. 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
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'&>
+.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 pair of arguments give the local address and port being proxied.
+.wen
+
.vitem &%-Mc%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
.oindex "&%-Mc%&"
.cindex "hints database" "not overridden by &%-Mc%&"
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"
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
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:
&$proxy_local_port$& &&&
&$proxy_session$&
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 "&$sender_host_name$&"
.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"
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
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
.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
deliver the message unauthenticated.
.endlist
-.new
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
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 alwats authenticates.
-.wen
+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
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.
.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:$h_sender:}}{/}{//}}
+.endd
.endlist
flagged with &`->`& instead of &`=>`&. When two or more messages are delivered
down a single SMTP connection, an asterisk follows the IP address in the log
lines for the second and subsequent messages.
+.new
+When two or more messages are delivered down a single TLS connection, the
+TLS-related information logged for the first message delivered
+(which may not be the earliest line in the log)
+will not be present in the log lines for the second and subsequent messages.
+.wen
.cindex "delivery" "cutthrough; logging"
.cindex "cutthrough" "logging"
&%proxy%&: The internal (closest to the system running Exim) IP address
of the proxy, tagged by PRX=, on the &"<="& line for a message accepted
on a proxied connection
-or the &"=>"& line for a message delivered on a proxied connection..
+or the &"=>"& line for a message delivered on a proxied connection.
See &<<SECTproxyInbound>>& for more information.
.next
.cindex "log" "incoming remote port"
.next
.vindex "&$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
git://git.exim.org / users / jgh / exim.git / blobdiff