. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.86"
+.set previousversion "4.89"
.include ./local_params
.set ACL "access control lists (ACLs)"
.set I " "
.macro copyyear
-2015
+2017
.endmacro
. /////////////////////////////////////////////////////////////////////////////
.row &_filter.txt_& "specification of the filter language"
.row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3"
.row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4"
+.row &_openssl.txt_& "installing a current OpenSSL release"
.endtable
The main specification and the specification of the filtering language are also
examples, tips, and know-how that have been contributed by Exim users.
.cindex Bugzilla
-An Exim Bugzilla exists at &url(http://bugs.exim.org). You can use
+An Exim Bugzilla exists at &url(https://bugs.exim.org). You can use
this to report bugs, and also to add items to the wish list. Please search
first to check that you are not duplicating a previous entry.
Please ask Debian-specific questions on this list and not on the general Exim
lists.
-.section "Exim training" "SECID4"
-.cindex "training courses"
-Training courses in Cambridge (UK) used to be run annually by the author of
-Exim, before he retired. At the time of writing, there are no plans to run
-further Exim courses in Cambridge. However, if that changes, relevant
-information will be posted at &url(http://www-tus.csx.cam.ac.uk/courses/exim/).
-
.section "Bug reports" "SECID5"
.cindex "bug reports"
.cindex "reporting bugs"
Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported
-via the Bugzilla (&url(http://bugs.exim.org)). However, if you are unsure
+via the Bugzilla (&url(https://bugs.exim.org)). However, if you are unsure
whether some behaviour is a bug or not, the best thing to do is to post a
message to the &'exim-dev'& mailing list and have it discussed.
.cindex "distribution" "ftp site"
The master ftp site for the Exim distribution is
.display
-&*ftp://ftp.csx.cam.ac.uk/pub/software/email/exim*&
-.endd
-This is mirrored by
-.display
&*ftp://ftp.exim.org/pub/exim*&
.endd
The file references that follow are relative to the &_exim_& directories at
the actual building takes place. In most cases, Exim can discover the machine
architecture and operating system for itself, but the defaults can be
overridden if necessary.
+.cindex compiler requirements
+.cindex compiler version
+A C99-capable compiler will be required for the build.
.section "PCRE library" "SECTpcre"
in the ASCII character set, and to label them as being in a particular
character set. When Exim is inspecting header lines by means of the &%$h_%&
mechanism, it decodes them, and translates them into a specified character set
-(default ISO-8859-1). The translation is possible only if the operating system
+(default is set at build time). The translation is possible only if the operating system
supports the &[iconv()]& function.
However, some of the operating systems that supply &[iconv()]& do not support
.cindex "&'From:'& header line"
.cindex "&'Sender:'& header line"
+.cindex "header lines" "From:"
+.cindex "header lines" "Sender:"
For a trusted user, there is never any check on the contents of the &'From:'&
header line, and a &'Sender:'& line is never added. Furthermore, any existing
&'Sender:'& line in incoming local (non-TCP/IP) messages is not removed.
continuation lines is ignored. Each argument or data line is passed through the
string expansion mechanism, and the result is output. Variable values from the
configuration file (for example, &$qualify_domain$&) are available, but no
-message-specific values (such as &$sender_domain$&) are set, because no message
+message-specific values (such as &$message_exim_id$&) are set, because no message
is being processed (but see &%-bem%& and &%-Mset%&).
&*Note*&: If you use this mechanism to test lookups, and you change the data
.oindex "&%-bmalware%&"
.cindex "testing", "malware"
.cindex "malware scan test"
-This debugging option causes Exim to scan the given file,
+This debugging option causes Exim to scan the given file or directory
+(depending on the used scanner interface),
using the malware scanning framework. The option of &%av_scanner%& influences
this option, so if &%av_scanner%&'s value is dependent upon an expansion then
the expansion should have defaults which apply to this invocation. ACLs are
.code
mysql_servers = <value not displayable>
.endd
-If &%configure_file%& is given as an argument, the name of the run time
-configuration file is output.
+If &%config%& is given as an argument, the config is
+output, as it was parsed, any include file resolved, any comment removed.
+
+If &%config_file%& is given as an argument, the name of the run time
+configuration file is output. (&%configure_file%& works too, for
+backward compatibility.)
If a list of configuration files was supplied, the value that is output here
is the name of the file that was actually used.
settings can be obtained by using &%routers%&, &%transports%&, or
&%authenticators%&.
+.cindex "environment"
+If &%environment%& is given as an argument, the set of environment
+variables is output, line by line. Using the &%-n%& flag suppresses the value of the
+variables.
+
.cindex "options" "macro &-- extracting"
If invoked by an admin user, then &%macro%&, &%macro_list%& and &%macros%&
are available, similarly to the drivers. Because macros are sometimes used
exim '-D ABC = something' ...
.endd
&%-D%& may be repeated up to 10 times on a command line.
+Only macro names up to 22 letters long can be set.
.vitem &%-d%&<&'debug&~options'&>
by Exim in conjunction with the &%-MC%& option. It signifies that the
remote host supports the ESMTP &_DSN_& extension.
+.vitem &%-MCG%&&~<&'queue&~name'&>
+.oindex "&%-MCG%&"
+This option is not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MC%& option. It signifies that an
+alternate queue is used, named by the following argument.
+
+.vitem &%-MCK%&
+.oindex "&%-MCK%&"
+This option is not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MC%& option. It signifies that an
+remote host supports the ESMTP &_CHUNKING_& extension.
+
.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, and passes on the fact that the
host to which Exim is connected supports TLS encryption.
+.new
+.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
+.oindex "&%-MCt%&"
+This option is not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
+connection is being proxied by a parent process for handling TLS encryption.
+The arguments give the local address and port being proxied, and the TLS cipher.
+.wen
+
.vitem &%-Mc%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
.oindex "&%-Mc%&"
.cindex "hints database" "not overridden by &%-Mc%&"
.oindex "&%-n%&"
This option is interpreted by Sendmail to mean &"no aliasing"&.
For normal modes of operation, it is ignored by Exim.
-When combined with &%-bP%& it suppresses the name of an option from being output.
+When combined with &%-bP%& it makes the output more terse (suppresses
+option names, environment values and config pretty printing).
.vitem &%-O%&&~<&'data'&>
.oindex "&%-O%&"
SMTP protocol names (see the description of &$received_protocol$& in section
&<<SECTexpvar>>&). For &%-bs%&, the protocol is always &"local-"& followed by
one of those same names. For &%-bS%& (batched SMTP) however, the protocol can
-be set by &%-oMr%&.
+be set by &%-oMr%&. Repeated use of this option is not supported.
.vitem &%-oMs%&&~<&'host&~name'&>
.oindex "&%-oMs%&"
Note the Exim already has two private options, &%-pd%& and &%-ps%&, that refer
to embedded Perl. It is therefore impossible to set a protocol value of &`d`&
or &`s`& using this option (but that does not seem a real limitation).
+Repeated use of this option is not supported.
.vitem &%-q%&
.oindex "&%-q%&"
and &%-S%& options).
.cindex "queue runner" "description of operation"
-The &%-q%& option starts one queue runner process. This scans the queue of
+If other commandline options do not specify an action,
+the &%-q%& option starts one queue runner process. This scans the queue of
waiting messages, and runs a delivery process for each one in turn. It waits
for each delivery process to finish before starting the next one. A delivery
process may not actually do any deliveries if the retry times for the addresses
be done. If a message requires any remote deliveries, it remains on the queue
for later delivery.
-.vitem &%-q%&<&'qflags'&>&~<&'start&~id'&>&~<&'end&~id'&>
+.vitem &%-q[q][i][f[f]][l][G<name>[/<time>]]]%&
+.oindex "&%-qG%&"
+.cindex queue named
+.cindex "named queues"
.cindex "queue" "delivering specific messages"
+If the &'G'& flag and a name is present, the queue runner operates on the
+queue with the given name rather than the default queue.
+The name should not contain a &'/'& character.
+For a periodic queue run (see below)
+append to the name a slash and a time value.
+
+If other commandline options specify an action, a &'-qG<name>'& option
+will specify a queue to operate on.
+For example:
+.code
+exim -bp -qGquarantine
+mailq -qGquarantine
+exim -qGoffpeak -Rf @special.domain.example
+.endd
+
+.vitem &%-q%&<&'qflags'&>&~<&'start&~id'&>&~<&'end&~id'&>
When scanning the queue, Exim can be made to skip over messages whose ids are
lexically less than a given value by following the &%-q%& option with a
starting message id. For example:
.endd
on a line by itself. Double quotes round the file name are optional. If you use
the first form, a configuration error occurs if the file does not exist; the
-second form does nothing for non-existent files. In all cases, an absolute file
+second form does nothing for non-existent files.
+The first form allows a relative name. It is resolved relative to
+the directory of the including file. For the second form an absolute file
name is required.
Includes may be nested to any depth, but remember that Exim reads its
section &<<SECTnamedlists>>&.
+.section "Builtin macros" "SECTbuiltinmacros"
+Exim defines some macros depending on facilities available, which may
+differ due to build-time definitions and from one release to another.
+All of these macros start with an underscore.
+They can be used to conditionally include parts of a configuration
+(see below).
+
+The following classes of macros are defined:
+.display
+&` _HAVE_* `& build-time defines
+&` _DRIVER_ROUTER_* `& router drivers
+&` _DRIVER_TRANSPORT_* `& transport drivers
+&` _DRIVER_AUTHENTICATOR_* `& authenticator drivers
+&` _OPT_MAIN_* `& main config options
+&` _OPT_ROUTERS_* `& generic router options
+&` _OPT_TRANSPORTS_* `& generic transport options
+&` _OPT_AUTHENTICATORS_* `& generic authenticator options
+&` _OPT_ROUTER_*_* `& private router options
+&` _OPT_TRANSPORT_*_* `& private transport options
+&` _OPT_AUTHENTICATOR_*_* `& private authenticator options
+.endd
+
+Use an &"exim -bP macros"& command to get the list of macros.
+
+
.section "Conditional skips in the configuration file" "SECID46"
.cindex "configuration file" "conditional skips"
.cindex "&`.ifdef`&"
hexadecimal number.
If an integer value is followed by the letter K, it is multiplied by 1024; if
-it is followed by the letter M, it is multiplied by 1024x1024. When the values
+it is followed by the letter M, it is multiplied by 1024x1024;
+if by the letter G, 1024x1024x1024.
+When the values
of integer option settings are output, values which are an exact multiple of
1024 or 1024x1024 are sometimes, but not always, printed using the letters K
and M. The printing style is independent of the actual input format that was
This is an almost obsolete form of explicit email routing. If you do not know
anything about it, you can safely ignore this topic.
-The last two settings in the main part of the default configuration are
+The next two settings in the main part of the default configuration are
concerned with messages that have been &"frozen"& on Exim's queue. When a
message is frozen, Exim no longer continues to try to deliver it. Freezing
occurs when a bounce message encounters a permanent failure because the sender
after a week. In this configuration, the first setting ensures that no failing
bounce message ever lasts a week.
+Exim queues it's messages in a spool directory. If you expect to have
+large queues, you may consider using this option. It splits the spool
+directory into subdirectories to avoid file system degradation from
+many files in a single directory, resulting in better performance.
+Manual manipulation of queued messages becomes more complex (though fortunately
+not often needed).
+.code
+# split_spool_directory = true
+.endd
+
+In an ideal world everybody follows the standards. For non-ASCII
+messages RFC 2047 is a standard, allowing a maximum line length of 76
+characters. Exim adheres that standard and won't process messages which
+violate this standard. (Even ${rfc2047:...} expansions will fail.)
+In particular, the Exim maintainers have had multiple reports of
+problems from Russian administrators of issues until they disable this
+check, because of some popular, yet buggy, mail composition software.
+.code
+# check_rfc2047_length = false
+.endd
+
+If you need to be strictly RFC compliant you may wish to disable the
+8BITMIME advertisement. Use this, if you exchange mails with systems
+that are not 8-bit clean.
+.code
+# accept_8bitmime = false
+.endd
+
+Libraries you use may depend on specific environment settings. This
+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
+option and by the TIMEZONE_DEFAULT buildtime option.
+.code
+# keep_environment = ^LDAP
+# add_environment = PATH=/usr/bin::/bin
+.endd
.section "ACL configuration" "SECID54"
This causes any temporarily failing address to be retried every 15 minutes for
2 hours, then at intervals starting at one hour and increasing by a factor of
1.5 until 16 hours have passed, then every 6 hours up to 4 days. If an address
-is not delivered after 4 days of temporary failure, it is bounced.
+is not delivered after 4 days of temporary failure, it is bounced. The time is
+measured from first failure, not from the time the message was received.
If the retry section is removed from the configuration, or is empty (that is,
if no retry rules are defined), Exim will not retry deliveries. This turns
Exim supports the use of regular expressions in many of its options. It
uses the PCRE regular expression library; this provides regular expression
matching that is compatible with Perl 5. The syntax and semantics of
-regular expressions is discussed in many Perl reference books, and also in
+regular expressions is discussed in
+online Perl manpages, in
+many Perl reference books, and also in
Jeffrey Friedl's &'Mastering Regular Expressions'&, which is published by
O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)).
.endlist ilist
-.section "Query-style lookup types" "SECID62"
+.section "Query-style lookup types" "SECTquerystylelookups"
.cindex "lookup" "query-style types"
.cindex "query-style lookup" "list of types"
The supported query-style lookup types are listed below. Further details about
&(pgsql)&: The format of the query is an SQL statement that is passed to a
PostgreSQL database. See section &<<SECTsql>>&.
+.next
+.cindex "Redis lookup type"
+.cindex lookup Redis
+&(redis)&: The format of the query is either a simple get or simple set,
+passed to a Redis database. See section &<<SECTsql>>&.
+
.next
.cindex "sqlite lookup type"
.cindex "lookup" "sqlite"
The form if &"retry_VAL"& where VAL is an integer.
The default count is set by the main configuration option &%dns_retry%&.
-.new
-.cindex cacheing "of dns lookup"
+.cindex caching "of dns lookup"
.cindex TTL "of dns lookup"
.cindex DNS TTL
Dnsdb lookup results are cached within a single process (and its children).
The cache entry lifetime is limited to the smallest time-to-live (TTL)
value of the set of returned DNS records.
-.wen
.section "Pseudo dnsdb record types" "SECID66"
must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP
library from trying to follow referrals issued by the LDAP server.
+.cindex LDAP timeout
+.cindex timeout "LDAP lookup"
The name CONNECT is an obsolete name for NETTIME, retained for
backwards compatibility. This timeout (specified as a number of seconds) is
enforced from the client end for operations that can be carried out over a
The &(ldapdn)& lookup type returns the Distinguished Name from a single entry
as a sequence of values, for example
.code
-cn=manager, o=University of Cambridge, c=UK
+cn=manager,o=University of Cambridge,c=UK
.endd
The &(ldap)& lookup type generates an error if more than one entry matches the
search filter, whereas &(ldapm)& permits this case, and inserts a newline in
In the common case where you specify a single attribute in your LDAP query, the
result is not quoted, and does not contain the attribute name. If the attribute
-has multiple values, they are separated by commas.
+has multiple values, they are separated by commas. Any comma that is
+part of an attribute's value is doubled.
If you specify multiple attributes, the result contains space-separated, quoted
strings, each preceded by the attribute name and an equals sign. Within the
Here are some examples of the output format. The first line of each pair is an
LDAP query, and the second is the data that is returned. The attribute called
&%attr1%& has two values, one of them with an embedded comma, whereas
-&%attr2%& has only one value:
+&%attr2%& has only one value. Both attributes are derived from &%attr%&
+(they have SUP &%attr%& in their schema definitions).
+
.code
ldap:///o=base?attr1?sub?(uid=fred)
value1.1,value1,,2
ldap:///o=base?attr2?sub?(uid=fred)
value two
+ldap:///o=base?attr?sub?(uid=fred)
+value1.1,value1,,2,value two
+
ldap:///o=base?attr1,attr2?sub?(uid=fred)
attr1="value1.1,value1,,2" attr2="value two"
.cindex "lookup" "Oracle"
.cindex "InterBase lookup type"
.cindex "lookup" "InterBase"
-Exim can support lookups in InterBase, MySQL, Oracle, PostgreSQL, and SQLite
+.cindex "Redis lookup type"
+.cindex lookup Redis
+Exim can support lookups in InterBase, MySQL, Oracle, PostgreSQL, Redis,
+and SQLite
databases. Queries for these databases contain SQL statements, so an example
might be
.code
with a newline between the data for each row.
-.section "More about MySQL, PostgreSQL, Oracle, and InterBase" "SECID72"
+.section "More about MySQL, PostgreSQL, Oracle, InterBase, and Redis" "SECID72"
.cindex "MySQL" "lookup type"
.cindex "PostgreSQL lookup type"
.cindex "lookup" "MySQL"
.cindex "lookup" "Oracle"
.cindex "InterBase lookup type"
.cindex "lookup" "InterBase"
-If any MySQL, PostgreSQL, Oracle, or InterBase lookups are used, the
-&%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, or &%ibase_servers%&
+.cindex "Redis lookup type"
+.cindex lookup Redis
+If any MySQL, PostgreSQL, Oracle, InterBase or Redis lookups are used, the
+&%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, &%ibase_servers%&,
+or &%redis_servers%&
option (as appropriate) must be set to a colon-separated list of server
information.
