X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/2eec84caa477a4b3b1f9fff999000768f65bd936..8588dd3559d895a9167d619b7f4449a59c7ddd21:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 75f28ef67..3b5cbbf5b 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 @@ -462,7 +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. @@ -491,18 +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. @@ -513,10 +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 @@ -1676,6 +1667,9 @@ Symbolic links to the sources are installed in this directory, which is where 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" @@ -2797,6 +2791,13 @@ files or databases you are using, you must exit and restart Exim before trying the same lookup again. Otherwise, because each Exim process caches the results of lookups, you will just get the same result as before. +.new +Macro processing is done on lines before string-expansion: new macros can be +defined and macros will be expanded. +Because macros in the config file are often used for secrets, those are only +available to admin users. +.wen + .vitem &%-bem%&&~<&'filename'&> .oindex "&%-bem%&" .cindex "testing" "string expansion" @@ -3826,11 +3827,17 @@ 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%&" @@ -3860,6 +3867,15 @@ 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%&" @@ -4268,7 +4284,7 @@ or &%-bs%& is used. For &%-bh%&, the protocol is forced to one of the standard SMTP protocol names (see the description of &$received_protocol$& in section &<>&). 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%&" @@ -4368,6 +4384,7 @@ host name and its colon can be omitted when only the protocol is to be set. 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%&" @@ -4480,7 +4497,7 @@ will specify a queue to operate on. For example: .code exim -bp -qGquarantine -mailq -qGquarantime +mailq -qGquarantine exim -qGoffpeak -Rf @special.domain.example .endd @@ -4920,11 +4937,9 @@ using this syntax: 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. @@ -6731,8 +6746,8 @@ 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" @@ -7110,7 +7125,7 @@ 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). @@ -7805,6 +7820,17 @@ 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 @@ -9105,7 +9131,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&& {*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" -.cindex "expansion" "extracting cerificate fields" +.cindex "expansion" "extracting certificate fields" .cindex "&%certextract%&" "certificate fields" .cindex "certificate" "extracting fields" The <&'certificate'&> must be a variable of type certificate. @@ -9423,17 +9449,13 @@ filter. Header lines that are added to a particular copy of a message by a router or transport are not accessible. For incoming SMTP messages, no header lines are visible in -.new ACLs that are obeyed before the data phase completes, -.wen because the header structure is not set up until the message is received. They are visible in DKIM, PRDR and DATA ACLs. Header lines that are added in a RCPT ACL (for example) are saved until the message's incoming header lines are available, at which point they are added. -.new When any of the above ACLs ar -.wen running, however, header lines added by earlier ACLs are visible. Upper case and lower case letters are synonymous in header names. If the @@ -9761,7 +9783,7 @@ locks out the use of this expansion item in filter files. .vitem "&*${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" @@ -9791,6 +9813,15 @@ 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: @@ -9943,7 +9974,7 @@ a regular expression, and a substitution string. For example: ${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}} @@ -10094,7 +10125,15 @@ character. For example: .code ${addresses:>& Chief , sec@base.ment (dogsbody)} .endd -expands to &`ceo@up.stairs&&sec@base.ment`&. Compare the &*address*& (singular) +expands to &`ceo@up.stairs&&sec@base.ment`&. The string is expanded +first, so if the expanded string starts with >, it may change the output +separator unintentionally. This can be avoided by setting the output +separator explicitly: +.code +${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. @@ -11011,9 +11050,14 @@ 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}... @@ -11170,8 +11214,8 @@ example is: ${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}{... @@ -11621,8 +11665,11 @@ contain the trailing slash. If &$config_file$& does not contain a slash, .vindex "&$config_file$&" The name of the main configuration file Exim is using. +.vitem &$dkim_verify_status$& &&& +Results of DKIM verification. +For details see chapter &<>&. + .vitem &$dkim_cur_signer$& &&& - &$dkim_verify_status$& &&& &$dkim_verify_reason$& &&& &$dkim_domain$& &&& &$dkim_identity$& &&& @@ -12042,6 +12089,9 @@ when the ACL &%malware%& condition is true (see section &<>&). 