. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.94"
+.set previousversion "4.96"
.include ./local_params
.set ACL "access control lists (ACLs)"
.set I " "
+.set drivernamemax "64"
+
.macro copyyear
-2020
+2022
.endmacro
. /////////////////////////////////////////////////////////////////////////////
.itable none 0 0 2 $1 left $2 left
.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
+. --- and including the .vitem and .vindex
+.macro tvar
+.vitem $1
+.vindex $1
+.tmark
+.endmacro
+
. --- A macro that generates .row, but puts &I; at the start of the first
. --- argument, thus indenting it. Assume a minimum of two arguments, and
. --- allow up to four arguments, which is as many as we'll ever need.
</revision></revhistory>
<copyright><year>
.copyyear
- </year><holder>University of Cambridge</holder></copyright>
+ </year><holder>The Exim Maintainers</holder></copyright>
</bookinfo>
.literal off
.chapter "Incorporated code" "CHID2"
.cindex "incorporated code"
.cindex "regular expressions" "library"
-.cindex "PCRE"
+.cindex "PCRE2"
.cindex "OpenDMARC"
A number of pieces of external code are included in the Exim distribution.
.ilist
Regular expressions are supported in the main Exim program and in the
-Exim monitor using the freely-distributable PCRE library, copyright
-© University of Cambridge. The source to PCRE is no longer shipped with
-Exim, so you will need to use the version of PCRE shipped with your system,
+Exim monitor using the freely-distributable PCRE2 library, copyright
+© University of Cambridge. The source to PCRE2 is not longer shipped with
+Exim, so you will need to use the version of PCRE2 shipped with your system,
or obtain and install the full version of the library from
-&url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre).
+&url(https://github.com/PhilipHazel/pcre2/releases).
.next
.cindex "cdb" "acknowledgment"
Support for the cdb (Constant DataBase) lookup method is provided by code
.next
If the &%domains%& option is set, the domain of the address must be in the set
of domains that it defines.
-.new
.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using router domains option"
A match verifies the variable &$domain$& (which carries tainted data)
and assigns an untainted value to the &$domain_data$& variable.
Such an untainted value is often needed in the transport.
When an untainted value is wanted, use this option
rather than the generic &%condition%& option.
-.wen
.next
.vindex "&$local_part_prefix$&"
.cindex affix "router precondition"
If the &%local_parts%& option is set, the local part of the address must be in
the set of local parts that it defines.
-.new
A match verifies the variable &$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.
When an untainted value is wanted, use this option
rather than the generic &%condition%& option.
-.wen
If &%local_part_prefix%& or
&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
uses an expanded string to allow you to set up your own custom preconditions.
Expanded strings are described in chapter &<<CHAPexpand>>&.
-.new
Note that while using
this option for address matching technically works,
it does not set any de-tainted values.
for transport options.
Using the &%domains%& and &%local_parts%& options is usually the most
convenient way to obtain them.
-.wen
.endlist
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"
.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
.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.
+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 = -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
+.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
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 1pt left 1pt 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`&
.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%&"
by Exim in conjunction with the &%-MC%& option. It signifies that a
remote host supports the ESMTP &_CHUNKING_& extension.
+.vitem &%-MCL%&
+.oindex "&%-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.
+
.vitem &%-MCP%&
.oindex "&%-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 &%-MCp%&
+.oindex "&%-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.
+
.vitem &%-MCQ%&&~<&'process&~id'&>&~<&'pipe&~fd'&>
.oindex "&%-MCQ%&"
This option is not intended for use by external callers. It is used internally
signals the final completion of the sequence of processes that are passing
messages through the same SMTP connection.
-.new
.vitem &%-MCq%&&~<&'recipient&~address'&>&~<&'size'&>
.oindex "&%-MCq%&"
This option is not intended for use by external callers. It is used internally
by Exim to implement quota checking for local users.
-.wen
.vitem &%-MCS%&
.oindex "&%-MCS%&"
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
host to which Exim is connected supports TLS encryption.
-.new
.vitem &%-MCr%&&~<&'SNI'&> &&&
&%-MCs%&&~<&'SNI'&>
.oindex "&%-MCs%&"
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.
