X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/796718d6133b8f3b868e09f22dbdcbd8bcdad10c..41720de55405891bbc8e7c3388598b9736abe902:/doc/doc-docbook/spec.xfpt?ds=sidebyside diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 2acd5d38e..9737aed05 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -45,14 +45,14 @@ . 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 . ///////////////////////////////////////////////////////////////////////////// @@ -371,11 +371,13 @@ contributors. .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 @@ -434,6 +436,7 @@ directory are: .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 @@ -461,7 +464,7 @@ which contains what used to be a separate FAQ, as well as various other examples, tips, and know-how that have been contributed by Exim users. .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. @@ -490,18 +493,11 @@ via this web page: 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. @@ -512,10 +508,6 @@ 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 @@ -3825,11 +3817,17 @@ This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the remote host supports the ESMTP &_DSN_& extension. -.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%&" @@ -3859,6 +3857,15 @@ 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%&" @@ -4474,12 +4481,12 @@ 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 speicify an action, a &'-qG'& option +If other commandline options specify an action, a &'-qG'& option will specify a queue to operate on. For example: .code exim -bp -qGquarantine -mailq -qGquarantime +mailq -qGquarantine exim -qGoffpeak -Rf @special.domain.example .endd @@ -4918,7 +4925,9 @@ using this syntax: .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 @@ -6726,8 +6735,8 @@ PostgreSQL database. See section &<>&. .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 &<>&. +&(redis)&: The format of the query is either a simple get or simple set, +passed to a Redis database. See section &<>&. .next .cindex "sqlite lookup type" @@ -7105,7 +7114,7 @@ Retries for the dnsdb lookup can be controlled by a retry modifier. 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). @@ -7800,6 +7809,17 @@ are rejected after a timeout period, during which the SQLite library 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 @@ -9100,7 +9120,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&& {*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" -.cindex "expansion" "extracting cerificate fields" +.cindex "expansion" "extracting certificate fields" .cindex "&%certextract%&" "certificate fields" .cindex "certificate" "extracting fields" The <&'certificate'&> must be a variable of type certificate. @@ -9418,17 +9438,13 @@ filter. Header lines that are added to a particular copy of a message by a router or transport are not accessible. For incoming SMTP messages, no header lines are visible in -.new ACLs that are obeyed before the data phase completes, -.wen because the header structure is not set up until the message is received. They are visible in DKIM, PRDR and DATA ACLs. Header lines that are added in a RCPT ACL (for example) are saved until the message's incoming header lines are available, at which point they are added. -.new When any of the above ACLs ar -.wen running, however, header lines added by earlier ACLs are visible. Upper case and lower case letters are synonymous in header names. If the @@ -9756,7 +9772,7 @@ locks out the use of this expansion item in filter files. .vitem "&*${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" @@ -9786,6 +9802,15 @@ 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: @@ -11006,9 +11031,14 @@ colon-separated components are permitted, each containing from one to four 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}... @@ -12205,7 +12235,7 @@ normally the gid of the Exim user. .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 @@ -12252,7 +12282,7 @@ qualified host name. See also &$smtp_active_hostname$&. &$proxy_local_port$& &&& &$proxy_session$& These variables are only available when built with Proxy Protocol -or Socks5 support +or SOCKS5 support. For details see chapter &<>&. .vitem &$prdr_requested$& @@ -12602,6 +12632,11 @@ validating resolver (e.g. unbound, or bind with suitable configuration). 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 "&$sender_host_name$&" @@ -12823,7 +12858,7 @@ If TLS has not been negotiated, the value will be 0. .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 @@ -13093,7 +13128,7 @@ initial startup, even if &%perl_at_start%& is set. .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. @@ -13523,6 +13558,7 @@ listed in more than one group. .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" @@ -13530,6 +13566,7 @@ listed in more than one group. .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 @@ -14013,6 +14050,7 @@ acknowledgment is sent. See chapter &<>& for further details. .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 &<>& for further details. @@ -14400,7 +14438,7 @@ 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 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&!!" * @@ -14410,6 +14448,13 @@ 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. +.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" @@ -14659,6 +14704,7 @@ record in the authoritative section is used instead. .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 @@ -14666,6 +14712,10 @@ on. 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 @@ -14764,7 +14814,7 @@ 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 &<>&. +For details see chapter &<>&. .option exim_group main string "compile-time configured" @@ -15115,7 +15165,7 @@ If the &%smtp_connection%& log selector is not set, this option has no effect. .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 &<>&. +connections. For details see section &<>&. .option hosts_treat_as_local main "domain list&!!" unset @@ -15289,6 +15339,7 @@ connecting on a regular LDAP port. This is the LDAP equivalent of SMTP's 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 @@ -15629,7 +15680,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.option openssl_options main "string list" "+no_sslv2 +single_dh_use" +.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, @@ -16705,7 +16756,7 @@ example, instead of &"Administrative prohibition"&, it might give: .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 &<>& for details of Exim's support for internationalisation. @@ -16771,6 +16822,25 @@ as failures in the configuration file. 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. + +Users of the local_scan() API (see &<>&), +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 @@ -16862,6 +16932,7 @@ generates any deliveries to files or pipes, or any new mail messages, the 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 &<>&. +A forced expansion failure results in no filter operation. .option system_filter_directory_transport main string&!! unset @@ -17104,7 +17175,8 @@ acceptable bound from 1024 to 2048. .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 @@ -20883,7 +20955,7 @@ 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 &<>&. +For details see chapter &<>&. .option group transports string&!! "Exim group" @@ -20998,7 +21070,7 @@ The control does not apply to shadow transports. .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 @@ -23255,12 +23327,10 @@ message_suffix = &`\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. @@ -23639,13 +23709,13 @@ the message. As a result, the overall timeout for a message depends on the size of the message. Its value must not be zero. See also &%final_timeout%&. -.option dkim_domain smtp string&!! unset +.