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" @@ -12084,6 +12134,12 @@ in bytes. The count starts from the character after the blank line that 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 @@ -12134,6 +12190,10 @@ deny message = Too many lines in message header 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" @@ -12210,7 +12270,7 @@ 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 @@ -12257,7 +12317,7 @@ 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 &$prdr_requested$& @@ -12607,6 +12667,11 @@ 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 "&$sender_host_name$&" @@ -12749,6 +12814,15 @@ argument, that is, the text that follows the command name, with leading white 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 @@ -12828,13 +12902,18 @@ 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 &%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator, or a &%def%& condition. +.new +&*Note*&: Under current versions of OpenSSL, when a list of more than one +file is used for &%tls_certificate%&, this variable is not reliable. +.wen + .vitem &$tls_in_peercert$& .vindex "&$tls_in_peercert$&" This variable refers to the certificate presented by the peer of an @@ -13098,7 +13177,7 @@ 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. @@ -13528,6 +13607,7 @@ 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" @@ -13535,6 +13615,7 @@ 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 @@ -13554,6 +13635,7 @@ listed in more than one group. .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" @@ -14018,6 +14100,7 @@ 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. @@ -14405,7 +14488,7 @@ 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&!!" * @@ -14415,6 +14498,21 @@ 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" @@ -14664,6 +14762,7 @@ 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 @@ -14671,6 +14770,10 @@ 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 @@ -15294,9 +15397,7 @@ 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%&. -.new This option is ignored for &`ldapi`& connections. -.wen .option ldap_version main integer unset @@ -15637,7 +15738,7 @@ 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, @@ -15886,12 +15987,13 @@ different spool directories. .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" @@ -15930,10 +16032,12 @@ next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&. .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 @@ -16713,7 +16817,7 @@ 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. @@ -16779,6 +16883,32 @@ 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. + +The following variables will not have useful values: +.code +$max_received_linelength +$body_linecount +$body_zerocount +.endd + +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 @@ -16870,6 +17000,7 @@ 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 @@ -16984,11 +17115,15 @@ 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 +.option tls_certificate main string list&!! unset .cindex "TLS" "server certificate; location of" .cindex "certificate" "server, location of" -The value of this option is expanded, and must then be the absolute path to a -file which contains the server's certificates. The server's private key is also +.new +The value of this option is expanded, and must then be a list of absolute paths to +files which contains the server's certificates. Commonly only one file is +needed. +.wen +The server's private key is also assumed to be in this file if &%tls_privatekey%& is unset. See chapter &<>& for further details. @@ -16997,6 +17132,16 @@ receiving incoming messages as a server. If you want to supply certificates for use when sending messages as a client, you must set the &%tls_certificate%& option in the relevant &(smtp)& transport. +.new +&*Note*&: If you use filenames based on IP addresses, change the list +separator in the usual way to avoid confusion under IPv6. + +&*Note*&: Under current versions of OpenSSL, when a list of more than one +file is used, the &$tls_in_ourcert$& veriable is unreliable. + +&*Note*&: OCSP stapling is not usable when a list of more than one file is used. +.wen + If the option contains &$tls_out_sni$& and Exim is built against OpenSSL, then if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in @@ -17112,7 +17257,8 @@ 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 @@ -17135,6 +17281,11 @@ Certificate Authority. Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later). +.new +&*Note*&: There is currently no support for multiple OCSP proofs to match the +multiple certificates facility. +.wen + .option tls_on_connect_ports main "string list" unset .cindex SSMTP @@ -17146,10 +17297,13 @@ further details, see section &<>&. -.option tls_privatekey main string&!! unset +.option tls_privatekey main string list&!! unset .cindex "TLS" "server private key; location of" -The value of this option is expanded, and must then be the absolute path to a -file which contains the server's private key. If this option is unset, or if +.new +The value of this option is expanded, and must then be a list of absolute paths to +files which contains the server's private keys. +.wen +If this option is unset, or if the expansion is forced to fail, or the result is an empty string, the private key is assumed to be in the same file as the server's certificates. See chapter &<>& for further details. @@ -19372,6 +19526,10 @@ instead of TRY_AGAIN. That is why the default action is to try a DNS 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 @@ -20249,11 +20407,15 @@ relative path is then passed to the transport unmodified. .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. @@ -20261,7 +20423,9 @@ If this option is set true, only Sieve filters are permitted when .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 @@ -20272,17 +20436,22 @@ locks out the Sieve's &"keep"& facility. .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' @@ -20290,27 +20459,37 @@ 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 @@ -20318,11 +20497,15 @@ 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: @@ -20331,6 +20514,8 @@ are not permitted in non-filter redirection lists. .