.
+Exim takes suitable precausions (requiring Extended Master Secret if TLS
+Session Resumption was used) for safety.
.option server_hostname gsasl string&!! "see below"
.option server_scram_iter gsasl string&!! 4096
This option provides data for the SCRAM family of mechanisms.
-.new
The &$auth1$&, &$auth2$& and &$auth3$& variables are available
when this option is expanded.
either the iteration count or the salt).
A minimum value of 4096 is required by the standards
for all current SCRAM mechanism variants.
-.wen
.option server_scram_salt gsasl string&!! unset
This option provides data for the SCRAM family of mechanisms.
-.new
The &$auth1$&, &$auth2$& and &$auth3$& variables are available
when this option is expanded.
The value should be a base64-encoded string,
of random data typically 4-to-16 bytes long.
If unset or empty after expansion the library will provides a value for the
protocol conversation.
-.wen
-.new
.option server_key gsasl string&!! unset
.option server_skey gsasl string&!! unset
These options can be used for the SCRAM family of mechanisms
The libgsasl library release includes a utility &'gsasl'& which can be used
to generate these values.
-.wen
.option server_service gsasl string &`smtp`&
Password Authentication'& mechanism,
which is also sometimes known as NTLM (NT LanMan). The code for client side of
this authenticator was contributed by Marc Prud'hommeaux, and much of it is
-taken from the Samba project (&url(https://www.samba.org/)). The code for the
+taken from the &url(https://www.samba.org/,Samba project). The code for the
server side was subsequently contributed by Tom Kistner. The mechanism works as
follows:
.cindex "Certificate-based authentication"
The &(external)& authenticator provides support for
authentication based on non-SMTP information.
-The specification is in RFC 4422 Appendix A
-(&url(https://tools.ietf.org/html/rfc4422)).
+The specification is in
+&url(https://tools.ietf.org/html/rfc4422,RFC 4422) Appendix A.
It is only a transport and negotiation mechanism;
the process of authentication is entirely controlled
by the server configuration.
this authentication method on a secure (eg. under TLS) connection.
One possible use, compatible with the
-K-9 Mail Andoid client (&url(https://k9mail.github.io/)),
+&url(https://k9mail.github.io/,K-9 Mail Android client)
is for using X509 client certificates.
It thus overlaps in function with the TLS authenticator
(see &<<CHAPTLS>>&).
If an authenticator of this type is configured it is
-run before any SMTP-level communication is done,
+run immediately after a TLS connection being negotiated
+(due to either STARTTLS or TLS-on-connect)
and can authenticate the connection.
-If it does, SMTP authentication is not offered.
+If it does, SMTP authentication is not subsequently offered.
A maximum of one authenticator of this type may be present.
level, and in particular, the way that public keys, private keys, and
certificates are used.
-RFC 3207 defines how SMTP connections can make use of encryption. Once a
+&url(https://www.rfc-editor.org/rfc/rfc3207,RFC 3207)
+defines how SMTP connections can make use of encryption. Once a
connection is established, the client issues a STARTTLS command. If the
server accepts this, the client and the server negotiate an encryption
mechanism. If the negotiation succeeds, the data that subsequently passes
.cindex "SMTP" "ssmtp protocol"
.cindex "SMTP" "smtps protocol"
The history of port numbers for TLS in SMTP is a little messy and has been
-contentious. As of RFC 8314, the common practice of using the historically
+contentious. As of
+&url(https://www.rfc-editor.org/rfc/rfc8314,RFC 8314),
+the common practice of using the historically
allocated port 465 for "email submission but with TLS immediately upon connect
instead of using STARTTLS" is officially blessed by the IETF, and recommended
by them in preference to STARTTLS.
.vindex "&$tls_in_peerdn$&"
.vindex "&$tls_out_peerdn$&"
Distinguished Name (DN) strings reported by the OpenSSL library use a slash for
-separating fields; GnuTLS uses commas, in accordance with RFC 2253. This
+separating fields; GnuTLS uses commas, in accordance with
+&url(https://www.rfc-editor.org/rfc/rfc2253,RFC 2253). This
affects the value of the &$tls_in_peerdn$& and &$tls_out_peerdn$& variables.
.next
OpenSSL identifies cipher suites using hyphens as separators, for example:
(If an API is found to let OpenSSL be configured in this way,
let the Exim Maintainers know and we'll likely use it).
.next
-With GnuTLS, if an explicit list is used for the &%tls_privatekey%& main option
-main option, it must be ordered to match the &%tls_certificate%& list.
+With GnuTLS, if an explicit list is used for the &%tls_privatekey%& main option,
+it must be ordered to match the &%tls_certificate%& list.
.next
Some other recently added features may only be available in one or the other.
This should be documented with the feature. If the documentation does not
explicitly state that the feature is infeasible in the other TLS
implementation, then patches are welcome.
+.next
+The output from "exim -bV" will show which (if any) support was included
+in the build.
+Also, the macro "_HAVE_OPENSSL" or "_HAVE_GNUTLS" will be defined.
.endlist
(again depending on the &%tls_cipher%& log selector).
-.section "Requesting and verifying client certificates" "SECID183"
+.subsection "Requesting and verifying client certificates"
.cindex "certificate" "verification of client"
.cindex "TLS" "client certificate verification"
If you want an Exim server to request a certificate when negotiating a TLS
certificate is supplied, &$tls_in_peerdn$& is empty.
-.section "Revoked certificates" "SECID184"
-.cindex "TLS" "revoked certificates"
-.cindex "revocation list"
-.cindex "certificate" "revocation list"
-.cindex "OCSP" "stapling"
-Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when
-certificates are revoked. If you have such a list, you can pass it to an Exim
-server using the global option called &%tls_crl%& and to an Exim client using
-an identically named option for the &(smtp)& transport. In each case, the value
-of the option is expanded and must then be the name of a file that contains a
-CRL in PEM format.
-The downside is that clients have to periodically re-download a potentially huge
-file from every certificate authority they know of.
-
-The way with most moving parts at query time is Online Certificate
-Status Protocol (OCSP), where the client verifies the certificate
-against an OCSP server run by the CA. This lets the CA track all
-usage of the certs. It requires running software with access to the
-private key of the CA, to sign the responses to the OCSP queries. OCSP
-is based on HTTP and can be proxied accordingly.
-
-The only widespread OCSP server implementation (known to this writer)
-comes as part of OpenSSL and aborts on an invalid request, such as
-connecting to the port and then disconnecting. This requires
-re-entering the passphrase each time some random client does this.
-
-The third way is OCSP Stapling; in this, the server using a certificate
-issued by the CA periodically requests an OCSP proof of validity from
-the OCSP server, then serves it up inline as part of the TLS
-negotiation. This approach adds no extra round trips, does not let the
-CA track users, scales well with number of certs issued by the CA and is
-resilient to temporary OCSP server failures, as long as the server
-starts retrying to fetch an OCSP proof some time before its current
-proof expires. The downside is that it requires server support.
-
-Unless Exim is built with the support disabled,
-or with GnuTLS earlier than version 3.3.16 / 3.4.8
-support for OCSP stapling is included.
-
-There is a global option called &%tls_ocsp_file%&.
-The file specified therein is expected to be in DER format, and contain
-an OCSP proof. Exim will serve it as part of the TLS handshake. This
-option will be re-expanded for SNI, if the &%tls_certificate%& option
-contains &`tls_in_sni`&, as per other TLS options.
-
-Exim does not at this time implement any support for fetching a new OCSP
-proof. The burden is on the administrator to handle this, outside of
-Exim. The file specified should be replaced atomically, so that the
-contents are always valid. Exim will expand the &%tls_ocsp_file%& option
-on each connection, so a new file will be handled transparently on the
-next connection.
-
-When built with OpenSSL Exim will check for a valid next update timestamp
-in the OCSP proof; if not present, or if the proof has expired, it will be
-ignored.
-
-For the client to be able to verify the stapled OCSP the server must
-also supply, in its stapled information, any intermediate
-certificates for the chain leading to the OCSP proof from the signer
-of the server certificate. There may be zero or one such. These
-intermediate certificates should be added to the server OCSP stapling
-file named by &%tls_ocsp_file%&.
-
-Note that the proof only covers the terminal server certificate,
-not any of the chain from CA to it.
-
-There is no current way to staple a proof for a client certificate.
-
-.code
- A helper script "ocsp_fetch.pl" for fetching a proof from a CA
- OCSP server is supplied. The server URL may be included in the
- server certificate, if the CA is helpful.
-
- One failure mode seen was the OCSP Signer cert expiring before the end
- of validity of the OCSP proof. The checking done by Exim/OpenSSL
- noted this as invalid overall, but the re-fetch script did not.
-.endd
+.subsection "Caching of static server configuration items" "SSECTserverTLScache"
+.cindex certificate caching
+.cindex privatekey caching
+.cindex crl caching
+.cindex ocsp caching
+.cindex ciphers caching
+.cindex "CA bundle" caching
+.cindex "certificate authorities" caching
+.cindex tls_certificate caching
+.cindex tls_privatekey caching
+.cindex tls_crl caching
+.cindex tls_ocsp_file caching
+.cindex tls_require_ciphers caching
+.cindex tls_verify_certificate caching
+.cindex caching certificate
+.cindex caching privatekey
+.cindex caching crl
+.cindex caching ocsp
+.cindex caching ciphers
+.cindex caching "certificate authorities
+If any of the main configuration options &%tls_certificate%&, &%tls_privatekey%&,
+&%tls_crl%& and &%tls_ocsp_file%& have values with no
+expandable elements,
+then the associated information is loaded at daemon startup.
+It is made available
+to child processes forked for handling received SMTP connections.
+
+This caching is currently only supported under Linux and FreeBSD.
+
+If caching is not possible, for example if an item has to be dependent
+on the peer host so contains a &$sender_host_name$& expansion, the load
+of the associated information is done at the startup of the TLS connection.
+
+The cache is invalidated and reloaded after any changes to the directories
+containing files specified by these options.
+
+The information specified by the main option &%tls_verify_certificates%&
+is similarly cached so long as it specifies files explicitly
+or (under GnuTLS) is the string &"system,cache"&.
+The latter case is not automatically invalidated;
+it is the operator's responsibility to arrange for a daemon restart
+any time the system certificate authority bundle is updated.
+A HUP signal is sufficient for this.
+The value &"system"& results in no caching under GnuTLS.
+
+The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system"
+is acceptable in configurations for the Exim executable.
+
+Caching of the system Certificate Authorities bundle can
+save significant time and processing on every TLS connection
+accepted by Exim.
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
+if it requests it.
+This is an optional thing for TLS connections, although either end
+may insist on 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*&: Do not use a certificate which has the OCSP-must-staple extension,
or need not succeed respectively.
The &%tls_verify_cert_hostnames%& option lists hosts for which additional
-checks are made: that the host name (the one in the DNS A record)
-is valid for the certificate.
+name checks are made on the server certificate.
+The match against this list is, as per other Exim usage, the
+IP for the host. That is most closely associated with the
+name on the DNS A (or AAAA) record for the host.
+However, the name that needs to be in the certificate
+is the one at the head of any CNAME chain leading to the A record.
The option defaults to always checking.
The &(smtp)& transport has two OCSP-related options:
+.subsection "Caching of static client configuration items" SECTclientTLScache
+.cindex certificate caching
+.cindex privatekey caching
+.cindex crl caching
+.cindex ciphers caching
+.cindex "CA bundle" caching
+.cindex "certificate authorities" caching
+.cindex tls_certificate caching
+.cindex tls_privatekey caching
+.cindex tls_crl caching
+.cindex tls_require_ciphers caching
+.cindex tls_verify_certificate caching
+.cindex caching certificate
+.cindex caching privatekey
+.cindex caching crl
+.cindex caching ciphers
+.cindex caching "certificate authorities
+If any of the transport configuration options &%tls_certificate%&, &%tls_privatekey%&
+and &%tls_crl%& have values with no
+expandable elements,
+then the associated information is loaded per smtp transport
+at daemon startup, at the start of a queue run, or on a
+command-line specified message delivery.
+It is made available
+to child processes forked for handling making SMTP connections.
+
+This caching is currently only supported under Linux.
+
+If caching is not possible, the load
+of the associated information is done at the startup of the TLS connection.
+
+The cache is invalidated in the daemon
+and reloaded after any changes to the directories
+containing files specified by these options.
+
+The information specified by the main option &%tls_verify_certificates%&
+is similarly cached so long as it specifies files explicitly
+or (under GnuTLS) is the string &"system,cache"&.
+The latter case is not automatically invaludated;
+it is the operator's responsibility to arrange for a daemon restart
+any time the system certificate authority bundle is updated.
+A HUP signal is sufficient for this.
+The value &"system"& results in no caching under GnuTLS.
+
+The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system"
+is acceptable in configurations for the Exim executable.
+
+Caching of the system Certificate Authorities bundle can
+save significant time and processing on every TLS connection
+initiated by Exim.
+
+
+
+
.section "Use of TLS Server Name Indication" "SECTtlssni"
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI
.vindex "&$tls_in_sni$&"
.oindex "&%tls_in_sni%&"
With TLS1.0 or above, there is an extension mechanism by which extra
information can be included at various points in the protocol. One of these
-extensions, documented in RFC 6066 (and before that RFC 4366) is
+extensions, documented in
+&url(https://www.rfc-editor.org/rfc/rfc6066,RFC 6066)
+(and before that &url(https://www.rfc-editor.org/rfc/rfc4366,RFC 4366)) is
&"Server Name Indication"&, commonly &"SNI"&. This extension is sent by the
client in the initial handshake, so that the server can examine the servername
within and possibly choose to use different certificates and keys (and more)
only point of caution. The &$tls_out_sni$& variable will be set to this string
for the lifetime of the client connection (including during authentication).
+If DANE validated the connection attempt then the value of the &%tls_sni%& option
+is forced to the name of the destination host, after any MX- or CNAME-following.
+
Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string
received from a client.
It can be logged with the &%log_selector%& item &`+tls_sni`&.
0.5.10. (Its presence predates the current API which Exim uses, so if Exim
built, then you have SNI support).
+.subsection ALPN
+.cindex TLS ALPN
+.cindex ALPN "general information"
+.cindex TLS "Application Layer Protocol Names"
+There is a TLS feature related to SNI
+called Application Layer Protocol Name (ALPN).
+This is intended to declare, or select, what protocol layer will be using a TLS
+connection.
+The client for the connection proposes a set of protocol names, and
+the server responds with a selected one.
+It is not, as of 2021, commonly used for SMTP connections.
+However, to guard against misdirected or malicious use of web clients
+(which often do use ALPN) against MTA ports, Exim by default check that
+there is no incompatible ALPN specified by a client for a TLS connection.
+If there is, the connection is rejected.
+
+As a client Exim does not supply ALPN by default.
+The behaviour of both client and server can be configured using the options
+&%tls_alpn%& and &%hosts_require_alpn%&.
+There are no variables providing observability.
+Some feature-specific logging may appear on denied connections, but this
+depends on the behaviour of the peer
+(not all peers can send a feature-specific TLS Alert).
+
+This feature is available when Exim is built with
+OpenSSL 1.1.0 or later or GnuTLS 3.2.0 or later;
+the macro _HAVE_TLS_ALPN will be defined when this is so.
+
.section "Multiple messages on the same encrypted TCP/IP connection" &&&
&url(https://www.ssllabs.com/).
-.section "Certificate chains" "SECID186"
-The file named by &%tls_certificate%& may contain more than one
+.subsection "Certificate chains" SECID186
+A 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
not have. Multiple certificates must be in the correct order in the file.
-.section "Self-signed certificates" "SECID187"
+.subsection "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(https://sourceforge.net/projects/ospkibook/).
+
+
+.subsection "Revoked certificates"
+.cindex "TLS" "revoked certificates"
+.cindex "revocation list"
+.cindex "certificate" "revocation list"
+.cindex "OCSP" "stapling"
+There are three ways for a certificate to be made unusable
+before its expiry.
+
+.ilist
+Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when
+certificates are revoked. If you have such a list, you can pass it to an Exim
+server using the global option called &%tls_crl%& and to an Exim client using
+an identically named option for the &(smtp)& transport. In each case, the value
+of the option is expanded and must then be the name of a file that contains a
+CRL in PEM format.
+The downside is that clients have to periodically re-download a potentially huge
+file from every certificate authority they know of.
+
+.next
+The way with most moving parts at query time is Online Certificate
+Status Protocol (OCSP), where the client verifies the certificate
+against an OCSP server run by the CA. This lets the CA track all
+usage of the certs. It requires running software with access to the
+private key of the CA, to sign the responses to the OCSP queries. OCSP
+is based on HTTP and can be proxied accordingly.
+
+The only widespread OCSP server implementation (known to this writer)
+comes as part of OpenSSL and aborts on an invalid request, such as
+connecting to the port and then disconnecting. This requires
+re-entering the passphrase each time some random client does this.
+
+.next
+The third way is OCSP Stapling; in this, the server using a certificate
+issued by the CA periodically requests an OCSP proof of validity from
+the OCSP server, then serves it up inline as part of the TLS
+negotiation. This approach adds no extra round trips, does not let the
+CA track users, scales well with number of certs issued by the CA and is
+resilient to temporary OCSP server failures, as long as the server
+starts retrying to fetch an OCSP proof some time before its current
+proof expires. The downside is that it requires server support.
+
+Unless Exim is built with the support disabled,
+or with GnuTLS earlier than version 3.3.16 / 3.4.8
+support for OCSP stapling is included.
+
+There is a global option called &%tls_ocsp_file%&.
+The file specified therein is expected to be in DER format, and contain
+an OCSP proof. Exim will serve it as part of the TLS handshake. This
+option will be re-expanded for SNI, if the &%tls_certificate%& option
+contains &`tls_in_sni`&, as per other TLS options.