-(For MySQL and PostgreSQL only, the global option need not be set if all
+(For MySQL and PostgreSQL, the global option need not be set if all
queries contain their own server information &-- see section
-&<<SECTspeserque>>&.) Each item in the list is a slash-separated list of four
+&<<SECTspeserque>>&.)
+For all but Redis
+each item in the list is a slash-separated list of four
items: host name, database name, user name, and password. In the case of
Oracle, the host name field is used for the &"service name"&, and the database
name field is not used and should be empty. For example:
found, but that is still a successful query. In other words, the list of
servers provides a backup facility, not a list of different places to look.
-.new
+For Redis the global option need not be specified if all queries contain their
+own server information &-- see section &<<SECTspeserque>>&.
+If specified, the option must be set to a colon-separated list of server
+information.
+Each item in the list is a slash-separated list of three items:
+host, database number, and password.
+.olist
+The host is required and may be either an IPv4 address and optional
+port number (separated by a colon, which needs doubling due to the
+higher-level list), or a Unix socket pathname enclosed in parentheses
+.next
+The database number is optional; if present that number is selected in the backend
+.next
+The password is optional; if present it is used to authenticate to the backend
+.endlist
+
The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators
convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b
respectively, and the characters single-quote, double-quote, and backslash
itself are escaped with backslashes.
-.wen
+
+The &%quote_redis%& expansion operator
+escapes whitespace and backslash characters with a backslash.
.section "Specifying the server in the query" "SECTspeserque"
-For MySQL and PostgreSQL lookups (but not currently for Oracle and InterBase),
+For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase),
it is possible to specify a list of servers with an individual query. This is
done by starting the query with
.display
.section "Special MySQL features" "SECID73"
For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
causes a connection to the server on the local host by means of a Unix domain
-socket. An alternate socket can be specified in parentheses. The full syntax of
-each item in &%mysql_servers%& is:
+socket. An alternate socket can be specified in parentheses.
+An option group name for MySQL option files can be specified in square brackets;
+the default value is &"exim"&.
+The full syntax of each item in &%mysql_servers%& is:
.display
-<&'hostname'&>::<&'port'&>(<&'socket name'&>)/<&'database'&>/&&&
- <&'user'&>/<&'password'&>
+<&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&&
+ <&'database'&>/<&'user'&>/<&'password'&>
.endd
-Any of the three sub-parts of the first field can be omitted. For normal use on
+Any of the four sub-parts of the first field can be omitted. For normal use on
the local host it can be left blank or set to just &"localhost"&.
No database need be supplied &-- but if it is absent here, it must be given in
The only character affected by the &%quote_sqlite%& operator is a single
quote, which it doubles.
+.cindex timeout SQLite
+.cindex sqlite "lookup timeout"
The SQLite library handles multiple simultaneous accesses to the database
internally. Multiple readers are permitted, but only one process can
update at once. Attempts to access the database while it is being updated
waits for the lock to be released. In Exim, the default timeout is set
to 5 seconds, but it can be changed by means of the &%sqlite_lock_timeout%&
option.
+
+.section "More about Redis" "SECTredis"
+.cindex "lookup" "Redis"
+.cindex "redis lookup type"
+Redis is a non-SQL database. Commands are simple get and set.
+Examples:
+.code
+${lookup redis{set keyname ${quote_redis:objvalue plus}}}
+${lookup redis{get keyname}}
+.endd
+
.ecindex IIDfidalo1
.ecindex IIDfidalo2
-.section "Expansion of lists" "SECID75"
+.section "Expansion of lists" "SECTlistexpand"
.cindex "expansion" "of lists"
-Each list is expanded as a single string before it is used. The result of
+Each list is expanded as a single string before it is used.
+
+&'Exception: the router headers_remove option, where list-item
+splitting is done before string-expansion.'&
+
+The result of
expansion must be a list, possibly containing empty items, which is split up
into separate items for matching. By default, colon is the separator character,
but this can be varied if necessary. See sections &<<SECTlistconstruct>>& and
.vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&&
{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&"
-.cindex "expansion" "extracting cerificate fields"
+.cindex "expansion" "extracting certificate fields"
.cindex "&%certextract%&" "certificate fields"
.cindex "certificate" "extracting fields"
The <&'certificate'&> must be a variable of type certificate.
.vitem "&*${env{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&"
.cindex "expansion" "extracting value from environment"
-.cindex "environment" "value from"
+.cindex "environment" "values from"
The key is first expanded separately, and leading and trailing white space
removed.
This is then searched for as a name in the environment.
If {<&'string1'&>} is omitted the search result is substituted on
search success.
+The environment is adjusted by the &%keep_environment%& and
+&%add_environment%& main section options.
+
.vitem "&*${extract{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&&
{*&<&'string3'&>&*}}*&"
.cindex "&%extract%&" "substrings by key"
The key and <&'string1'&> are first expanded separately. Leading and trailing
white space is removed from the key (but not from any of the strings). The key
-must not consist entirely of digits. The expanded <&'string1'&> must be of the
-form:
+must not be empty and must not consist entirely of digits.
+The expanded <&'string1'&> must be of the form:
.display
<&'key1'&> = <&'value1'&> <&'key2'&> = <&'value2'&> ...
.endd
filter. Header lines that are added to a particular copy of a message by a
router or transport are not accessible.
-For incoming SMTP messages, no header lines are visible in ACLs that are obeyed
-before the DATA ACL, because the header structure is not set up until the
-message is received. Header lines that are added in a RCPT ACL (for example)
+For incoming SMTP messages, no header lines are visible in
+ACLs that are obeyed before the data phase completes,
+because the header structure is not set up until the message is received.
+They are visible in DKIM, PRDR and DATA ACLs.
+Header lines that are added in a RCPT ACL (for example)
are saved until the message's incoming header lines are available, at which
-point they are added. When a DATA ACL is running, however, header lines added
-by earlier ACLs are visible.
+point they are added.
+When any of the above ACLs ar
+running, however, header lines added by earlier ACLs are visible.
Upper case and lower case letters are synonymous in header names. If the
following character is white space, the terminating colon may be omitted, but
condition = ${if >{$acl_m4}{3}}
.endd
+
+
+.vitem &*${imapfolder{*&<&'foldername'&>&*}}*&
+.cindex expansion "imap folder"
+.cindex "&%imapfolder%& expansion item"
+This item converts a (possibly multilevel, or with non-ASCII characters)
+folder specification to a Maildir name for filesystem use.
+For information on internationalisation support see &<<SECTi18nMDA>>&.
+
+
+
.vitem &*${length{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&
.cindex "expansion" "string truncation"
.cindex "&%length%& expansion item"
.vitem "&*${readsocket{*&<&'name'&>&*}{*&<&'request'&>&*}&&&
- {*&<&'timeout'&>&*}{*&<&'eol&~string'&>&*}{*&<&'fail&~string'&>&*}}*&"
+ {*&<&'options'&>&*}{*&<&'eol&~string'&>&*}{*&<&'fail&~string'&>&*}}*&"
.cindex "expansion" "inserting from a socket"
.cindex "socket, use of in expansion"
.cindex "&%readsocket%& expansion item"
Only a single host name may be given, but if looking it up yields more than
one IP address, they are each tried in turn until a connection is made. For
both kinds of socket, Exim makes a connection, writes the request string
-(unless it is an empty string) and reads from the socket until an end-of-file
+unless it is an empty string; and 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:
.code
${readsocket{/socket/name}{request string}{3s}}
.endd
+The third argument is a list of options, of which the first element is the timeout
+and must be present if the argument is given.
+Further elements are options of form &'name=value'&.
+One option type is currently recognised, defining whether (the default)
+or not a shutdown is done on the connection after sending the request.
+Example, to not do so (preferred, eg. by some webservers):
+.code
+${readsocket{/socket/name}{request string}{3s:shutdown=no}}
+.endd
A fourth argument allows you to change any newlines that are in the data
that is read, in the same way as for &%readfile%& (see above). This example
turns them into spaces:
${sg{abcdefabcdef}{abc}{xyz}}
.endd
yields &"xyzdefxyzdef"&. Because all three arguments are expanded before use,
-if any $ or \ characters are required in the regular expression or in the
+if any $, } or \ characters are required in the regular expression or in the
substitution string, they have to be escaped. For example:
.code
${sg{abcdef}{^(...)(...)\$}{\$2\$1}}
.code
${addresses:>& Chief <ceo@up.stairs>, sec@base.ment (dogsbody)}
.endd
-expands to &`ceo@up.stairs&&sec@base.ment`&. Compare the &*address*& (singular)
+expands to &`ceo@up.stairs&&sec@base.ment`&. The string is expanded
+first, so if the expanded string starts with >, it may change the output
+separator unintentionally. This can be avoided by setting the output
+separator explicitly:
+.code
+${addresses:>:$h_from:}
+.endd
+
+Compare the &*address*& (singular)
expansion item, which extracts the working address from a single RFC2822
address. See the &*filter*&, &*map*&, and &*reduce*& items for ways of
processing lists.
user@example.com
.endd
+.vitem &*${base32:*&<&'digits'&>&*}*&
+.cindex "&%base32%& expansion item"
+.cindex "expansion" "conversion to base 32"
+The string must consist entirely of decimal digits. The number is converted to
+base 32 and output as a (empty, for zero) string of characters.
+Only lowercase letters are used.
+
+.vitem &*${base32d:*&<&'base-32&~digits'&>&*}*&
+.cindex "&%base32d%& expansion item"
+.cindex "expansion" "conversion to base 32"
+The string must consist entirely of base-32 digits.
+The number is converted to decimal and output as a string.
+
.vitem &*${base62:*&<&'digits'&>&*}*&
.cindex "&%base62%& expansion item"
.cindex "expansion" "conversion to base 62"
identifiers, base-36 digits. The number is converted to decimal and output as a
string.
+.vitem &*${base64:*&<&'string'&>&*}*&
+.cindex "expansion" "base64 encoding"
+.cindex "base64 encoding" "in string expansion"
+.cindex "&%base64%& expansion item"
+.cindex certificate "base64 of DER"
+This operator converts a string into one that is base64 encoded.
+
+If the string is a single variable of type certificate,
+returns the base64 encoding of the DER form of the certificate.
+
+
+.vitem &*${base64d:*&<&'string'&>&*}*&
+.cindex "expansion" "base64 decoding"
+.cindex "base64 decoding" "in string expansion"
+.cindex "&%base64d%& expansion item"
+This operator converts a base64-encoded string into the un-coded form.
+
.vitem &*${domain:*&<&'string'&>&*}*&
.cindex "domain" "extraction"
significant bit set (so-called &"8-bit characters"&) count as printing or not
is controlled by the &%print_topbitchars%& option.
+.vitem &*${escape8bit:*&<&'string'&>&*}*&
+.cindex "expansion" "escaping 8-bit characters"
+.cindex "&%escape8bit%& expansion item"
+If the string contains and characters with the most significant bit set,
+they are converted to escape sequences starting with a backslash.
+Backslashes and DEL characters are also converted.
+
.vitem &*${eval:*&<&'string'&>&*}*&&~and&~&*${eval10:*&<&'string'&>&*}*&
.cindex "expansion" "expression evaluation"
byte value 127 is converted to &`\x7f`&.
-.new
.vitem &*${ipv6denorm:*&<&'string'&>&*}*&
.cindex "&%ipv6denorm%& expansion item"
.cindex "IP address" normalisation
set of zero-valued groups is replaced with a double colon.
A trailing ipv4-style dotted-decimal set is converted to hex.
Pure IPv4 addresses are converted to IPv4-mapped IPv6.
-.wen
.vitem &*${lc:*&<&'string'&>&*}*&
.vitem &*${md5:*&<&'string'&>&*}*&
.cindex "MD5 hash"
.cindex "expansion" "MD5 hash"
-.cindex "certificate fingerprint"
+.cindex certificate fingerprint
.cindex "&%md5%& expansion item"
The &%md5%& operator computes the MD5 hash value of the string, and returns it
as a 32-digit hexadecimal number, in which any letters are in lower case.
+If the string is a single variable of type certificate,
+returns the MD5 hash fingerprint of the certificate.
+
.vitem &*${nhash_*&<&'n'&>&*_*&<&'m'&>&*:*&<&'string'&>&*}*&
.cindex "expansion" "numeric hash"
This operator encodes text according to the rules of RFC 2047. This is an
encoding that is used in header lines to encode non-ASCII characters. It is
assumed that the input string is in the encoding specified by the
-&%headers_charset%& option, which defaults to ISO-8859-1. If the string
+&%headers_charset%& option, which gets its default at build time. If the string
contains only characters in the range 33&--126, and no instances of the
characters
.code
.vitem &*${sha1:*&<&'string'&>&*}*&
.cindex "SHA-1 hash"
.cindex "expansion" "SHA-1 hashing"
-.cindex "certificate fingerprint"
-.cindex "&%sha2%& expansion item"
+.cindex certificate fingerprint
+.cindex "&%sha1%& expansion item"
The &%sha1%& operator computes the SHA-1 hash value of the string, and returns
it as a 40-digit hexadecimal number, in which any letters are in upper case.
+If the string is a single variable of type certificate,
+returns the SHA-1 hash fingerprint of the certificate.
-.vitem &*${sha256:*&<&'certificate'&>&*}*&
+
+.vitem &*${sha256:*&<&'string'&>&*}*&
.cindex "SHA-256 hash"
-.cindex "certificate fingerprint"
+.cindex certificate fingerprint
.cindex "expansion" "SHA-256 hashing"
.cindex "&%sha256%& expansion item"
-The &%sha256%& operator computes the SHA-256 hash fingerprint of the
-certificate,
+The &%sha256%& operator computes the SHA-256 hash value of the string
+and returns
+it as a 64-digit hexadecimal number, in which any letters are in upper case.
+
+If the string is a single variable of type certificate,
+returns the SHA-256 hash fingerprint of the certificate.
+
+
+.vitem &*${sha3:*&<&'string'&>&*}*& &&&
+ &*${sha3_<n>:*&<&'string'&>&*}*&
+.cindex "SHA3 hash"
+.cindex "expansion" "SHA3 hashing"
+.cindex "&%sha3%& expansion item"
+The &%sha3%& operator computes the SHA3-256 hash value of the string
and returns
it as a 64-digit hexadecimal number, in which any letters are in upper case.
-Only arguments which are a single variable of certificate type are supported.
+
+If a number is appended, separated by an underbar, it specifies
+the output length. Values of 224, 256, 384 and 512 are accepted;
+with 256 being the default.
+
+The &%sha3%& expansion item is only supported if Exim has been
+compiled with GnuTLS 3.5.0 or later.
.vitem &*${stat:*&<&'string'&>&*}*&
systems for files larger than 2GB.
.vitem &*${str2b64:*&<&'string'&>&*}*&
-.cindex "expansion" "base64 encoding"
-.cindex "base64 encoding" "in string expansion"
.cindex "&%str2b64%& expansion item"
-This operator converts a string into one that is base64 encoded.
+Now deprecated, a synonym for the &%base64%& expansion operator.
.cindex "expansion" "utf-8 forcing"
.cindex "&%utf8clean%& expansion item"
This replaces any invalid utf-8 sequence in the string by the character &`?`&.
+
+.vitem "&*${utf8_domain_to_alabel:*&<&'string'&>&*}*&" &&&
+ "&*${utf8_domain_from_alabel:*&<&'string'&>&*}*&" &&&
+ "&*${utf8_localpart_to_alabel:*&<&'string'&>&*}*&" &&&
+ "&*${utf8_localpart_from_alabel:*&<&'string'&>&*}*&"
+.cindex expansion UTF-8
+.cindex UTF-8 expansion
+.cindex EAI
+.cindex internationalisation
+.cindex "&%utf8_domain_to_alabel%& expansion item"
+.cindex "&%utf8_domain_from_alabel%& expansion item"
+.cindex "&%utf8_localpart_to_alabel%& expansion item"
+.cindex "&%utf8_localpart_from_alabel%& expansion item"
+These convert EAI mail name components between UTF-8 and a-label forms.
+For information on internationalisation support see &<<SECTi18nMTA>>&.
.endlist
hexadecimal digits. There may be fewer than eight components if an empty
component (adjacent colons) is present. Only one empty component is permitted.
-&*Note*&: The checks are just on the form of the address; actual numerical
-values are not considered. Thus, for example, 999.999.999.999 passes the IPv4
-check. The main use of these tests is to distinguish between IP addresses and
+.new
+&*Note*&: The checks used to be just on the form of the address; actual numerical
+values were not considered. Thus, for example, 999.999.999.999 passed the IPv4
+check.
+This is no longer the case.
+.wen
+
+The main use of these tests is to distinguish between IP addresses and
host names, or between IPv4 and IPv6 addresses. For example, you could use
.code
${if isip4{$sender_host_address}...
