. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.88"
+.set previousversion "4.89"
.include ./local_params
.set ACL "access control lists (ACLs)"
.set I " "
.macro copyyear
-2016
+2017
.endmacro
. /////////////////////////////////////////////////////////////////////////////
.section "Exim documentation" "SECID1"
. Keep this example change bar when updating the documentation!
+.new
.cindex "documentation"
This edition of the Exim specification applies to version &version() of Exim.
Substantive changes from the &previousversion; edition are marked in some
renditions of the document; this paragraph is so marked if the rendition is
capable of showing a change indicator.
+.wen
This document is very much a reference manual; it is not a tutorial. The reader
is expected to have some familiarity with the SMTP mail transfer protocol and
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.
.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.
by Exim in conjunction with the &%-MC%& option. It signifies that the
remote host supports the ESMTP &_DSN_& extension.
-.vitem &%-MCG%&
+.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 option.
+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%&"
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%&"
For example:
.code
exim -bp -qGquarantine
-mailq -qGquarantime
+mailq -qGquarantine
exim -qGoffpeak -Rf @special.domain.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.
-.new
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.
-.wen
Includes may be nested to any depth, but remember that Exim reads its
configuration file often, so it is a good idea to keep them to a minimum.
.next
.cindex "Redis lookup type"
.cindex lookup Redis
-&(redis)&: The format of the query is an SQL statement that is passed to a
-Redis database. See section &<<SECTsql>>&.
+&(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"
The form if &"retry_VAL"& where VAL is an integer.
The default count is set by the main configuration option &%dns_retry%&.
-.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).
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
.vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&&
{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&"
-.cindex "expansion" "extracting cerificate fields"
+.cindex "expansion" "extracting certificate fields"
.cindex "&%certextract%&" "certificate fields"
.cindex "certificate" "extracting fields"
The <&'certificate'&> must be a variable of type certificate.
router or transport are not accessible.
For incoming SMTP messages, no header lines are visible in
-.new
ACLs that are obeyed before the data phase completes,
-.wen
because the header structure is not set up until the message is received.
They are visible in DKIM, PRDR and DATA ACLs.
Header lines that are added in a RCPT ACL (for example)
are saved until the message's incoming header lines are available, at which
point they are added.
-.new
When any of the above ACLs ar
-.wen
running, however, header lines added by earlier ACLs are visible.
Upper case and lower case letters are synonymous in header names. If the
.vitem "&*${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"
.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:
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}...
.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
&$proxy_local_port$& &&&
&$proxy_session$&
These variables are only available when built with Proxy Protocol
-or Socks5 support
+or SOCKS5 support.
For details see chapter &<<SECTproxyInbound>>&.
.vitem &$prdr_requested$&
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 "&$sender_host_name$&"
.vitem &$tls_in_ourcert$&
.vindex "&$tls_in_ourcert$&"
-.cindex certificate veriables
+.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
.oindex "&%perl_taintmode%&"
.cindex "Perl" "taintmode"
To provide more security executing Perl code via the embedded Perl
-interpeter, the &%perl_taintmode%& option can be set. This enables the
+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 "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"
There is a slight performance penalty for these checks.
Versions of Exim preceding 4.88 had these disabled by default;
-high-rate intallations confident they will never run out of resources
+high-rate installations confident they will never run out of resources
may wish to deliberately disable them.
.option chunking_advertise_hosts main "host list&!!" *
these hosts.
Hosts may use the BDAT command as an alternate to DATA.
+.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 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
of SSL-on-connect.
In the event of failure to negotiate TLS, the action taken is controlled
by &%ldap_require_cert%&.
-.new
This option is ignored for &`ldapi`& connections.
-.wen
.option ldap_version main integer unset
.option smtputf8_advertise_hosts main "host list&!!" *
.cindex "SMTPUTF8" "advertising"
When Exim is built with support for internationalised mail names,
-the availability therof is advertised in
+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.
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 tls_eccurve main string&!! &`auto`&
.cindex TLS "EC cryptography"
-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.