-.wen
.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
.oindex "&%-MCt%&"
.vitem &%-m%&
.oindex "&%-m%&"
-This is apparently a synonym for &%-om%& that is accepted by Sendmail, so Exim
-treats it that way too.
+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%&"
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.
-.new
.vitem &%-oY%&
.oindex &%-oY%&
.cindex "daemon notifier socket"
.next
obtaining a current queue size
.endlist
-.wen
.vitem &%-pd%&
.oindex "&%-pd%&"
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"
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
# 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;
.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,
domains = lsearch;/some/file
.endd
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.
In the second example, the lookup is a single item in a domain list. It causes
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 key must be given explicitly.
+
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.
-.new
The lookup type may optionally be followed by a comma
and a comma-separated list of options.
Each option is a &"name=value"& pair.
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.
-.wen
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
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.
.cindex "tainted data" "single-key lookups"
-The file string may not be tainted
+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.
-.cindex "tainted data" "de-tainting"
.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.
+.cindex "tainted data" "quoting for lookups"
+If tainted data is used in the query then it should be quuted 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
IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this
notation before executing the lookup.)
-.new
One option is supported, "ret=full", to request the return of the entire line
-rather than omitting the key porttion.
+rather than omitting the key portion.
Note however that the key portion will have been de-quoted.
-.wen
.next
.cindex lookup json
For elements of type string, the returned value is de-quoted.
-.new
.next
.cindex LMDB
.cindex lookup lmdb
You will need to separately create the LMDB database file,
possibly using the &"mdb_load"& utility.
-.wen
.next
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
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 1pt left 1pt 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
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%&
There are two ways of
specifying the file.
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.
-.wen
A deprecated method is available, prefixing the query with the filename
separated by white space.
A &%local_parts%& router option or &%local_parts%& ACL condition
will store a result in the &$local_part_data$& variable.
.vitem domains
-.new
A &%domains%& router option or &%domains%& ACL condition
-will store a result in the &$domain_data$& variable
-.wen
+will store a result in the &$domain_data$& variable.
.vitem senders
A &%senders%& router option or &%senders%& ACL condition
will store a result in the &$sender_data$& variable.
&$domain_data$& variable and can be referred to in other router options or
other statements in the same ACL.
.cindex "tainted data" "de-tainting"
+.cindex "de-tainting" "using ACL domains condition"
The value will be untainted.
-.new
&*Note*&: If the data result of the lookup (as opposed to the key)
is empty, then this empty value is stored in &$domain_data$&.
The option to return the key for the lookup, as the value,
may be what is wanted.
-.wen
.next
&%domains%& option on a router, the value is preserved in the &$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
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 "=".
+Each item starts with a tag and and equals "=" sign.
.next
.cindex "domain list" "matching literal domain name"
.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.
.cindex "tainted data" definition
.cindex expansion "tainted data"
and expansion of data deriving from the sender (&"tainted data"&)
-.new
is not permitted (including acessing a file using a tainted name).
-.wen
-.new
Common ways of obtaining untainted equivalents of variables with
tainted values
.cindex "tainted data" "de-tainting"
or the password file,
or accessed via a DBMS.
Specific methods are indexed under &"de-tainting"&.
-.wen
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
You can use &`fail`& instead of {<&'string3'&>} as in a string extract.
-.new
.vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*&
.cindex quoting "for list"
.cindex list quoting
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.
-.wen
.vitem "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&&
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:
&*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
This item inserts &"raw"& header lines. It is described with the &%header%&
expansion item in section &<<SECTexpansionitems>>& above.
-.vitem "&*${run{*&<&'command'&>&*&~*&<&'args'&>&*}{*&<&'string1'&>&*}&&&
+.vitem "&*${run <&'options'&> {*&<&'command&~arg&~list'&>&*}{*&<&'string1'&>&*}&&&
{*&<&'string2'&>&*}}*&"
.cindex "expansion" "running a command"
.cindex "&%run%& expansion item"
-The command and its arguments are first expanded as one string. The string is
-split apart into individual arguments by spaces, and then the command is run
+This item runs an external command, as a subprocess.
+One option is supported after the word &'run'&, comma-separated.
+
+If the option &'preexpand'& is not used,
+the command string is split into individual arguments by spaces
+and then each argument is expanded.