+
+Exim does not at this time implement any support for fetching a new OCSP
+proof. The burden is on the administrator to handle this, outside of
+Exim. The file specified should be replaced atomically, so that the
+contents are always valid. Exim will expand the &%tls_ocsp_file%& option
+on each connection, so a new file will be handled transparently on the
+next connection.
+
+When built with OpenSSL Exim will check for a valid next update timestamp
+in the OCSP proof; if not present, or if the proof has expired, it will be
+ignored.
+
+For the client to be able to verify the stapled OCSP the server must
+also supply, in its stapled information, any intermediate
+certificates for the chain leading to the OCSP proof from the signer
+of the server certificate. There may be zero or one such. These
+intermediate certificates should be added to the server OCSP stapling
+file named by &%tls_ocsp_file%&.
+
+Note that the proof only covers the terminal server certificate,
+not any of the chain from CA to it.
+
+There is no current way to staple a proof for a client certificate.
+
+.code
+ A helper script "ocsp_fetch.pl" for fetching a proof from a CA
+ OCSP server is supplied. The server URL may be included in the
+ server certificate, if the CA is helpful.
+
+ One failure mode seen was the OCSP Signer cert expiring before the end
+ of validity of the OCSP proof. The checking done by Exim/OpenSSL
+ noted this as invalid overall, but the re-fetch script did not.
+.endd
+.endlist
+
+
.ecindex IIDencsmtp1
.ecindex IIDencsmtp2
+.section "TLS Resumption" "SECTresumption"
+.cindex TLS resumption
+TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined
+in &url(https://www.rfc-editor.org/rfc/rfc5077,RFC 5077) for 1.2).
+The support for this requires GnuTLS 3.6.3 or OpenSSL 1.1.1 (or later).
+
+Session resumption (this is the "stateless" variant) involves the server sending
+a "session ticket" to the client on one connection, which can be stored by the
+client and used for a later session. The ticket contains sufficient state for
+the server to reconstruct the TLS session, avoiding some expensive crypto
+calculation and (on TLS1.2) one full packet roundtrip time.
+
+.ilist
+Operational cost/benefit:
+
+ The extra data being transmitted costs a minor amount, and the client has
+ extra costs in storing and retrieving the data.
+
+ In the Exim/Gnutls implementation the extra cost on an initial connection
+ which is TLS1.2 over a loopback path is about 6ms on 2017-laptop class hardware.
+ The saved cost on a subsequent connection is about 4ms; three or more
+ connections become a net win. On longer network paths, two or more
+ connections will have an average lower startup time thanks to the one
+ saved packet roundtrip. TLS1.3 will save the crypto cpu costs but not any
+ packet roundtrips.
+
+.cindex "hints database" tls
+ Since a new hints DB is used on the TLS client,
+ the hints DB maintenance should be updated to additionally handle "tls".
+
+.next
+Security aspects:
+
+ The session ticket is encrypted, but is obviously an additional security
+ vulnarability surface. An attacker able to decrypt it would have access
+ all connections using the resumed session.
+ The session ticket encryption key is not committed to storage by the server
+ and is rotated regularly (OpenSSL: 1hr, and one previous key is used for
+ overlap; GnuTLS 6hr but does not specify any overlap).
+ Tickets have limited lifetime (2hr, and new ones issued after 1hr under
+ OpenSSL. GnuTLS 2hr, appears to not do overlap).
+
+ There is a question-mark over the security of the Diffie-Helman parameters
+ used for session negotiation.
+
+.next
+Observability:
+
+ The &%log_selector%& "tls_resumption" appends an asterisk to the tls_cipher "X="
+ element.
+
+ The variables &$tls_in_resumption$& and &$tls_out_resumption$&
+ have bits 0-4 indicating respectively
+ support built, client requested ticket, client offered session,
+ server issued ticket, resume used. A suitable decode list is provided
+ in the builtin macro _RESUME_DECODE for in &%listextract%& expansions.
+
+.next
+Control:
+
+The &%tls_resumption_hosts%& main option specifies a hostlist for which
+exim, operating as a server, will offer resumption to clients.
+Current best practice is to not offer the feature to MUA connection.
+Commonly this can be done like this:
+.code
+tls_resumption_hosts = ${if inlist {$received_port}{587:465} {:}{*}}
+.endd
+If the peer host matches the list after expansion then resumption
+is offered and/or accepted.
+
+The &%tls_resumption_hosts%& smtp transport option performs the
+equivalent function for operation as a client.
+If the peer host matches the list after expansion then resumption
+is attempted (if a stored session is available) or the information
+stored (if supplied by the peer).
+
+
+.next
+Issues:
+
+ In a resumed session:
+.ilist
+ The variables &$tls_{in,out}_cipher$& will have values different
+ to the original (under GnuTLS).
+.next
+ The variables &$tls_{in,out}_ocsp$& will be "not requested" or "no response",
+ and the &%hosts_require_ocsp%& smtp trasnport option will fail.
+. XXX need to do something with that hosts_require_ocsp
+.endlist
+
+.endlist
+
.section DANE "SECDANE"
.cindex DANE
It also allows the server to declare (implicitly) that connections to it should use TLS. An MITM could simply
fail to pass on a server's STARTTLS.
-DANE scales better than having to maintain (and side-channel communicate) copies of server certificates
+DANE scales better than having to maintain (and communicate via side-channel) copies of server certificates
for every possible target server. It also scales (slightly) better than having to maintain on an SMTP
client a copy of the standard CAs bundle. It also means not having to pay a CA for certificates.
-DANE requires a server operator to do three things: 1) run DNSSEC. This provides assurance to clients
+DANE requires a server operator to do three things:
+.olist
+Run DNSSEC. This provides assurance to clients
that DNS lookups they do for the server have not been tampered with. The domain MX record applying
to this server, its A record, its TLSA record and any associated CNAME records must all be covered by
DNSSEC.
-2) add TLSA DNS records. These say what the server certificate for a TLS connection should be.
-3) offer a server certificate, or certificate chain, in TLS connections which is is anchored by one of the TLSA records.
+.next
+Add TLSA DNS records. These say what the server certificate for a TLS connection should be.
+.next
+Offer a server certificate, or certificate chain, in TLS connections which is anchored by one of the TLSA records.
+.endlist
There are no changes to Exim specific to server-side operation of DANE.
Support for client-side operation of DANE can be included at compile time by defining SUPPORT_DANE=yes
in &_Local/Makefile_&.
If it has been included, the macro "_HAVE_DANE" will be defined.
+.subsection "DNS records"
A TLSA record consist of 4 fields, the "Certificate Usage", the
"Selector", the "Matching type", and the "Certificate Association Data".
For a detailed description of the TLSA record see
This means no MD5 and no SHA-1. SHA2-256 is the minimum for reliable
interoperability (and probably the maximum too, in 2018).
+.subsection "Interaction with OCSP"
The use of OCSP-stapling should be considered, allowing for fast revocation of certificates (which would otherwise
be limited by the DNS TTL on the TLSA records). However, this is likely to only be usable with DANE-TA. NOTE: the
default of requesting OCSP for all hosts is modified iff DANE is in use, to:
those who use &%hosts_require_ocsp%&, should consider the interaction with DANE in their OCSP settings.
+.subsection "Client configuration"
For client-side DANE there are three new smtp transport options, &%hosts_try_dane%&, &%hosts_require_dane%&
and &%dane_require_tls_ciphers%&.
The &"require"& variant will result in failure if the target host is not
DANE will only be usable if the target host has DNSSEC-secured MX, A and TLSA records.
-A TLSA lookup will be done if either of the above options match and the host-lookup succeeded using dnssec.
+A TLSA lookup will be done if either of the above options match and the host-lookup succeeded using DNSSEC.
If a TLSA lookup is done and succeeds, a DANE-verified TLS connection
will be required for the host. If it does not, the host will not
be used; there is no fallback to non-DANE or non-TLS.
tls_verify_certificates
tls_crl
tls_verify_cert_hostnames
+ tls_sni
.endd
If DANE is not usable, whether requested or not, and CA-anchored
The router and transport option &%dnssec_request_domains%& must not be
set to &"never"&, and &%dnssec_require_domains%& is ignored.
+.subsection Observability
If verification was successful using DANE then the "CV" item in the delivery log line will show as "CV=dane".
There is a new variable &$tls_out_dane$& which will have "yes" if
The &$event_data$& will be one of the Result Types defined in
Section 4.3 of that document.
+.subsection General
Under GnuTLS, DANE is only supported from version 3.0.0 onwards.
-DANE is specified in published RFCs and decouples certificate authority trust
+DANE is specified in &url(https://www.rfc-editor.org/rfc/rfc6698,RFC 6698).
+It decouples certificate authority trust
selection from a "race to the bottom" of "you must trust everything for mail
-to get through". There is an alternative technology called MTA-STS, which
-instead publishes MX trust anchor information on an HTTPS website. At the
-time this text was last updated, MTA-STS was still a draft, not yet an RFC.
+to get through".
+It does retain the need to trust the assurances provided by the DNSSEC tree.
+
+There is an alternative technology called MTA-STS
+(&url(https://www.rfc-editor.org/rfc/rfc8461,RFC 8461)), which
+instead publishes MX trust anchor information on an HTTPS website.
+The discovery of the address for that website does not (per standard)
+require DNSSEC, and could be regarded as being less secure than DANE
+as a result.
+
Exim has no support for MTA-STS as a client, but Exim mail server operators
can choose to publish information describing their TLS configuration using
MTA-STS to let those clients who do use that protocol derive trust
.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 "ATRN" "ACL for"
.cindex "AUTH" "ACL for"
.cindex "DATA" "ACLs for"
+.cindex "DKIM" "ACL for"
.cindex "ETRN" "ACL for"
.cindex "EXPN" "ACL for"
.cindex "HELO" "ACL for"
.cindex "EHLO" "ACL for"
-.cindex "DKIM" "ACL for"
.cindex "MAIL" "ACL for"
-.cindex "QUIT, ACL for"
+.cindex "QUIT" "ACL for"
+.cindex "PRDR" "ACL for"
.cindex "RCPT" "ACL for"
.cindex "STARTTLS, ACL for"
.cindex "VRFY" "ACL for"
+.cindex "WELLKNOWN" "ACL for"
.cindex "SMTP" "connection, ACL for"
.cindex "non-SMTP messages" "ACLs for"
.cindex "MIME content scanning" "ACL for"
-.cindex "PRDR" "ACL for"
.table2 140pt
.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_atrn%& "ACL for ATRN"
.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_rcpt%& "ACL for RCPT"
.irow &%acl_smtp_starttls%& "ACL for STARTTLS"
.irow &%acl_smtp_vrfy%& "ACL for VRFY"
+.irow &%acl_smtp_wellknown%& "ACL for WELLKNOWN"
.endtable
For example, if you set
testing as possible at RCPT time.
-.section "The non-SMTP ACLs" "SECID190"
+.subsection "The non-SMTP ACLs" SECnonSMTP
.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
temporary error for these kinds of message.
-.section "The SMTP connect ACL" "SECID191"
+.subsection "The SMTP connect ACL" SECconnectACL
.cindex "SMTP" "connection, ACL for"
.oindex &%smtp_banner%&
The ACL test specified by &%acl_smtp_connect%& happens at the start of an SMTP
the message override the banner message that is otherwise specified by the
&%smtp_banner%& option.
+For tls-on-connect connections, the ACL is run before the TLS connection
+is accepted; if the ACL does not accept then the TCP connection is dropped without
+any TLS startup attempt and without any SMTP response being transmitted.
-.section "The EHLO/HELO ACL" "SECID192"
+
+.subsection "The EHLO/HELO ACL" SECheloACL
.cindex "EHLO" "ACL for"
.cindex "HELO" "ACL for"
The ACL test specified by &%acl_smtp_helo%& happens when the client issues an
an EHLO response.
-.section "The DATA ACLs" "SECID193"
+.subsection "The DATA ACLs" SECdataACLS
.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.
the &%acl_smtp_dkim%&
and the &%acl_smtp_mime%& ACLs.
-.section "The SMTP DKIM ACL" "SECTDKIMACL"
+.subsection "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).
+If, for a specific message, an ACL control
+&*dkim_disable_verify*&
+has been set, this &%acl_smtp_dkim%& ACL is not called.
+
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 section &<<SECDKIM>>&.
-.section "The SMTP MIME ACL" "SECID194"
+.subsection "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>>&.
This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&.
-.section "The SMTP PRDR ACL" "SECTPRDRACL"
+.subsection "The SMTP PRDR ACL" SECTPRDRACL
.cindex "PRDR" "ACL for"
.oindex "&%prdr_enable%&"
The &%acl_smtp_data_prdr%& ACL is available only when Exim is compiled
If the ACL is not defined, processing completes as if
the feature was not requested by the client.
-.section "The QUIT ACL" "SECTQUITACL"
+.subsection "The SMTP WELLKNOWN ACL" SECTWELLKNOWNACL
+.cindex "WELLKNOWN" "ACL for"
+.oindex "&%acl_smtp_wellknown%&"
+The &%acl_smtp_wellknown%& ACL is available only when Exim is compiled
+with WELLKNOWN support enabled.
+
+The ACL determines the response to an SMTP WELLKNOWN command, using the normal
+accept/defer/deny verbs for the response code,
+and a new &"control=wellknown"& modifier.
+This modifier takes a single option, separated by a '/'
+character, which must be the name of a file containing the response
+cleartext. The modifier is expanded before use in the usual way before
+it is used. The configuration is responsible for picking a suitable file
+to return and, most importantly, not returning any unexpected file.
+The argument for the SMTP verb will be available in the &$smtp_command_argument$&
+variable and can be used for building the file path.
+If the file path given in the modifier is empty or inacessible, the control will
+fail.
+
+For example:
+.code
+ check_wellknown:
+ accept control = wellknown/\
+ ${lookup {${xtextd:$smtp_command_argument}} \
+ dsearch,key=path,filter=file,ret=full \
+ {$spooldir/wellknown.d}}
+.endd
+File content will be encoded in &"xtext"& form, and line-wrapping
+for line-length limitation will be done before transmission.
+A response summary line will be prepended, with the (pre-encoding) file size.
+
+The above example uses the expansion operator ${xtextd:<coded-string>}
+which is needed to decode the xtext-encoded key from the SMTP verb.
+
+Under the util directory there is a "mailtest" utility which can be used
+to test/retrieve WELLKNOWN items. Syntax is
+.code
+ mailtest -h host.example.com -w security.txt
+.endd
+
+WELLKNOWN is a ESMTP extension providing access to extended
+information about the server. It is modelled on the webserver
+facilities documented in
+&url(https://www.rfc-editor.org/rfc/rfc8615,RFC 8615)
+and can be used for a security.txt file
+and could be used for ACME handshaking
+(&url(https://www.rfc-editor.org/rfc/rfc8555,RFC 8555)).
+
+Exim will advertise WELLKNOWN support in the EHLO response
+.oindex &%wellknown_advertise_hosts%&
+(conditional on a new option &%wellknown_advertise_hosts%&)
+and service WELLKNOWN smtp verbs having a single parameter
+giving a key for an item of "site-wide metadata".
+The verb and key are separated by whitespace,
+and the key is xtext-encoded
+(per &url(https://www.rfc-editor.org/rfc/rfc3461,RFC 3461) section 4).
+
+
+.subsection "The QUIT ACL" SECTQUITACL
.cindex "QUIT, ACL for"
The ACL for the SMTP QUIT command is anomalous, in that the outcome of the ACL
does not affect the response code to QUIT, which is always 221. Thus, the ACL
connection is closed. In these special cases, the QUIT ACL does not run.
-.section "The not-QUIT ACL" "SECTNOTQUITACL"
+.subsection "The not-QUIT ACL" SECTNOTQUITACL
.vindex &$acl_smtp_notquit$&
The not-QUIT ACL, specified by &%acl_smtp_notquit%&, is run in most cases when
an SMTP session ends without sending QUIT. However, when Exim itself is in bad
{acl_check_rcpt} {acl_check_rcpt_submit} }
.endd
In the default configuration file there are some example settings for
-providing an RFC 4409 message &"submission"& service on port 587 and
-an RFC 8314 &"submissions"& service on port 465. You can use a string
+providing an
+&url(https://www.rfc-editor.org/rfc/rfc4409,RFC 4409)
+message &"submission"& service on port 587 and an
+&url(https://www.rfc-editor.org/rfc/rfc8314,RFC 8314)
+&"submissions"& service on port 465. You can use a string
expansion like this to choose an ACL for MUAs on these ports which is
more appropriate for this purpose than the default ACL on port 25.
&%acl_smtp_mime%&, &%acl_smtp_predata%&, and &%acl_smtp_starttls%&, the action
when the ACL is not defined is &"accept"&.
-For the others (&%acl_smtp_etrn%&, &%acl_smtp_expn%&, &%acl_smtp_rcpt%&, and
-&%acl_smtp_vrfy%&), the action when the ACL is not defined is &"deny"&.
-This means that &%acl_smtp_rcpt%& must be defined in order to receive any
-messages over an SMTP connection. For an example, see the ACL in the default
-configuration file.
-
+.new
+For the others (&%acl_smtp_atrn%&,
+.wen
+&%acl_smtp_etrn%&, &%acl_smtp_expn%&, &%acl_smtp_rcpt%&,
+&%acl_smtp_vrfy%& and &%acl_smtp_wellknown%&),
+the action when the ACL
+is not defined is &"deny"&. This means that &%acl_smtp_rcpt%& must be
+defined in order to receive any messages over an SMTP connection.
+For an example, see the ACL in the default configuration file.