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 @@ -20338,6 +20523,8 @@ forward file. This option is forced to be true if &%one_time%& is set. .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. @@ -21006,7 +21193,7 @@ 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 @@ -22002,10 +22189,14 @@ the obvious value which users understand most easily. 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 @@ -22040,6 +22231,8 @@ can only be used if &%quota%& is also set. The value is expanded; an expansion 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. @@ -23264,9 +23457,7 @@ message_suffix = .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 @@ -23647,12 +23838,14 @@ 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 +.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 &<>&. @@ -23896,6 +24089,25 @@ 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 @@ -23970,9 +24182,9 @@ 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 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" @@ -23988,6 +24200,9 @@ 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" @@ -25864,6 +26079,17 @@ 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 @@ -26919,6 +27145,11 @@ When using OpenSSL, this option is ignored. (If an API is found to let OpenSSL be configured in this way, let the Exim Maintainers know and we'll likely use it). .next +.new +With GnuTLS, if an explicit list is used for the &%tls_privatekey%& main option +main option, it must be ordered to match the &%tls_certificate%& list. +.wen +.next Some other recently added features may only be available in one or the other. This should be documented with the feature. If the documentation does not explicitly state that the feature is infeasible in the other TLS @@ -27074,6 +27305,12 @@ tls_require_ciphers = ${if =={$received_port}{25}\ {HIGH:!MD5:!SHA1}} .endd +.new +This example will prefer ECDSA-authenticated ciphers over RSA ones: +.code +tls_require_ciphers = ECDSA:RSA:!COMPLEMENTOFDEFAULT +.endd +.wen .section "Requiring specific ciphers or other parameters in GnuTLS" &&& @@ -27135,10 +27372,12 @@ 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 @@ -27160,8 +27399,7 @@ 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, +To make TLS work you need to set, in the server, .code tls_certificate = /some/file/name tls_privatekey = /some/file/name @@ -27180,6 +27418,15 @@ is assumed to be the case. The certificate file may also contain intermediate certificates that need to be sent to the client to enable it to authenticate the server's certificate. +.new +For dual-stack (eg. RSA and ECDSA) configurations, these options can be +colon-separated lists of file paths. Ciphers using given authentication +algorithms require the presence of a suitable certificate to supply the +public-key. The server selects among the certificates to present to the +client depending on the selected cipher, hence the priority ordering for +ciphers will affect which certificate is used. +.wen + If you do not understand about certificates and keys, please try to find a source of this background information, which is not Exim-specific. (There are a few comments below in section &<>&.) @@ -27413,11 +27660,10 @@ if it requests it. If the server is Exim, it will request a certificate only if If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it specifies a collection of expected server certificates. -These may be the system default set (depending on library version), -a file or, -depending on library version, a directory, -must name a file or, -for OpenSSL only (not GnuTLS), a directory. +These may be +the system default set (depending on library version), +a file, +or (depending on library version) a directory. The client verifies the server's certificate against this collection, taking into account any revoked certificates that are in the list defined by &%tls_crl%&. @@ -27535,7 +27781,7 @@ 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. @@ -27557,13 +27803,22 @@ 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. @@ -28079,6 +28334,9 @@ 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 @@ -28789,6 +29047,7 @@ This modifier puts a value into one of the ACL variables (see section .vitem &*udpsend*&&~=&~<&'parameters'&> +.cindex "UDP communications" This modifier sends a UDP packet, for purposes such as statistics collection or behaviour monitoring. The parameters are expanded, and the result of the expansion must be a colon-separated list consisting @@ -28888,6 +29147,11 @@ and cannot depend on content of received headers. 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 @@ -28898,7 +29162,9 @@ 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. @@ -28912,7 +29178,7 @@ 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) @@ -28923,12 +29189,14 @@ 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 @@ -29749,6 +30017,13 @@ 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 @@ -29808,7 +30083,7 @@ 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), @@ -29921,7 +30196,7 @@ 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. @@ -30811,6 +31086,23 @@ 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 @@ -31044,6 +31336,7 @@ address and some time-based randomizing information. The &%prvs%& expansion item creates a signed address, and the &%prvscheck%& expansion item checks one. The syntax of these expansion items is described in section &<>&. +The validity period on signed addresses is seven days. As an example, suppose the secret per-address keys are stored in an MySQL database. A query to look up the key for an address could be defined as a macro @@ -31447,6 +31740,18 @@ 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 @@ -31490,14 +31795,18 @@ an address (which may be an IP address and port, or the path of a Unix socket), 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" @@ -32337,9 +32646,15 @@ C variables are as follows: .