+Then the command is run
in a separate process, but under the same uid and gid. As in other command
executions from Exim, a shell is not used by default. If the command requires
a shell, you must explicitly code it.
+The command name may not be tainted, but the remaining arguments can be.
+
+&*Note*&: if tainted arguments are used, they are supplied by a
+potential attacker;
+a careful assessment for security vulnerabilities should be done.
+If the option &'preexpand'& is used,
+the command and its arguments are first expanded as one string. The result is
+split apart into individual arguments by spaces, and then the command is run
+as above.
Since the arguments are split by spaces, when there is a variable expansion
which has an empty result, it will cause the situation that the argument will
simply be omitted when the program is actually executed by Exim. If the
around the command arguments. A possible guard against this is to wrap the
variable in the &%sg%& operator to change any quote marks to some other
character.
+Neither the command nor any argument may be tainted.
The standard input for the command exists, but is empty. The standard output
and standard error are set to the same file descriptor.
-.new
.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*&
SRS encoding. See SECT &<<SECTSRS>>& for details.
-.wen
-.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 &*${escape8bit:*&<&'string'&>&*}*&
.cindex "expansion" "escaping 8-bit characters"
.cindex "&%escape8bit%& expansion item"
-If the string contains and characters with the most significant bit set,
+If the string contains any characters with the most significant bit set,
they are converted to escape sequences starting with a backslash.
Backslashes and DEL characters are also converted.
and selects address-, domain-, host- or localpart- lists to search among respectively.
Otherwise all types are searched in an undefined order and the first
matching list is returned.
+&*Note*&: Neither string-expansion of lists referenced by named-list syntax elements,
+nor expansion of lookup elements, is done by the &%listnamed%& operator.
.vitem &*${local_part:*&<&'string'&>&*}*&
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.
.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 "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 1pt left 1pt 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.
-.new
&*Note:*& Testing a path using this condition is not a sufficient way of
de-tainting it.
Consider using a dsearch lookup.
-.wen
.vitem &*first_delivery*&
.cindex "delivery" "first"
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'&>&*}*& &&&
${if forany{fOo:NeeDLE:bAr}{eqi{$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$& is restored after the if.
+
+
.vitem &*isip&~{*&<&'string'&>&*}*& &&&
&*isip4&~{*&<&'string'&>&*}*& &&&
&*isip6&~{*&<&'string'&>&*}*&
have their local parts matched casefully. Domains are always matched
caselessly.
+The variable &$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.
.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
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$&"
the ACL's as well.
-.vitem &$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$&
.cindex "content scanning" "AV scanner failure"
looked up, the contents of any associated TXT record, and the value from the
main A record. See section &<<SECID204>>& for more details.
-.vitem &$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$&.
.vitem &$domain_data$&
.vindex "&$domain_data$&"
When the &%domains%& condition on a router
-.new
or an ACL
matches a domain
against a list, the match value is copied to &$domain_data$&.
This is an enhancement over previous versions of Exim, when it only
applied to the data read by a lookup.
For details on match values see section &<<SECTlistresults>>& et. al.
-.wen
If the router routes the
address to a transport, the value is available in that transport. If the
This value may be overridden by the &%exim_version%& main config option.
.vitem &$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
deny hosts = net-lsearch;/some/file
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$&
When an address is being routed, or delivered on its own, this
variable contains the local part. When a number of addresses are being
delivered together (for example, multiple RCPT commands in an SMTP
.vindex "&$local_part_data$&"
When the &%local_parts%& condition on a router or ACL
matches a local part list
-.new
the match value is copied to &$local_part_data$&.
This is an enhancement over previous versions of Exim, when it only
applied to the data read by a lookup.
For details on match values see section &<<SECTlistresults>>& et. al.
-.wen
The &%check_local_user%& router option also sets this variable.
This variable contains the number of bytes in the longest line that was
received as part of the message, not counting the line termination
character(s).
-It is not valid if the &%spool_files_wireformat%& option is used.
+It is not valid if the &%spool_wireformat%& option is used.
.vitem &$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$& except that no processing of the
contents of header lines is done.
In the MAIL and RCPT ACLs, the value is zero because at that stage the
message has not yet been received.
-This variable is not valid if the &%spool_files_wireformat%& option is used.