.cindex "&ACL;" "data for non-message ACL"
.vindex &$smtp_command_argument$&
.vindex &$smtp_command$&
-When an ACL is being run for AUTH, EHLO, ETRN, EXPN, HELO, STARTTLS, or VRFY,
+When an ACL is being run for ATRN, AUTH, EHLO, ETRN, EXPN, HELO, STARTTLS, or VRFY,
the remainder of the SMTP command line is placed in &$smtp_command_argument$&,
and the entire SMTP command is available in &$smtp_command$&.
These variables can be tested using a &%condition%& condition. For example,
.section "Format of an ACL" "SECID199"
.cindex "&ACL;" "format of"
.cindex "&ACL;" "verbs, definition of"
-An individual ACL consists of a number of statements. Each statement starts
+An individual ACL definition 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,
set variables, insert delays, and vary the processing of accepted messages.
all the conditions make sense at every testing point. For example, you cannot
test a sender address in the ACL that is run for a VRFY command.
+The definition of an ACL ends where another starts,
+or a different configuration section starts.
+
.section "ACL verbs" "SECID200"
The ACL verbs are as follows:
&%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
-drop message = I don't take more than 20 RCPTs
- condition = ${if > {$rcpt_count}{20}}
+drop condition = ${if > {$rcpt_count}{20}}
+ message = I don't take more than 20 RCPTs
.endd
There is no difference between &%deny%& and &%drop%& for the connect-time ACL.
The connection is always dropped after sending a 550 response.
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
+anyway.
+If the message contains newlines, this gives rise to a multi-line SMTP
response.
+A long message line will also be split into multi-line SMTP responses,
+on word boundaries if possible.
.vindex "&$acl_verify_message$&"
-For ACLs that are called by an &%acl =%& ACL condition, the message is
-stored in &$acl_verify_message$&, from which the calling ACL may use it.
+While the text is being expanded, the &$acl_verify_message$& variable
+contains any message previously set.
+Afterwards, &$acl_verify_message$& is cleared.
If &%message%& is used on a statement that verifies an address, the message
specified overrides any message that is generated by the verification process.
This control turns on debug logging, almost as though Exim had been invoked
with &`-d`&, with the output going to a new logfile in the usual logs directory,
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.
-Logging started this way may be stopped, and the file removed,
-with the &'kill'& option.
+
+Logging set up by the control will be maintained across spool residency.
+
+Options are a slash-separated list.
+If an option takes an argument, the option name and argument are separated by
+an equals character.
+Several options are supported:
+.display
+tag=<&'suffix'&> The filename can be adjusted with thise option.
+ The argument, which may access any variables already defined,
+ is appended to the default name.
+
+opts=<&'debug&~options'&> The argument specififes what is to be logged,
+ using the same values as the &`-d`& command-line option.
+
+stop Logging started with this control may be
+ stopped by using this option.
+
+kill Logging started with this control may be
+ stopped by using this option.
+ Additionally the debug file will be removed,
+ providing one means for speculative debug tracing.
+
+pretrigger=<&'size'&> This option specifies a memory buffuer to be used
+ for pre-trigger debug capture.
+ Debug lines are recorded in the buffer until
+ and if) a trigger occurs; at which time they are
+ dumped to the debug file. Newer lines displace the
+ oldest if the buffer is full. After a trigger,
+ immediate writes to file are done as normal.
+
+trigger=<&'reason'&> This option selects cause for the pretrigger buffer
+ see above) to be copied to file. A reason of &*now*&
+ take effect immediately; one of &*paniclog*& triggers
+ on a write to the panic log.
+.endd
+
Some examples (which depend on variables that don't exist in all
contexts):
.code
control = debug/opts=+expand+acl
control = debug/tag=.$message_exim_id/opts=+expand
control = debug/kill
+ control = debug/opts=+all/pretrigger=1024/trigger=paniclog
+ control = debug/trigger=now
.endd
the operation and configuration of DKIM, see section &<<SECDKIM>>&.
-.vitem &*control&~=&~dmarc_disable_verify*&
+.vitem &*control&~=&~dmarc_disable_verify*& &&&
+ &*control&~=&~dmarc_enable_forensic*&
.cindex "disable DMARC verify"
-.cindex "DMARC" "disable verify"
-This control turns off DMARC verification processing entirely. For details on
+.cindex DMARC "disable verify"
+.cindex DMARC controls
+.cindex DMARC "forensic mails"
+These control affect DMARC processing. For details on
the operation and configuration of DMARC, see section &<<SECDMARC>>&.
+The &"disable"& turns off DMARC verification processing entirely.
+
.vitem &*control&~=&~dscp/*&<&'value'&>
.cindex "&ACL;" "setting DSCP value"
.vitem &*control&~=&~fakedefer/*&<&'message'&>
.cindex "fake defer"
.cindex "defer, fake"
+.cindex fakedefer
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
.vitem &*control&~=&~fakereject/*&<&'message'&>
.cindex "fake rejection"
.cindex "rejection, fake"
+.cindex fakereject
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.
.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.
+SMTP responses, despite the fact that
+&url(https://www.rfc-editor.org/rfc/rfc821,RFC 821)
+defined them over 20 years ago.
If this control is set, multiline SMTP responses from ACL rejections are
suppressed. One way of doing this would have been to put out these responses as
-one long line. However, RFC 2821 specifies a maximum of 512 bytes per response
+one long line. However,
+&url(https://www.rfc-editor.org/rfc/rfc2821,RFC 2821)
+specifies a maximum of 512 bytes per response
(&"use multiline responses for more"& it says &-- ha!), and some of the
responses might get close to that. So this facility, which is after all only a
sop to broken clients, is implemented by doing two very easy things:
controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also
&%pipelining_advertise_hosts%&.
-.new
.vitem &*control&~=&~queue/*&<&'options'&>* &&&
&*control&~=&~queue_only*&
.oindex "&%queue%&"
The control only applies to the current message, not to any subsequent ones that
may be received in the same SMTP connection.
-.wen
.vitem &*control&~=&~submission/*&<&'options'&>
.cindex "message" "submission"
This control enables conversion of UTF-8 in message envelope addresses
to a-label form.
For details see section &<<SECTi18nMTA>>&.
+
+.vitem &*control&~=&~wellknown*&
+This control sets up a response data file for a WELLKNOWN SMTP command.
+It may only be used in an ACL servicing that command.
+For details see section &<<SECTWELLKNOWNACL>>&.
.endlist vlist
DATA, MIME or DKIM ACLs for a message delivered by cutthrough routing.
More than one header can be removed at the same time by using a colon separated
-list of header names. The header matching is case insensitive. Wildcards are
-not permitted, nor is list expansion performed, so you cannot use hostlists to
+list of header specifiers.
+If a specifier does not start with a circumflex (^)
+then it is treated as a header name.
+The header name matching is case insensitive.
+If it does, then it is treated as a (front-anchored)
+regular expression applied to the whole header.
+
+&*Note*&: The colon terminating a header name will need to be doubled
+if used in an RE, and there can legitimately be whitepace before it.
+
+Example:
+.code
+remove_header = \N^(?i)Authentication-Results\s*::\s*example.org;\N
+.endd
+
+List expansion is not performed, so you cannot use hostlists to
create a list of headers, however both connection and message variable expansion
are performed (&%$acl_c_*%& and &%$acl_m_*%&), illustrated in this example:
.code
warn message = Remove internal headers
remove_header = $acl_c_ihdrs
.endd
-Header names for removal are accumulated during the MAIL, RCPT, and predata ACLs.
+Header specifiers for removal are accumulated during the MAIL, RCPT, and predata ACLs.
Matching header lines are removed from the message before processing the DATA and MIME ACLs.
If multiple header lines match, all are removed.
There is no harm in attempting to remove the same header twice nor in removing
-a non-existent header. Further header lines to be removed may be accumulated
-during the DATA and MIME ACLs, after which they are removed from the message,
-if present. In the case of non-SMTP messages, headers to be removed are
-accumulated during the non-SMTP ACLs, and are removed from the message after
+a non-existent header. Further header specifiers for removal may be accumulated
+during the DATA and MIME ACLs, after which matching headers are removed
+if present. In the case of non-SMTP messages, remove specifiers are
+accumulated during the non-SMTP ACLs, and are acted on after
all the ACLs have run. If a message is rejected after DATA or by the non-SMTP
ACL, there really is no effect because there is no logging of what headers
would have been removed.
circumstances. For example, different ACLs can be used to handle RCPT commands
for different local users or different local domains.
+.new
+.vitem &*atrn_domains&~=&~*&<&'domain&~list'&>
+.cindex ATRN "checking for queued messages"
+This condition is only usable in the ATRN ACL.
+It returns true if there are any messages queued for any of the domains given
+in the list.
+The list supplied must not be tainted
+.cindex "tainted data" "de-tainting"
+and should contain only domains relevant for the authenticated user
+(to avoid leaking information about other users).
+.wen
+
.vitem &*authenticated&~=&~*&<&'string&~list'&>
.cindex "&%authenticated%& ACL condition"
.cindex "authentication" "ACL checking"
.cindex "domain" "ACL checking"
.cindex "&ACL;" "testing a recipient domain"
.vindex "&$domain_data$&"
-This condition is relevant only after a RCPT command. It checks that the domain
+This condition is relevant only in a RCPT ACL. It checks that the domain
of the recipient address is in the domain list. If percent-hack processing is
enabled, it is done before this test is done. If the check succeeds with a
lookup, the result of the lookup is placed in &$domain_data$& until the next
allows you, for example, to set up a statement like this:
.code
deny hosts = net-lsearch;/some/file
-message = $host_data
+ message = $host_data
.endd
which gives a custom error message for each denied host.
.cindex "local part" "ACL checking"
.cindex "&ACL;" "testing a local part"
.vindex "&$local_part_data$&"
-This condition is relevant only after a RCPT command. It checks that the local
+This condition is relevant only in a RCPT ACL. It checks that the local
part of the recipient address is in the list. If percent-hack processing is
enabled, it is done before this test. If the check succeeds with a lookup, the
result of the lookup is placed in &$local_part_data$&, which remains set until
.cindex "&%recipients%& ACL condition"
.cindex "recipient" "ACL checking"
.cindex "&ACL;" "testing a recipient"
-This condition is relevant only after a RCPT command. It checks the entire
+This condition is relevant only in a RCPT ACL. It checks the entire
recipient address against a list of recipients.
.vitem &*regex&~=&~*&<&'list&~of&~regular&~expressions'&>
non-SMTP ACLs. It causes the incoming message to be scanned for a match with
any of the regular expressions. For details, see chapter &<<CHAPexiscan>>&.
+.vitem &*seen&~=&~*&<&'parameters'&>
+.cindex "&%seen%& ACL condition"
+This condition can be used to test if a situation has been previously met,
+for example for greylisting.
+Details are given in section &<<SECTseen>>&.
+
.vitem &*sender_domains&~=&~*&<&'domain&~list'&>
.cindex "&%sender_domains%& ACL condition"
.cindex "sender" "ACL checking"
.cindex "header lines" "verifying header names only ASCII"
.cindex "verifying" "header names only ASCII"
This condition is relevant only in an ACL that is run after a message has been
-received, that is, in an ACL specified by &%acl_smtp_data%& or
-&%acl_not_smtp%&. It checks all header names (not the content) to make sure
+received.
+This usually means an ACL specified by &%acl_smtp_data%& or &%acl_not_smtp%&.
+It checks all header names (not the content) to make sure
there are no non-ASCII characters, also excluding control characters. The
allowable characters are decimal ASCII values 33 through 126.
condition to restrict it to bounce messages only:
.code
deny senders = :
- message = A valid sender header is required for bounces
!verify = header_sender
+ message = A valid sender header is required for bounces
.endd
.vitem &*verify&~=&~header_syntax*&
(eg. is generated from the received message)
they must be protected from the options parsing by doubling:
.code
-verify = sender=${sg{${address:$h_sender:}}{/}{//}}
+verify = sender=${listquote{/}{${address:$h_sender:}}}
.endd
.endlist
(which is the most common usage), because it prevents a DNS failure from
blocking mail. However, you can change this behaviour by putting one of the
following special items in the list:
-.display
-&`+include_unknown `& behave as if the item is on the list
-&`+exclude_unknown `& behave as if the item is not on the list (default)
-&`+defer_unknown `& give a temporary error
-.endd
+.itable none 0 0 2 25* left 75* left
+.irow "+include_unknown" "behave as if the item is on the list"
+.irow "+exclude_unknown" "behave as if the item is not on the list (default)"
+.irow "+defer_unknown " "give a temporary error"
+.endtable
.cindex "&`+include_unknown`&"
.cindex "&`+exclude_unknown`&"
.cindex "&`+defer_unknown`&"
warn for one list and block for another, you can use two different statements:
.code
deny dnslists = blackholes.mail-abuse.org
-warn message = X-Warn: sending host is on dialups list
- dnslists = dialups.mail-abuse.org
+warn dnslists = dialups.mail-abuse.org
+ message = X-Warn: sending host is on dialups list
.endd
.cindex caching "of dns lookup"
.cindex DNS TTL
-.section "Specifying the IP address for a DNS list lookup" "SECID201"
+.subsection "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" "SECID202"
+.subsection "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, e.g., the &'domain based zones'& link at
with these lists. You can change the name that is looked up in a DNS list by
listing it after the domain name, introduced by a slash. For example,
.code
-deny message = Sender's domain is listed at $dnslist_domain
- dnslists = dsn.rfc-ignorant.org/$sender_address_domain
+deny dnslists = dsn.rfc-ignorant.org/$sender_address_domain
+ message = Sender's domain is listed at $dnslist_domain
.endd
This particular example is useful only in ACLs that are obeyed after the
RCPT or DATA commands, when a sender address is available. If (for
-.section "Multiple explicit keys for a DNS list" "SECTmulkeyfor"
+.subsection "Multiple explicit keys for a DNS list" SECTmulkeyfor
.cindex "DNS list" "multiple keys for"
The syntax described above for looking up explicitly-defined values (either
names or IP addresses) in a DNS blacklist is a simplification. After the domain
However, when the data for the list is obtained from a lookup, the second form
is usually much more convenient. Consider this example:
.code
-deny message = The mail servers for the domain \
+deny dnslists = sbl.spamhaus.org/<|${lookup dnsdb {>|a=<|\
+ ${lookup dnsdb {>|mxh=\
+ $sender_address_domain} }} }
+ message = The mail servers for the domain \
$sender_address_domain \
are listed at $dnslist_domain ($dnslist_value); \
see $dnslist_text.
- dnslists = sbl.spamhaus.org/<|${lookup dnsdb {>|a=<|\
- ${lookup dnsdb {>|mxh=\
- $sender_address_domain} }} }
.endd
Note the use of &`>|`& in the dnsdb lookup to specify the separator for
multiple DNS records. The inner dnsdb lookup produces a list of MX hosts
-.section "Data returned by DNS lists" "SECID203"
+.subsection "Data returned by DNS lists" SECID203
.cindex "DNS list" "data returned from"
DNS lists are constructed using address records in the DNS. The original RBL
just used the address 127.0.0.1 on the right hand side of each record, but the
RBL+ list and some other lists use a number of values with different meanings.
The values used on the RBL+ list are:
-.display
-127.1.0.1 RBL
-127.1.0.2 DUL
-127.1.0.3 DUL and RBL
-127.1.0.4 RSS
-127.1.0.5 RSS and RBL
-127.1.0.6 RSS and DUL
-127.1.0.7 RSS and DUL and RBL
-.endd
+.itable none 0 0 2 20* left 80* left
+.irow 127.1.0.1 "RBL"
+.irow 127.1.0.2 "DUL"
+.irow 127.1.0.3 "DUL and RBL"
+.irow 127.1.0.4 "RSS"
+.irow 127.1.0.5 "RSS and RBL"
+.irow 127.1.0.6 "RSS and DUL"
+.irow 127.1.0.7 "RSS and DUL and RBL"
+.endtable
Section &<<SECTaddmatcon>>& below describes how you can distinguish between
different values. Some DNS lists may return more than one address record;
see section &<<SECThanmuldnsrec>>& for details of how they are checked.
+Values returned by a properly running DBSBL should be in the 127.0.0.0/8
+range. If a DNSBL operator loses control of the domain, lookups on it
+may start returning other addresses. Because of this, Exim now ignores
+returned values outside the 127/8 region.
-.section "Variables set from DNS lists" "SECID204"
+
+.subsection "Variables set from DNS lists" SECID204
.cindex "expansion" "variables, set from DNS list"
.cindex "DNS list" "variables set from"
.vindex "&$dnslist_domain$&"
information.
You can use the DNS list variables in &%message%& or &%log_message%& modifiers
-&-- although these appear before the condition in the ACL, they are not
+&-- even if these appear before the condition in the ACL, they are not
expanded until after it has failed. For example:
.code
deny hosts = !+local_networks
-.section "Additional matching conditions for DNS lists" "SECTaddmatcon"
+.subsection "Additional matching conditions for DNS lists" SECTaddmatcon
.cindex "DNS list" "matching specific returned data"
You can add an equals sign and an IP address after a &%dnslists%& domain name
in order to restrict its action to DNS records with a matching right hand side.
-.section "Negated DNS matching conditions" "SECID205"
+.subsection "Negated DNS matching conditions" SECID205
You can supply a negative list of IP addresses as part of a &%dnslists%&
condition. Whereas
.code
.endd
which is less clear, and harder to maintain.
+Negation can also be used with a bitwise-and restriction.
+The dnslists condition with only be trus if a result is returned
+by the lookup which, anded with the restriction, is all zeroes.