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 @@ -35663,6 +35978,12 @@ 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" @@ -35775,6 +36096,7 @@ 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 @@ -35788,6 +36110,7 @@ the following table: &`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 @@ -35869,6 +36192,7 @@ selection marked by asterisks: &` incoming_interface `& local interface on <= and => lines &` incoming_port `& remote port on <= lines &`*lost_incoming_connection `& as it says (includes timeouts) +&` millisec `& millisecond timestamps and QT,DT,D times &` outgoing_interface `& local interface on => lines &` outgoing_port `& add remote port to => lines &`*queue_run `& start and end queue runs @@ -35958,6 +36282,8 @@ process is started because &%queue_only%& is set or &%-odq%& was used. .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" @@ -36014,7 +36340,7 @@ 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" @@ -36033,6 +36359,14 @@ important with the widening use of NAT (see RFC 2505). &%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" @@ -36045,7 +36379,7 @@ 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 @@ -36071,6 +36405,8 @@ includes reception time as well as the delivery time for the current address. This means that it may be longer than the difference between the arrival and delivery log line times, because the arrival log line is not written until the message has been successfully received. +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 @@ -36523,8 +36859,7 @@ 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. @@ -37774,6 +38109,13 @@ the contents of files on the spool via the Exim monitor (which runs 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" @@ -37874,9 +38216,8 @@ 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 @@ -37895,6 +38236,13 @@ file remains in existence. When Exim next processes the message, it notices the -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" @@ -37972,8 +38320,8 @@ 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 @@ -38055,6 +38403,14 @@ 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 &$spam_score_int$&. +.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. @@ -38162,6 +38518,20 @@ unqualified domain &'foundation'&. .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 + . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -38193,8 +38563,12 @@ In typical Exim style, the verification implementation does not include any default "policy". Instead it enables you to build your own policy using Exim's standard controls. +.new Please note that verification of DKIM signatures in incoming mail is turned -on by default for logging purposes. For each signature in incoming email, +on by default for logging (in the <= line) purposes. + +Additional log detail can be enabled using the &%dkim_verbose%& log_selector. +When set, for each signature in incoming email, exim will log a line displaying the most important signature details, and the signature status. Here is an example (with line-breaks added for clarity): .code @@ -38203,6 +38577,8 @@ signature status. Here is an example (with line-breaks added for clarity): c=relaxed/relaxed a=rsa-sha1 i=@facebookmail.com t=1252484542 [verification succeeded] .endd +.wen + You might want to turn off DKIM verification processing entirely for internal or relay mail sources. To do that, set the &%dkim_disable_verify%& ACL control modifier. This should typically be done in the RCPT ACL, at points @@ -38213,25 +38589,45 @@ senders). .section "Signing outgoing messages" "SECDKIMSIGN" .cindex "DKIM" "signing" +.new +For signing to be usable you must have published a DKIM record in DNS. +Note that RFC 8301 says: +.code +rsa-sha1 MUST NOT be used for signing or verifying. + +Signers MUST use RSA keys of at least 1024 bits for all keys. +Signers SHOULD use RSA keys of at least 2048 bits. +.endd +.wen +.wen + 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 &%$dkim_domain%& expansion variable. -If it is empty after expansion, DKIM signing is not done. +.option dkim_domain smtp string list&!! unset +The domain(s) you want to sign with. +.new +After expansion, this can be a list. +Each element in turn is put into the &%$dkim_domain%& expansion variable +while expanding the remaining signing options. +.wen +If it is empty after expansion, DKIM signing is not done, +and no error will result even if &%dkim_strict%& is set. -.option dkim_selector smtp string&!! unset -MANDATORY: -This sets the key selector string. You can use the &%$dkim_domain%& expansion -variable to look up a matching selector. The result is put in the expansion +.option dkim_selector smtp string list&!! unset +This sets the key selector string. +.new +After expansion, which can use &$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 &%$dkim_domain%&. +.wen +If the option is empty after expansion, DKIM signing is not done for this domain, +and no error will result even if &%dkim_strict%& is set. .option dkim_private_key smtp string&!! unset -MANDATORY: -This sets the private key to use. You can use the &%$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 @@ -38245,27 +38641,68 @@ be signed. This case will not result in an error, even if &%dkim_strict%& is set. .endlist +.new +Note that RFC 8301 says: +.code +Signers MUST use RSA keys of at least 1024 bits for all keys. +Signers SHOULD use RSA keys of at least 2048 bits. +.endd +.wen + +.option dkim_hash smtp string&!! sha256 +Can be set alternatively to &"sha1"& to use an alternate hash +method. + +.new +Note that RFC 8301 says: +.code +rsa-sha1 MUST NOT be used for signing or verifying. +.endd +.wen + +.