After expansion it must contain a valid EC curve parameter, such as
&`prime256v1`&, &`secp384r1`&, or &`P-512`&. Consult your OpenSSL manual
.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
.option path pipe string&!! "/bin:/usr/bin"
-.new
This option is expanded and
-.wen
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
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
.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 conjuction with a transport filter.
+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"
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
.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
attacks in the string (&`../`& or SQL), and ensuring that a valid filename
can always be referenced; it is important to remember that &$tls_in_sni$& is
arbitrary unverified data provided prior to authentication.
-Further, the initial cerificate is loaded before SNI is arrived, so
+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.
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
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.
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 receipient verify conditions in the ACL.
+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)
.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
(but limited by the DNS return TTL value),
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
.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
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"
&%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..
+or the &"=>"& line for a message delivered on a proxied connection.
See &<<SECTproxyInbound>>& for more information.
.next
.cindex "log" "incoming remote port"
.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.
The local port is also added if &%incoming_interface%& and
.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.
.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$&, which is stored in the -H file, will be incorrect and can
+cause incomplete transmission of messages or undeliverable messages.
.next
If the message is in MIME format, you must take care not to break it.
.next
Use of a proxy is enabled by setting the &%hosts_proxy%&
main configuration option to a hostlist; connections from these
hosts will use Proxy Protocol.
+Exim supports both version 1 and version 2 of the Proxy Protocol and
+automatically determines which version is in use.
+
+The Proxy Protocol header is the first data received on a TCP connection
+and is inserted before any TLS-on-connect handshake from the client; Exim
+negotiates TLS between Exim-as-server and the remote client, not between
+Exim and the proxy server.
The following expansion variables are usable
(&"internal"& and &"external"& here refer to the interfaces
.display
&'proxy_external_address '& IP of host being proxied or IP of remote interface of proxy
&'proxy_external_port '& Port of host being proxied or Port on remote interface of proxy
-&'proxy_local_address '& IP of proxy server inbound or IP of local interface of proxy
-&'proxy_local_port '& Port of proxy server inbound or Port on local interface of proxy
-&'proxy_session '& boolean: SMTP connection via proxy
+&'proxy_local_address '& IP of proxy server inbound or IP of local interface of proxy
+&'proxy_local_port '& Port of proxy server inbound or Port on local interface of proxy
+&'proxy_session '& boolean: SMTP connection via proxy
.endd
If &$proxy_session$& is set but &$proxy_external_address$& is empty
there was a protocol error.
To include this it must be built with SUPPORT_I18N and the libidn library.
Standards supported are RFCs 2060, 5890, 6530 and 6533.
+If Exim is built with SUPPORT_I18N_2008 (in addition to SUPPORT_I18N, not
+instead of it) then IDNA2008 is supported; this adds an extra library
+requirement, upon libidn2.
+
.section "MTA operations" SECTi18nMTA
.cindex SMTPUTF8 "ESMTP option"
The main configuration option &%smtputf8_advertise_hosts%& specifies
&`msg:rcpt:host:defer after transport `& per recipient per host
&`msg:rcpt:defer after transport `& per recipient
&`msg:host:defer after transport `& per attempt
-&`msg:fail:delivery after main `& per recipient
+&`msg:fail:delivery after transport `& per recipient
&`msg:fail:internal after main `& per recipient
&`tcp:connect before transport `& per connection
&`tcp:close after transport `& per connection
before or after the action is associates with. Those which fire before
can be used to affect that action (more on this below).
+.new
+The third column in the table above says what section of the configumration
+should define the event action.
+.wen
+
An additional variable, &$event_data$&, is filled with information varying
with the event type:
.display
-&`msg:delivery `& smtp confirmation mssage
+&`msg:delivery `& smtp confirmation message
&`msg:rcpt:host:defer `& error string
&`msg:rcpt:defer `& error string
&`msg:host:defer `& error string
git://git.exim.org / users / heiko / exim.git / blobdiff