+For example:
+.code
+deny dnslists = zen.spamhaus.org!&0.255.255.0
+.endd
+
-.section "Handling multiple DNS records from a DNS list" "SECThanmuldnsrec"
+.subsection "Handling multiple DNS records from a DNS list" SECThanmuldnsrec
A DNS lookup for a &%dnslists%& condition may return more than one DNS record,
thereby providing more than one IP address. When an item in a &%dnslists%& list
is followed by &`=`& or &`&&`& and a list of IP addresses, in order to restrict
-.section "Detailed information from merged DNS lists" "SECTmordetinf"
+.subsection "Detailed information from merged DNS lists" SECTmordetinf
.cindex "DNS list" "information from merged"
When the facility for restricting the matching IP values in a DNS list is used,
the text from the TXT record that is set in &$dnslist_text$& may not reflect
a check that the IP being tested is indeed on the first list. The first
domain is the one that is put in &$dnslist_domain$&. For example:
.code
-deny message = \
- rejected because $sender_host_address is blacklisted \
- at $dnslist_domain\n$dnslist_text
- dnslists = \
+deny dnslists = \
sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \
dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
+ message = \
+ rejected because $sender_host_address is blacklisted \
+ at $dnslist_domain\n$dnslist_text
.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
-.section "DNS lists and IPv6" "SECTmorednslistslast"
+.subsection "DNS lists and IPv6" SECTmorednslistslast
.cindex "IPv6" "DNS black lists"
.cindex "DNS list" "IPv6 usage"
If Exim is asked to do a dnslist lookup for an IPv6 address, it inverts it
dnslists = <; dnsbl.example.com/<|$acl_m_addrslist
.endd
+
+.section "Previously seen user and hosts" "SECTseen"
+.cindex "&%seen%& ACL condition"
+.cindex greylisting
+The &%seen%& ACL condition can be used to test whether a
+situation has been previously met.
+It uses a hints database to record a timestamp against a key.
+The syntax of the condition is:
+.display
+&`seen =`& <&'optional flag'&><&'time interval'&> &`/`& <&'options'&>
+.endd
+
+For example,
+.code
+defer seen = -5m / key=${sender_host_address}_$local_part@$domain
+.endd
+in a RCPT ACL will implement simple greylisting.
+
+The parameters for the condition are
+a possible minus sign,
+then an interval,
+then, slash-separated, a list of options.
+The interval is taken as an offset before the current time,
+and used for the test.
+If the interval is preceded by a minus sign then the condition returns
+whether a record is found which is before the test time.
+Otherwise, the condition returns whether one is found which is since the
+test time.
+
+Options are read in order with later ones overriding earlier ones.
+
+The default key is &$sender_host_address$&.
+An explicit key can be set using a &%key=value%& option.
+
+If a &%readonly%& option is given then
+no record create or update is done.
+If a &%write%& option is given then
+a record create or update is always done.
+An update is done if the test is for &"since"&.
+If none of those hold and there was no existing record,
+a record is created.
+
+Creates and updates are marked with the current time.
+
+Finally, a &"before"& test which succeeds, and for which the record
+is old enough, will be refreshed with a timestamp of the test time.
+This can prevent tidying of the database from removing the entry.
+The interval for this is, by default, 10 days.
+An explicit interval can be set using a
+&%refresh=value%& option.
+
+Note that &"seen"& should be added to the list of hints databases
+for maintenance if this ACL condition is used.
+
+
.section "Rate limiting incoming messages" "SECTratelimiting"
.cindex "rate limiting" "client sending"
.cindex "limiting client sending rates"
the &%count=%& option.
-.section "Ratelimit options for what is being measured" "ratoptmea"
+.subsection "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
+.vlist
+.vitem per_conn
+.cindex "rate limiting" per_conn
+This 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_mail%& option limits the client's rate of sending messages. This is
+.vitem per_mail
+.cindex "rate limiting" per_conn
+This 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
+.vitem per_byte
+.cindex "rate limiting" per_conn
+This 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
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
+.vitem per_rcpt
+.cindex "rate limiting" per_rcpt
+This 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_mime%&, or &%acl_smtp_data%& 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 (accepted) 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
+.vitem per_addr
+.cindex "rate limiting" per_addr
+This 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
+.vitem per_cmd
+.cindex "rate limiting" per_cmd
+This 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=$message_size`&. If there is no &%count=%& option, Exim
+.vitem count
+.cindex "rate limiting" count
+This option can be used to alter how much Exim adds to the client's
+measured rate.
+A value is required, after an equals sign.
+For example, the &%per_byte%& option is equivalent to
+&`per_mail/count=$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.
+other than &%acl_smtp_rcpt%&).
+The count does not have to be an integer.
-The &%unique=%& option is described in section &<<ratoptuniq>>& below.
+.vitem unique
+.cindex "rate limiting" unique
+This option is described in section &<<ratoptuniq>>& below.
+.endlist
-.section "Ratelimit update modes" "ratoptupd"
+.subsection "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%&
.code
acl_check_connect:
deny ratelimit = 100 / 5m / readonly
- log_message = RATE CHECK: $sender_rate/$sender_rate_period \
+ 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 \
+ log_message = RATE UPDATE: $sender_rate/$sender_rate_period \
(max $sender_rate_limit)
.endd
next section) so you must specify the &%readonly%& option explicitly.
-.section "Ratelimit options for handling fast clients" "ratoptfast"
+.subsection "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
.endd
-.section "Limiting the rate of different events" "ratoptuniq"
+.subsection "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
as intended.
-.section "Using rate limiting" "useratlim"
+.subsection "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
ratelimit = 100 / 1d / strict / $authenticated_id
# System-wide rate limit
-defer message = Sorry, too busy. Try again later.
- ratelimit = 10 / 1s / $primary_hostname
+defer ratelimit = 10 / 1s / $primary_hostname
+ message = Sorry, too busy. Try again later.
# 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} \
+defer ratelimit = ${lookup {$sender_host_address} \
cdb {DB/ratelimits.cdb} \
{$value} {RATELIMIT} }
+ message = Sender rate exceeds $sender_rate_limit \
+ messages per $sender_rate_period
.endd
&*Warning*&: If you have a busy server with a lot of &%ratelimit%& tests,
especially with the &%per_rcpt%& option, you may suffer from a performance
immediately after a successful redirection. By default, if a redirection
generates just one address, that address is also verified. See further
discussion in section &<<SECTredirwhilveri>>&.
+.next
+If the &%quota%& option is specified for recipient verify,
+successful routing to an appendfile transport is followed by a call into
+the transport to evaluate the quota status for the recipient.
+No actual delivery is done, but verification will succeed if the quota
+is sufficient for the message (if the sender gave a message size) or
+not already exceeded (otherwise).
.endlist
.cindex "verifying address" "differentiating failures"
If you are writing your own custom rejection message or log message when
denying access, you can use this variable to include information about the
verification failure.
+This variable is cleared at the end of processing the ACL verb.
In addition, &$sender_verify_failure$& or &$recipient_verify_failure$& (as
appropriate) contains one of the following words:
&%recipient%&: The RCPT command in a callout was rejected.
.next
&%postmaster%&: The postmaster check in a callout was rejected.
+.next
+&%quota%&: The quota check for a local recipient did non pass.
.endlist
The main use of these variables is expected to be to distinguish between
clients when the SMTP PIPELINING extension is in use. The flushing can be
disabled by using a &%control%& modifier to set &%no_callout_flush%&.
+.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using recipient verify"
+A recipient callout which gets a 2&'xx'& code
+will assign untainted values to the
+&$domain_data$& and &$local_part_data$& variables,
+corresponding to the domain and local parts of the recipient address.
+
-.section "Additional parameters for callouts" "CALLaddparcall"
+.subsection "Additional parameters for callouts" CALLaddparcall
.cindex "callout" "additional parameters for"
The &%callout%& option can be followed by an equals sign and a number of
optional parameters, separated by commas. For example:
.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.
+accordance with the specification in
+&url(https://www.rfc-editor.org/rfc/rfc2821,RFC 2821).
+The RFC states that the unqualified address &'postmaster'& should be accepted.
.vitem &*mailfrom&~=&~*&<&'email&~address'&>
-.section "Callout caching" "SECTcallvercache"
+.subsection "Callout caching" SECTcallvercache
.cindex "hints database" "callout cache"
.cindex "callout" "cache, description of"
.cindex "caching" "callout"
entire domain (for example, that it accepts the local part &'postmaster'&).
When an original callout fails, a detailed SMTP error message is given about
-the failure. However, for subsequent failures use the cache data, this message
+the failure. However, for subsequent failures that use the cache data, this message
is not available.
The expiry times for negative and positive address cache records are
+.section "Quota caching" "SECTquotacache"
+.cindex "hints database" "quota cache"
+.cindex "quota" "cache, description of"
+.cindex "caching" "quota"
+Exim caches the results of quota verification
+in order to reduce the amount of resources used.
+The &"callout"& hints database is used.
+
+The default cache periods are five minutes for a positive (good) result
+and one hour for a negative result.
+To change the periods the &%quota%& option can be followed by an equals sign
+and a number of optional paramemters, separated by commas.
+For example:
+.code
+verify = recipient/quota=cachepos=1h,cacheneg=1d
+.endd
+Possible parameters are:
+.vlist
+.vitem &*cachepos&~=&~*&<&'time&~interval'&>
+.cindex "quota cache" "positive entry expiry, specifying"
+Set the lifetime for a positive cache entry.
+A value of zero seconds is legitimate.
+
+.vitem &*cacheneg&~=&~*&<&'time&~interval'&>
+.cindex "quota cache" "negative entry expiry, specifying"
+As above, for a negative entry.
+
+.vitem &*no_cache*&
+Set both positive and negative lifetimes to zero.
+
.section "Sender address verification reporting" "SECTsenaddver"
.cindex "verifying" "suppressing error details"
See section &<<SECTaddressverification>>& for a general discussion of
use this:
.code
# Bounces: drop unsigned addresses for BATV senders
-deny message = This address does not send an unsigned reverse path
- senders = :
+deny senders = :
recipients = +batv_senders
+ message = This address does not send an unsigned reverse path
# Bounces: In case of prvs-signed address, check signature.
-deny message = Invalid reverse path signature.
- senders = :
+deny senders = :
condition = ${prvscheck {$local_part@$domain}\
{PRVSCHECK_SQL}{1}}
!condition = $prvscheck_result
+ message = Invalid reverse path signature.
.endd
The first statement rejects recipients for bounce messages that are addressed
to plain BATV sender addresses, because it is known that BATV senders do not
Here is a very simple scanning example:
.code
-deny message = This message contains malware ($malware_name)
- malware = *
+deny malware = *
+ message = This message contains malware ($malware_name)
.endd
The next example accepts messages when there is a problem with the scanner:
.code
-deny message = This message contains malware ($malware_name)
- malware = */defer_ok
+deny malware = */defer_ok
+ message = This message contains malware ($malware_name)
.endd
The next example shows how to use an ACL variable to scan with both sophie and
aveserver. It assumes you have set:
.endd
in the main Exim configuration.
.code
-deny message = This message contains malware ($malware_name)
- set acl_m0 = sophie
+deny set acl_m0 = sophie
malware = *
+ message = This message contains malware ($malware_name)
-deny message = This message contains malware ($malware_name)
- set acl_m0 = aveserver
+deny set acl_m0 = aveserver
malware = *
+ message = This message contains malware ($malware_name)
.endd
.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
+deny spam = joe
+ message = This message was classified as SPAM
.endd
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
are quite small, it is recommended that you do not scan the big ones. For
example:
.code
-deny message = This message was classified as SPAM
- condition = ${if < {$message_size}{10K}}
+deny condition = ${if < {$message_size}{10K}}
spam = nobody
+ message = This message was classified as SPAM
.endd
The &%spam%& condition returns true if the threshold specified in the user's
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
+deny spam = joe/defer_ok
+ message = This message was classified as SPAM
.endd
This causes messages to be accepted even if there is a problem with &%spamd%&.
add_header = Subject: *SPAM* $h_Subject:
# reject spam at high scores (> 12)
-deny message = This message scored $spam_score spam points.
- spam = nobody:true
+deny spam = nobody:true
condition = ${if >{$spam_score_int}{120}{1}{0}}
+ message = This message scored $spam_score spam points.
.endd
filename, and the default path is then used.
.endlist
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 = $mime_filename
-.endd
-However, you should keep in mind that &$mime_filename$& might contain
-anything. If you place files outside of the default path, they are not
+errors or unusual circumstances such as memory shortages.
+The variable &$mime_filename$& will have the suggested name for the file.
+Note however that this might contain anything, and is very difficult
+to safely use as all or even part of the filename.
+If you place files outside of the default path, they are not
automatically unlinked.
For RFC822 attachments (these are messages attached to messages, with a
This is perhaps the most important of the MIME variables. It contains a
proposed filename for an attachment, if one was found in either the
&'Content-Type:'& or &'Content-Disposition:'& headers. The filename will be
-RFC2047
-or RFC2231
+&url(https://www.rfc-editor.org/rfc/rfc2047,RFC 2047) or
+&url(https://www.rfc-editor.org/rfc/rfc2231,RFC 2231)
decoded, but no additional sanity checks are done.
If no filename was
found, this variable contains the empty string.
alternative plain text), while allowing HTML files to be attached. HTML
coverletter mail attached to non-HTML coverletter mail will also be allowed:
.code
-deny message = HTML mail is not accepted here
-!condition = $mime_is_rfc822
-condition = $mime_is_coverletter
-condition = ${if eq{$mime_content_type}{text/html}{1}{0}}
+deny !condition = $mime_is_rfc822
+ condition = $mime_is_coverletter
+ condition = ${if eq{$mime_content_type}{text/html}{1}{0}}
+ message = HTML mail is not accepted here
.endd
.vitem &$mime_is_multipart$&
with more backslashes, or use the &`\N`& facility to disable expansion.
Here is a simple example that contains two regular expressions:
.code
-deny message = contains blacklisted regex ($regex_match_string)
- regex = [Mm]ortgage : URGENT BUSINESS PROPOSAL
+deny regex = [Mm]ortgage : URGENT BUSINESS PROPOSAL
+ message = contains blacklisted regex ($regex_match_string)
.endd
The conditions returns true if any one of the regular expressions matches. The
&$regex_match_string$& expansion variable is then set up and contains the
LOCAL_SCAN_SOURCE=Local/local_scan.c
.endd
for example. The function must be called &[local_scan()]&;
-.new
the source file(s) for it should first #define LOCAL_SCAN
and then #include "local_scan.h".
-.wen
It is called by
Exim after it has received a message, when the success return code is about to
be sent. This is after all the ACLs have been run. The return code from your
(the -D file). The file is open for reading and writing, but updating it is not
recommended. &*Warning*&: You must &'not'& close this file descriptor.
-The descriptor is positioned at character 19 of the file, which is the first
-character of the body itself, because the first 19 characters are the message
-id followed by &`-D`& and a newline. If you rewind the file, you should use the
+The descriptor is positioned at character 26 of the file, which is the first
+character of the body itself, because the first 26 characters (19 characters
+before Exim 4.97) are the message id followed by &`-D`& and a newline.
+If you rewind the file, you should use the
macro SPOOL_DATA_START_OFFSET to reset to the start of the data, just in
case this changes in some future version.
.next
.vlist
.vitem &*int&~body_linecount*&
This variable contains the number of lines in the message's body.
-It is not valid if the &%spool_files_wireformat%& option is used.
+It is not valid if the &%spool_wireformat%& option is used.
.vitem &*int&~body_zerocount*&
This variable contains the number of binary zero bytes in the message's body.
-It is not valid if the &%spool_files_wireformat%& option is used.
+It is not valid if the &%spool_wireformat%& option is used.
.vitem &*unsigned&~int&~debug_selector*&
This variable is set to zero when no debugging is taking place. Otherwise, it
.vitem &*header_line&~*header_last*&
A pointer to the last of the header lines.
-.vitem &*uschar&~*headers_charset*&
+.vitem &*const&~uschar&~*headers_charset*&
The value of the &%headers_charset%& configuration option.
.vitem &*BOOL&~host_checking*&
.vitem &*void&~debug_printf(char&~*,&~...)*&
-This is Exim's debugging function, with arguments as for &'(printf()'&. The
+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,
calls to &'debug_printf()'& have no effect. Normally, you should make calls
conditional on the &`local_scan`& debug selector by coding like this:
.vitem &*int&~lss_match_domain(uschar&~*domain,&~uschar&~*list)*&
This function checks for a match in a domain list. Domains are always
matched caselessly. The return value is one of the following:
-.display
-&`OK `& match succeeded
-&`FAIL `& match failed
-&`DEFER `& match deferred
-.endd
+.itable none 0 0 2 15* left 85* left
+.irow &`OK`& "match succeeded"
+.irow &`FAIL`& "match failed"
+.irow &`DEFER`& "match deferred"
+.endtable
DEFER is usually caused by some kind of lookup defer, such as the
inability to contact a database.
.vlist
.vitem "&*uschar&~rfc2047_decode(uschar&~*string,&~BOOL&~lencheck,&&&
&~uschar&~*target,&~int&~zeroval,&~int&~*lenptr, &~&~uschar&~**error)*&"
-This function decodes strings that are encoded according to RFC 2047. Typically
+This function decodes strings that are encoded according to
+&url(https://www.rfc-editor.org/rfc/rfc2047,RFC 2047). Typically
these are the contents of header lines. First, each &"encoded word"& is decoded
from the Q or B encoding into a byte-string. Then, if provided with the name of
a charset encoding, and if the &[iconv()]& function is available, an attempt is
arguments. It flushes the output stream, and returns a non-zero value if there
is an error.
-.new
.vitem &*void&~*store_get(int,BOOL)*&
This function accesses Exim's internal store (memory) manager. It gets a new
chunk of memory whose size is given by the first argument.
FALSE if it is locally-sourced.
Exim bombs out if it ever
runs out of memory. See the next section for a discussion of memory handling.