+This variable is not valid if the &%spool_wireformat%& option is used.
.vitem &$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$&
+These variables are used in conjunction with the &%prvscheck%& expansion item,
which is described in sections &<<SECTexpansionitems>>& and
&<<SECTverifyPRVS>>&.
is available in the DATA ACL, the non-SMTP ACL, and while routing and
delivering.
-.vitem &$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$&"
+.tvar &$recipients$&
This variable contains a list of envelope recipients for a message. A comma and
a space separate the addresses in the replacement text. However, the variable
is not generally available, to prevent exposure of Bcc recipients in
When a &%regex%& or &%mime_regex%& ACL condition succeeds,
these variables contain the
captured substrings identified by the regular expression.
+If the subject string was tainted then so will any captured substring.
-.vitem &$reply_address$&
-.vindex "&$reply_address$&"
+.tvar &$reply_address$&
When a message is being processed, this variable contains the contents of the
&'Reply-To:'& header line if one exists and it is not empty, or otherwise the
contents of the &'From:'& header line. Apart from the removal of leading
happens, &$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$&
When a message is received from a remote host that has issued a HELO or EHLO
command, the argument of that command is placed in this variable. It is also
set if HELO or EHLO is used when a message is received using SMTP locally via
is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3).
-.vitem &$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$&, this variable is
which is not the leaf.
-.new
.vitem &$tls_in_resumption$& &&&
&$tls_out_resumption$&
.vindex &$tls_in_resumption$&
.vindex &$tls_out_resumption$&
.cindex TLS resumption
Observability for TLS session resumption. See &<<SECTresumption>>& for details.
-.wen
-.vitem &$tls_in_sni$&
-.vindex "&$tls_in_sni$&"
+.tvar &$tls_in_sni$&
.vindex "&$tls_sni$&"
.cindex "TLS" "Server Name Indication"
.cindex "TLS" SNI
option to a true value. To avoid breaking existing installations, it
defaults to false.
-.new
&*Note*&: This is entirely separate from Exim's tainted-data tracking.
-.wen
.section "Calling Perl subroutines" "SECID86"
.section "Miscellaneous" "SECID96"
.table2
+.row &%add_environment%& "environment variables"
.row &%bi_command%& "to run for &%-bi%& command line option"
.row &%debug_store%& "do extra internal checks"
.row &%disable_ipv6%& "do no IPv6 processing"
+.row &%keep_environment%& "environment variables"
.row &%keep_malformed%& "for broken files &-- should not happen"
.row &%localhost_number%& "for unique message ids in clusters"
.row &%message_body_newlines%& "retain newlines in &$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
.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"
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
.cindex "ESMTP extensions" DSN
DSN extensions (RFC3461) 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.
.code
hosts_connection_nolog = :
.endd
-If the &%smtp_connection%& log selector is not set, this option has no effect.
+.new
+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.
+.wen
+
+
+.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
If the platform supports Linux-style abstract socket names, the result
is used with a nul byte prefixed.
Otherwise,
-.new "if nonempty,"
it should be a full path name and use a directory accessible
to Exim.
-.new
If this option is set as empty,
or the command line &%-oY%& option is used, or
-.wen
the command line uses a &%-oX%& option and does not use &%-oP%&,
then a notifier socket is not created.
The option is available only if Exim has been built with Oracle support.
+.new
+.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.
+.wen
+
.option percent_hack_domains main "domain list&!!" unset
.cindex "&""percent hack""&"
.cindex "source routing" "in email address"
.option pipelining_connect_advertise_hosts main "host list&!!" *
.cindex "pipelining" "early connection"
-.cindex "pipelining" PIPE_CONNECT
-.cindex "ESMTP extensions" 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.
-.new
-The SMTP service extension keyword advertised is &"PIPE_CONNECT"&.
-.wen
+The SMTP service extension keyword advertised is &"PIPECONNECT"&;
+it permits the client to pipeline
+TCP connection and hello command (inclear phase),
+or TLS-establishment and hello command (encrypted phase),
+on later connections to the same host.
.option prdr_enable main boolean false
&%queue_list_requires_admin%& and &%commandline_checks_require_admin%&.
-.new
.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>>&.
-.wen
.option qualify_domain main string "see below"
next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&.