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 -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. +.option dkim_sign_headers smtp string&!! "see below" +If set, this option must expand to a colon-separated +list of header names. +.new +Headers with these names, or the absence or such a header, will be included +in the message signature. +When unspecified, the header names listed in RFC4871 will be used, +whether or not each header is present in the message. +The default list is available for the expansion in the macro +"_DKIM_SIGN_HEADERS". + +If a name is repeated, multiple headers by that name (or the absence therof) +will be signed. The textually later headers in the headers part of the +message are signed first, if there are multiples. + +A name can be prefixed with either an '=' or a '+' character. +If an '=' prefix is used, all headers that are present with this name +will be signed. +If a '+' prefix if used, all headers that are present with this name +will be signed, and one signtature added for a missing header with the +name will be appended. +.wen .section "Verifying DKIM signatures in incoming mail" "SECID514" @@ -38276,7 +38713,7 @@ Verification of DKIM signatures in SMTP incoming email is implemented via the 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 @@ -38314,6 +38751,11 @@ dkim_verify_signers = $sender_address_domain:$dkim_signers If a domain or identity is listed several times in the (expanded) value of &%dkim_verify_signers%&, the ACL is only called once for that domain or identity. +.new +If multiple signatures match a domain (or identity), the ACL is called once +for each matching signature. +.wen + Inside the &%acl_smtp_dkim%&, the following expansion variables are available (from most to least important): @@ -38326,7 +38768,8 @@ an identity. This is one of the list items from the expanded main option &%dkim_verify_signers%& (see above). .vitem &%$dkim_verify_status%& -A string describing the general status of the signature. One of +Within the DKIM ACL, +a string describing the general status of the signature. One of .ilist &%none%&: There is no signature in the message for the current domain or identity (as reflected by &%$dkim_cur_signer%&). @@ -38340,6 +38783,22 @@ available in &%$dkim_verify_reason%&. &%pass%&: The signature passed verification. It is valid. .endlist +.new +This variable can be overwritten using an ACL 'set' modifier. +This might, for instance, be done to enforce a policy restriction on +hash-method or key-size: +.code + warn condition = ${if eq {$dkim_algo}{rsa-sha1}} + condition = ${if eq {$dkim_verify_status}{pass}} + logwrite = NOTE: forcing dkim verify fail (was pass) + set dkim_verify_status = fail + set dkim_verify_reason = hash too weak +.endd + +After all the DKIM ACL runs have completed, the value becomes a +colon-separated list of the values after each run. +.wen + .vitem &%$dkim_verify_reason%& A string giving a little bit more detail when &%$dkim_verify_status%& is either "fail" or "invalid". One of @@ -38360,6 +38819,10 @@ 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 +.new +This variable can be overwritten, with any value, using an ACL 'set' modifier. +.wen + .vitem &%$dkim_domain%& The signing domain. IMPORTANT: This variable is only populated if there is an actual signature in the message for the current domain or identity (as @@ -38376,10 +38839,23 @@ The key record selector string. .vitem &%$dkim_algo%& The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'. +.new +Note that RFC 8301 says: +.code +rsa-sha1 MUST NOT be used for signing or verifying. + +DKIM signatures identified as having been signed with historic +algorithms (currently, rsa-sha1) have permanently failed evaluation +.endd + +To enforce this you must have a DKIM ACL which checks this variable +and overwrites the &$dkim_verify_status$& variable as discussed above. +.wen + .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 &%$dkim_copiedheaders%& @@ -38426,6 +38902,18 @@ Notes from the key record (tag n=). .vitem &%$dkim_key_length%& Number of bits in the key. + +.new +Note that RFC 8301 says: +.code +Verifiers MUST NOT consider signatures using RSA keys of +less than 1024 bits as valid signatures. +.endd + +To enforce this you must have a DKIM ACL which checks this variable +and overwrites the &$dkim_verify_status$& variable as discussed above. +.wen + .endlist In addition, two ACL conditions are provided: @@ -38489,9 +38977,9 @@ 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 @@ -38505,6 +38993,13 @@ 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 @@ -38512,9 +39007,9 @@ 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. @@ -38625,6 +39120,10 @@ 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 @@ -38777,7 +39276,7 @@ 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 @@ -38794,10 +39293,15 @@ 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