-.wen
.vitem &*void&~*store_get_perm(int,BOOL)*&
This function is like &'store_get()'&, but it always gets memory from the
is done. If a message fails to be completely delivered at the first attempt,
the system filter is run again at the start of every retry.
If you want your filter to do something only once per message, you can make use
+.cindex retry condition
of the &%first_delivery%& condition in an &%if%& command in the filter to
prevent it happening on retries.
.endd
The argument for the &%headers add%& is a string that is expanded and then
added to the end of the message's headers. It is the responsibility of the
-filter maintainer to make sure it conforms to RFC 2822 syntax. Leading white
+filter maintainer to make sure it conforms to
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822) syntax. Leading white
space is ignored, and if the string is otherwise empty, or if the expansion is
forced to fail, the command has no effect.
.section "Per-address filtering" "SECTperaddfil"
-.vindex "&$domain$&"
-.vindex "&$local_part$&"
+.vindex "&$domain_data$&"
+.vindex "&$local_part_data$&"
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
-such as &$local_part$& and &$domain$& can be used, and indeed, the choice of
-filter file could be made dependent on them. This is an example of a router
-which implements such a filter:
+such as &$local_part_data$& and &$domain_data$& can be used,
+and indeed, the choice of filter file could be made dependent on them.
+This is an example of a router which implements such a filter:
.code
central_filter:
check_local_user
.cindex "line endings"
.cindex "carriage return"
.cindex "linefeed"
-RFC 2821 specifies that CRLF (two characters: carriage-return, followed by
+&url(https://www.rfc-editor.org/rfc/rfc2821,RFC 2821)
+specifies that CRLF (two characters: carriage-return, followed by
linefeed) is the line ending for messages transmitted over the Internet using
SMTP over TCP/IP. However, within individual operating systems, different
conventions are used. For example, Unix-like systems use just LF, but others
follows:
.ilist
-LF not preceded by CR is treated as a line ending.
-.next
CR is treated as a line ending; if it is immediately followed by LF, the LF
is ignored.
.next
.next
If the first header line received in a message ends with CRLF, a subsequent
bare LF in a header line is treated in the same way as a bare CR in a header
-line.
+line and a bare LF in a body line is replaced with a space.
+.next
+If the first header line received in a message does not end with CRLF, a subsequent
+LF not preceded by CR is treated as a line ending.
.endlist
From a.oakley@berlin.mus Fri Jan 5 12:35 GMT 1996
From f.butler@berlin.mus Fri, 7 Jan 97 14:00:00 GMT
.endd
-This line precedes the RFC 2822 header lines. For compatibility with Sendmail,
+This line precedes the
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+header lines. For compatibility with Sendmail,
Exim recognizes such lines at the start of messages that are submitted to it
via the command line (that is, on the standard input). It does not recognize
such lines in incoming SMTP messages, unless the sending host matches
When the caller of Exim for a non-SMTP message that contains a &"From"& line is
a trusted user, the message's sender address is constructed by expanding the
contents of &%uucp_sender_address%&, whose default value is &"$1"&. This is
-then parsed as an RFC 2822 address. If there is no domain, the local part is
+then parsed as an
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+address. If there is no domain, the local part is
qualified with &%qualify_domain%& unless it is the empty string. However, if
the command line &%-f%& option is used, it overrides the &"From"& line.
-.section "Resent- header lines" "SECID220"
-.cindex "&%Resent-%& header lines"
-.cindex "header lines" "Resent-"
-RFC 2822 makes provision for sets of header lines starting with the string
+.section "Header lines"
+.subsection "Resent- header lines" SECID220
+.chindex Resent-
+&url(https://www.rfc-editor.org/rfc/rfc2822,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
recipient to somebody else. These headers are &'Resent-Date:'&,
&'Resent-From:'&, &'Resent-Sender:'&, &'Resent-To:'&, &'Resent-Cc:'&,
-.section "The Auto-Submitted: header line" "SECID221"
+.subsection Auto-Submitted: SECID221
Whenever Exim generates an autoreply, a bounce, or a delay warning message, it
includes the header line:
.code
Auto-Submitted: auto-replied
.endd
-.section "The Bcc: header line" "SECID222"
+.subsection Bcc: 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" "SECID223"
-.cindex "&'Date:'& header line"
-.cindex "header lines" "Date:"
+.subsection Date: SECID223
+.cindex Date:
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.
-.section "The Delivery-date: header line" "SECID224"
+.subsection Delivery-date: SECID224
.cindex "&'Delivery-date:'& header line"
.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
+&'Delivery-date:'& header lines are not part of the standard
+&url(https://www.rfc-editor.org/rfc/rfc2822,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
in messages in transit. If the &%delivery_date_remove%& configuration option is
set (the default), Exim removes &'Delivery-date:'& header lines from incoming
messages.
-.section "The Envelope-to: header line" "SECID225"
-.cindex "&'Envelope-to:'& header line"
-.cindex "header lines" "Envelope-to:"
+.subsection Envelope-to: SECID225
+.chindex Envelope-to:
.oindex "&%envelope_to_remove%&"
-&'Envelope-to:'& header lines are not part of the standard RFC 2822 header set.
+&'Envelope-to:'& header lines are not part of the standard
+&url(https://www.rfc-editor.org/rfc/rfc2822,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
messages in transit. If the &%envelope_to_remove%& configuration option is set
messages.
-.section "The From: header line" "SECTthefrohea"
-.cindex "&'From:'& header line"
-.cindex "header lines" "From:"
+.subsection From: SECTthefrohea
+.chindex From:
.cindex "Sendmail compatibility" "&""From""& line"
.cindex "message" "submission"
.cindex "submission mode"
name as described in section &<<SECTconstr>>&.
-.section "The Message-ID: header line" "SECID226"
-.cindex "&'Message-ID:'& header line"
-.cindex "header lines" "Message-ID:"
+.subsection Message-ID: SECID226
+.chindex Message-ID:
.cindex "message" "submission"
.oindex "&%message_id_header_text%&"
If a locally-generated or submission-mode incoming message does not contain a
&%message_id_header_domain%& options.
-.section "The Received: header line" "SECID227"
-.cindex "&'Received:'& header line"
-.cindex "header lines" "Received:"
+.subsection Received: SECID227
+.chindex Received:
A &'Received:'& header line is added at the start of every message. The
contents are defined by the &%received_header_text%& configuration option, and
Exim automatically adds a semicolon and a timestamp to the configured string.
-H spool file is written) the earliest time at which delivery could start.
-.section "The References: header line" "SECID228"
-.cindex "&'References:'& header line"
-.cindex "header lines" "References:"
+.subsection References: SECID228
+.chindex References:
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
+section 3.64 of
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+(which states that replies should contain such a header line),
+and section 3.14 of &url(https://datatracker.ietf.org/doc/html/rfc3834,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
-.section "The Return-path: header line" "SECID229"
-.cindex "&'Return-path:'& header line"
-.cindex "header lines" "Return-path:"
+.subsection Return-path: SECID229
+.chindex Return-path:
.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%&
-.section "The Sender: header line" "SECTthesenhea"
+.subsection Sender: SECTthesenhea
.cindex "&'Sender:'& header line"
.cindex "message" "submission"
-.cindex "header lines" "Sender:"
+.chindex Sender:
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
expansions all occur before the message is actually transported.
For both routers and transports, the argument of a &%headers_add%&
-option must be in the form of one or more RFC 2822 header lines, separated by
-newlines (coded as &"\n"&). For example:
+option must be in the form of one or more
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+header lines, separated by newlines (coded as &"\n"&). For example:
.code
headers_add = X-added-header: added by $primary_hostname\n\
X-added-second: another added header line
there is no password file entry.
.cindex "RFC 2047"
-In all cases, the user name is made to conform to RFC 2822 by quoting all or
+In all cases, the user name is made to conform to
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+by quoting all or
parts of it if necessary. In addition, if it contains any non-printing
-characters, it is encoded as described in RFC 2047, which defines a way of
+characters, it is encoded as described in
+&url(https://www.rfc-editor.org/rfc/rfc2047,RFC 2047), which defines a way of
including non-ASCII characters in header lines. The value of the
&%headers_charset%& option specifies the name of the encoding that is used (the
characters are assumed to be in this encoding). The setting of
.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
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+states that the case of letters in the local parts of addresses cannot
be assumed to be non-significant. Exim preserves the case of local parts of
addresses, but by default it uses a lower-cased form when it is routing,
because on most Unix systems, usernames are in lower case and case-insensitive
.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
+&url(https://www.rfc-editor.org/rfc/rfc2822,RFC 2822)
+forbids empty components in local parts. That is, an unquoted local
part may not begin or end with a dot, nor have two consecutive dots in the
middle. However, it seems that many MTAs do not enforce this, so Exim permits
empty components for compatibility.
suppressed.
If the remote server advertises support for PIPELINING, Exim uses the
-pipelining extension to SMTP (RFC 2197) to reduce the number of TCP/IP packets
-required for the transaction.
+pipelining extension to SMTP
+(&url(https://datatracker.ietf.org/doc/html/rfc2197,RFC 2197))
+to reduce the number of TCP/IP packets required for the transaction.
If the remote server advertises support for the STARTTLS command, and Exim
was built to support TLS encryption, it tries to start a TLS session unless the
.cindex "SMTP" "batching over TCP/IP"
When a message is successfully delivered over a TCP/IP SMTP connection, Exim
looks in the hints database for the transport to see if there are any queued
-messages waiting for the host to which it is connected. If it finds one, it
-creates a new Exim process using the &%-MC%& option (which can only be used by
-a process running as root or the Exim user) and passes the TCP/IP socket to it
-so that it can deliver another message using the same socket. The new process
-does only those deliveries that are routed to the connected host, and may in
-turn pass the socket on to a third process, and so on.
+messages waiting for the host to which it is connected.
+If it finds one, it arranges to attempt that message on the same connection.
The &%connection_max_messages%& option of the &(smtp)& transport can be used to
limit the number of messages sent down a single TCP/IP connection.
-.section "Errors in outgoing SMTP" "SECToutSMTPerr"
+.subsection "Errors in outgoing SMTP" SECToutSMTPerr
.cindex "error" "in outgoing SMTP"
.cindex "SMTP" "errors in outgoing"
.cindex "host" "error"
Exim can be configured to verify addresses in incoming SMTP commands as they
are received. See chapter &<<CHAPACL>>& for details. It can also be configured
to rewrite addresses at this time &-- before any syntax checking is done. See
-section &<<SECTrewriteS>>&.
+section &<<SSECTrewriteS>>&.
Exim can also be configured to limit the rate at which a client host submits
MAIL and RCPT commands in a single SMTP session. See the
-.section "Unrecognized SMTP commands" "SECID234"
+.subsection "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" "SECID235"
+.subsection "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" "SECID236"
+.subsection "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
-.section "The VRFY and EXPN commands" "SECID237"
+.subsection "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.
than a verification (the &%-bv%& option). If an unqualified local part is given
as the argument to EXPN, it is qualified with &%qualify_domain%&. Rejections
of VRFY and EXPN commands are logged on the main and reject logs, and
-VRFY verification failures are logged on the main log for consistency with
+VRFY verification failures are logged in the main log for consistency with
RCPT failures.
-.section "The ETRN command" "SECTETRN"
+.subsection "The ETRN command" SECTETRN
.cindex "ETRN" "processing"
.cindex "ESMTP extensions" ETRN
-RFC 1985 describes an ESMTP command called ETRN that is designed to
+Most modern installations never need to use this.
+It is used for managing messages queued for an intermittently-connecting
+destination (eg. one using a dialup connection).
+
+.oindex "&%acl_smtp_etrn%&"
+The command is only available if permitted by an ACL
+specfied by the main-section &%acl_smtp_etrn%& option.
+
+&url(https://www.rfc-editor.org/rfc/rfc1985,RFC 1985)
+describes an ESMTP command called ETRN that is designed to
overcome the security problems of the TURN command (which has fallen into
disuse). When Exim receives an ETRN command on a TCP/IP connection, it runs
the ACL specified by &%acl_smtp_etrn%& in order to decide whether the command
for it to change them before running the command.
+.new
+.subsection "The ATRN command" SECTATRN
+.cindex ATRN processing
+.cindex "ESMTP extensions" ATRN
+A second method for intermittently-connecting destinations
+is specified by
+&url(https://www.rfc-editor.org/rfc/rfc2645.html,RFC 2645).
+
+This describes an ESMTP command called ATRN which requests
+a swap in server/client roles of the communicating endpoints, and delivery
+of queued messages.
+Note that this supports customers having IP addresses that
+change frequently.
+
+Exim supports the &"provider"& side of ATRN, using the terms
+of that specification:
+initially as an SMTP server, then transferring to an SMTP client
+role if an ATRN command is accepted.
+
+.oindex "&%acl_smtp_atrn%&"
+The command is only available if permitted by an ACL
+specfied by the main-section &%acl_smtp_atrn%& option.
+Per the standard, this should only be for a specific
+provider port number (386, named "odmr");
+Exim should be configured to listen on that port
+(in addition to other duties) via &%daemon_smtp_ports%&
+or equivalent commandline options, and restrict the
+advertising of the facility to the port:
+.code
+acl_smtp_atrn = ${if = {$received_port}{386} {check_atrn}{}}
+.endd
+
+A recieved ATRN command will be rejected unless
+authentication has previously been done on the connection.
+
+Any arguments supplied with an ATRN command are (per standard)
+a comma-separated list of requested domains,
+and will be available in the &$smtp_command_argument$&
+variable.
+
+The ACL configured may return &"deny"& for any policy reaons
+(for example, the authenticated user is not permitted the facility).
+Otherwise it should use the ACL &"atrn_domains"& condition,
+which returns true if there are queued messages for any of
+the given list of domains.
+If that condition fails the ACL should return &"defer"&
+with a "453 You have no mail" response;
+else it should return &"accept"&.
+
+For example (with default domain handling, and one possible de-taint method) :
+.code
+check_atrn:
+ warn set acl_m0 = clientdom.net
+ deny condition = ${if def:smtp_command_argument}
+ set acl_m0 = ${map \
+ {<, $smtp_command_argument} \
+ {${if inlist{$item}{clientdom.net:cl2dom.net} {$value}}} \
+ }
+ condition = ${if !def:acl_m0}
+ defer !atrn_domains = <, $acl_m0
+ message = 453 You have no mail
+ accept
+.endd
+
+Acceptance by the ACL will result in a queue-run for messages
+having addresses with the given domains.
+A suitable router and transport must be configured for the deliveries.
+
+To access a named queue
+.cindex queue named
+the ACL should use a "queue =" modifier before the "atrn_domains"
+condition.
+If the ACL does not accept, re-set the queue to an empty value
+so as to not disrupt any later SMTP operations on the connection.
+
+Use of the &"atrn_domains"& condition additionally sets up
+the &$atrn_host$& variable, which can be used by a manualroute
+router. Being otherwise empty, this router will decline in
+other situations so can be safely placed in a general router chain.
+
+For example:
+.code
+begin routers
+odmr_client:
+ driver = manualroute
+ route_data = <;$atrn_host
+ transport = client_smtp
+
+begin transports
+client_smtp:
+ driver = smtp
+.endd
+
+Although not discssed in the specification document,
+Exim supports use of ATRN within a STARTTLS-
+or TLS-on-connect- encrypted connection
+(which is wise if a plaintext authentication mechanism is used).
+In such cases the TLS connection will remain open across the
+role-swap, and be used for the sending of queued messages.
+
+Note that the RFC requires that the CRAM-MD5 authentication
+method be supported.
+Exim does not enforce this, but leaves it up to the configuration;
+see chapter &<<CHID9>>&.
+
+.wen
+
+
.section "Incoming local SMTP" "SECID238"
.cindex "SMTP" "local incoming"
-.section "Outgoing batched SMTP" "SECTbatchSMTP"
+.section "Batched SMTP" "SECTgenbatchSMTP"
+.subsection "Outgoing batched SMTP" "SECTbatchSMTP"
.cindex "SMTP" "batched outgoing"
.cindex "batched SMTP output"
Both the &(appendfile)& and &(pipe)& transports can be used for handling
-.section "Incoming batched SMTP" "SECTincomingbatchedSMTP"
+.subsection "Incoming batched SMTP" "SECTincomingbatchedSMTP"
.cindex "SMTP" "batched incoming"
.cindex "batched SMTP input"
The &%-bS%& command line option causes Exim to accept one or more messages by
lists_post:
driver = redirect
domains = lists.example
- senders = ${if exists {/usr/lists/$local_part}\
- {lsearch;/usr/lists/$local_part}{*}}
+ local_parts = ${lookup {$local_part} dsearch,filter=file,ret=full {/usr/lists}}
+ senders = ${if exists {$local_part_data} {lsearch;$local_part_data}{*}}
file = ${lookup {$local_part} dsearch,ret=full {/usr/lists}}
forbid_pipe
forbid_file
data = ${lookup{$local_part}lsearch{/etc/mail/virtual/$domain_data}}
no_more
.endd
-.new
The &%domains%& option specifies that the router is to be skipped, unless there
is a file in the &_/etc/mail/virtual_& directory whose name is the same as the
domain that is being processed.
The &(dsearch)& lookup used results in an untainted version of &$domain$&
being placed into the &$domain_data$& variable.