-.new
-.option queue_fast_ramp main boolean false
+.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.
-.wen
.option queue_list_requires_admin main boolean true
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
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
. 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 &&&
+.option "smtp_accept_max_per_connection" main integer&!! 1000 &&&
smtp_accept_max_per_connection
.cindex "SMTP" "limiting incoming message count"
.cindex "limit" "messages per SMTP connection"
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
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"
.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
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
+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
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.
(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 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,
-.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>>&.
-.new
.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.
-.wen
.option tls_try_verify_hosts main "host list&!!" unset
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.
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
holding password data (such as NIS) are supported. If the local part is a local
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
.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.
When a router runs, the strings are evaluated in order,
to create variables which are added to the set associated with
the address.
-.new
This is done immediately after all the preconditions, before the
evaluation of the &%address_data%& option.
-.wen
The variable is set with the expansion of the value.
The variables can be used by the router options
(not including any preconditions)
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
.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 &%rcpt_max%& 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
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 $pipe_addresses
.endd
Two problems arise if you want to use more complicated expansion items to
used to determine the file or directory name for the delivery. Normally, the
contents of &$address_file$& are used in some way in the string expansion.
.endlist
+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.
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 &%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
.cindex "&(pipe)& transport" "environment for command"
.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 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.
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.
+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$& variable will have the
+server's EHLO response.
+The result of the option expansion is included in the key used to store and
+retrieve the TLS session, for session resumption.
+
+Operators of high-load sites may wish to evaluate their logs for indications
+of other destination sites operating load-balancers, and develop a suitable
+expression for this option.
+The smtp:ehlo event and the &$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
TLS session for any host that matches this list.
&%tls_verify_certificates%& should also be set for the transport.
+.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
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
-.new
and &%hosts_require_auth%& permits,
-.wen
Exim will try to transfer the message unauthenticated.
See also chapter &<<CHAPSMTPAUTH>>& for details of authentication.
.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&!!" *
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
so can cause parallel connections to the same host if &%remote_max_parallel%&
-permits this.
+permits this. A value setting of zero disables the limit.
-.new
.option message_linelength_limit smtp integer 998
.cindex "line length" limit
This option sets the maximum line length, in bytes, that the transport
It is generally wise to also check in the data ACL so that messages
received via SMTP can be refused without producing a bounce.
-.wen
.option multi_domain smtp boolean&!! true
&$address_data$&, &$domain_data$&, &$local_part_data$&,
&$host$&, &$host_address$& and &$host_port$&.
-.new
If the connection is DANE-enabled then this option is ignored;
only messages having the domain used for the DANE TLSA lookup are
sent on the connection.
-.wen
.option port smtp string&!! "see below"
.cindex "port" "sending TCP/IP"
transport. For details see section &<<SECTproxySOCKS>>&.
+.option tls_alpn smtp string&!! unset
+.cindex TLS "Application Layer Protocol Names"
+.cindex TLS ALPN
+.cindex ALPN "set name in client"
+If this option is set
+and the TLS library supports ALPN,
+the value given is used.
+
+As of writing no value has been standardised for email use.
+The authors suggest using &"smtp"&.
+
+
+
.option tls_certificate smtp string&!! unset
.cindex "TLS" "client certificate, location of"
.cindex "certificate" "client, location of"
ciphers is a preference order.
-.new
.option tls_resumption_hosts smtp "host list&!!" unset
.cindex TLS resumption
This option controls which connections to use the TLS resumption feature.
See &<<SECTresumption>>& for details.
-.wen
.cindex SNI "setting in client"
.vindex "&$tls_sni$&"
If this option is set
-.new
and the connection is not DANE-validated
-.wen
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
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"
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:
.endd
The lack of colons means that the entire text is sent with the AUTH
command, with the circumflex characters converted to NULs.
-.new
Note that due to the ambiguity of parsing three consectutive circumflex characters
there is no way to provide a password having a leading circumflex.
-.wen
A similar example
The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined
when this happens.
-.new
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.
-.wen
.option client_authz gsasl string&!! unset
.option client_spassword gsasl string&!! unset
-.new
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.
-.wen
If a SCRAM mechanism is being used and this option is set
and correctly sized
Note that this value will depend on the salt and iteration-count
supplied by the server.
The option is expanded before use.