${if match_domain{a.b.c}{x.y.z:a.b.c:p.q.r}{yes}{no}}
.endd
In each case, the second argument may contain any of the allowable items for a
-list of the appropriate type. Also, because the second argument (after
-expansion) is a standard form of list, it is possible to refer to a named list.
+list of the appropriate type. Also, because the second argument
+is a standard form of list, it is possible to refer to a named list.
Thus, you can use conditions like this:
.code
${if match_domain{$domain}{+local_domains}{...
.vitem "&$auth1$& &-- &$auth3$&"
.vindex "&$auth1$&, &$auth2$&, etc"
These variables are used in SMTP authenticators (see chapters
-&<<CHAPplaintext>>&&--&<<CHAPspa>>&). Elsewhere, they are empty.
+&<<CHAPplaintext>>&&--&<<CHAPtlsauth>>&). Elsewhere, they are empty.
.vitem &$authenticated_id$&
.cindex "authentication" "id"
.vindex "&$config_file$&"
The name of the main configuration file Exim is using.
-.vitem &$demime_errorlevel$&
-.vindex "&$demime_errorlevel$&"
-This variable is available when Exim is compiled with
-the content-scanning extension and the obsolete &%demime%& condition. For
-details, see section &<<SECTdemimecond>>&.
-
-.vitem &$demime_reason$&
-.vindex "&$demime_reason$&"
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete &%demime%& condition. For details,
-see section &<<SECTdemimecond>>&.
-
.vitem &$dkim_cur_signer$& &&&
&$dkim_verify_status$& &&&
&$dkim_verify_reason$& &&&
&$dkim_key_nosubdomains$& &&&
&$dkim_key_srvtype$& &&&
&$dkim_key_granularity$& &&&
- &$dkim_key_notes$&
+ &$dkim_key_notes$& &&&
+ &$dkim_key_length$&
These variables are only available within the DKIM ACL.
For details see chapter &<<CHAPdkim>>&.
Then after a dot, the next group of digits is a minor version number.
There may be other characters following the minor version.
-.vitem &$found_extension$&
-.vindex "&$found_extension$&"
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete &%demime%& condition. For details,
-see section &<<SECTdemimecond>>&.
-
.vitem &$header_$&<&'name'&>
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
by a setting on the transport itself.
When running a filter test via the &%-bf%& option, &$home$& is set to the value
-of the environment variable HOME.
+of the environment variable HOME, which is subject to the
+&%keep_environment%& and &%add_environment%& main config options.
.vitem &$host$&
.vindex "&$host$&"
This variable is set to the remote host's TCP port whenever &$host$& is set
for an outbound connection.
+.vitem &$initial_cwd$&
+.vindex "&$initial_cwd$&
+This variable contains the full path name of the initial working
+directory of the current Exim process. This may differ from the current
+working directory, as Exim changes this to "/" during early startup, and
+to &$spool_directory$& later.
.vitem &$inode$&
.vindex "&$inode$&"
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).
+.new
+It is not valid if the &%spool_files_wireformat%& option is used.
+.wen
.vitem &$message_age$&
.cindex "message" "age of"
separates the body from the header. Newlines are included in the count. See
also &$message_size$&, &$body_linecount$&, and &$body_zerocount$&.
+.new
+If the spool file is wireformat
+(see the &%spool_files_wireformat%& main option)
+the CRLF line-terminators are included in the count.
+.wen
+
.vitem &$message_exim_id$&
.vindex "&$message_exim_id$&"
When a message is being received or delivered, this variable contains the
In the MAIL and RCPT ACLs, the value is zero because at that stage the
message has not yet been received.
+.new
+This variable is not valid if the &%spool_files_wireformat%& option is used.
+.wen
+
.vitem &$message_size$&
.cindex "size" "of message"
.cindex "message" "size"
.cindex "uid (user id)" "of originating user"
.cindex "sender" "uid"
.vindex "&$caller_uid$&"
-.vindex "&$originaltor_uid$&"
+.vindex "&$originator_uid$&"
The value of &$caller_uid$& that was set when the message was received. For
messages received via the command line, this is the uid of the sending user.
For messages received by SMTP over TCP/IP, this is normally the uid of the Exim
qualified host name. See also &$smtp_active_hostname$&.
-.new
+.vitem &$proxy_external_address$& &&&
+ &$proxy_external_port$& &&&
+ &$proxy_local_address$& &&&
+ &$proxy_local_port$& &&&
+ &$proxy_session$&
+These variables are only available when built with Proxy Protocol
+or SOCKS5 support.
+For details see chapter &<<SECTproxyInbound>>&.
+
.vitem &$prdr_requested$&
.cindex "PRDR" "variable for"
This variable is set to &"yes"& if PRDR was requested by the client for the
current message, otherwise &"no"&.
-.wen
.vitem &$prvscheck_address$&
This variable is used in conjunction with the &%prvscheck%& expansion item,
The value set for the &%qualify_recipient%& option in the configuration file,
or if not set, the value of &$qualify_domain$&.
+.vitem &$queue_name$&
+.vindex &$queue_name$&
+.cindex "named queues"
+.cindex queues named
+The name of the spool queue in use; empty for the default queue.
+
.vitem &$rcpt_count$&
.vindex "&$rcpt_count$&"
When a message is being received by SMTP, this variable contains the number of
If you have changed &%host_lookup_order%& so that &`bydns`& is not the first
mechanism in the list, then this variable will be false.
+This requires that your system resolver library support EDNS0 (and that
+DNSSEC flags exist in the system headers). If the resolver silently drops
+all EDNS0 options, then this will have no effect. OpenBSD's asr resolver
+is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3).
+
.vitem &$sender_host_name$&
.vindex "&$sender_host_name$&"
space removed. Following the introduction of &$smtp_command$&, this variable is
somewhat redundant, but is retained for backwards compatibility.
+.new
+.vitem &$smtp_command_history$&
+.cindex SMTP "command history"
+.vindex "&$smtp_command_history$&"
+A comma-separated list (with no whitespace) of the most-recent SMTP commands
+received, in time-order left to right. Only a limited number of commands
+are remembered.
+.wen
+
.vitem &$smtp_count_at_connection_start$&
.vindex "&$smtp_count_at_connection_start$&"
This variable is set greater than zero only in processes spawned by the Exim
.vitem &$tls_in_ourcert$&
.vindex "&$tls_in_ourcert$&"
+.cindex certificate variables
This variable refers to the certificate presented to the peer of an
inbound connection when the message was received.
It is only useful as the argument of a
connection, this variable is set to the cipher suite that was negotiated, for
example DES-CBC3-SHA. In other circumstances, in particular, for message
received over unencrypted connections, the variable is empty. Testing
-&$tls_cipher$& for emptiness is one way of distinguishing between encrypted and
+&$tls_in_cipher$& for emptiness is one way of distinguishing between encrypted and
non-encrypted connections during ACL processing.
The deprecated &$tls_cipher$& variable is the same as &$tls_in_cipher$& during message reception,
.vitem &$tls_in_peerdn$&
.vindex "&$tls_in_peerdn$&"
.vindex "&$tls_peerdn$&"
+.cindex certificate "extracting fields"
When a message is received from a remote host over an encrypted SMTP
connection, and Exim is configured to request a certificate from the client,
the value of the Distinguished Name of the certificate is made available in the
.vitem &$verify_mode$&
.vindex "&$verify_mode$&"
-While a router or transport is being run in verify mode
-or for cutthrough delivery,
+While a router or transport is being run in verify mode or for cutthrough delivery,
contains "S" for sender-verification or "R" for recipient-verification.
Otherwise, empty.
There is also a command line option &%-pd%& (for delay) which suppresses the
initial startup, even if &%perl_at_start%& is set.
+.ilist
+.oindex "&%perl_taintmode%&"
+.cindex "Perl" "taintmode"
+To provide more security executing Perl code via the embedded Perl
+interpreter, the &%perl_taintmode%& option can be set. This enables the
+taint mode of the Perl interpreter. You are encouraged to set this
+option to a true value. To avoid breaking existing installations, it
+defaults to false.
+
.section "Calling Perl subroutines" "SECID86"
When the configuration file includes a &%perl_startup%& option you can make use
.section "Miscellaneous" "SECID96"
.table2
.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_malformed%& "for broken files &-- should not happen"
.row &%localhost_number%& "for unique message ids in clusters"
.row &%message_body_visible%& "how much to show in &$message_body$&"
.row &%mua_wrapper%& "run in &""MUA wrapper""& mode"
.row &%print_topbitchars%& "top-bit characters are printing"
+.row &%spool_wireformat%& "use wire-format spool data files when possible"
.row &%timezone%& "force time zone"
.endtable
.section "Privilege controls" "SECID98"
.table2
.row &%admin_groups%& "groups that are Exim admin users"
+.row &%commandline_checks_require_admin%& "require admin for various checks"
.row &%deliver_drop_privilege%& "drop root for delivery processes"
.row &%local_from_check%& "insert &'Sender:'& if necessary"
.row &%local_from_prefix%& "for testing &'From:'& for local sender"
.section "Logging" "SECID99"
.table2
+.row &%event_action%& "custom logging"
.row &%hosts_connection_nolog%& "exemption from connect logging"
.row &%log_file_path%& "override compiled-in value"
.row &%log_selector%& "set/unset optional logging"
.row &%slow_lookup_log%& "control logging of slow DNS lookups"
.row &%syslog_duplication%& "controls duplicate log lines on syslog"
.row &%syslog_facility%& "set syslog &""facility""& field"
+.row &%syslog_pid%& "pid in syslog lines"
.row &%syslog_processname%& "set syslog &""ident""& field"
.row &%syslog_timestamp%& "timestamp syslog lines"
.row &%write_rejectlog%& "control use of message log"
.table2
.row &%perl_at_start%& "always start the interpreter"
.row &%perl_startup%& "code to obey when starting Perl"
+.row &%perl_taintmode%& "enable taint mode in Perl"
.endtable
.row &%helo_verify_hosts%& "HELO hard-checked for these hosts"
.row &%host_lookup%& "host name looked up for these hosts"
.row &%host_lookup_order%& "order of DNS and local name lookups"
+.row &%hosts_proxy%& "use proxy protocol for these hosts"
.row &%host_reject_connection%& "reject connection from these hosts"
.row &%hosts_treat_as_local%& "useful in some cluster configurations"
.row &%local_scan_timeout%& "timeout for &[local_scan()]&"
.table2
.row &%accept_8bitmime%& "advertise 8BITMIME"
.row &%auth_advertise_hosts%& "advertise AUTH to these hosts"
+.row &%chunking_advertise_hosts%& "advertise CHUNKING to these hosts"
.row &%dsn_advertise_hosts%& "advertise DSN extensions to these hosts"
.row &%ignore_fromline_hosts%& "allow &""From ""& from these hosts"
.row &%ignore_fromline_local%& "allow &""From ""& from local SMTP"
.row &%pipelining_advertise_hosts%& "advertise pipelining to these hosts"
.row &%prdr_enable%& "advertise PRDR to all hosts"
+.row &%smtputf8_advertise_hosts%& "advertise SMTPUTF8 to these hosts"
.row &%tls_advertise_hosts%& "advertise TLS to these hosts"
.endtable
.row &%bounce_message_file%& "content of bounce"
.row &%bounce_message_text%& "content of bounce"
.row &%bounce_return_body%& "include body if returning message"
+.row &%bounce_return_linesize_limit%& "limit on returned message line length"
.row &%bounce_return_message%& "include original message in bounce"
.row &%bounce_return_size_limit%& "limit on returned message"
.row &%bounce_sender_authentication%& "send authenticated sender with bounce"
.option acl_smtp_dkim main string&!! unset
.cindex DKIM "ACL for"
This option defines the ACL that is run for each DKIM signature
+(by default, or as specified in the dkim_verify_signers option)
of a received message.
See chapter &<<CHAPdkim>>& for further details.
This option defines the ACL that is run when an SMTP VRFY command is
received. See chapter &<<CHAPACL>>& for further details.
+.option add_environment main "string list" empty
+.cindex "environment" "set values"
+This option allows to set individual environment variables that the
+currently linked libraries and programs in child processes use.
+See &<<SECTpipeenv>>& for the environment of &(pipe)& transports.
+
.option admin_groups main "string list&!!" unset
.cindex "admin user"
This option is expanded just once, at the start of Exim's processing. If the
point at which the error was detected are returned.
.cindex "bounce message" "including original"
+.option bounce_return_linesize_limit main integer 998
+.cindex "size" "of bounce lines, limit"
+.cindex "bounce message" "line length limit"
+.cindex "limit" "bounce message line length"
+This option sets a limit in bytes on the line length of messages
+that are returned to senders due to delivery problems,
+when &%bounce_return_message%& is true.
+The default value corresponds to RFC limits.
+If the message being returned has lines longer than this value it is
+treated as if the &%bounce_return_size_limit%& (below) restriction was exceeded.
+
+The option also applies to bounces returned when an error is detected
+during reception of a message.
+In this case lines from the original are truncated.
+
+The option does not apply to messages generated by an &(autoreply)& transport.
+
+
.option bounce_return_message main boolean true
If this option is set false, none of the original message is included in
bounce messages generated by Exim. See also &%bounce_return_size_limit%& and
See section &<<CALLaddparcall>>& for details of how this value is used.
-.option check_log_inodes main integer 0
+.option check_log_inodes main integer 100
See &%check_spool_space%& below.
-.option check_log_space main integer 0
+.option check_log_space main integer 10M
See &%check_spool_space%& below.
.oindex "&%check_rfc2047_length%&"
set false, Exim recognizes encoded words of any length.
-.option check_spool_inodes main integer 0
+.option check_spool_inodes main integer 100
See &%check_spool_space%& below.
-.option check_spool_space main integer 0
+.option check_spool_space main integer 10M
.cindex "checking disk space"
.cindex "disk space, checking"
.cindex "spool directory" "checking space"
.vindex "&$log_space$&"
.vindex "&$spool_inodes$&"
.vindex "&$spool_space$&"
-When any of these options are set, they apply to all incoming messages. If you
+When any of these options are nonzero, they apply to all incoming messages. If you
want to apply different checks to different kinds of message, you can do so by
testing the variables &$log_inodes$&, &$log_space$&, &$spool_inodes$&, and
&$spool_space$& in an ACL with appropriate additional conditions.
&%check_spool_space%& and &%check_spool_inodes%& check the spool partition if
either value is greater than zero, for example:
.code
-check_spool_space = 10M
+check_spool_space = 100M
check_spool_inodes = 100
.endd
The spool partition is the one that contains the directory defined by
&%check_spool_space%& is zero, unless &%no_smtp_check_spool_space%& is set.
The values for &%check_spool_space%& and &%check_log_space%& are held as a
-number of kilobytes. If a non-multiple of 1024 is specified, it is rounded up.
+number of kilobytes (though specified in bytes).
+If a non-multiple of 1024 is specified, it is rounded up.
For non-SMTP input and for batched SMTP input, the test is done at start-up; on
failure a message is written to stderr and Exim exits with a non-zero code, as
it obviously cannot send an error message of any kind.
+There is a slight performance penalty for these checks.
+Versions of Exim preceding 4.88 had these disabled by default;
+high-rate installations confident they will never run out of resources
+may wish to deliberately disable them.
+
+.option chunking_advertise_hosts main "host list&!!" *
+.cindex CHUNKING advertisement
+.cindex "RFC 3030" "CHUNKING"
+The CHUNKING extension (RFC3030) will be advertised in the EHLO message to
+these hosts.
+Hosts may use the BDAT command as an alternate to DATA.
+
+.new
+.option commandline_checks_require_admin main boolean &`false`&
+.cindex "restricting access to features"
+This option restricts various basic checking features to require an
+administrative user.
+This affects most of the &%-b*%& options, such as &%-be%&.
+.wen
+
+.option debug_store main boolean &`false`&
+.cindex debugging "memory corruption"
+.cindex memory debugging
+This option, when true, enables extra checking in Exim's internal memory
+management. For use when a memory corruption issue is being investigated,
+it should normally be left as default.
+
.option daemon_smtp_ports main string &`smtp`&
.cindex "port" "for daemon"
.cindex "TCP/IP" "setting listening ports"
.option delay_warning main "time list" 24h
.cindex "warning of delay"
.cindex "delay warning, specifying"
+.cindex "queue" "delay warning"
When a message is delayed, Exim sends a warning message to the sender at
intervals specified by this option. The data is a colon-separated list of times
after which to send warning messages. If the value of the option is an empty
.option dns_use_edns0 main integer -1
.cindex "DNS" "resolver options"
.cindex "DNS" "EDNS0"
+.cindex "DNS" "OpenBSD
If this option is set to a non-negative number then Exim will initialise the
DNS resolver library to either use or not use EDNS0 extensions, overriding
the system default. A value of 0 coerces EDNS0 off, a value of 1 coerces EDNS0
If the resolver library does not support EDNS0 then this option has no effect.