-.wen
When the router runs, it looks up the local
part in the file to find a new address (or list of addresses). The &%no_more%&
.code
my_mailboxes:
driver = appendfile
- file = /var/mail/$domain/$local_part_data
+ file = /var/mail/$domain_data/$local_part_data
user = mail
.endd
This uses a directory of mailboxes for each domain. The &%user%& setting is
cases by testing the variable &$local_part_suffix$&. For example:
.code
if $local_part_suffix contains -special then
-save /home/$local_part/Mail/special
+save /home/$local_part_data/Mail/special
endif
.endd
If the filter file does not exist, or does not deal with such addresses, they
When Exim encounters an empty item in the list, it searches the list defined by
LOG_FILE_PATH, and uses the first item it finds that is neither empty nor
&"syslog"&. This means that an empty item in &%log_file_path%& can be used to
-mean &"use the path specified at build time"&. It no such item exists, log
+mean &"use the path specified at build time"&. If no such item exists, log
files are written in the &_log_& subdirectory of the spool directory. This is
-equivalent to the setting:
+equivalent to the configuration file setting:
.code
log_file_path = $spool_directory/log/%slog
.endd
A log file path may also contain &`%D`& or &`%M`& if datestamped log filenames
are in use &-- see section &<<SECTdatlogfil>>& below.
-Here are some examples of possible settings:
+Here are some examples of possible Makefile settings:
.display
&`LOG_FILE_PATH=syslog `& syslog only
&`LOG_FILE_PATH=:syslog `& syslog and default path
870 data characters. (This allows for a total syslog line length of 1024, when
additions such as timestamps are added.) If you are running a syslog
replacement that can handle lines longer than the 1024 characters allowed by
-RFC 3164, you should set
+&url(https://www.rfc-editor.org/rfc/rfc3164,RFC 3164), you should set
.code
SYSLOG_LONG_LINES=yes
.endd
successful, unsuccessful, and delayed delivery. These lines can readily be
picked out by the distinctive two-character flags that immediately follow the
timestamp. The flags are:
-.display
-&`<=`& message arrival
-&`(=`& message fakereject
-&`=>`& normal message delivery
-&`->`& additional address in same delivery
-&`>>`& cutthrough message delivery
-&`*>`& delivery suppressed by &%-N%&
-&`**`& delivery failed; address bounced
-&`==`& delivery deferred; temporary problem
-.endd
+.itable none 0 0 2 10* left 90* left
+.irow &%<=%& "message arrival"
+.irow &%(=%& "message fakereject"
+.irow &%=>%& "normal message delivery"
+.irow &%->%& "additional address in same delivery"
+.irow &%>>%& "cutthrough message delivery"
+.irow &%*>%& "delivery suppressed by &%-N%&"
+.irow &%**%& "delivery failed; address bounced"
+.irow &%==%& "delivery deferred; temporary problem"
+.endtable
.section "Logging message reception" "SECID251"
If SMTP AUTH was used for the delivery 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 &%client_set_id%&
-option, this is logged too, separated by a colon from the authenticator name.
+option, this is logged too, as a second colon-separated list item.
+Optionally (see the &%smtp_mailauth%& &%log_selector%&) there may be a third list item.
If a shadow transport was run after a successful local delivery, the log line
for the successful delivery has an item added on the end, of the form
When more than one address is included in a single delivery (for example, two
SMTP RCPT commands in one transaction) the second and subsequent addresses are
flagged with &`->`& instead of &`=>`&. When two or more messages are delivered
-down a single SMTP connection, an asterisk follows the IP address in the log
-lines for the second and subsequent messages.
+down a single SMTP connection, an asterisk follows the
+remote IP address (and port if enabled)
+in the log lines for the second and subsequent messages.
When two or more messages are delivered down a single TLS connection, the
DNS and some TLS-related information logged for the first message delivered
will not be present in the log lines for the second and subsequent messages.
.display
&`A `& authenticator name (and optional id and sender)
&`C `& SMTP confirmation on delivery
+&`Ci `& connection identifier
&` `& command list for &"no mail in SMTP session"&
&`CV `& certificate verification status
&`D `& duration of &"no mail in SMTP session"&
.section "Reducing or increasing what is logged" "SECTlogselector"
.cindex "log" "selectors"
By setting the &%log_selector%& global option, you can disable some of Exim's
-default logging, or you can request additional logging. The value of
+default logging to the main log, or you can request additional logging. The value of
&%log_selector%& is made up of names preceded by plus or minus characters. For
example:
.code
.endd
The list of optional log items is in the following table, with the default
selection marked by asterisks:
-.display
-&` 8bitmime `& received 8BITMIME status
-&`*acl_warn_skipped `& skipped &%warn%& statement in ACL
-&` address_rewrite `& address rewriting
-&` all_parents `& all parents in => lines
-&` arguments `& command line arguments
-&`*connection_reject `& connection rejections
-&`*delay_delivery `& immediate delivery delayed
-&` deliver_time `& time taken to attempt delivery
-&` delivery_size `& add &`S=`&&'nnn'& to => lines
-&`*dkim `& DKIM verified domain on <= lines
-&` dkim_verbose `& separate full DKIM verification result line, per signature
-&`*dnslist_defer `& defers of DNS list (aka RBL) lookups
-&` dnssec `& DNSSEC secured lookups
-&`*etrn `& ETRN commands
-&`*host_lookup_failed `& as it says
-&` ident_timeout `& timeout for ident connection
-&` incoming_interface `& local interface on <= and => lines
-&` incoming_port `& remote port on <= lines
-&`*lost_incoming_connection `& as it says (includes timeouts)
-&` millisec `& millisecond timestamps and RT,QT,DT,D times
-&`*msg_id `& on <= lines, Message-ID: header value
-&` msg_id_created `& on <= lines, Message-ID: header value when one had to be added
-&` outgoing_interface `& local interface on => lines
-&` outgoing_port `& add remote port to => lines
-&`*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
-&` pipelining `& PIPELINING use, on <= and => lines
-&` proxy `& proxy address on <= and => lines
-&` receive_time `& time taken to receive message
-&` 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
-&` 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 `& incoming SMTP connections
-&` smtp_incomplete_transaction`& incomplete SMTP transactions
-&` smtp_mailauth `& AUTH argument to MAIL commands
-&` 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
-.endd
+.itable none 0 0 3 2.8in left 10pt center 3in left
+.irow &`8bitmime`& "received 8BITMIME status"
+.irow &`acl_warn_skipped`& * "skipped &%warn%& statement in ACL"
+.irow &`address_rewrite`& "address rewriting"
+.irow &`all_parents`& "all parents in => lines"
+.irow &`arguments`& "command line arguments"
+.irow &`connection_id`& "connection identifier"
+.irow &`connection_reject`& * "connection rejections"
+.irow &`delay_delivery`& * "immediate delivery delayed"
+.irow &`deliver_time`& "time taken to attempt delivery"
+.irow &`delivery_size`& "add &`S=`&&'nnn'& to => lines"
+.irow &`dkim`& * "DKIM verified domain on <= lines"
+.irow &`dkim_verbose`& "separate full DKIM verification result line, per signature; DKIM signing"
+.irow &`dnslist_defer`& * "defers of DNS list (aka RBL) lookups"
+.irow &`dnssec`& "DNSSEC secured lookups"
+.irow &`etrn`& * "ETRN commands"
+.irow &`host_lookup_failed`& * "as it says"
+.irow &`ident_timeout`& "timeout for ident connection"
+.irow &`incoming_interface`& "local interface & port on <= and => lines"
+.irow &`incoming_port`& "remote port on <= lines"
+.irow &`lost_incoming_connection`& * "as it says (includes timeouts)"
+.irow &`millisec`& "millisecond timestamps and RT,QT,DT,D times"
+.irow &`msg_id`& * "on <= lines, Message-ID: header value"
+.irow &`msg_id_created`& "on <= lines, Message-ID: header value when one had to be added"
+.irow &`outgoing_interface`& "local interface on => lines"
+.irow &`outgoing_port`& "add remote port to => lines"
+.irow &`queue_run`& * "start and end queue runs"
+.irow &`queue_time`& "time on queue for one recipient"
+.irow &`queue_time_exclusive`& "exclude recieve time from QT times"
+.irow &`queue_time_overall`& "time on queue for whole message"
+.irow &`pid`& "Exim process id"
+.irow &`pipelining`& "PIPELINING use, on <= and => lines"
+.irow &`proxy`& "proxy address on <= and => lines"
+.irow &`receive_time`& "time taken to receive message"
+.irow &`received_recipients`& "recipients on <= lines"
+.irow &`received_sender`& "sender on <= lines"
+.irow &`rejected_header`& * "header contents on reject log"
+.irow &`retry_defer`& * "&<quote>&retry time not reached&</quote>&"
+.irow &`return_path_on_delivery`& "put return path on => and ** lines"
+.irow &`sender_on_delivery`& "add sender to => lines"
+.irow &`sender_verify_fail`& * "sender verification failures"
+.irow &`size_reject`& * "rejection because too big"
+.irow &`skip_delivery`& * "delivery skipped in a queue run"
+.irow &`smtp_confirmation`& * "SMTP confirmation on => lines"
+.irow &`smtp_connection`& "incoming SMTP connections"
+.irow &`smtp_incomplete_transaction`& "incomplete SMTP transactions"
+.irow &`smtp_mailauth`& "AUTH argument to MAIL commands"
+.irow &`smtp_no_mail`& "session with no MAIL commands"
+.irow &`smtp_protocol_error`& "SMTP protocol errors"
+.irow &`smtp_syntax_error`& "SMTP syntax errors"
+.irow &`subject`& "contents of &'Subject:'& on <= lines"
+.irow &`tls_certificate_verified`& * "certificate verification status"
+.irow &`tls_cipher`& * "TLS cipher suite on <= and => lines"
+.irow &`tls_peerdn`& "TLS peer DN on <= and => lines"
+.irow &`tls_resumption`& "append * to cipher field"
+.irow &`tls_sni`& "TLS SNI on <= lines"
+.irow &`unknown_in_list`& "lookup failed in list match"
+.irow &`all`& "&*all of the above*&"
+.endtable
See also the &%slow_lookup_log%& main configuration option,
section &<<SECID99>>&
only way to log such cases is to interpose a script such as &_util/logargs.sh_&
between the caller and Exim.
.next
-.cindex "log" "connection rejections"
+.cindex log "connection identifier"
+.cindex connection "identifier logging"
+&%connection_id%&: An identifier for the accepted connection is added to
+connection start and end lines and to message accept lines.
+The identifier is tagged by Ci=.
+The value is PID-based, so will reset on reboot and will wrap.
+.next
+.cindex log "connection rejections"
+.cindex connection "rejection logging"
&%connection_reject%&: A log entry is written whenever an incoming SMTP
connection is rejected, for whatever reason.
.next
-.cindex "log" "delayed delivery"
+.cindex log "delayed delivery"
.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
.cindex log "DKIM verification"
.cindex DKIM "verification logging"
&%dkim_verbose%&: A log entry is written for each attempted DKIM verification.
+Also, on message delivery lines signing information (domain and selector)
+is added, tagged with DKIM=.
.next
.cindex "log" "dnslist defer"
.cindex "DNS list" "logging defer"
client's ident port times out.
.next
.cindex "log" "incoming interface"
+.cindex "log" "outgoing interface"
.cindex "log" "local interface"
.cindex "log" "local address and port"
.cindex "TCP/IP" "logging local address and port"
to the &"<="& line as an IP address in square brackets, tagged by I= and
followed by a colon and the port number. The local interface and port are also
added to other SMTP log lines, for example, &"SMTP connection from"&, to
-rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines.
+rejection lines, and (despite the name) to outgoing
+&"=>"&, &"->"&, &"=="& and &"**"& lines.
The latter can be disabled by turning off the &%outgoing_interface%& option.
.next
.cindex log "incoming proxy address"
in square brackets, and separated from it by a colon. This is implemented by
changing the value that is put in the &$sender_fullhost$& and
&$sender_rcvhost$& variables. Recording the remote port number has become more
-important with the widening use of NAT (see RFC 2505).
+important with the widening use of NAT
+(see &url(https://www.rfc-editor.org/rfc/rfc2505,RFC 2505)).
.next
.cindex "log" "dropped connection"
&%lost_incoming_connection%&: A log line is written when an incoming SMTP
the field has a minus appended.
.cindex "pipelining" "early connection"
-If Exim is built with the SUPPORT_PIPE_CONNECT build option
+If Exim is built without the DISABLE_PIPE_CONNECT build option
accept "L" fields have a period appended if the feature was
offered but not used, or an asterisk appended if used.
Delivery "L" fields have an asterisk appended if used.
.cindex "log" "queue time"
&%queue_time%&: The amount of time the message has been in the queue on the
local host is logged as QT=<&'time'&> on delivery (&`=>`&) lines, for example,
-&`QT=3m45s`&. The clock starts when Exim starts to receive the message, so it
-includes reception time as well as the delivery time for the current address.
-This means that it may be longer than the difference between the arrival and
-delivery log line times, because the arrival log line is not written until the
-message has been successfully received.
+&`QT=3m45s`&.
If millisecond logging is enabled, short times will be shown with greater
precision, eg. &`QT=1.578s`&.
.next
&%queue_time_overall%&: The amount of time the message has been in the queue on
the local host is logged as QT=<&'time'&> on &"Completed"& lines, for
-example, &`QT=3m45s`&. The clock starts when Exim starts to receive the
-message, so it includes reception time as well as the total delivery time.
+example, &`QT=3m45s`&.
.next
.cindex "log" "receive duration"
&%receive_time%&: For each message, the amount of real time it has taken to
.cindex "log" "frozen messages; skipped"
.cindex "frozen messages" "logging skipping"
&%skip_delivery%&: A log line is written whenever a message is skipped during a
-queue run because it is frozen or because another process is already delivering
-it.
+queue run because it another process is already delivering it or because
+it is frozen.
.cindex "&""spool file is locked""&"
-The message that is written is &"spool file is locked"&.
+.cindex "&""message is frozen""&"
+The message that is written is either &"spool file is locked"& or
+&"message is frozen"&.
.next
.cindex "log" "smtp confirmation"
.cindex "SMTP" "logging confirmation"
when TLS is in use. The item is &`CV=yes`& if the peer's certificate was
verified
using a CA trust anchor,
-&`CA=dane`& if using a DNS trust anchor,
+&`CV=dane`& if using a DNS trust anchor,
and &`CV=no`& if not.
.next
.cindex "log" "TLS cipher"
connection, and a certificate is supplied by the remote host, the peer DN is
added to the log line, preceded by DN=.
.next
+.cindex "log" "TLS resumption"
+.cindex "TLS" "logging session resumption"
+&%tls_resumption%&: When a message is sent or received over an encrypted
+connection and the TLS session resumed one used on a previous TCP connection,
+an asterisk is appended to the X= cipher field in the log line.
+.next
.cindex "log" "TLS SNI"
.cindex "TLS" "logging SNI"
+.cindex SNI logging
&%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.
+result of a list match is failure because a DNS lookup failed, or because
+a bad IP address was in the list.
.endlist
"check address acceptance from given IP"
.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 &<<SECTdumpdb>>& &'exim_dumpdb'& "dump a hints database"
+.irow &<<SECTtidydb>>& &'exim_tidydb'& "clean up a hints database"
+.irow &<<SECTfixdb>>& &'exim_fixdb'& "patch a hints database"
.irow &<<SECTmailboxmaint>>& &'exim_lock'& "lock a mailbox file"
+.irow &<<SECTexim_msgdate>>& &'exim_msgdate'& "Message Ids for humans (exim_msgdate)"
.endtable
Another utility that might be of use to sites with many MTAs is Tom Kistner's
system configuration options that configure exactly how &'exiwhat'& works. If
it doesn't seem to be working for you, check the following compile-time
options:
-.display
-&`EXIWHAT_PS_CMD `& the command for running &'ps'&
-&`EXIWHAT_PS_ARG `& the argument for &'ps'&
-&`EXIWHAT_EGREP_ARG `& the argument for &'egrep'& to select from &'ps'& output
-&`EXIWHAT_KILL_ARG `& the argument for the &'kill'& command
-.endd
+.itable none 0 0 2 30* left 70* left
+.irow &`EXIWHAT_PS_CMD`& "the command for running &'ps'&"
+.irow &`EXIWHAT_PS_ARG`& "the argument for &'ps'&"
+.irow &`EXIWHAT_EGREP_ARG`& "the argument for &'egrep'& to select from &'ps'& output"
+.irow &`EXIWHAT_KILL_ARG`& "the argument for the &'kill'& command"
+.endtable
An example of typical output from &'exiwhat'& is
.code
164 daemon: -q1h, listening on port 25
.code
exim -bp
.endd
-The &*-C*& option is used to specify an alternate &_exim.conf_& which might
-contain alternate exim configuration the queue management might be using.
-
to obtain a queue listing, and then greps the output to select messages
that match given criteria. The following selection options are available:
Include delivered recipients in queue listing.
.endlist
+The following options give alternates for configuration:
+
+.vlist
+.vitem &*-C*&&~<&'config&~file'&>
+is used to specify an alternate &_exim.conf_& which might
+contain alternate exim configuration the queue management might be using.
+
+.vitem &*-E*&&~<&'path'&>
+can be used to specify a path for the exim binary,
+overriding the built-in one.
+.endlist
+
There is one more option, &%-h%&, which outputs a list of options.
+At least one selection option, or either the &*-c*& or &*-h*& option, must be given.
.next
&'ratelimit'&: the data for implementing the ratelimit ACL condition
.next
+&'tls'&: TLS session resumption data
+.next
&'misc'&: other hints data
.endlist
The &'misc'& database is used for
.ilist
-Serializing ETRN runs (when &%smtp_etrn_serialize%& is set)
-.next
Serializing delivery to a specific host (when &%serialize_hosts%& is set in an
&(smtp)& transport)
.next
Limiting the concurrency of specific transports (when &%max_parallel%& is set
in a transport)
+.next
+Recording EHLO-time facilities advertised by hosts
+.next
+Serializing ETRN runs (when &%smtp_etrn_serialize%& is set)
.endlist
-.section "exim_dumpdb" "SECID261"
+.subsection "exim_dumpdb" "SECTdumpdb"
.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
-spool and database names. For example, to dump the retry database:
+&'exim_dumpdb'& program,
+taking as arguments the spool and database names.