-.new
During the expansion &$auth1$& is set with the client username,
&$auth2$& with the iteration count, and
&$auth3$& with the salt.
plus the calculated salted password value value in &$auth4$&,
during the expansion of the &%client_set_id%& option.
A side-effect of this expansion can be used to prime the cache.
-.wen
.option server_channelbinding gsasl boolean false
. Do not plan to rely upon this feature for security, ever, without consulting
. with a subject matter expert (a cryptographic engineer).
-.new
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.
-.wen
.option server_hostname gsasl string&!! "see below"
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.
-.new
.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.
-.wen
.endlist
.endd
-.new
.section "Caching of static server configuration items" "SECTserverTLScache"
.cindex certificate caching
.cindex privatekey caching
Caching of the system Certificate Authorities bundle can
save siginificant time and processing on every TLS connection
accepted by Exim.
-.wen
The &%tls_verify_cert_hostnames%& option lists hosts for which additional
name checks are made on the server certificate.
-.new
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.
-.wen
The option defaults to always checking.
The &(smtp)& transport has two OCSP-related options:
-.new
.section "Caching of static client configuration items" "SECTclientTLScache"
.cindex certificate caching
.cindex privatekey caching
Caching of the system Certificate Authorities bundle can
save siginificant time and processing on every TLS connection
initiated by Exim.
-.wen
only point of caution. The &$tls_out_sni$& variable will be set to this string
for the lifetime of the client connection (including during authentication).
-.new
If DANE validated the connection attempt then the value of the &%tls_sni%& option
-is forced to the domain part of the recipient address.
-.wen
+is forced to the name of the destination host, after any MX- or CNAME-following.
Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string
received from a client.
0.5.10. (Its presence predates the current API which Exim uses, so if Exim
built, then you have SNI support).
+.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 misirected 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 behavious 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" &&&
.section "Certificate chains" "SECID186"
-The file named by &%tls_certificate%& may contain more than one
+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.
.ecindex IIDencsmtp2
-.new
.section "TLS Resumption" "SECTresumption"
.cindex TLS resumption
TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined
.endlist
.endlist
-.wen
.section DANE "SECDANE"
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.
the message override the banner message that is otherwise specified by the
&%smtp_banner%& option.
+For tls-on-connect connections, the ACL is run after the TLS connection
+is accepted (however, &%host_reject_connection%& is tested before).
+
.section "The EHLO/HELO ACL" "SECID192"
.cindex "EHLO" "ACL for"
response.
.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
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 "&%sseen%& 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"
(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 1pt left 1pt 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`&"
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 1pt left 1pt 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.
-.new
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.
-.wen
.section "Variables set from DNS lists" "SECID204"
dnslists = <; dnsbl.example.com/<|$acl_m_addrslist
.endd
+
+.section "Previously seen user and hosts" "SECTseen"
+.cindex "&%sseen%& ACL condition"
+.cindex greylisting
+The &%seen%& ACL condition can be used to test whether a
+situation has been previously met.
+It uses a hints database to record a timestamp against a key.
+host. The syntax of the condition is:
+.display
+&`seen =`& <&'optional flag'&><&'time interval'&> &`/`& <&'options'&>
+.endd
+
+For example,
+.code
+defer seen = -5m / key=${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"
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>>&.
-.new
.next
If the &%quota%& option is specified for recipient verify,
successful routing to an appendfile transport is followed by a call into
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).
-.wen
.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.
-.new
.next
&%quota%&: The quota check for a local recipient did non pass.
.endlist
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 receipient 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.
+
-.new
.section "Quota caching" "SECTquotacache"
.cindex "hints database" "quota cache"
.cindex "quota" "cache, description of"
.vitem &*no_cache*&
Set both positive and negative lifetimes to zero.
-.wen
.section "Sender address verification reporting" "SECTsenaddver"
.cindex "verifying" "suppressing error details"
.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 &*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 1pt left 1pt 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.
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
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
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 1pt left 1pt 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"
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
-.new
remote IP address (and port if enabled)
-.wen
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
.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_resumption `& append * to cipher field
-&` 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 1pt left 10pt center 1pt 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_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"
+.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 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`& "DNS lookup failed in list match"
+.irow &`all`& "&*all of the above*&"
+.endtable
See also the &%slow_lookup_log%& main configuration option,
section &<<SECID99>>&
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
-.new
&"=>"&, &"->"&, &"=="& and &"**"& lines.