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&!! unset -DKIM signing options. For details see &<>&. +DKIM signing options. For details see section &<>&. .option delay_after_cutoff smtp boolean true @@ -23888,6 +23958,25 @@ been started will not be passed to a new delivery process for sending another message on the same connection. See section &<>& 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 @@ -23962,12 +24051,12 @@ unauthenticated. See also &%hosts_require_auth%&, and chapter .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 -.option "fast open, TCP" "enabling, in client" -.option "TCP Fast Open" "enabling, in client" -.option "RFC 7413" "TCP Fast Open" +.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. @@ -24151,7 +24240,7 @@ 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 &<>&. +transport. For details see section &<>&. .option tls_certificate smtp string&!! unset @@ -25856,6 +25945,17 @@ turned into a permanent error if you wish. In the second case, Exim tries to 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 @@ -27127,10 +27227,12 @@ tls_require_ciphers = ${if =={$received_port}{25}\ .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 @@ -27527,7 +27629,7 @@ 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 &$tls_in_sni$& 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. @@ -27549,13 +27651,22 @@ built, then you have SNI support). "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. @@ -28071,6 +28182,9 @@ run. A &"discard"& return from the DATA or the non-SMTP ACL discards all the 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 @@ -28890,7 +29004,9 @@ 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. @@ -28904,7 +29020,7 @@ 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 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) @@ -28915,12 +29031,14 @@ 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. -Logging may be stopped, and the file removed, with the &'kill'& 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 @@ -29128,7 +29246,7 @@ 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 &<>&. +For details see section &<>&. .endlist vlist @@ -29741,6 +29859,13 @@ to avoid doing it more than once per message. .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 @@ -29800,7 +29925,7 @@ deny dnslists = blackholes.mail-abuse.org 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), @@ -29913,7 +30038,7 @@ multiple DNS records. The inner dnsdb lookup produces a list of MX hosts 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. @@ -30803,6 +30928,23 @@ command when performing the callout, instead of an empty address. There is no 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 @@ -31439,6 +31581,18 @@ av_scanner = f-protd:localhost 10200-10204 .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 @@ -35655,6 +35809,12 @@ SMTP RCPT commands in one transaction) the second and subsequent addresses are flagged with &`->`& instead of &`=>`&. When two or more messages are delivered down a single SMTP connection, an asterisk follows the IP address in the log lines for the second and subsequent messages. +.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" @@ -35767,6 +35927,7 @@ the following table: &`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 @@ -36006,7 +36167,7 @@ The latter can be disabled by turning off the &%outgoing_interface%& option. &%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 &<>& for more information. .next .cindex "log" "incoming remote port" @@ -36037,7 +36198,7 @@ off the &%outgoing_interface%& option. .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 @@ -36515,8 +36676,7 @@ autodetection of some well known compression extensions. .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. @@ -37866,9 +38026,8 @@ lock will be lost at the instant of rename. .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$&, which is stored in the -H file, will be incorrect and can +cause incomplete transmission of messages or undeliverable messages. .next If the message is in MIME format, you must take care not to break it. .next @@ -37964,8 +38123,8 @@ The address of an authenticated sender &-- the value of the &$authenticated_sender$& variable. .vitem "&%-body_linecount%&&~<&'number'&>" -This records the number of lines in the body of the message, and is always -present. +This records the number of lines in the body of the message, and is +present unless &%-spool_file_wireformat%& is. .vitem "&%-body_zerocount%&&~<&'number'&>" This records the number of binary zero bytes in the body of the message, and is @@ -38047,6 +38206,12 @@ to ensure that the caller is displayed in queue listings). If a message was scanned by SpamAssassin, this is present. It records the value of &$spam_score_int$&. +.vitem &%-spool_file_wireformat%& +The -D file for this message is in wire-format (for ESMTP CHUNKING) +rather than Unix-format. +The line-ending is CRLF rather than newline. +There is still, however, no leading-dot-stuffing. + .vitem &%-tls_certificate_verified%& A TLS certificate was received from the client that sent this message, and the certificate was verified by the server. @@ -38208,22 +38373,26 @@ senders). Signing is enabled by setting private options on the SMTP transport. These options take (expandable) strings as arguments. -.option dkim_domain smtp string&!! unset -MANDATORY: -The domain you want to sign with. The result of this expanded -option is put into the &%$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 +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 may be used in the &%dkim_private_key%& option along with &%$dkim_domain%&. +If the option is empty after expansion, DKIM signing is not done. .option dkim_private_key smtp string&!! unset -MANDATORY: -This sets the private key to use. You can use the &%$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 @@ -38236,16 +38405,15 @@ be "0", "false" or the empty string, in which case the message will not 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. .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 @@ -38253,11 +38421,10 @@ 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 +If set, this option must expand to (or be specified as) 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. .section "Verifying DKIM signatures in incoming mail" "SECID514" @@ -38481,9 +38648,9 @@ To include this support, include &"SUPPORT_PROXY=yes"& in Local/Makefile. It was built on specifications from: -http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt +(&url(http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt)). That URL was revised in May 2014 to version 2 spec: -http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e +(&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 @@ -38497,6 +38664,13 @@ 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 @@ -38504,9 +38678,9 @@ 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 +&'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. @@ -38617,6 +38791,10 @@ 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 @@ -38769,7 +38947,7 @@ The current list of events is: &`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 @@ -38786,10 +38964,15 @@ 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 mssage +&`msg:delivery `& smtp confirmation message &`msg:rcpt:host:defer `& error string &`msg:rcpt:defer `& error string &`msg:host:defer `& error string