+An option &'-z'& may be given to request times in UTC;
+otherwise times are in the local timezone.
+An option &'-k'& may be given to dump only the record keys.
+For example, to dump the retry database:
.code
exim_dumpdb /var/spool/exim retry
.endd
-Two lines of output are produced for each entry:
+For the retry database
+two lines of output are produced for each entry:
.code
T:mail.ref.example:192.168.242.242 146 77 Connection refused
31-Oct-1995 12:00:12 02-Nov-1995 12:21:39 02-Nov-1995 20:21:39 *
-.section "exim_tidydb" "SECID262"
+.subsection "exim_tidydb" "SECTtidydb"
.cindex "&'exim_tidydb'&"
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
-.section "exim_fixdb" "SECID263"
+.subsection "exim_fixdb" "SECTfixdb"
.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
-getting round problems in a live system. It has no options, and its interface
+getting round problems in a live system. Its interface
is somewhat crude. On entry, it prompts for input with a right angle-bracket. A
key of a database record can then be entered, and the data for that record is
displayed.
sequence of digit pairs for year, month, day, hour, and minute. Colons can be
used as optional separators.
+Both displayed and input times are in the local timezone by default.
+If an option &'-z'& is used on the command line, displayed times
+are in UTC.
+
.endd
Note that if a command is supplied, it must be entirely contained within the
second argument &-- hence the quotes.
-.ecindex IIDutils
+.section "Message Ids for humans (exim_msgdate)" "SECTexim_msgdate"
+.cindex "exim_msgdate"
+The &'exim_msgdate'& utility is written by Andrew Aitchison and included in the Exim distribution.
+This Perl script converts an Exim Mesage ID back into a human readable form.
+For details of &'exim_msgdate'&'s options, run &'exim_msgdate'& with the &%--help%& option.
+
+Section &<<SECTmessiden>>& (Message identification) describes Exim Mesage IDs.
+.ecindex IIDutils
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
.next
A queue runner process retains root privilege throughout its execution. Its
job is to fork a controlled sequence of delivery processes.
+
+.next
+A delivery process retains root privilege throughout most of its execution.,
+including while the recipient addresses in a message are being routed.
+
+.ilist
+However, if a user's filter file has to be processed,
+this is done in a subprocess that runs under the individual user's uid and
+gid. A system filter is run as root unless &%system_filter_user%& is set.
+.endlist
+
+Any actual deliveries (that is, the transports themselves) are run in
+subprocesses which always change to a non-root uid and gid.
+.ilist
+For local
+deliveries this is typically the uid and gid of the owner of the mailbox.
.next
-A delivery process retains root privilege throughout most of its execution,
-but any actual deliveries (that is, the transports themselves) are run in
-subprocesses which always change to a non-root uid and gid. For local
-deliveries this is typically the uid and gid of the owner of the mailbox; for
-remote deliveries, the Exim uid and gid are used. Once all the delivery
+For remote deliveries, the Exim uid and gid are used.
+.endlist
+
+Once all the delivery
subprocesses have been run, a delivery process changes to the Exim uid and gid
while doing post-delivery tidying up such as updating the retry database and
generating bounce and warning messages.
-While the recipient addresses in a message are being routed, the delivery
-process runs as root. However, if a user's filter file has to be processed,
-this is done in a subprocess that runs under the individual user's uid and
-gid. A system filter is run as root unless &%system_filter_user%& is set.
.next
A process that is testing addresses (the &%-bt%& option) runs as root so that
the routing is done in the same environment as a message delivery.
.cindex "security" "data sources"
.cindex "security" "regular expressions"
.cindex "regular expressions" "security"
-.cindex "PCRE" "security"
+.cindex "PCRE2" "security"
If configuration data for Exim can come from untrustworthy sources, there
are some issues to be aware of:
Letting untrusted data provide a regular expression is unwise.
.next
Using &%${match...}%& to apply a fixed regular expression against untrusted
-data may result in pathological behaviour within PCRE. Be aware of what
+data may result in pathological behaviour within PCRE2. Be aware of what
"backtracking" means and consider options for being more strict with a regular
expression. Avenues to explore include limiting what can match (avoiding &`.`&
when &`[a-z0-9]`& or other character class will do), use of atomic grouping and
start of the epoch. The second number is a count of the number of messages
warning of delayed delivery that have been sent to the sender.
-There follow a number of lines starting with a hyphen. These can appear in any
-order, and are omitted when not relevant:
+There follow a number of lines starting with a hyphen.
+These contain variables, can appear in any
+order, and are omitted when not relevant.
+
+If there is a second hyphen after the first,
+the corresponding data is tainted.
+If there is a value in parentheses, the data is quoted for a lookup.
+
+The following word specifies a variable,
+and the remainder of the item depends on the variable.
.vlist
.vitem "&%-acl%&&~<&'number'&>&~<&'length'&>"
certificate.
.endlist
-Any of the above may have an extra hyphen prepended, to indicate the the
-corresponding data is untrusted.
-
Following the options there is a list of those addresses to which the message
is not to be delivered. This set of addresses is initialized from the command
line when the &%-t%& option is used and &%extract_addresses_remove_arguments%&
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "DKIM, SPF and DMARC" "CHAPdkim" &&&
- "DKIM, SPF and DMARC Support"
+.chapter "DKIM, SPF, SRS and DMARC" "CHAPdkim" &&&
+ "DKIM, SPF, SRS and DMARC Support"
.section "DKIM (DomainKeys Identified Mail)" SECDKIM
.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 6376.
+DKIM is documented in &url(https://www.rfc-editor.org/rfc/rfc6376,RFC 6376).
As DKIM relies on the message being unchanged in transit, messages handled
by a mailing-list (which traditionally adds to the message) will not match
.olist
Signing outgoing messages: This function is implemented in the SMTP transport.
It can co-exist with all other Exim features
-(including transport filters)
-except cutthrough delivery.
+(including transport filters) except cutthrough delivery.
+However, signing options may not depend on headers modified by
+routers, the transport or a transport filter.
.next
Verifying signatures in incoming messages: This is implemented by an additional
ACL (acl_smtp_dkim), which can be called several times per message, with
senders).
-.section "Signing outgoing messages" "SECDKIMSIGN"
-.cindex "DKIM" "signing"
+.subsection "Signing outgoing messages" SECDKIMSIGN
+.cindex DKIM signing
For signing to be usable you must have published a DKIM record in DNS.
-Note that RFC 8301 (which does not cover EC keys) says:
+Note that &url(https://www.rfc-editor.org/rfc/rfc8301,RFC 8301)
+(which does not cover EC keys) says:
.code
rsa-sha1 MUST NOT be used for signing or verifying.
Signing is enabled by setting private options on the SMTP transport.
These options take (expandable) strings as arguments.
-.option dkim_domain smtp string list&!! unset
+.option dkim_domain smtp "string list&!!" unset
The domain(s) you want to sign with.
After expansion, this can be a list.
Each element in turn,
lowercased,
+.vindex "&$dkim_domain$&"
is put into the &%$dkim_domain%& expansion variable
while expanding the remaining signing options.
If it is empty after expansion, DKIM signing is not done,
and no error will result even if &%dkim_strict%& is set.
-.option dkim_selector smtp string list&!! unset
+.option dkim_selector smtp "string list&!!" unset
This sets the key selector string.
After expansion, which can use &$dkim_domain$&, this can be a list.
Each element in turn is put in the expansion
+.vindex "&$dkim_selector$&"
variable &%$dkim_selector%& which may be used in the &%dkim_private_key%&
option along with &%$dkim_domain%&.
If the option is empty after expansion, DKIM signing is not done for this domain,
and no error will result even if &%dkim_strict%& is set.
+To do, for example, dual-signing with RSA and EC keys
+this could be be used:
+.code
+dkim_selector = ec_sel : rsa_sel
+dkim_private_key = KEYS_DIR/$dkim_selector
+.endd
+
.option dkim_private_key smtp string&!! unset
This sets the private key to use.
You can use the &%$dkim_domain%& and
openssl genrsa -out dkim_rsa.private 2048
openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM
.endd
-The result file from the first command should be retained, and
-this option set to use it.
+The result file from the first command should be retained,
+permissions set so that Exim can read it,
+and this option set to use it.
Take the base-64 lines from the output of the second command, concatenated,
for the DNS TXT record.
-See section 3.6 of RFC6376 for the record specification.
+See section 3.6 of &url(https://www.rfc-editor.org/rfc/rfc6376,RFC 6376)
+for the record specification.
Under GnuTLS:
.code
certtool --load-privkey=dkim_rsa.private --pubkey-info
.endd
-Note that RFC 8301 says:
+Note that &url(https://www.rfc-editor.org/rfc/rfc8301,RFC 8301) says:
.code
Signers MUST use RSA keys of at least 1024 bits for all keys.
Signers SHOULD use RSA keys of at least 2048 bits.
.endd
-EC keys for DKIM are defined by RFC 8463.
+EC keys for DKIM are defined by
+&url(https://www.rfc-editor.org/rfc/rfc8463,RFC 8463).
They are considerably smaller than RSA keys for equivalent protection.
As they are a recent development, users should consider dual-signing
(by setting a list of selectors, and an expansion for this option)
&`sha512`& &-- possibly more secure but less well supported
.endlist
-Note that RFC 8301 says:
+Note that &url(https://www.rfc-editor.org/rfc/rfc8301,RFC 8301) says:
.code
rsa-sha1 MUST NOT be used for signing or verifying.
.endd
.option dkim_sign_headers smtp string&!! "see below"
If set, this option must expand to a colon-separated
list of header names.
-Headers with these names, or the absence or such a header, will be included
+Headers with these names, or the absence of such a header, will be included
in the message signature.
-When unspecified, the header names listed in RFC4871 will be used,
+When unspecified, the header names listed in
+&url(https://www.rfc-editor.org/rfc/rfc4871,RFC 4871) will be used,
whether or not each header is present in the message.
The default list is available for the expansion in the macro
&"_DKIM_SIGN_HEADERS"&
-.new
and an oversigning variant is in &"_DKIM_OVERSIGN_HEADERS"&.
-.wen
If a name is repeated, multiple headers by that name (or the absence thereof)
will be signed. The textually later headers in the headers part of the
.option dkim_timestamps smtp integer&!! unset
This option controls the inclusion of timestamp information in the signature.
If not set, no such information will be included.
-Otherwise, must be an unsigned number giving an offset in seconds from the current time
-for the expiry tag
-(eg. 1209600 for two weeks);
-both creation (t=) and expiry (x=) tags will be included.
+Otherwise, must be an unsigned number giving an offset in seconds from the
+current time for the expiry tag (e.g. 1209600 for two weeks); both creation
+(t=) and expiry (x=) tags will be included unless the offset is 0 (no expiry).
-RFC 6376 lists these tags as RECOMMENDED.
+&url(https://www.rfc-editor.org/rfc/rfc6376,RFC 6376)
+lists these tags as RECOMMENDED.
-.section "Verifying DKIM signatures in incoming mail" "SECDKIMVFY"
-.cindex "DKIM" "verification"
+.subsection "Verifying DKIM signatures in incoming mail" SECDKIMVFY
+.cindex DKIM verification
Verification of DKIM signatures in SMTP incoming email is done for all
messages for which an ACL control &%dkim_disable_verify%& has not been set.
+
.cindex DKIM "selecting signature algorithms"
-Individual classes of signature algorithm can be ignored by changing
+Individual classes of DKIM signature algorithm can be ignored by changing
the main options &%dkim_verify_hashes%& or &%dkim_verify_keytypes%&.
The &%dkim_verify_minimal%& option can be set to cease verification
processing for a message once the first passing signature is found.
of this section can be ignored.
The results of verification are made available to the
-&%acl_smtp_dkim%& ACL, which can examine and modify them.
+&%acl_smtp_dkim%& ACL, which (for complex needs) can examine and modify them.
A missing ACL definition defaults to accept.
By default, the ACL is called once for each
syntactically(!) correct signature in the incoming message.
&%dkim_verify_signers%& (see above).
.vitem &%$dkim_verify_status%&
+So long as a DKIM ACL is defined
+(it need do no more than accept, which is the default),
+after all the DKIM ACL runs have completed, the value becomes a
+colon-separated list of the values after each run.
+The value is maintained for the MIME, PRDR and DATA ACLs.
+
Within the DKIM ACL,
a string describing the general status of the signature. One of
.ilist
set dkim_verify_reason = hash too weak or key too short
.endd
-So long as a DKIM ACL is defined (it need do no more than accept),
-after all the DKIM ACL runs have completed, the value becomes a
-colon-separated list of the values after each run.
-This is maintained for the mime, prdr and data ACLs.
-
.vitem &%$dkim_verify_reason%&
A string giving a little bit more detail when &%$dkim_verify_status%& is either
"fail" or "invalid". One of
The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
for EC keys.
-Note that RFC 8301 says:
+Note that &url(https://www.rfc-editor.org/rfc/rfc8301,RFC 8301) says:
.code
rsa-sha1 MUST NOT be used for signing or verifying.
.vitem &%$dkim_copiedheaders%&
A transcript of headers and their values which are included in the signature
(copied from the 'z=' tag of the signature).
-Note that RFC6376 requires that verification fail if the From: header is
+Note that &url(https://www.rfc-editor.org/rfc/rfc6376,RFC 6376)
+requires that verification fail if the From: header is
not included in the signature. Exim does not enforce this; sites wishing
strict enforcement should code the check explicitly.
.vitem &%$dkim_key_length%&
Number of bits in the key.
-.new
Valid only once the key is loaded, which is at the time the header signature
is verified, which is after the body hash is.
-.wen
-Note that RFC 8301 says:
+Note that &url(https://www.rfc-editor.org/rfc/rfc8301,RFC 8301) says:
.code
Verifiers MUST NOT consider signatures using RSA keys of
less than 1024 bits as valid signatures.
.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 &%$dkim_cur_signer%&). This is typically used to restrict an ACL
+(reflected by &%$dkim_cur_signer%&).
+This condition is only usable in a DKIM ACL.
+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 gmail signature
-warn log_message = GMail sender without gmail.com DKIM signature
- sender_domains = gmail.com
+warn sender_domains = gmail.com
dkim_signers = gmail.com
dkim_status = none
+ log_message = GMail sender without gmail.com DKIM signature
.endd
Note that the above does not check for a total lack of DKIM signing;
.vitem &%dkim_status%&
ACL condition that checks a colon-separated list of possible DKIM verification
-results against the actual result of verification. This is typically used
+results against the actual result of verification,
+given by &$dkim_verify_status$& if that is non-empty or "none" if empty.
+This condition may be used in DKIM, MIME, PRDR and DATA ACLs.
+
+A basic verification might be:
+.code
+deny !dkim_status = pass:none:invalid
+.endd
+
+A more complex use could be
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
+deny sender_domains = paypal.com:paypal.de
dkim_signers = paypal.com:paypal.de
dkim_status = none:invalid:fail
+ message = Mail from Paypal with invalid/missing signature
.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.
+
+The condition is true if the status
+(or any of the list of status values)
+is any one of the supplied list.
.endlist
.cindex SPF verification
SPF is a mechanism whereby a domain may assert which IP addresses may transmit
-messages with its domain in the envelope from, documented by RFC 7208.
+messages with its domain in the envelope from, documented by
+&url(https://www.rfc-editor.org/rfc/rfc7208,RFC 7208).
For more information on SPF see &url(http://www.open-spf.org), a static copy of
the &url(http://openspf.org).
. --- 2019-10-28: still not https, open-spf.org is told to be a
SPF verification support is built into Exim if SUPPORT_SPF=yes is set in
&_Local/Makefile_&. The support uses the &_libspf2_& library
&url(https://www.libspf2.org/).
+.new
+.cindex "dynamic modules"
+The support can be built as a dynamic-load module if desired;
+see the comments in that Makefile.
+.wen
+
There is no Exim involvement in the transmission of messages;
publishing certain DNS records is all that is required.
.vitem &%temperror%&
This indicates a temporary error during all processing, including Exim's
SPF processing. You may defer messages when this occurs.
+
+.vitem &%invalid%&
+There was an error during processing of the SPF lookup
.endlist
You can prefix each string with an exclamation mark to invert
message = $sender_host_address is not allowed to send mail from \
${if def:sender_address_domain \
{$sender_address_domain}{$sender_helo_name}}. \
- Please see http://www.open-spf.org/Why?scope=\
- ${if def:sender_address_domain {mfrom}{helo}};\
+ Please see http://www.open-spf.org/Why;\
identity=${if def:sender_address_domain \
{$sender_address}{$sender_helo_name}};\
ip=$sender_host_address
.endd
+Note: The above mentioned URL may not be as helpful as expected. You are
+encouraged to replace the link with a link to a site with more
+explanations.
+
When the spf condition has run, it sets up several expansion
variables:
.vitem &$spf_received$&
.vindex &$spf_received$&
- This contains a complete Received-SPF: header that can be
- added to the message. Please note that according to the SPF
- draft, this header must be added at the top of the header
- list. Please see section 10 on how you can do this.
+ This contains a complete Received-SPF: header (name and
+ content) that can be added to the message. Please note that
+ according to the SPF draft, this header must be added at the
+ top of the header list, i.e. with
+.code
+add_header = :at_start:$spf_received
+.endd
+ See section &<<SECTaddheadacl>>& for further details.
Note: in case of "Best-guess" (see below), the convention is
to put this string in a header called X-SPF-Guess: instead.