-.wen
The latter can be disabled by turning off the &%outgoing_interface%& option.
.next
.cindex log "incoming proxy address"
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"
.next
.cindex "log" "TLS resumption"
.cindex "TLS" "logging session resumption"
-.new
&%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.
-.wen
.next
.cindex "log" "TLS SNI"
.cindex "TLS" "logging SNI"
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 1pt left 1pt 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
-.new
&'tls'&: TLS session resumption data
-.wen
.next
&'misc'&: other hints data
.endlist
.section "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 *
.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.
+
.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%&
After expansion, this can be a list.
Each element in turn,
lowercased,
+.vindex "&$dkim_domain$&"
is put into the &%$dkim_domain%& expansion variable
while expanding the remaining signing options.
If it is empty after expansion, DKIM signing is not done,
This sets the key selector string.
After expansion, which can use &$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 &%$dkim_domain%& and
.vitem &%temperror%&
This indicates a temporary error during all processing, including Exim's
SPF processing. You may defer messages when this occurs.
+
+.vitem &%invalid%&
+There was an error during processing of the SPF lookup
.endlist
You can prefix each string with an exclamation mark to invert
.vitem &$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 &$spf_result_guessed$&
.section "SRS (Sender Rewriting Scheme)" SECTSRS
.cindex SRS "sender rewriting scheme"
-.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
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.
.endlist
.endd
-.wen
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 RFC5322.From field
-&'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 1pt left 1pt 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 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 1pt left 1pt 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$&
Options are a string <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 1pt left 1pt 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:
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 1pt right 1pt 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
expansion must check this, as it will be called for every possible event type.
The current list of events is:
-.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
+.itable all 0 0 4 1pt left 1pt center 1pt center 1pt left
+.irow dane:fail after transport "per connection"
+.irow msg:complete after main "per message"
+.irow msg:defer after transport "per message per delivery try"
+.irow msg:delivery after transport "per recipient"
+.irow msg:rcpt:host:defer after transport "per recipient per host"
+.irow msg:rcpt:defer after transport "per recipient"
+.irow msg:host:defer after transport "per host per delivery try; host errors"
+.irow msg:fail:delivery after transport "per recipient"
+.irow msg:fail:internal after main "per recipient"
+.irow tcp:connect before transport "per connection"
+.irow tcp:close after transport "per connection"
+.irow tls:cert before both "per certificate in verification chain"
+.irow tls:fail:connect after main "per connection"
+.irow smtp:connect after transport "per connection"
+.irow smtp:ehlo after transport "per connection"
+.endtable
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$&, is filled with information varying
with the event type:
-.display
-&`dane:fail `& failure reason
-&`msg:defer `& error string
-&`msg:delivery `& smtp confirmation message
-&`msg:fail:internal `& failure reason
-&`msg:fail:delivery `& smtp error message
-&`msg:host:defer `& error string
-&`msg:rcpt:host:defer `& error string
-&`msg:rcpt:defer `& error string
-&`tls:cert `& verification chain depth
-&`smtp:connect `& smtp banner
-&`smtp:ehlo `& smtp ehlo response
-.endd
+.itable all 0 0 2 1pt left 1pt left
+.irow dane:fail "failure reason"
+.irow msg:defer "error string"
+.irow msg:delivery "smtp confirmation message"
+.irow msg:fail:internal "failure reason"
+.irow msg:fail:delivery "smtp error message"
+.irow msg:host:defer "error string"
+.irow msg:rcpt:host:defer "error string"
+.irow msg:rcpt:defer "error string"
+.irow tls:cert "verification chain depth"
+.irow tls:fail:connect "error string"
+.irow smtp:connect "smtp banner"
+.irow smtp:ehlo "smtp ehlo response"
+.endtable
The :defer events populate one extra variable: &$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 1pt left 1pt left
+.irow tcp:connect "do not connect"
+.irow tls:cert "refuse verification"
+.irow smtp:connect "close connection"
+.endtable
All other message types ignore the result string, and
no other use is made of it.
git://git.exim.org / exim.git / blobdiff