+OpenBSD's asr resolver routines are known to ignore the EDNS0 option; this
+means that DNSSEC will not work with Exim on that platform either, unless Exim
+is linked against an alternative DNS client library.
+
.option drop_cr main boolean false
This is an obsolete option that is now a no-op. It used to affect the way Exim
not used.
+.option event_action main string&!! unset
+.cindex events
+This option declares a string to be expanded for Exim's events mechanism.
+For details see chapter &<<CHAPevents>>&.
+
+
.option exim_group main string "compile-time configured"
.cindex "gid (group id)" "Exim's own"
.cindex "Exim group"
+.option hosts_proxy main "host list&!!" unset
+.cindex proxy "proxy protocol"
+This option enables use of Proxy Protocol proxies for incoming
+connections. For details see section &<<SECTproxyInbound>>&.
+
+
.option hosts_treat_as_local main "domain list&!!" unset
.cindex "local host" "domains treated as"
.cindex "host" "treated as local"
.option ignore_fromline_local main boolean false
See &%ignore_fromline_hosts%& above.
+.option keep_environment main "string list" unset
+.cindex "environment" "values from"
+This option contains a string list of environment variables to keep.
+You have to trust these variables or you have to be sure that
+these variables do not impose any security risk. Keep in mind that
+during the startup phase Exim is running with an effective UID 0 in most
+installations. As the default value is an empty list, the default
+environment for using libraries, running embedded Perl code, or running
+external binaries is empty, and does not not even contain PATH or HOME.
+
+Actually the list is interpreted as a list of patterns
+(&<<SECTlistexpand>>&), except that it is not expanded first.
+
+WARNING: Macro substitution is still done first, so having a macro
+FOO and having FOO_HOME in your &%keep_environment%& option may have
+unexpected results. You may work around this using a regular expression
+that does not match the macro name: ^[F]OO_HOME$.
+
+Current versions of Exim issue a warning during startup if you do not mention
+&%keep_environment%& in your runtime configuration file and if your
+current environment is not empty. Future versions may not issue that warning
+anymore.
+
+See the &%add_environment%& main config option for a way to set
+environment variables to a fixed value. The environment for &(pipe)&
+transports is handled separately, see section &<<SECTpipeenv>>& for
+details.
+
.option keep_malformed main time 4d
This option specifies the length of time to keep messages whose spool files
.option ldap_ca_cert_dir main string unset
.cindex "LDAP", "TLS CA certificate directory"
+.cindex certificate "directory for LDAP"
This option indicates which directory contains CA certificates for verifying
a TLS certificate presented by an LDAP server.
While Exim does not provide a default value, your SSL library may.
.option ldap_ca_cert_file main string unset
.cindex "LDAP", "TLS CA certificate file"
+.cindex certificate "file for LDAP"
This option indicates which file contains CA certificates for verifying
a TLS certificate presented by an LDAP server.
While Exim does not provide a default value, your SSL library may.
.option ldap_cert_file main string unset
.cindex "LDAP" "TLS client certificate file"
+.cindex certificate "file for LDAP"
This option indicates which file contains an TLS client certificate which
Exim should present to the LDAP server during TLS negotiation.
Should be used together with &%ldap_cert_key%&.
.option ldap_cert_key main string unset
.cindex "LDAP" "TLS client key file"
+.cindex certificate "key for LDAP"
This option indicates which file contains the secret/private key to use
to prove identity to the LDAP server during TLS negotiation.
Should be used together with &%ldap_cert_file%&, which contains the
of SSL-on-connect.
In the event of failure to negotiate TLS, the action taken is controlled
by &%ldap_require_cert%&.
+This option is ignored for &`ldapi`& connections.
.option ldap_version main integer unset
transport driver.
-.option openssl_options main "string list" "+no_sslv2"
+.option openssl_options main "string list" "+no_sslv2 +single_dh_use +no_ticket"
.cindex "OpenSSL "compatibility options"
This option allows an administrator to adjust the SSL options applied
by OpenSSL to connections. It is given as a space-separated list of items,
.option perl_at_start main boolean false
+.cindex "Perl"
This option is available only when Exim is built with an embedded Perl
interpreter. See chapter &<<CHAPperl>>& for details of its use.
.option perl_startup main string unset
+.cindex "Perl"
This option is available only when Exim is built with an embedded Perl
interpreter. See chapter &<<CHAPperl>>& for details of its use.
+.option perl_startup main boolean false
+.cindex "Perl"
+This Option enables the taint mode of the embedded Perl interpreter.
+
.option pgsql_servers main "string list" unset
.cindex "PostgreSQL lookup type" "server list"
.option prod_requires_admin main boolean true
+.cindex "restricting access to features"
.oindex "&%-M%&"
.oindex "&%-R%&"
.oindex "&%-q%&"
The &%-M%&, &%-R%&, and &%-q%& command-line options require the caller to be an
admin user unless &%prod_requires_admin%& is set false. See also
-&%queue_list_requires_admin%&.
+&%queue_list_requires_admin%& and &%commandline_checks_require_admin%&.
.option qualify_domain main string "see below"
.option queue_list_requires_admin main boolean true
+.cindex "restricting access to features"
.oindex "&%-bp%&"
The &%-bp%& command-line option, which lists the messages that are on the
queue, requires the caller to be an admin user unless
-&%queue_list_requires_admin%& is set false. See also &%prod_requires_admin%&.
+&%queue_list_requires_admin%& is set false.
+See also &%prod_requires_admin%& and &%commandline_checks_require_admin%&.
.option queue_only main boolean false
-.option queue_run_max main integer 5
+.option queue_run_max main integer&!! 5
.cindex "queue runner" "maximum number of"
This controls the maximum number of queue runner processes that an Exim daemon
can run simultaneously. This does not mean that it starts them all at once,
run. If you do not want queue runs to occur, omit the &%-q%&&'xx'& setting on
the daemon's command line.
+.cindex queues named
+.cindex "named queues"
+To set limits for different named queues use
+an expansion depending on the &$queue_name$& variable.
+
.option queue_smtp_domains main "domain list&!!" unset
.cindex "queueing incoming messages"
.cindex "message" "queueing remote deliveries"
&%sender_unqualified_hosts%&, or if the message was submitted locally (not
using TCP/IP), and the &%-bnq%& option was not set.
+.option set_environment main "string list" empty
+.cindex "environment"
+This option allows to set individual environment variables that the
+currently linked libraries and programs in child processes use. The
+default list is empty,
+
.option slow_lookup_log main integer 0
.cindex "logging" "slow lookups"
550 failing address in "From" header is: <user@dom.ain
.endd
+
+.option smtputf8_advertise_hosts main "host list&!!" *
+.cindex "SMTPUTF8" "advertising"
+When Exim is built with support for internationalised mail names,
+the availability thereof is advertised in
+response to EHLO only to those client hosts that match this option. See
+chapter &<<CHAPi18n>>& for details of Exim's support for internationalisation.
+
+
.option spamd_address main string "see below"
This option is available when Exim is compiled with the content-scanning
extension. It specifies how Exim connects to SpamAssassin's &%spamd%& daemon.
By using this option to override the compiled-in path, it is possible to run
tests of Exim without using the standard spool.
+.new
+.option spool_wireformat main boolean false
+.cindex "spool directory" "file formats"
+If this option is set, Exim may for some messages use an alternate format
+for data-files in the spool which matches the wire format.
+Doing this permits more efficient message reception and transmission.
+Currently it is only done for messages received using the EMSTP CHUNKING
+option.
+
+The following variables will not have useful values:
+.code
+$max_received_linelength
+$body_linecount
+$body_zerocount
+.endd
+
+Users of the local_scan() API (see &<<CHAPlocalscan>>&),
+and any external programs which are passed a reference to a message data file
+(except via the &"regex"&, &"malware"& or &"spam"&) ACL conditions)
+will need to be aware of the potential different format.
+
+Using any of the ACL conditions noted will negate the reception benefit
+(as a Unix-mbox-format file is contructed for them).
+The transimssion benefit is maintained.
+.wen
+
.option sqlite_lock_timeout main time 5s
.cindex "sqlite lookup type" "lock timeout"
This option controls the timeout that the &(sqlite)& lookup uses when trying to
details of Exim's logging.
+.option syslog_pid main boolean true
+.cindex "syslog" "pid"
+If &%syslog_pid%& is set false, the PID on Exim's log lines are
+omitted when these lines are sent to syslog. (Syslog normally prefixes
+the log lines with the PID of the logging process automatically.) You need
+to enable the &`+pid`& log selector item, if you want Exim to write it's PID
+into the logs.) See chapter &<<CHAPlog>>& for details of Exim's logging.
+
+
.option syslog_processname main string &`exim`&
.cindex "syslog" "process name; setting"
appropriate &%system_filter_..._transport%& option(s) must be set, to define
which transports are to be used. Details of this facility are given in chapter
&<<CHAPsystemfilter>>&.
+A forced expansion failure results in no filter operation.
.option system_filter_directory_transport main string&!! unset
.option timezone main string unset
.cindex "timezone, setting"
+.cindex "environment" "values from"
The value of &%timezone%& is used to set the environment variable TZ while
running Exim (if it is different on entry). This ensures that all timestamps
created by Exim are in the required timezone. If you want all your timestamps
unfortunately not all, operating systems.
-.new
.option tls_advertise_hosts main "host list&!!" *
-.wen
.cindex "TLS" "advertising"
.cindex "encryption" "on SMTP connection"
.cindex "SMTP" "encrypted connection"
of the STARTTLS command to set up an encrypted session is advertised in
response to EHLO only to those client hosts that match this option. See
chapter &<<CHAPTLS>>& for details of Exim's support for TLS.
-.new
Note that the default value requires that a certificate be supplied
-using the &%tls_certificate%& option. If no certificate is available then
-the &%tls_advertise_hosts%& option should be set empty.
-.wen
+using the &%tls_certificate%& option. If TLS support for incoming connections
+is not required the &%tls_advertise_hosts%& option should be set empty.
.option tls_certificate main string&!! unset
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.
+
.option tls_crl main string&!! unset
.cindex "TLS" "server certificate revocation list"
.cindex "certificate" "revocation list for server"
The value of this option is expanded and indicates the source of DH parameters
to be used by Exim.
-If it is a filename starting with a &`/`&, then it names a file from which DH
+&*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.
+
+If &%tls_dhparam%& is a filename starting with a &`/`&,
+then it names a file from which DH
parameters should be loaded. If the file exists, it should hold a PEM-encoded
PKCS#3 representation of the DH prime. If the file does not exist, for
OpenSSL it is an error. For GnuTLS, Exim will attempt to create the file and
See section &<<SECTgnutlsparam>>& for further details.
If Exim is using OpenSSL and this option is empty or unset, then Exim will load
-a default DH prime; the default is the 2048 bit prime described in section
+a default DH prime; the default is Exim-specific but lacks verifiable provenance.
+
+In older versions of Exim the default was the 2048 bit prime described in section
2.2 of RFC 5114, "2048-bit MODP Group with 224-bit Prime Order Subgroup", which
in IKE is assigned number 23.
Otherwise, the option must expand to the name used by Exim for any of a number
-of DH primes specified in RFC 2409, RFC 3526 and RFC 5114. As names, Exim uses
-"ike" followed by the number used by IKE, of "default" which corresponds to
-"ike23".
+of DH primes specified in RFC 2409, RFC 3526, RFC 5114, RFC 7919, or from other
+sources. As names, Exim uses a standard specified name, else "ike" followed by
+the number used by IKE, or "default" which corresponds to
+&`exim.dev.20160529.3`&.
-The available primes are:
+The available standard primes are:
+&`ffdhe2048`&, &`ffdhe3072`&, &`ffdhe4096`&, &`ffdhe6144`&, &`ffdhe8192`&,
&`ike1`&, &`ike2`&, &`ike5`&,
&`ike14`&, &`ike15`&, &`ike16`&, &`ike17`&, &`ike18`&,
-&`ike22`&, &`ike23`& (aka &`default`&) and &`ike24`&.
+&`ike22`&, &`ike23`& and &`ike24`&.
+
+The available additional primes are:
+&`exim.dev.20160529.1`&, &`exim.dev.20160529.2`& and &`exim.dev.20160529.3`&.
Some of these will be too small to be accepted by clients.
Some may be too large to be accepted by clients.
+The open cryptographic community has suspicions about the integrity of some
+of the later IKE values, which led into RFC7919 providing new fixed constants
+(the "ffdhe" identifiers).
+
+At this point, all of the "ike" values should be considered obsolete;
+they're still in Exim to avoid breaking unusual configurations, but are
+candidates for removal the next time we have backwards-incompatible changes.
The TLS protocol does not negotiate an acceptable size for this; clients tend
to hard-drop connections if what is offered by the server is unacceptable,
acceptable bound from 1024 to 2048.
-.option tls_eccurve main string&!! prime256v1
+.option tls_eccurve main string&!! &`auto`&
.cindex TLS "EC cryptography"
-If built with a recent-enough version of OpenSSL,
-this option selects a EC curve for use by Exim.
+This option selects a EC curve for use by Exim when used with OpenSSL.
+It has no effect when Exim is used with GnuTLS.
-Curve names of the form &'prime256v1'& are accepted.
-For even more-recent library versions, names of the form &'P-512'&
-are also accepted, plus the special value &'auto'&
-which tell the library to choose.
+After expansion it must contain a valid EC curve parameter, such as
+&`prime256v1`&, &`secp384r1`&, or &`P-512`&. Consult your OpenSSL manual
+for valid selections.
-If the option is set to an empty string, no EC curves will be enabled.
+For OpenSSL versions before (and not including) 1.0.2, the string
+&`auto`& selects &`prime256v1`&. For more recent OpenSSL versions
+&`auto`& tells the library to choose.
+
+If the option expands to an empty string, no EC curves will be enabled.
.option tls_ocsp_file main string&!! unset
status proof for the server's certificate, as obtained from the
Certificate Authority.
-.new
Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later).
-.wen
.option tls_on_connect_ports main "string list" unset
.cindex "DNSSEC" "MX lookup"
.cindex "security" "MX lookup"
.cindex "DNS" "DNSSEC"
-DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+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
(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.
lookup first. Only if that gives a definite &"no such host"& is the local
function called.
+&*Compatibility*&: From Exim 4.85 until fixed for 4.90, there was an
+inadvertent constraint that a transport name as an option had to be the last
+option specified.
+
If no IP address for a host can be found, what happens is controlled by the
.endd
.next
.cindex "address redirection" "to black hole"
-Sometimes you want to throw away mail to a particular local part. Making the
-&%data%& option expand to an empty string does not work, because that causes
-the router to decline. Instead, the alias item
+.cindex "delivery" "discard"
+.cindex "delivery" "blackhole"
.cindex "black hole"
.cindex "abandoning mail"
-&':blackhole:'& can be used. It does what its name implies. No delivery is
+Sometimes you want to throw away mail to a particular local part. Making the
+&%data%& option expand to an empty string does not work, because that causes
+the router to decline. Instead, the alias item
+.code
+:blackhole:
+.endd
+can be used. It does what its name implies. No delivery is
done, and no error message is generated. This has the same effect as specifying
&_/dev/null_& as a destination, but it can be independently disabled.
.option forbid_blackhole redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, the &':blackhole:'& item may not appear in a
redirection list.
.option forbid_exim_filter redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is set true, only Sieve filters are permitted when
&%allow_filter%& is true.
.option forbid_file redirect boolean false
+.cindex "restricting access to features"
.cindex "delivery" "to file; forbidding"
+.cindex "filter" "locking out certain features"
.cindex "Sieve filter" "forbidding delivery to a file"
.cindex "Sieve filter" "&""keep""& facility; disabling"
If this option is true, this router may not generate a new address that
.option forbid_filter_dlfunc redirect boolean false
+.cindex "restricting access to features"
.cindex "filter" "locking out certain features"
If this option is true, string expansions in Exim filters are not allowed to
make use of the &%dlfunc%& expansion facility to run dynamically loaded
functions.
.option forbid_filter_existstest redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
.cindex "expansion" "statting a file"
If this option is true, string expansions in Exim filters are not allowed to
make use of the &%exists%& condition or the &%stat%& expansion item.
.option forbid_filter_logwrite redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, use of the logging facility in Exim filters is not
permitted. Logging is in any case available only if the filter is being run
under some unprivileged uid (which is normally the case for ordinary users'
.option forbid_filter_lookup redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, string expansions in Exim filter files are not allowed
to make use of &%lookup%& items.
.option forbid_filter_perl redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
This option has an effect only if Exim is built with embedded Perl support. If
it is true, string expansions in Exim filter files are not allowed to make use
of the embedded Perl support.
.option forbid_filter_readfile redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, string expansions in Exim filter files are not allowed
to make use of &%readfile%& items.
.option forbid_filter_readsocket redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, string expansions in Exim filter files are not allowed
to make use of &%readsocket%& items.
.option forbid_filter_reply redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, this router may not generate an automatic reply
message. Automatic replies can be generated only from Exim or Sieve filter
files, not from traditional forward files. This option is forced to be true if
.option forbid_filter_run redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, string expansions in Exim filter files are not allowed
to make use of &%run%& items.