.vitem &$spf_result$&
.vindex &$spf_result$&
This contains the outcome of the SPF check in string form,
- one of pass, fail, softfail, none, neutral, permerror or
- temperror.
+ currently one of pass, fail, softfail, none, neutral, permerror,
+ temperror, or &"(invalid)"&.
.vitem &$spf_result_guessed$&
.vindex &$spf_result_guessed$&
.vitem &$spf_smtp_comment$&
.vindex &$spf_smtp_comment$&
+.vindex &%spf_smtp_comment_template%&
This contains a string that can be used in a SMTP response
to the calling party. Useful for "fail".
+ The string is generated by the SPF library from the template configured in the main config
+ option &%spf_smtp_comment_template%&.
.endlist
-.section "SRS (Sender Rewriting Scheme)" SECTSRS
+.subsection "SRS (Sender Rewriting Scheme)" SECTSRS
.cindex SRS "sender rewriting scheme"
+.cindex VERP "variable envelope return path"
-.new
SRS can be used to modify sender addresses when forwarding so that
SPF verification does not object to them.
-It operates by encoding the original envelope sender in a new
+It can also be used to identify a received bounce message as
+likely (or not) having been trigged by a message from the
+local system, and for identifying dead addresses in mailing lists.
+It is one implementation of a VERP (Variable Envelope Return Path) method.
+
+SRS operates by encoding the original envelope sender in a new
sender local part and using a domain run by the forwarding site
as the new domain for the sender. Any DSN message should be returned
to this new sender at the forwarding site, which can extract the
encoded.
The second argument should be given as the envelope sender address before this
encoding operation.
+If this value is empty the the expansion result will be empty.
The third argument should be the recipient domain of the message when
it arrived at this system.
+All arguments are expanded before use.
+
+The result of the expansion is the replacement envelope-from (return path)
+to be used.
.endlist
.cindex SRS decoding
To decode an address use this expansion condition:
.vlist
.vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*&
-The first argument should be the recipient local prt as is was received.
+The first argument should be the recipient local part as it was received.
The second argument is the site secret.
+Both arguments are expanded before use.
If the messages is not for an SRS-encoded recipient the condition will
-return false. If it is, the condition will return true and the variable
+return false.
+If it is, the condition will return true and the variable
&$srs_recipient$& will be set to the decoded (original) value.
+
+If the second argument is empty then the condition returns true if
+the first argument is in valid SRS formet, else false.
+The variable &$srs_recipient$& is not set for this case.
.endlist
Example usage:
.code
#macro
SRS_SECRET = <pick something unique for your site for this. Use on all MXs.>
-
+
#routers
outbound:
transport = ${if eq {$local_part@$domain} \
{$original_local_part@$original_domain} \
{remote_smtp} {remote_forwarded_smtp}}
-
+
inbound_srs:
driver = redirect
senders = :
# detect inbound bounces which are SRS'd, and decode them
condition = ${if inbound_srs {$local_part} {SRS_SECRET}}
data = $srs_recipient
-
+
inbound_srs_failure:
driver = redirect
senders = :
allow_fail
data = :fail: Invalid SRS recipient address
- #... further routers here
+ #... further routers here get inbound_srs-redirected recipients
+ # and any that were not SRS'd
+
-
# transport; should look like the non-forward outbound
# one, plus the max_rcpt and return_path options
remote_forwarded_smtp:
driver = smtp
- # modify the envelope from, for mails that we forward
+ # single-recipient so that $original_domain is valid
max_rcpt = 1
+ # modify the envelope from, for mails that we forward
return_path = ${srs_encode {SRS_SECRET} {$return_path} {$original_domain}}
.endd
-.wen
DMARC combines feedback from SPF, DKIM, and header From: in order
to attempt to provide better indicators of the authenticity of an
email. This document does not explain the fundamentals; you
-should read and understand how it works by visiting the website at
-&url(http://www.dmarc.org/).
+should read and understand how it works by visiting the
+&url(http://www.dmarc.org/,DMARC website).
If Exim is built with DMARC support,
the libopendmarc library is used.
For building Exim yourself, obtain the library from
-&url(http://sourceforge.net/projects/opendmarc/)
+&url(http://sourceforge.net/projects/opendmarc/,sourceforge)
to obtain a copy, or find it in your favorite package
repository. You will need to attend to the local/Makefile feature
SUPPORT_DMARC and the associated LDFLAGS addition.
that headers will be in /usr/local/include, and that the libraries
are in /usr/local/lib.
-. subsection
+.subsection Configuration SSECDMARCCONFIG
+.cindex DMARC configuration
There are three main-configuration options:
.cindex DMARC "configuration options"
the most current version can be downloaded
from a link at &url(https://publicsuffix.org/list/public_suffix_list.dat).
See also the util/renew-opendmarc-tlds.sh script.
-.new
The default for the option is unset.
If not set, DMARC processing is disabled.
-.wen
The &%dmarc_history_file%& option, if set
the dsn_from option, and <> is used for the
envelope from.
-. I wish we had subsections...
-
+.subsection Controls SSECDMARCCONTROLS
.cindex DMARC controls
+
By default, the DMARC processing will run for any remote,
non-authenticated user. It makes sense to only verify DMARC
status of messages coming from remote, untrusted sources. You can
There are no options to either control. Both must appear before
the DATA acl.
-. subsection
+.subsection ACL SSECDMARCACL
+.cindex DMARC "ACL condition"
-DMARC checks cam be run on incoming SMTP messages by using the
+DMARC checks can be run on incoming SMTP messages by using the
&"dmarc_status"& ACL condition in the DATA ACL. You are required to
call the &"spf"& condition first in the ACLs, then the &"dmarc_status"&
condition. Putting this condition in the ACLs is required in order
right-hand side. These strings describe recommended action based
on the DMARC check. To understand what the policy recommendations
mean, refer to the DMARC website above. Valid strings are:
-.display
-&'accept '& The DMARC check passed and the library recommends accepting the email.
-&'reject '& The DMARC check failed and the library recommends rejecting the email.
-&'quarantine '& The DMARC check failed and the library recommends keeping it for further inspection.
-&'none '& The DMARC check passed and the library recommends no specific action, neutral.
-&'norecord '& No policy section in the DMARC record for this sender domain.
-&'nofrom '& Unable to determine the domain of the sender.
-&'temperror '& Library error or dns error.
-&'off '& The DMARC check was disabled for this email.
-.endd
+.itable none 0 0 2 20* left 80* left
+.irow &'accept'& "The DMARC check passed and the library recommends accepting the email"
+.irow &'reject'& "The DMARC check failed and the library recommends rejecting the email"
+.irow &'quarantine'& "The DMARC check failed and the library recommends keeping it for further inspection"
+.irow &'none'& "The DMARC check passed and the library recommends no specific action, neutral"
+.irow &'norecord'& "No policy section in the DMARC record for this RFC5322.From field"
+.irow &'nofrom'& "Unable to determine the domain of the sender"
+.irow &'temperror'& "Library error or dns error"
+.irow &'off'& "The DMARC check was disabled for this email"
+.endtable
You can prefix each string with an exclamation mark to invert its
meaning, for example "!accept" will match all results but
"accept". The string list is evaluated left-to-right in a
The policy declared in the DMARC record. Valid values
are "none", "reject" and "quarantine". It is blank when there
is any error, including no DMARC record.
+
+.new
+.vitem &$dmarc_alignment_spf$&
+.vindex &$dmarc_alignment_spf$&
+The result of the SPF alignment portion of the test status;
+"yes" or "no".
+
+.vitem &$dmarc_alignment_dkim$&
+.vindex &$dmarc_alignment_dkim$&
+The result of the DKIM alignment portion of the test status;
+"yes" or "no".
+.wen
.endlist
-. subsection
+.subsection Logging SSECDMARCLOGGING
+.cindex DMARC logging
By default, Exim's DMARC configuration is intended to be
non-intrusive and conservative. To facilitate this, Exim will not
enable sending DMARC forensic reports
.endlist
-. subsection
+.subsection Example SSECDMARCEXAMPLE
+.cindex DMARC example
Example usage:
.code
The Proxy Protocol header is the first data received on a TCP connection
and is inserted before any TLS-on-connect handshake from the client; Exim
negotiates TLS between Exim-as-server and the remote client, not between
-Exim and the proxy server.
+Exim and the proxy server. The Proxy Protocol header must be received
+within &%proxy_protocol_timeout%&, which defaults to 3s.
The following expansion variables are usable
(&"internal"& and &"external"& here refer to the interfaces
of the proxy):
-.display
-&'proxy_external_address '& IP of host being proxied or IP of remote interface of proxy
-&'proxy_external_port '& Port of host being proxied or Port on remote interface of proxy
-&'proxy_local_address '& IP of proxy server inbound or IP of local interface of proxy
-&'proxy_local_port '& Port of proxy server inbound or Port on local interface of proxy
-&'proxy_session '& boolean: SMTP connection via proxy
-.endd
+.itable none 0 0 2 30* left 70* left
+.irow $proxy_external_address "IP of host being proxied or IP of remote interface of proxy"
+.irow $proxy_external_port "Port of host being proxied or Port on remote interface of proxy"
+.irow $proxy_local_address "IP of proxy server inbound or IP of local interface of proxy"
+.irow $proxy_local_port "Port of proxy server inbound or Port on local interface of proxy"
+.irow $proxy_session "boolean: SMTP connection via proxy"
+.endtable
If &$proxy_session$& is set but &$proxy_external_address$& is empty
there was a protocol error.
The variables &$sender_host_address$& and &$sender_host_port$&
# Or do some kind of IP lookup in a flat file or database
# LIMIT = ${lookup{$sender_host_address}iplsearch{/etc/exim/proxy_limits}}
- defer message = Too many connections from this IP right now
- ratelimit = LIMIT / 5s / per_conn / strict
+ defer ratelimit = LIMIT / 5s / per_conn / strict
+ message = Too many connections from this IP right now
.endd
.cindex proxy SOCKS
.cindex SOCKS proxy
Exim has support for sending outbound SMTP via a proxy
-using a protocol called SOCKS5 (defined by RFC1928).
+using a protocol called SOCKS5 (defined by
+&url(https://www.rfc-editor.org/rfc/rfc1928,RFC 1928)).
The support can be optionally included by defining SUPPORT_SOCKS=yes in
Local/Makefile.
Use of a proxy is enabled by setting the &%socks_proxy%& option
on an smtp transport.
-The option value is expanded and should then be a list
+.new
+If unset (or empty after expansion) then proxying is not done.
+.wen
+Otherwise, expansion should result in a list
(colon-separated by default) of proxy specifiers.
Each proxy specifier is a list
(space-separated by default) where the initial element
is an IP address and any subsequent elements are options.
-Options are a string <name>=<value>.
+Each option is a string of form <name>=<value>.
The list of options is in the following table:
-.display
-&'auth '& authentication method
-&'name '& authentication username
-&'pass '& authentication password
-&'port '& tcp port
-&'tmo '& connection timeout
-&'pri '& priority
-&'weight '& selection bias
-.endd
+.itable none 0 0 2 10* left 90* left
+.irow &'auth'& "authentication method"
+.irow &'name'& "authentication username"
+.irow &'pass'& "authentication password"
+.irow &'port'& "tcp port"
+.irow &'tmo'& "connection timeout"
+.irow &'pri'& "priority"
+.irow &'weight'& "selection bias"
+.endtable
More details on each of these options follows:
.cindex authentication "to proxy"
.cindex proxy authentication
&%auth%&: Either &"none"& (default) or &"name"&.
-Using &"name"& selects username/password authentication per RFC 1929
+Using &"name"& selects username/password authentication per
+&url(https://www.rfc-editor.org/rfc/rfc1929,RFC 1929)
for access to the proxy.
Default is &"none"&.
.next
Exim has support for Internationalised mail names.
To include this it must be built with SUPPORT_I18N and the libidn library.
-Standards supported are RFCs 2060, 5890, 6530 and 6533.
+Standards supported are RFCs
+&url(https://www.rfc-editor.org/rfc/rfc2060.html,2060),
+&url(https://www.rfc-editor.org/rfc/rfc5890.html,5890),
+&url(https://www.rfc-editor.org/rfc/rfc6530.html,6530) and
+&url(https://www.rfc-editor.org/rfc/rfc6533.html,6533).
If Exim is built with SUPPORT_I18N_2008 (in addition to SUPPORT_I18N, not
instead of it) then IDNA2008 is supported; this adds an extra library
but could be used for any message.
If a value is appended it may be:
-.display
-&`1 `& mandatory downconversion
-&`0 `& no downconversion
-&`-1 `& if SMTPUTF8 not supported by destination host
-.endd
+.itable none 0 0 2 5* right 95* left
+.irow &`1`& "mandatory downconversion"
+.irow &`0`& "no downconversion"
+.irow &`-1`& "if SMTPUTF8 not supported by destination host"
+.endtable
If no value is given, 1 is used.
If mua_wrapper is set, the utf8_downconvert control
the "headers charset" command (in a filter file)
or &%headers_charset%& main configuration option (otherwise),
to the
-modified UTF-7 encoding specified by RFC 2060,
+modified UTF-7 encoding specified by
+&url(https://www.rfc-editor.org/rfc/rfc2060.html,RFC 2060),
with the following exception: All occurrences of <sep>
(which has to be a single character)
are replaced with periods ("."), and all periods and slashes that are not
.new
The current list of events is:
+.itable all 0 0 4 25* left 10* center 15* center 50* left
+.row auth:fail after both "per driver per authentication attempt"
+.row dane:fail after transport "per connection"
+.row dns:fail after both "per lookup"
+.row msg:complete after main "per message"
+.row msg:defer after transport "per message per delivery try"
+.row msg:delivery after transport "per recipient"
+.row msg:rcpt:host:defer after transport "per recipient per host"
+.row msg:rcpt:defer after transport "per recipient"
+.row msg:host:defer after transport "per host per delivery try; host errors"
+.row msg:fail:delivery after transport "per recipient"
+.row msg:fail:internal after main "per recipient"
+.row tcp:connect before transport "per connection"
+.row tcp:close after transport "per connection"
+.row tls:cert before both "per certificate in verification chain"
+.row tls:fail:connect after main "per connection"
+.row smtp:connect after transport "per connection"
+.row smtp:ehlo after transport "per connection"
+.row smtp:fail:protocol after main "per connection"
+.row smtp:fail:syntax after main "per connection"
+.endtable
.wen
-.display
-&`dane:fail after transport `& per connection
-&`msg:complete after main `& per message
-&`msg:defer after transport `& per message per delivery try
-&`msg:delivery after transport `& per recipient
-&`msg:rcpt:host:defer after transport `& per recipient per host
-&`msg:rcpt:defer after transport `& per recipient
-&`msg:host:defer after transport `& per host per delivery try; host errors
-&`msg:fail:delivery after transport `& per recipient
-&`msg:fail:internal after main `& per recipient
-&`tcp:connect before transport `& per connection
-&`tcp:close after transport `& per connection
-&`tls:cert before both `& per certificate in verification chain
-&`smtp:connect after transport `& per connection
-&`smtp:ehlo after transport `& per connection
-.endd
New event types may be added in future.
The event name is a colon-separated list, defining the type of
An additional variable, &$event_data$&, is filled with information varying
with the event type:
-.display
-&`dane:fail `& failure reason
-&`msg:defer `& error string
-&`msg:delivery `& smtp confirmation message
-&`msg:fail:internal `& failure reason
-&`msg:fail:delivery `& smtp error message
-&`msg:host:defer `& error string
-&`msg:rcpt:host:defer `& error string
-&`msg:rcpt:defer `& error string
-&`tls:cert `& verification chain depth
-&`smtp:connect `& smtp banner
-&`smtp:ehlo `& smtp ehlo response
-.endd
+.new
+.itable all 0 0 2 20* left 80* left
+.row auth:fail "smtp response"
+.row dane:fail "failure reason"
+.row dns:fail "failure reason, key and lookup-type"
+.row msg:defer "error string"
+.row msg:delivery "smtp confirmation message"
+.row msg:fail:internal "failure reason"
+.row msg:fail:delivery "smtp error message"
+.row msg:host:defer "error string"
+.row msg:rcpt:host:defer "error string"
+.row msg:rcpt:defer "error string"
+.row tls:cert "verification chain depth"
+.row tls:fail:connect "error string"
+.row smtp:connect "smtp banner"
+.row smtp:ehlo "smtp ehlo response"
+.row smtp:fail:protocol "error string"
+.row smtp:fail:syntax "error string"
+.endtable
+.wen
The :defer events populate one extra variable: &$event_defer_errno$&.
-For complex operations an ACL expansion can be used in &%event_action%&
+For complex operations an ACL expansion can be used in &%event_action%&,
however due to the multiple contexts that Exim operates in during
the course of its processing:
.ilist
The expansion of the event_action option should normally
return an empty string. Should it return anything else the
following will be forced:
-.display
-&`tcp:connect `& do not connect
-&`tls:cert `& refuse verification
-&`smtp:connect `& close connection
-.endd
+.itable all 0 0 2 20* left 80* left
+.row auth:fail "log information to write"
+.row tcp:connect "do not connect"
+.row tls:cert "refuse verification"
+.row smtp:connect "close connection"
+.endtable
All other message types ignore the result string, and
no other use is made of it.
For a tcp:connect event, if the connection is being made to a proxy
-then the address and port variables will be that of the proxy and not
-the target system.
+then the &$host_address$& and &$host_port$& variables
+will be that of the proxy and not the target system.
For tls:cert events, if GnuTLS is in use this will trigger only per
chain element received on the connection.
For OpenSSL it will trigger for every chain element including those
loaded locally.
+For dns:fail events from dnsdb lookups, a &"defer_never"& option does not
+affect the reporting of DNS_AGAIN.
+
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
git://git.exim.org / exim.git / blobdiff