.option forbid_include redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is true, items of the form
.code
:include:<path name>
.option forbid_pipe redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
.cindex "delivery" "to pipe; forbidding"
If this option is true, this router may not generate a new address which
specifies delivery to a pipe, either from an Exim filter or from a conventional
.option forbid_sieve_filter redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
If this option is set true, only Exim filters are permitted when
&%allow_filter%& is true.
.chapter "Environment for running local transports" "CHAPenvironment" &&&
"Environment for local transports"
.scindex IIDenvlotra1 "local transports" "environment for"
-.scindex IIDenvlotra2 "environment for local transports"
+.scindex IIDenvlotra2 "environment" "local transports"
.scindex IIDenvlotra3 "transport" "local; environment for"
Local transports handle deliveries to files and pipes. (The &(autoreply)&
transport can be thought of as similar to a pipe.) Exim always runs transports
resent to other recipients.
+.option event_action transports string&!! unset
+.cindex events
+This option declares a string to be expanded for Exim's events mechanism.
+For details see chapter &<<CHAPevents>>&.
+
+
.option group transports string&!! "Exim group"
.cindex "transport" "group; specifying"
This option specifies a gid for running the transport process, overriding any
errors and cause the delivery to be deferred.
Unlike most options, &%headers_remove%& can be specified multiple times
-for a router; all listed headers are removed.
+for a transport; all listed headers are removed.
&*Warning*&: Because of the separate expansion of the list items,
items that contain a list separator must have it doubled.
to ensure that any additional groups associated with the uid are set up.
-.new
.option max_parallel transports integer&!! unset
.cindex limit "transport parallelism"
.cindex transport "parallel processes"
.cindex "hints database" "transport concurrency control"
Exim implements this control by means of a hints database in which a record is
-incremented whenever a transport process is beaing created. The record
+incremented whenever a transport process is being created. The record
is decremented and possibly removed when the process terminates.
Obviously there is scope for
records to get left lying around if there is a system or program crash. To
start with &_misc_& and they are kept in the &_spool/db_& directory. There
may be one or two files, depending on the type of DBM in use. The same files
are used for ETRN and smtp transport serialization.
-.wen
.option message_size_limit transports string&!! 0
This option sets up a filtering (in the Unix shell sense) process for messages
at transport time. It should not be confused with mail filtering as set up by
individual users or via a system filter.
-.new
If unset, or expanding to an empty string, no filtering is done.
-.wen
When the message is about to be written out, the command specified by
&%transport_filter%& is started up in a separate, parallel process, and
The value of the option is expanded, and must then be a numerical value
(decimal point allowed), optionally followed by one of the letters K, M, or G,
-for kilobytes, megabytes, or gigabytes. If Exim is running on a system with
+for kilobytes, megabytes, or gigabytes, optionally followed by a slash
+and further option modifiers. If Exim is running on a system with
large file support (Linux and FreeBSD have this), mailboxes larger than 2G can
be handled.
+The option modifier &%no_check%& can be used to force delivery even if the over
+quota condition is met. The quota gets updated as usual.
+
&*Note*&: A value of zero is interpreted as &"no quota"&.
The expansion happens while Exim is running as root, before it changes uid for
failure causes delivery to be deferred. A value of zero is interpreted as
&"no quota"&.
+The option modifier &%no_check%& can be used to force delivery even if the over
+quota condition is met. The quota gets updated as usual.
.option quota_is_inclusive appendfile boolean true
See &%quota%& above.
delivery, the two pipe transports may be run concurrently. You must ensure that
any pipe commands you set up are robust against this happening. If the commands
write to a file, the &%exim_lock%& utility might be of use.
-.new
Alternatively the &%max_parallel%& option could be used with a value
of "1" to enforce serialization.
-.wen
.section "Environment variables" "SECTpipeenv"
.cindex "&(pipe)& transport" "environment for command"
-.cindex "environment for pipe transport"
+.cindex "environment" "&(pipe)& transport"
The environment variables listed below are set up when the command is invoked.
This list is a compromise for maximum compatibility with other MTAs. Note that
the &%environment%& option can be used to add additional variables to this
-environment.
+environment. The environment for the &(pipe)& transport is not subject
+to the &%add_environment%& and &%keep_environment%& main config options.
.display
&`DOMAIN `& the domain of the address
&`HOME `& the home directory, if set
.option environment pipe string&!! unset
.cindex "&(pipe)& transport" "environment for command"
-.cindex "environment for &(pipe)& transport"
+.cindex "environment" "&(pipe)& transport"
This option is used to add additional variables to the environment in which the
command runs (see section &<<SECTpipeenv>>& for the default list). Its value is
a string which is expanded, and then interpreted as a colon-separated list of
&`\n`& to &`\r\n`& in &%message_suffix%&.
-.option path pipe string "see below"
-This option specifies the string that is set up in the PATH environment
-variable of the subprocess. The default is:
-.code
-/bin:/usr/bin
-.endd
+.option path pipe string&!! "/bin:/usr/bin"
+This option is expanded and
+specifies the string that is set up in the PATH environment
+variable of the subprocess.
If the &%command%& option does not yield an absolute path name, the command is
sought in the PATH directories, in the usual way. &*Warning*&: This does not
apply to a command specified as a transport filter.
of the message. Its value must not be zero. See also &%final_timeout%&.
+.option dkim_domain smtp string list&!! unset
+.option dkim_selector smtp string&!! unset
+.option dkim_private_key smtp string&!! unset
+.option dkim_canon smtp string&!! unset
+.option dkim_strict smtp string&!! unset
+.option dkim_sign_headers smtp string&!! per RFC
+.option dkim_hash smtp string&!! sha256
+.option dkim_identity smtp string&!! unset
+DKIM signing options. For details see section &<<SECDKIMSIGN>>&.
+
+
.option delay_after_cutoff smtp boolean true
This option controls what happens when all remote IP addresses for a given
domain have been inaccessible for so long that they have passed their retry
.cindex "DNSSEC" "MX lookup"
.cindex "security" "MX lookup"
.cindex "DNS" "DNSSEC"
-DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+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
(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.
message on the same connection. See section &<<SECTmulmessam>>& for an
explanation of when this might be needed.
+.new
+.option hosts_noproxy_tls smtp "host list&!!" *
+.cindex "TLS" "passing connection"
+.cindex "multiple SMTP deliveries"
+.cindex "TLS" "multiple message deliveries"
+For any host that matches this list, a TLS session which has
+been started will not be passed to a new delivery process for sending another
+message on the same session.
+
+The traditional implementation closes down TLS and re-starts it in the new
+process, on the same open TCP connection, for each successive message
+sent. If permitted by this option a pipe to to the new process is set up
+instead, and the original process maintains the TLS connection and proxies
+the SMTP connection from and to the new process and any subsequents.
+The new process has no access to TLS information, so cannot include it in
+logging.
+.wen
+
+
.option hosts_override smtp boolean false
If this option is set and the &%hosts%& option is also set, any hosts that are
unauthenticated. See also &%hosts_require_auth%&, and chapter
&<<CHAPSMTPAUTH>>& for details of authentication.
+.option hosts_try_chunking smtp "host list&!!" *
+.cindex CHUNKING "enabling, in client"
+.cindex BDAT "SMTP command"
+.cindex "RFC 3030" "CHUNKING"
+This option provides a list of servers to which, provided they announce
+CHUNKING support, Exim will attempt to use BDAT commands rather than DATA.
+BDAT will not be used in conjunction with a transport filter.
+
+.option hosts_try_fastopen smtp "host list&!!" unset
+.cindex "fast open, TCP" "enabling, in client"
+.cindex "TCP Fast Open" "enabling, in client"
+.cindex "RFC 7413" "TCP Fast Open"
+This option provides a list of servers to which, provided
+the facility is supported by this system, Exim will attempt to
+perform a TCP Fast Open.
+No data is sent on the SYN segment but, if the remote server also
+supports the facility, it can send its SMTP banner immediately after
+the SYN,ACK segment. This can save up to one round-trip time.
+
+The facility is only active for previously-contacted servers,
+as the initiator must present a cookie in the SYN segment.
+
+On (at least some) current Linux distributions the facility must be enabled
+in the kernel by the sysadmin before the support is usable.
+There is no option for control of the server side; if the system supports
+it it is always enebled. Note that legthy operations in the connect ACL,
+such as DNSBL lookups, will still delay the emission of the SMTP banner.
+
.option hosts_try_prdr smtp "host list&!!" *
.cindex "PRDR" "enabling, optional in client"
This option provides a list of servers to which, provided they announce
may be one or two files, depending on the type of DBM in use. The same files
are used for ETRN serialization.
-.new
See also the &%max_parallel%& generic transport option.
-.wen
.option size_addition smtp integer 1024
the use of the SIZE option altogether.
+.option socks_proxy smtp string&!! unset
+.cindex proxy SOCKS
+This option enables use of SOCKS proxies for connections made by the
+transport. For details see section &<<SECTproxySOCKS>>&.
+
+
.option tls_certificate smtp string&!! unset
.cindex "TLS" "client certificate, location of"
.cindex "certificate" "client, location of"
.option tls_verify_hosts smtp "host list&!!" unset
.cindex "TLS" "server certificate verification"
.cindex "certificate" "verification of server"
-This option gives a list of hosts for which. on encrypted connections,
+This option gives a list of hosts for which, on encrypted connections,
certificate verification must succeed.
The &%tls_verify_certificates%& option must also be set.
If both this option and &%tls_try_verify_hosts%& are unset
2822 address, including the angle brackets if necessary. If text outside angle
brackets contains a character whose value is greater than 126 or less than 32
(except for tab), the text is encoded according to RFC 2047. The character set
-is taken from &%headers_charset%&, which defaults to ISO-8859-1.
+is taken from &%headers_charset%&, which gets its default at build time.
When the &"w"& flag is set on a rule that causes an envelope address to be
rewritten, all but the working part of the replacement address is discarded.
deliver the message unauthenticated.
.endlist
+Note that the hostlist test for whether to do authentication can be
+confused if name-IP lookups change between the time the peer is decided
+on and the transport running. For example, with a manualroute
+router given a host name, and DNS "round-robin" use by that name: if
+the local resolver cache times out between the router and the transport
+running, the transport may get an IP for the name for its authentication
+check which does not match the connection peer IP.
+No authentication will then be done, despite the names being identical.
+
+For such cases use a separate transport which always authenticates.
+
.cindex "AUTH" "on MAIL command"
When Exim has authenticated itself to a remote server, it adds the AUTH
parameter to the MAIL commands it sends, if it has an authenticated sender for
} } } }
server_set_id = ${if = {1}{${listcount:$auth1}} {$auth1}{}}
.endd
+This accepts a client certificate that is verifiable against any
+of your configured trust-anchors
+(which usually means the full set of public CAs)
+and which has a SAN with a good account name.
+Note that the client cert is on the wire in-clear, including the SAN,
+whereas a plaintext SMTP AUTH done inside TLS is not.
+
+. An alternative might use
+. .code
+. server_param1 = ${sha256:$tls_in_peercert}
+. .endd
+. to require one of a set of specific certs that define a given account
+. (the verification is still required, but mostly irrelevant).
+. This would help for per-device use.
+.
+. However, for the future we really need support for checking a
+. user cert in LDAP - which probably wants a base-64 DER.
+
.ecindex IIDtlsauth1
.ecindex IIDtlsauth2
&url(http://www.gnutls.org/manual/html_node/Priority-Strings.html),
but beware that this relates to GnuTLS 3, which may be newer than the version
installed on your system. If you are using GnuTLS 3,
-&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string, then the example code)
+then the example code
+&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string)
on that site can be used to test a given string.
For example:
.cindex "TLS" "configuring an Exim server"
When Exim has been built with TLS support, it advertises the availability of
the STARTTLS command to client hosts that match &%tls_advertise_hosts%&,
-but not to any others. The default value of this option is unset, which means
-that STARTTLS is not advertised at all. This default is chosen because you
-need to set some other options in order to make TLS available, and also it is
-sensible for systems that want to use TLS only as a client.
+but not to any others. The default value of this option is *, which means
+that STARTTLS is alway advertised. Set it to blank to never advertise;
+this is reasonble for systems that want to use TLS only as a client.
+
+If STARTTLS is to be used you
+need to set some other options in order to make TLS available.
If a client issues a STARTTLS command and there is some configuration
problem in the server, the command is rejected with a 454 error. If the client
If a STARTTLS command is issued within an existing TLS session, it is
rejected with a 554 error code.
-To enable TLS operations on a server, you must set &%tls_advertise_hosts%& to
-match some hosts. You can, of course, set it to * to match all hosts.
-However, this is not all you need to do. TLS sessions to a server won't work
-without some further configuration at the server end.
+To enable TLS operations on a server, the &%tls_advertise_hosts%& option
+must be set to match some hosts. The default is * which matches all hosts.
+
+If this is all you do, TLS encryption will be enabled but not authentication -
+meaning that the peer has no assurance it is actually you he is talking to.
+You gain protection from a passive sniffer listening on the wire but not
+from someone able to intercept the communication.
+
+Further protection requires some further configuration at the server end.
It is rumoured that all existing clients that support TLS/SSL use RSA
encryption. To make this work you need to set, in the server,
proof expires. The downside is that it requires server support.
Unless Exim is built with the support disabled,
-.new
or with GnuTLS earlier than version 3.3.16 / 3.4.8
-.wen
support for OCSP stapling is included.
There is a global option called &%tls_ocsp_file%&.
Great care should be taken to deal with matters of case, various injection
attacks in the string (&`../`& or SQL), and ensuring that a valid filename
-can always be referenced; it is important to remember that &$tls_sni$& is
+can always be referenced; it is important to remember that &$tls_in_sni$& is
arbitrary unverified data provided prior to authentication.
+Further, the initial certificate is loaded before SNI is arrived, so
+an expansion for &%tls_certificate%& must have a default which is used
+when &$tls_in_sni$& is empty.
The Exim developers are proceeding cautiously and so far no other TLS options
are re-expanded.
"SECTmulmessam"
.cindex "multiple SMTP deliveries with TLS"
.cindex "TLS" "multiple message deliveries"
+.new
Exim sends multiple messages down the same TCP/IP connection by starting up
an entirely new delivery process for each message, passing the socket from
one process to the next. This implementation does not fit well with the use
of TLS, because there is quite a lot of state information associated with a TLS
connection, not just a socket identification. Passing all the state information
-to a new process is not feasible. Consequently, Exim shuts down an existing TLS
-session before passing the socket to a new process. The new process may then
+to a new process is not feasible. Consequently, for sending using TLS Exim
+starts an additional proxy process for handling the encryption, piping the
+unencrypted data stream from and to the delivery processes.
+
+An older mode of operation can be enabled on a per-host basis by the
+&%hosts_noproxy_tls%& option on the &(smtp)& transport. If the host matches
+this list the proxy process descibed above is not used; instead Exim
+.wen
+shuts down an existing TLS session being run by the delivery process
+before passing the socket to a new process. The new process may then
try to start a new TLS session, and if successful, may try to re-authenticate
if AUTH is in use, before sending the next message.
.section "Testing ACLs" "SECID188"
The &%-bh%& command line option provides a way of testing your ACL
configuration locally by running a fake SMTP session with which you interact.
-The host &'relay-test.mail-abuse.org'& provides a service for checking your
-relaying configuration (see section &<<SECTcheralcon>>& for more details).
-
.section "Specifying when ACLs are used" "SECID189"
session, and indeed is required to issue a new EHLO or HELO after successfully
setting up encryption following a STARTTLS command.
+Note also that a deny neither forces the client to go away nor means that
+mail will be refused on the connection. Consider checking for
+&$sender_helo_name$& being defined in a MAIL or RCPT ACL to do that.
+
If the command is accepted by an &%accept%& verb that has a &%message%&
modifier, the message may not contain more than one line (it will be truncated
at the first newline and a panic logged if it does). Such a message cannot
the ACL specified by &%acl_smtp_data%&, which is the second ACL that is
associated with the DATA command.
+.cindex CHUNKING "BDAT command"
+.cindex BDAT "SMTP command"
+.cindex "RFC 3030" CHUNKING
+If CHUNKING was advertised and a BDAT command sequence is received,
+the &%acl_smtp_predata%& ACL is not run.
+. XXX why not? It should be possible, for the first BDAT.
+The &%acl_smtp_data%& is run after the last BDAT command and all of
+the data specified is received.
+
For both of these ACLs, it is not possible to reject individual recipients. An
error response rejects the entire message. Unfortunately, it is known that some
MTAs do not treat hard (5&'xx'&) responses to the DATA command (either
PRDR may be used to support per-user content filtering. Without it
one must defer any recipient after the first that has a different
content-filter configuration. With PRDR, the RCPT-time check
-.new
.cindex "PRDR" "variable for"
for this can be disabled when the variable &$prdr_requested$&
is &"yes"&.
-.wen
Any required difference in behaviour of the main DATA-time
ACL should however depend on the PRDR-time ACL having run, as Exim
will avoid doing so in some situations (e.g. single-recipient mails).
remaining recipients. The &"discard"& return is not permitted for the
&%acl_smtp_predata%& ACL.
+If the ACL for VRFY returns &"accept"&, a recipient verify (without callout)
+is done on the address and the result determines the SMTP response.
+
.cindex "&[local_scan()]& function" "when all recipients discarded"
The &[local_scan()]& function is always run, even if there are no remaining
example:
.code
deny dnslists = list1.example
-dnslists = list2.example
+ dnslists = list2.example
.endd
If there are no conditions, the verb is always obeyed. Exim stops evaluating
the conditions and modifiers when it reaches a condition that fails. What
check a RCPT command:
.code
accept domains = +local_domains
-endpass
-verify = recipient
+ endpass
+ verify = recipient
.endd
If the recipient domain does not match the &%domains%& condition, control
passes to the next statement. If it does match, the recipient is verified, and
effect.
+.vitem &*queue*&&~=&~<&'text'&>
+This modifier specifies the use of a named queue for spool files
+for the message.
+It can only be used before the message is received (i.e. not in
+the DATA ACL).
+This could be used, for example, for known high-volume burst sources
+of traffic, or for quarantine of messages.
+Separate queue-runner processes will be needed for named queues.
+If the text after expansion is empty, the default queue is used.
+
+
.vitem &*remove_header*&&~=&~<&'text'&>
This modifier specifies one or more header names in a colon-separated list
that are to be removed from an incoming message, assuming, of course, that
is what is wanted for subsequent tests.
-.vitem &*control&~=&~cutthrough_delivery*&
+.vitem &*control&~=&~cutthrough_delivery/*&<&'options'&>
.cindex "&ACL;" "cutthrough routing"
.cindex "cutthrough" "requesting"
This option requests delivery be attempted while the item is being received.
An attempt to set this option for any recipient but the first
for a mail will be quietly ignored.
-If a recipient-verify callout connection is subsequently
+If a recipient-verify callout
+(with use_sender)
+connection is subsequently
requested in the same ACL it is held open and used for
any subsequent recipients and the data,
otherwise one is made after the initial RCPT ACL completes.
Note also that headers cannot be
modified by any of the post-data ACLs (DATA, MIME and DKIM).
Headers may be modified by routers (subject to the above) and transports.
+.new
+The Received-By: header is generated as soon as the body reception starts,
+rather than the traditional time after the full message is received;
+this will affect the timestamp.
+.wen
+
+All the usual ACLs are called; if one results in the message being
+rejected, all effort spent in delivery (including the costs on
+the ultimate destination) will be wasted.
+Note that in the case of data-time ACLs this includes the entire
+message body.
Cutthrough delivery is not supported via transport-filters or when DKIM signing
of outgoing messages is done, because it sends data to the ultimate destination
before the entire message has been received from the source.
-It is not supported for messages received with the SMTP PRDR option in use.
+It is not supported for messages received with the SMTP PRDR
+or CHUNKING
+options in use.
Should the ultimate destination system positively accept or reject the mail,
a corresponding indication is given to the source system and nothing is queued.
-If there is a temporary error the item is queued for later delivery in the
-usual fashion. If the item is successfully delivered in cutthrough mode
+If the item is successfully delivered in cutthrough mode
the delivery log lines are tagged with ">>" rather than "=>" and appear
before the acceptance "<=" line.
+If there is a temporary error the item is queued for later delivery in the
+usual fashion.
+This behaviour can be adjusted by appending the option &*defer=*&<&'value'&>
+to the control; the default value is &"spool"& and the alternate value
+&"pass"& copies an SMTP defer response from the target back to the initiator
+and does not queue the message.
+Note that this is independent of any recipient verify conditions in the ACL.
+
Delivery in this mode avoids the generation of a bounce mail to a
(possibly faked)
sender when the destination system is doing content-scan based rejection.
.cindex "&ACL;" "enabling debug logging"
.cindex "debugging" "enabling from an ACL"
This control turns on debug logging, almost as though Exim had been invoked
-with &`-d`&, with the output going to a new logfile, by default called
-&'debuglog'&. The filename can be adjusted with the &'tag'& option, which
+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. Some examples (which depend on variables that don't exist in all
+option.
+Logging started this way may be stopped, and the file removed,
+with the &'kill'& option.
+Some examples (which depend on variables that don't exist in all
contexts):
.code
control = debug
control = debug/tag=.$sender_host_address
control = debug/opts=+expand+acl
control = debug/tag=.$message_exim_id/opts=+expand
+ control = debug/kill
.endd
&*Note:*& This control applies only to the current message, not to any others
that are being submitted at the same time using &%-bs%& or &%-bS%&.
+
+.vitem &*control&~=&~utf8_downconvert*&
+This control enables conversion of UTF-8 in message addresses
+to a-label form.
+For details see section &<<SECTi18nMTA>>&.
.endlist vlist
RCPT ACL).
Headers will not be added to the message if the modifier is used in
-DATA, MIME or DKIM ACLs for messages delivered by cutthrough routing.
+DATA, MIME or DKIM ACLs for a message delivered by cutthrough routing.
Leading and trailing newlines are removed from
the data for the &%add_header%& modifier; if it then
with any ACL verb, including &%deny%&, though this is really not useful for
any verb that doesn't result in a delivered message.
-Headers will not be removed to the message if the modifier is used in
-DATA, MIME or DKIM ACLs for messages delivered by cutthrough routing.
+Headers will not be removed from the message if the modifier is used in
+DATA, MIME or DKIM ACLs for a message delivered by cutthrough routing.
More than one header can be removed at the same time by using a colon separated
list of header names. The header matching is case insensitive. Wildcards are
problems such as a syntax error or a memory shortage. For more details, see
chapter &<<CHAPexiscan>>&.
-.vitem &*demime&~=&~*&<&'extension&~list'&>
-.cindex "&%demime%& ACL condition"
-This condition is available only when Exim is compiled with the
-content-scanning extension. Its use is described in section
-&<<SECTdemimecond>>&.
-
.vitem &*dnslists&~=&~*&<&'list&~of&~domain&~names&~and&~other&~data'&>
.cindex "&%dnslists%& ACL condition"
.cindex "DNS list" "in ACL"
.cindex "&%verify%& ACL condition"
This is a variation of the previous option, in which a modified address is
verified as a sender.
+
+Note that '/' is legal in local-parts; if the address may have such
+(eg. is generated from the received message)
+they must be protected from the options parsing by doubling:
+.code
+verify = sender=${sg{${address:$h_sender:}}{/}{//}}
+.endd
.endlist
warn message = X-Warn: sending host is on dialups list
dnslists = dialups.mail-abuse.org
.endd
-.cindex cacheing "of dns lookup"
+.cindex caching "of dns lookup"
.cindex DNS TTL
DNS list lookups are cached by Exim for the duration of the SMTP session
-.new
(but limited by the DNS return TTL value),
-.wen
so a lookup based on the IP address is done at most once for any incoming
connection (assuming long-enough TTL).
Exim does not share information between multiple incoming
and the outer dnsdb lookup finds the IP addresses for these hosts. The result
of expanding the condition might be something like this:
.code
-dnslists = sbl.spahmaus.org/<|192.168.2.3|192.168.5.6|...
+dnslists = sbl.spamhaus.org/<|192.168.2.3|192.168.5.6|...
.endd
Thus, this example checks whether or not the IP addresses of the sender
domain's mail servers are on the Spamhaus black list.
need to use this option unless you know that the called hosts make use of the
sender when checking recipients. If used indiscriminately, it reduces the
usefulness of callout caching.
+
+.new
+.vitem &*hold*&
+This option applies to recipient callouts only. For example:
+.code
+require verify = recipient/callout=use_sender,hold
+.endd
+It causes the connection to be helod open and used for any further recipients
+and for eventual delivery (should that be done quickly).
+Doing this saves on TCP and SMTP startup costs, and TLS costs also
+when that is used for the connections.
+The advantage is only gained if there are no callout cache hits
+(which could be enforced by the no_cache option),
+if the use_sender option is used,
+if neither the random nor the use_postmaster option is used,
+and if no other callouts intervene.
+.wen
.endlist
If you use any of the parameters that set a non-empty sender for the MAIL
You can check the relay characteristics of your configuration in the same way
that you can test any ACL behaviour for an incoming SMTP connection, by using
the &%-bh%& option to run a fake SMTP session with which you interact.
-
-For specifically testing for unwanted relaying, the host
-&'relay-test.mail-abuse.org'& provides a useful service. If you telnet to this
-host from the host on which Exim is running, using the normal telnet port, you
-will see a normal telnet connection message and then quite a long delay. Be
-patient. The remote host is making an SMTP connection back to your host, and
-trying a number of common probes to test for open relay vulnerability. The
-results of the tests will eventually appear on your terminal.
.ecindex IIDacl
Two new main configuration options: &%av_scanner%& and &%spamd_address%&.
.endlist
-There is another content-scanning configuration option for &_Local/Makefile_&,
-called WITH_OLD_DEMIME. If this is set, the old, deprecated &%demime%& ACL
-condition is compiled, in addition to all the other content-scanning features.
-
Content-scanning is continually evolving, and new features are still being
added. While such features are still unstable and liable to incompatible
changes, they are made available in Exim by setting options whose names begin
.endd
If you omit the argument, the default values show above are used.
+.new
+.vitem &%f-prot6d%&
+.cindex "virus scanners" "f-prot6d"
+The f-prot6d scanner is accessed using the FPSCAND protocol over TCP.
+One argument is taken, being a space-separated hostname and port number.
+For example:
+.code
+av_scanner = f-prot6d:localhost 10200
+.endd
+If you omit the argument, the default values show above are used.
+.wen
+
.vitem &%fsecure%&
.cindex "virus scanners" "F-Secure"
The F-Secure daemon scanner (&url(http://www.f-secure.com)) takes one
parts of documentation are now available in English. You can get it at
&url(http://linux.mks.com.pl/). The only option for this scanner type is
the maximum number of processes used simultaneously to scan the attachments,
-provided that the demime facility is employed and also provided that mksd has
+provided that mksd has
been run with at least the same number of child processes. For example:
.code
av_scanner = mksd:2
a commandline to send (may include a single %s which will be replaced with
the path to the mail file to be scanned),
an RE to trigger on from the returned data,
-an RE to extract malware_name from the returned data.
+and an RE to extract malware_name from the returned data.
For example:
.code
-av_scanner = sock:127.0.0.1 6001:%s:(SPAM|VIRUS):(.*)\$
+av_scanner = sock:127.0.0.1 6001:%s:(SPAM|VIRUS):(.*)$
.endd
-Default for the socket specifier is &_/tmp/malware.sock_&.
-Default for the commandline is &_%s\n_&.
-Both regular-expressions are required.
+.new
+Note that surrounding whitespace is stripped from each option, meaning
+there is no way to specify a trailing newline.
+The socket specifier and both regular-expressions are required.
+Default for the commandline is &_%s\n_& (note this does have a trailing newline);
+specify an empty element to get this.
+.wen
.vitem &%sophie%&
.cindex "virus scanners" "Sophos and Sophie"
&%message%& modifier that specifies the error returned to the sender, and/or in
logging data.
-If your virus scanner cannot unpack MIME and TNEF containers itself, you should
-use the &%demime%& condition (see section &<<SECTdemimecond>>&) before the
-&%malware%& condition.
-
Beware the interaction of Exim's &%message_size_limit%& with any size limits
imposed by your anti-virus scanner.
Here is a very simple scanning example:
.code
deny message = This message contains malware ($malware_name)
- demime = *
malware = *
.endd
The next example accepts messages when there is a problem with the scanner:
.code
deny message = This message contains malware ($malware_name)
- demime = *
malware = */defer_ok
.endd
The next example shows how to use an ACL variable to scan with both sophie and
.code
spamd_address = 192.168.99.45 387
.endd
+The SpamAssassin protocol relies on a TCP half-close from the client.
+If your SpamAssassin client side is running a Linux system with an
+iptables firewall, consider setting
+&%net.netfilter.nf_conntrack_tcp_timeout_close_wait%& to at least the
+timeout, Exim uses when waiting for a response from the SpamAssassin
+server (currently defaulting to 120s). With a lower value the Linux
+connection tracking may consider your half-closed connection as dead too
+soon.
+
To use Rspamd (which by default listens on all local addresses
on TCP port 11333)
Unix and TCP socket specifications may be mixed in any order.
Each element of the list is a list itself, space-separated by default
-and changeable in the usual way.
+and changeable in the usual way; take care to not double the separator.
For TCP socket specifications a host name or IP (v4 or v6, but
subject to list-separator quoting rules) address can be used,
A multiline text table, containing the full SpamAssassin report for the
message. Useful for inclusion in headers or reject messages.
This variable is only usable in a DATA-time ACL.
+Beware that SpamAssassin may return non-ASCII characters, especially
+when running in country-specific locales, which are not legal
+unencoded in headers.
.vitem &$spam_action$&
For SpamAssassin either 'reject' or 'no action' depending on the
&*Warning*&: With large messages, these conditions can be fairly
CPU-intensive.
-
-
-
-.section "The demime condition" "SECTdemimecond"
-.cindex "content scanning" "MIME checking"
-.cindex "MIME content scanning"
-The &%demime%& ACL condition provides MIME unpacking, sanity checking and file
-extension blocking. It is usable only in the DATA and non-SMTP ACLs. The
-&%demime%& condition uses a simpler interface to MIME decoding than the MIME
-ACL functionality, but provides no additional facilities. Please note that this
-condition is deprecated and kept only for backward compatibility. You must set
-the WITH_OLD_DEMIME option in &_Local/Makefile_& at build time to be able to
-use the &%demime%& condition.
-
-The &%demime%& condition unpacks MIME containers in the message. It detects
-errors in MIME containers and can match file extensions found in the message
-against a list. Using this facility produces files containing the unpacked MIME
-parts of the message in the temporary scan directory. If you do antivirus
-scanning, it is recommended that you use the &%demime%& condition before the
-antivirus (&%malware%&) condition.
-
-On the right-hand side of the &%demime%& condition you can pass a
-colon-separated list of file extensions that it should match against. For
-example:
-.code
-deny message = Found blacklisted file attachment
- demime = vbs:com:bat:pif:prf:lnk
-.endd
-If one of the file extensions is found, the condition is true, otherwise it is
-false. If there is a temporary error while demimeing (for example, &"disk
-full"&), the condition defers, and the message is temporarily rejected (unless
-the condition is on a &%warn%& verb).
-
-The right-hand side is expanded before being treated as a list, so you can have
-conditions and lookups there. If it expands to an empty string, &"false"&, or
-zero (&"0"&), no demimeing is done and the condition is false.
-
-The &%demime%& condition set the following variables:
-
-.vlist
-.vitem &$demime_errorlevel$&
-.vindex "&$demime_errorlevel$&"
-When an error is detected in a MIME container, this variable contains the
-severity of the error, as an integer number. The higher the value, the more
-severe the error (the current maximum value is 3). If this variable is unset or
-zero, no error occurred.
-
-.vitem &$demime_reason$&
-.vindex "&$demime_reason$&"
-When &$demime_errorlevel$& is greater than zero, this variable contains a
-human-readable text string describing the MIME error that occurred.
-.endlist
-
-.vlist
-.vitem &$found_extension$&
-.vindex "&$found_extension$&"
-When the &%demime%& condition is true, this variable contains the file
-extension it found.
-.endlist
-
-Both &$demime_errorlevel$& and &$demime_reason$& are set by the first call of
-the &%demime%& condition, and are not changed on subsequent calls.
-
-If you do not want to check for file extensions, but rather use the &%demime%&
-condition for unpacking or error checking purposes, pass &"*"& as the
-right-hand side value. Here is a more elaborate example of how to use this
-facility:
-.code
-# Reject messages with serious MIME container errors
-deny message = Found MIME error ($demime_reason).
- demime = *
- condition = ${if >{$demime_errorlevel}{2}{1}{0}}
-
-# Reject known virus spreading file extensions.
-# Accepting these is pretty much braindead.
-deny message = contains $found_extension file (blacklisted).
- demime = com:vbs:bat:pif:scr
-
-# Freeze .exe and .doc files. Postmaster can
-# examine them and eventually thaw them.
-deny log_message = Another $found_extension file.
- demime = exe:doc
- control = freeze
-.endd
.ecindex IIDcosca
.vlist
.vitem &*int&~body_linecount*&
This variable contains the number of lines in the message's body.
+.new
+It is not valid if the &%spool_files_wireformat%& option is used.
+.wen
.vitem &*int&~body_zerocount*&
This variable contains the number of binary zero bytes in the message's body.
+.new
+It is not valid if the &%spool_files_wireformat%& option is used.
+.wen
.vitem &*unsigned&~int&~debug_selector*&
This variable is set to zero when no debugging is taking place. Otherwise, it
.section "Resent- header lines" "SECID220"
.cindex "&%Resent-%& header lines"
+.cindex "header lines" "Resent-"
RFC 2822 makes provision for sets of header lines starting with the string
&`Resent-`& to be added to a message when it is resent by the original
recipient to somebody else. These headers are &'Resent-Date:'&,
.section "The Date: header line" "SECID223"
.cindex "&'Date:'& header line"
+.cindex "header lines" "Date:"
If a locally-generated or submission-mode message has no &'Date:'& header line,
Exim adds one, using the current date and time, unless the
&%suppress_local_fixups%& control has been specified.
.section "The Envelope-to: header line" "SECID225"
.cindex "&'Envelope-to:'& header line"
+.cindex "header lines" "Envelope-to:"
.oindex "&%envelope_to_remove%&"
&'Envelope-to:'& header lines are not part of the standard RFC 2822 header set.
Exim can be configured to add them to the final delivery of messages. (See the
.section "The From: header line" "SECTthefrohea"
.cindex "&'From:'& header line"
+.cindex "header lines" "From:"
.cindex "Sendmail compatibility" "&""From""& line"
.cindex "message" "submission"
.cindex "submission mode"
.section "The Message-ID: header line" "SECID226"
.cindex "&'Message-ID:'& header line"
+.cindex "header lines" "Message-ID:"
.cindex "message" "submission"
.oindex "&%message_id_header_text%&"
If a locally-generated or submission-mode incoming message does not contain a
.section "The Received: header line" "SECID227"
.cindex "&'Received:'& header line"
+.cindex "header lines" "Received:"
A &'Received:'& header line is added at the start of every message. The
contents are defined by the &%received_header_text%& configuration option, and
Exim automatically adds a semicolon and a timestamp to the configured string.
.section "The References: header line" "SECID228"
.cindex "&'References:'& header line"
+.cindex "header lines" "References:"
Messages created by the &(autoreply)& transport include a &'References:'&
header line. This is constructed according to the rules that are described in
section 3.64 of RFC 2822 (which states that replies should contain such a
.section "The Return-path: header line" "SECID229"
.cindex "&'Return-path:'& header line"
+.cindex "header lines" "Return-path:"
.oindex "&%return_path_remove%&"
&'Return-path:'& header lines are defined as something an MTA may insert when
it does the final delivery of messages. (See the generic &%return_path_add%&
.section "The Sender: header line" "SECTthesenhea"
.cindex "&'Sender:'& header line"
.cindex "message" "submission"
+.cindex "header lines" "Sender:"
For a locally-originated message from an untrusted user, Exim may remove an
existing &'Sender:'& header line, and it may add a new one. You can modify
these actions by setting the &%local_sender_retain%& option true, the
When Exim receives a VRFY or EXPN command on a TCP/IP connection, it
runs the ACL specified by &%acl_smtp_vrfy%& or &%acl_smtp_expn%& (as
appropriate) in order to decide whether the command should be accepted or not.
-If no ACL is defined, the command is rejected.
.cindex "VRFY" "processing"
+When no ACL is defined for VRFY, or if it rejects without
+setting an explicit response code, the command is accepted
+(with a 252 SMTP response code)
+in order to support awkward clients that do a VRFY before every RCPT.
When VRFY is accepted, it runs exactly the same code as when Exim is
-called with the &%-bv%& option.
+called with the &%-bv%& option, and returns 250/451/550
+SMTP response codes.
.cindex "EXPN" "processing"
+If no ACL for EXPN is defined, the command is rejected.
When EXPN is accepted, a single-level expansion of the address is done.
EXPN is treated as an &"address test"& (similar to the &%-bt%& option) rather
than a verification (the &%-bv%& option). If an unqualified local part is given
timestamp. The flags are:
.display
&`<=`& message arrival
+&`(=`& message fakereject
&`=>`& normal message delivery
&`->`& additional address in same delivery
&`>>`& cutthrough message delivery
session was encrypted, there is an additional X field that records the cipher
suite that was used.
+.cindex log protocol
The protocol is set to &"esmtpsa"& or &"esmtpa"& for messages received from
hosts that have authenticated themselves using the SMTP AUTH command. The first
value is used when the SMTP connection was encrypted (&"secure"&). In this case
.cindex "log" "delivery line"
The format of the single-line entry in the main log that is written for every
delivery is shown in one of the examples below, for local and remote
-deliveries, respectively. Each example has been split into two lines in order
+deliveries, respectively. Each example has been split into multiple lines in order
to fit it on the page:
.code
2002-10-31 08:59:13 16ZCW1-0005MB-00 => marv
flagged with &`->`& instead of &`=>`&. When two or more messages are delivered
down a single SMTP connection, an asterisk follows the IP address in the log
lines for the second and subsequent messages.
+.new
+When two or more messages are delivered down a single TLS connection, the
+DNS and some TLS-related information logged for the first message delivered
+will not be present in the log lines for the second and subsequent messages.
+TLS cipher information is still available.
+.wen
.cindex "delivery" "cutthrough; logging"
.cindex "cutthrough" "logging"
&`CV `& certificate verification status
&`D `& duration of &"no mail in SMTP session"&
&`DN `& distinguished name from peer certificate
+&`DS `& DNSSEC secured lookups
&`DT `& on &`=>`& lines: time taken for a delivery
&`F `& sender address (on delivery lines)
&`H `& host name and IP address
&`I `& local interface used
+&`K `& CHUNKING extension used
&`id `& message id for incoming message
+&`M8S `& 8BITMIME status for incoming message
&`P `& on &`<=`& lines: protocol used
&` `& on &`=>`& and &`**`& lines: return path
+&`PRDR`& PRDR extension used
+&`PRX `& on &`<=`& and &`=>`& lines: proxy address
+&`Q `& alternate queue name
&`QT `& on &`=>`& lines: time spent on queue so far
&` `& on &"Completed"& lines: time spent on queue
&`R `& on &`<=`& lines: reference for local bounce
-&` `& on &`=>`& &`**`& and &`==`& lines: router name
-&`S `& size of message
+&` `& on &`=>`& &`>>`& &`**`& and &`==`& lines: router name
+&`S `& size of message in bytes
&`SNI `& server name indication from TLS client hello
&`ST `& shadow transport name
&`T `& on &`<=`& lines: message subject (topic)
+&`TFO `& connection took advantage of TCP Fast Open
&` `& on &`=>`& &`**`& and &`==`& lines: transport name
&`U `& local user or RFC 1413 identity
&`X `& TLS cipher suite
&` deliver_time `& time taken to perform delivery
&` delivery_size `& add &`S=`&&'nnn'& to => lines
&`*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)
-.new
+&` millisec `& millisecond timestamps and QT,DT,D times
&` outgoing_interface `& local interface on => lines
-.wen
&` 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
+&` proxy `& proxy address on <= and => lines
&` received_recipients `& recipients on <= lines
&` received_sender `& sender on <= lines
&`*rejected_header `& header contents on reject log
.cindex "log" "delivery duration"
&%deliver_time%&: For each delivery, the amount of real time it has taken to
perform the actual delivery is logged as DT=<&'time'&>, for example, &`DT=1s`&.
+If millisecond logging is enabled, short times will be shown with greater
+precision, eg. &`DT=0.304`&.
.next
.cindex "log" "message size on delivery"
.cindex "size" "of message"
&%dnslist_defer%&: A log entry is written if an attempt to look up a host in a
DNS black list suffers a temporary error.
.next
+.cindex log dnssec
+.cindex dnssec logging
+&%dnssec%&: For message acceptance and (attempted) delivery log lines, when
+dns lookups gave secure results a tag of DS is added.
+For acceptance this covers the reverse and forward lookups for host name verification.
+It does not cover helo-name verification.
+For delivery this covers the SRV, MX, A and/or AAAA lookups.
+.next
.cindex "log" "ETRN commands"
.cindex "ETRN" "logging"
&%etrn%&: Every valid ETRN command that is received is logged, before the ACL
followed by a colon and the port number. The local interface and port are also
added to other SMTP log lines, for example &"SMTP connection from"&, to
rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines.
-.new
The latter can be disabled by turning off the &%outgoing_interface%& option.
-.wen
+.next
+.cindex log "incoming proxy address"
+.cindex proxy "logging proxy address"
+.cindex "TCP/IP" "logging proxy address"
+&%proxy%&: The internal (closest to the system running Exim) IP address
+of the proxy, tagged by PRX=, on the &"<="& line for a message accepted
+on a proxied connection
+or the &"=>"& line for a message delivered on a proxied connection.
+See &<<SECTproxyInbound>>& for more information.
.next
.cindex "log" "incoming remote port"
.cindex "port" "logging remote"
&%lost_incoming_connection%&: A log line is written when an incoming SMTP
connection is unexpectedly dropped.
.next
+.new
+.cindex "log" "millisecond timestamps"
+.cindex millisecond logging
+.cindex timstamps "millisecond, in logs"
+&%millisec%&: Timestamps have a period and three decimal places of finer granularity
+appended to the seconds value.
+.wen
+.next
.cindex "log" "outgoing interface"
.cindex "log" "local interface"
.cindex "log" "local address and port"
.cindex "TCP/IP" "logging local address and port"
.cindex "interface" "logging"
-.new
&%outgoing_interface%&: If &%incoming_interface%& is turned on, then the
interface on which a message was sent is added to delivery lines as an I= tag
followed by IP address in square brackets. You can disable this by turning
off the &%outgoing_interface%& option.
-.wen
.next
.cindex "log" "outgoing remote port"
.cindex "port" "logging outgoint remote"
-.cindex "TCP/IP" "logging ougtoing remote port"
+.cindex "TCP/IP" "logging outgoing remote port"
&%outgoing_port%&: The remote port number is added to delivery log lines (those
containing => tags) following the IP address.
-.new
The local port is also added if &%incoming_interface%& and
&%outgoing_interface%& are both enabled.
-.wen
This option is not included in the default setting, because for most ordinary
configurations, the remote port number is always 25 (the SMTP port), and the
local port is a random ephemeral port.
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.
+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
.cindex "&'exipick'&"
John Jetmore's &'exipick'& utility is included in the Exim distribution. It
lists messages from the queue according to a variety of criteria. For details
-of &'exipick'&'s facilities, visit the web page at
-&url(http://www.exim.org/eximwiki/ToolExipickManPage) or run &'exipick'& with
+of &'exipick'&'s facilities, run &'exipick'& with
the &%--help%& option.
unprivileged), Exim must be built to allow group read access to its spool
files.
+.new
+By default, regular users are trusted to perform basic testing and
+introspection commands, as themselves. This setting can be tightened by
+setting the &%commandline_checks_require_admin%& option.
+This affects most of the checking options,
+such as &%-be%& and anything else &%-b*%&.
+.wen
.section "Spool files" "SECID275"
.next
.vindex "&$body_linecount$&"
If you change the number of lines in the file, the value of
-&$body_linecount$&, which is stored in the -H file, will be incorrect. At
-present, this value is not used by Exim, but there is no guarantee that this
-will always be the case.
+&$body_linecount$&, which is stored in the -H file, will be incorrect and can
+cause incomplete transmission of messages or undeliverable messages.
.next
If the message is in MIME format, you must take care not to break it.
.next
-J file and uses it to update the -H file before starting the next delivery
attempt.
+.new
+Files whose names end with -K or .eml may also be seen in the spool.
+These are temporaries used for DKIM or malware processing, when that is used.
+They should be tidied up by normal operations; any old ones are probably
+relics of crashes and can be removed.
+.wen
+
.section "Format of the -H file" "SECID282"
.cindex "uid (user id)" "in spool file"
.cindex "gid (group id)" "in spool file"
&$authenticated_sender$& variable.
.vitem "&%-body_linecount%&&~<&'number'&>"
-This records the number of lines in the body of the message, and is always
-present.
+This records the number of lines in the body of the message, and is
+present unless &%-spool_file_wireformat%& is.
.vitem "&%-body_zerocount%&&~<&'number'&>"
This records the number of binary zero bytes in the body of the message, and is
If a message was scanned by SpamAssassin, this is present. It records the value
of &$spam_score_int$&.
+.new
+.vitem &%-spool_file_wireformat%&
+The -D file for this message is in wire-format (for ESMTP CHUNKING)
+rather than Unix-format.
+The line-ending is CRLF rather than newline.
+There is still, however, no leading-dot-stuffing.
+.wen
+
.vitem &%-tls_certificate_verified%&
A TLS certificate was received from the client that sent this message, and the
certificate was verified by the server.
.ecindex IIDforspo2
.ecindex IIDforspo3
+.new
+.section "Format of the -D file" "SECID282a"
+The data file is traditionally in Unix-standard format: lines are ended with
+an ASCII newline character.
+However, when the &%spool_wireformat%& main option is used some -D files
+can have an alternate format.
+This is flagged by a &%-spool_file_wireformat%& line in the corresponding -H file.
+The -D file lines (not including the first name-component line) are
+suitable for direct copying to the wire when transmitting using the
+ESMTP CHUNKING option, meaning lower processing overhead.
+Lines are terminated with an ASCII CRLF pair.
+There is no dot-stuffing (and no dot-termination).
+.wen
+
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
be tracked on a per-domain basis, rather than merely upon source IP address.
DKIM is documented in RFC 4871.
-Since version 4.70, DKIM support is compiled into Exim by default. It can be
-disabled by setting DISABLE_DKIM=yes in Local/Makefile.
+DKIM support is compiled into Exim by default if TLS support is present.
+It can be disabled by setting DISABLE_DKIM=yes in &_Local/Makefile_&.
-Exim's DKIM implementation allows to
+Exim's DKIM implementation allows for
.olist
-Sign outgoing messages: This function is implemented in the SMTP transport.
+Signing outgoing messages: This function is implemented in the SMTP transport.
It can co-exist with all other Exim features
(including transport filters)
except cutthrough delivery.
.next
-Verify signatures in incoming messages: This is implemented by an additional
+Verifying signatures in incoming messages: This is implemented by an additional
ACL (acl_smtp_dkim), which can be called several times per message, with
different signature contexts.
.endlist
senders).
-.section "Signing outgoing messages" "SECID513"
+.section "Signing outgoing messages" "SECDKIMSIGN"
.cindex "DKIM" "signing"
-Signing is implemented by setting private options on the SMTP transport.
+Signing is enabled by setting private options on the SMTP transport.
These options take (expandable) strings as arguments.
-.option dkim_domain smtp string&!! unset
-MANDATORY:
-The domain you want to sign with. The result of this expanded
-option is put into the &%$dkim_domain%& expansion variable.
+.option dkim_domain smtp string list&!! unset
+The domain(s) you want to sign with.
+.new
+After expansion, this can be a list.
+Each element in turn is put into the &%$dkim_domain%& expansion variable
+while expanding the remaining signing options.
+.wen
+If it is empty after expansion, DKIM signing is not done.
-.option dkim_selector smtp string&!! unset
-MANDATORY:
-This sets the key selector string. You can use the &%$dkim_domain%& expansion
-variable to look up a matching selector. The result is put in the expansion
-variable &%$dkim_selector%& which should be used in the &%dkim_private_key%&
+.option dkim_selector smtp string list&!! unset
+This sets the key selector string.
+.new
+After expansion, which can use &$dkim_domain$&, this can be a list.
+Each element in turn is put in the expansion
+variable &%$dkim_selector%& which may be used in the &%dkim_private_key%&
option along with &%$dkim_domain%&.
+If the option is empty after expansion, DKIM signing is not done for this domain.
+.wen
.option dkim_private_key smtp string&!! unset
-MANDATORY:
-This sets the private key to use. You can use the &%$dkim_domain%& and
+This sets the private key to use.
+You can use the &%$dkim_domain%& and
&%$dkim_selector%& expansion variables to determine the private key to use.
The result can either
.ilist
be signed. This case will not result in an error, even if &%dkim_strict%&
is set.
.endlist
+If the option is empty after expansion, DKIM signing is not done.
+
+.new
+.option dkim_hash smtp string&!! sha256
+Can be set alternatively to &"sha1"& to use an alternate hash
+method. Note that sha1 is now condidered insecure, and deprecated.
+
+.option dkim_identity smtp string&!! unset
+If set after expansion, the value is used to set an "i=" tag in
+the signing header. The DKIM standards restrict the permissible
+syntax of this optional tag to a mail address, with possibly-empty
+local part, an @, and a domain identical to or subdomain of the "d="
+tag value. Note that Exim does not check the value.
+.wen
.option dkim_canon smtp string&!! unset
-OPTIONAL:
This option sets the canonicalization method used when signing a message.
The DKIM RFC currently supports two methods: "simple" and "relaxed".
The option defaults to "relaxed" when unset. Note: the current implementation
only supports using the same canonicalization method for both headers and body.
.option dkim_strict smtp string&!! unset
-OPTIONAL:
This option defines how Exim behaves when signing a message that
should be signed fails for some reason. When the expansion evaluates to
either "1" or "true", Exim will defer. Otherwise Exim will send the message
unsigned. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion
variables here.
-.option dkim_sign_headers smtp string&!! unset
-OPTIONAL:
-When set, this option must expand to (or be specified as) a colon-separated
+.option dkim_sign_headers smtp string&!! see below
+If set, this option must expand to a colon-separated
list of header names. Headers with these names will be included in the message
-signature. When unspecified, the header names recommended in RFC4871 will be
-used.
+signature.
+When unspecified, the header names recommended in RFC4871 will be used.
+The default list is available for the expansion in the macro
+"_DKIM_SIGN_HEADERS".
.section "Verifying DKIM signatures in incoming mail" "SECID514"
.cindex "DKIM" "verification"
-Verification of DKIM signatures in incoming email is implemented via the
+Verification of DKIM signatures in SMTP incoming email is implemented via the
&%acl_smtp_dkim%& ACL. By default, this ACL is called once for each
syntactically(!) correct signature in the incoming message.
A missing ACL definition defaults to accept.
If any ACL call does not accept, the message is not accepted.
-If a cutthrough delivery was in progress for the message it is
+If a cutthrough delivery was in progress for the message, that is
summarily dropped (having wasted the transmission effort).
To evaluate the signature in the ACL a large number of expansion variables
The signer that is being evaluated in this ACL run. This can be a domain or
an identity. This is one of the list items from the expanded main option
&%dkim_verify_signers%& (see above).
+
.vitem &%$dkim_verify_status%&
A string describing the general status of the signature. One of
.ilist
.next
&%pass%&: The signature passed verification. It is valid.
.endlist
+
.vitem &%$dkim_verify_reason%&
A string giving a little bit more detail when &%$dkim_verify_status%& is either
"fail" or "invalid". One of
re-written or otherwise changed in a way which is incompatible with
DKIM verification. It may of course also mean that the signature is forged.
.endlist
+
.vitem &%$dkim_domain%&
The signing domain. IMPORTANT: This variable is only populated if there is
an actual signature in the message for the current domain or identity (as
reflected by &%$dkim_cur_signer%&).
+
.vitem &%$dkim_identity%&
The signing identity, if present. IMPORTANT: This variable is only populated
if there is an actual signature in the message for the current domain or
identity (as reflected by &%$dkim_cur_signer%&).
+
.vitem &%$dkim_selector%&
The key record selector string.
+
.vitem &%$dkim_algo%&
The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'.
+
.vitem &%$dkim_canon_body%&
The body canonicalization method. One of 'relaxed' or 'simple'.
-.vitem &%dkim_canon_headers%&
+
+.vitem &%$dkim_canon_headers%&
The header canonicalization method. One of 'relaxed' or 'simple'.
+
.vitem &%$dkim_copiedheaders%&
A transcript of headers and their values which are included in the signature
(copied from the 'z=' tag of the signature).
+Note that RFC6376 requires that verification fail if the From: header is
+not included in the signature. Exim does not enforce this; sites wishing
+strict enforcement should code the check explicitly.
+
.vitem &%$dkim_bodylength%&
The number of signed body bytes. If zero ("0"), the body is unsigned. If no
limit was set by the signer, "9999999999999" is returned. This makes sure
that this variable always expands to an integer value.
+
.vitem &%$dkim_created%&
UNIX timestamp reflecting the date and time when the signature was created.
When this was not specified by the signer, "0" is returned.
+
.vitem &%$dkim_expires%&
UNIX timestamp reflecting the date and time when the signer wants the
signature to be treated as "expired". When this was not specified by the
signer, "9999999999999" is returned. This makes it possible to do useful
integer size comparisons against this value.
+
.vitem &%$dkim_headernames%&
A colon-separated list of names of headers included in the signature.
+
.vitem &%$dkim_key_testing%&
"1" if the key record has the "testing" flag set, "0" if not.
+
.vitem &%$dkim_key_nosubdomains%&
"1" if the key record forbids subdomaining, "0" otherwise.
+
.vitem &%$dkim_key_srvtype%&
Service type (tag s=) from the key record. Defaults to "*" if not specified
in the key record.
+
.vitem &%$dkim_key_granularity%&
Key granularity (tag g=) from the key record. Defaults to "*" if not specified
in the key record.
+
.vitem &%$dkim_key_notes%&
Notes from the key record (tag n=).
+
+.vitem &%$dkim_key_length%&
+Number of bits in the key.
.endlist
In addition, two ACL conditions are provided:
verb to a group of domains or identities. For example:
.code
-# Warn when Mail purportedly from GMail has no signature at all
-warn log_message = GMail sender without DKIM signature
+# Warn when Mail purportedly from GMail has no gmail signature
+warn log_message = GMail sender without gmail.com DKIM signature
sender_domains = gmail.com
dkim_signers = gmail.com
dkim_status = none
.endd
+Note that the above does not check for a total lack of DKIM signing;
+for that check for empty &$h_DKIM-Signature:$& in the data ACL.
+
.vitem &%dkim_status%&
ACL condition that checks a colon-separated list of possible DKIM verification
results against the actual result of verification. This is typically used
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
+.chapter "Proxies" "CHAPproxies" &&&
+ "Proxy support"
+.cindex "proxy support"
+.cindex "proxy" "access via"
+
+A proxy is an intermediate system through which communication is passed.
+Proxies may provide a security, availability or load-distribution function.
+
+
+.section "Inbound proxies" SECTproxyInbound
+.cindex proxy inbound
+.cindex proxy "server side"
+.cindex proxy "Proxy protocol"
+.cindex "Proxy protocol" proxy
+
+Exim has support for receiving inbound SMTP connections via a proxy
+that uses &"Proxy Protocol"& to speak to it.
+To include this support, include &"SUPPORT_PROXY=yes"&
+in Local/Makefile.
+
+It was built on specifications from:
+(&url(http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt)).
+That URL was revised in May 2014 to version 2 spec:
+(&url(http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e)).
+
+The purpose of this facility is so that an application load balancer,
+such as HAProxy, can sit in front of several Exim servers
+to distribute load.
+Exim uses the local protocol communication with the proxy to obtain
+the remote SMTP system IP address and port information.
+There is no logging if a host passes or
+fails Proxy Protocol negotiation, but it can easily be determined and
+recorded in an ACL (example is below).
+
+Use of a proxy is enabled by setting the &%hosts_proxy%&
+main configuration option to a hostlist; connections from these
+hosts will use Proxy Protocol.
+Exim supports both version 1 and version 2 of the Proxy Protocol and
+automatically determines which version is in use.
+
+The Proxy Protocol header is the first data received on a TCP connection
+and is inserted before any TLS-on-connect handshake from the client; Exim
+negotiates TLS between Exim-as-server and the remote client, not between
+Exim and the proxy server.
+
+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
+If &$proxy_session$& is set but &$proxy_external_address$& is empty
+there was a protocol error.
+
+Since the real connections are all coming from the proxy, and the
+per host connection tracking is done before Proxy Protocol is
+evaluated, &%smtp_accept_max_per_host%& must be set high enough to
+handle all of the parallel volume you expect per inbound proxy.
+With the option set so high, you lose the ability
+to protect your server from many connections from one IP.
+In order to prevent your server from overload, you
+need to add a per connection ratelimit to your connect ACL.
+A possible solution is:
+.display
+ # Set max number of connections per host
+ LIMIT = 5
+ # Or do some kind of IP lookup in a flat file or database
+ # LIMIT = ${lookup{$sender_host_address}iplsearch{/etc/exim/proxy_limits}}
+
+ defer message = Too many connections from this IP right now
+ ratelimit = LIMIT / 5s / per_conn / strict
+.endd
+
+
+
+.section "Outbound proxies" SECTproxySOCKS
+.cindex proxy outbound
+.cindex proxy "client side"
+.cindex proxy SOCKS
+.cindex SOCKS proxy
+Exim has support for sending outbound SMTP via a proxy
+using a protocol called SOCKS5 (defined by RFC1928).
+The support can be optionally included by defining SUPPORT_SOCKS=yes in
+Local/Makefile.
+
+Use of a proxy is enabled by setting the &%socks_proxy%& option
+on an smtp transport.
+The option value is expanded and should then be a list
+(colon-separated by default) of proxy specifiers.
+Each proxy specifier is a list
+(space-separated by default) where the initial element
+is an IP address and any subsequent elements are options.
+
+Options are a string <name>=<value>.
+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
+
+More details on each of these options follows:
+
+.ilist
+.cindex authentication "to proxy"
+.cindex proxy authentication
+&%auth%&: Either &"none"& (default) or &"name"&.
+Using &"name"& selects username/password authentication per RFC 1929
+for access to the proxy.
+Default is &"none"&.
+.next
+&%name%&: sets the username for the &"name"& authentication method.
+Default is empty.
+.next
+&%pass%&: sets the password for the &"name"& authentication method.
+Default is empty.
+.next
+&%port%&: the TCP port number to use for the connection to the proxy.
+Default is 1080.
+.next
+&%tmo%&: sets a connection timeout in seconds for this proxy.
+Default is 5.
+.next
+&%pri%&: specifies a priority for the proxy within the list,
+higher values being tried first.
+The default priority is 1.
+.next
+&%weight%&: specifies a selection bias.
+Within a priority set servers are queried in a random fashion,
+weighted by this value.
+The default value for selection bias is 1.
+.endlist
+
+Proxies from the list are tried according to their priority
+and weight settings until one responds. The timeout for the
+overall connection applies to the set of proxied attempts.
+
+.section Logging SECTproxyLog
+To log the (local) IP of a proxy in the incoming or delivery logline,
+add &"+proxy"& to the &%log_selector%& option.
+This will add a component tagged with &"PRX="& to the line.
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
+.chapter "Internationalisation" "CHAPi18n" &&&
+ "Internationalisation""
+.cindex internationalisation "email address"
+.cindex EAI
+.cindex i18n
+.cindex UTF-8 "mail name handling"
+
+Exim has support for Internationalised mail names.
+To include this it must be built with SUPPORT_I18N and the libidn library.
+Standards supported are RFCs 2060, 5890, 6530 and 6533.
+
+If Exim is built with SUPPORT_I18N_2008 (in addition to SUPPORT_I18N, not
+instead of it) then IDNA2008 is supported; this adds an extra library
+requirement, upon libidn2.
+
+.section "MTA operations" SECTi18nMTA
+.cindex SMTPUTF8 "ESMTP option"
+The main configuration option &%smtputf8_advertise_hosts%& specifies
+a host list. If this matches the sending host and
+accept_8bitmime is true (the default) then the ESMTP option
+SMTPUTF8 will be advertised.
+
+If the sender specifies the SMTPUTF8 option on a MAIL command
+international handling for the message is enabled and
+the expansion variable &$message_smtputf8$& will have value TRUE.
+
+The option &%allow_utf8_domains%& is set to true for this
+message. All DNS lookups are converted to a-label form
+whatever the setting of &%allow_utf8_domains%&
+when Exim is built with SUPPORT_I18N.
+
+Both localparts and domain are maintained as the original
+UTF-8 form internally; any comparison or regular-expression use will
+require appropriate care. Filenames created, eg. by
+the appendfile transport, will have UTF-8 names.
+
+HELO names sent by the smtp transport will have any UTF-8
+components expanded to a-label form,
+and any certificate name checks will be done using the a-label
+form of the name.
+
+.cindex log protocol
+.cindex SMTPUTF8 logging
+Log lines and Received-by: header lines will acquire a "utf8"
+prefix on the protocol element, eg. utf8esmtp.
+
+The following expansion operators can be used:
+.code
+${utf8_domain_to_alabel:str}
+${utf8_domain_from_alabel:str}
+${utf8_localpart_to_alabel:str}
+${utf8_localpart_from_alabel:str}
+.endd
+
+ACLs may use the following modifier:
+.display
+control = utf8_downconvert
+control = utf8_downconvert/<value>
+.endd
+This sets a flag requiring that addresses are converted to
+a-label form before smtp delivery, for use in a
+Message Submission Agent context.
+If a value is appended it may be:
+.display
+&`1 `& (default) mandatory downconversion
+&`0 `& no downconversion
+&`-1 `& if SMTPUTF8 not supported by destination host
+.endd
+
+If mua_wrapper is set, the utf8_downconvert control
+is initially set to -1.
+
+
+There is no explicit support for VRFY and EXPN.
+Configurations supporting these should inspect
+&$smtp_command_argument$& for an SMTPUTF8 argument.
+
+There is no support for LMTP on Unix sockets.
+Using the "lmtp" protocol option on an smtp transport,
+for LMTP over TCP, should work as expected.
+
+There is no support for DSN unitext handling,
+and no provision for converting logging from or to UTF-8.
+
+
+
+.section "MDA operations" SECTi18nMDA
+To aid in constructing names suitable for IMAP folders
+the following expansion operator can be used:
+.code
+${imapfolder {<string>} {<sep>} {<specials>}}
+.endd
+
+The string is converted from the charset specified by
+the "headers charset" command (in a filter file)
+or &%headers_charset%& main configuration option (otherwise),
+to the
+modified UTF-7 encoding specified by RFC 2060,
+with the following exception: All occurences of <sep>
+(which has to be a single character)
+are replaced with periods ("."), and all periods and slashes that are not
+<sep> and are not in the <specials> string are BASE64 encoded.
+
+The third argument can be omitted, defaulting to an empty string.
+The second argument can be omitted, defaulting to "/".
+
+This is the encoding used by Courier for Maildir names on disk, and followed
+by many other IMAP servers.
+
+Examples:
+.display
+&`${imapfolder {Foo/Bar}} `& yields &`Foo.Bar`&
+&`${imapfolder {Foo/Bar}{.}{/}} `& yields &`Foo&&AC8-Bar`&
+&`${imapfolder {Räksmörgås}} `& yields &`R&&AOQ-ksm&&APY-rg&&AOU-s`&
+.endd
+
+Note that the source charset setting is vital, and also that characters
+must be representable in UTF-16.
+
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
+.chapter "Events" "CHAPevents" &&&
+ "Events"
+.cindex events
+
+The events mechanism in Exim can be used to intercept processing at a number
+of points. It was originally invented to give a way to do customised logging
+actions (for example, to a database) but can also be used to modify some
+processing actions.
+
+Most installations will never need to use Events.
+The support can be left out of a build by defining DISABLE_EVENT=yes
+in &_Local/Makefile_&.
+
+There are two major classes of events: main and transport.
+The main configuration option &%event_action%& controls reception events;
+a transport option &%event_action%& controls delivery events.
+
+Both options are a string which is expanded when the event fires.
+An example might look like:
+.cindex logging custom
+.code
+event_action = ${if eq {msg:delivery}{$event_name} \
+{${lookup pgsql {SELECT * FROM record_Delivery( \
+ '${quote_pgsql:$sender_address_domain}',\
+ '${quote_pgsql:${lc:$sender_address_local_part}}', \
+ '${quote_pgsql:$domain}', \
+ '${quote_pgsql:${lc:$local_part}}', \
+ '${quote_pgsql:$host_address}', \
+ '${quote_pgsql:${lc:$host}}', \
+ '${quote_pgsql:$message_exim_id}')}} \
+} {}}
+.endd
+
+Events have names which correspond to the point in process at which they fire.
+The name is placed in the variable &$event_name$& and the event action
+expansion must check this, as it will be called for every possible event type.
+
+The current list of events is:
+.display
+&`msg:complete after main `& per message
+&`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 attempt
+&`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
+.endd
+New event types may be added in future.
+
+The event name is a colon-separated list, defining the type of
+event in a tree of possibilities. It may be used as a list
+or just matched on as a whole. There will be no spaces in the name.
+
+The second column in the table above describes whether the event fires
+before or after the action is associates with. Those which fire before
+can be used to affect that action (more on this below).
+
+.new
+The third column in the table above says what section of the configumration
+should define the event action.
+.wen
+
+An additional variable, &$event_data$&, is filled with information varying
+with the event type:
+.display
+&`msg:delivery `& smtp confirmation message
+&`msg:rcpt:host:defer `& error string
+&`msg:rcpt:defer `& error string
+&`msg:host:defer `& error string
+&`tls:cert `& verification chain depth
+&`smtp:connect `& smtp banner
+.endd
+
+The :defer events populate one extra variable: &$event_defer_errno$&.
+
+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
+variables set in transport events will not be visible outside that
+transport call
+.next
+acl_m variables in a server context are lost on a new connection,
+and after smtp helo/ehlo/mail/starttls/rset commands
+.endlist
+Using an ACL expansion with the logwrite modifier can be
+a useful way of writing to the main log.
+
+The expansion of the event_action option should normally
+return an empty string. Should it return anything else the
+following will be forced:
+.display
+&`msg:delivery `& (ignored)
+&`msg:host:defer `& (ignored)
+&`msg:fail:delivery`& (ignored)
+&`tcp:connect `& do not connect
+&`tcp:close `& (ignored)
+&`tls:cert `& refuse verification
+&`smtp:connect `& close connection
+.endd
+No other use is made of the result string.
+
+For a tcp:connect event, if the connection is being made to a proxy
+then the address and port variables will be that of the proxy and not
+the target system.
+
+For tls:cert events, if GnuTLS is in use this will trigger only per
+chain element received on the connection.
+For OpenSSL it will trigger for every chain element including those
+loaded locally.
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
.chapter "Adding new drivers or lookup types" "CHID13" &&&
"Adding drivers or lookups"
.cindex "adding drivers"
git://git.exim.org / users / heiko / exim.git / blobdiff