X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/f444c2c7e41c8a2b43b6270708e7eb88831f11e0..23bb69826c8d600ce4a268ad27e14b0390e540c8:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 6b4b5f314..ba32403d6 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 "4.86" +.set previousversion "4.87" .include ./local_params .set ACL "access control lists (ACLs)" .set I "    " .macro copyyear -2015 +2016 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -2788,7 +2788,7 @@ continuations. As in Exim's run time configuration, white space at the start of continuation lines is ignored. Each argument or data line is passed through the string expansion mechanism, and the result is output. Variable values from the configuration file (for example, &$qualify_domain$&) are available, but no -message-specific values (such as &$sender_domain$&) are set, because no message +message-specific values (such as &$message_exim_id$&) are set, because no message is being processed (but see &%-bem%& and &%-Mset%&). &*Note*&: If you use this mechanism to test lookups, and you change the data @@ -3049,7 +3049,8 @@ trusted user for the sender of a message to be set in this way. .oindex "&%-bmalware%&" .cindex "testing", "malware" .cindex "malware scan test" -This debugging option causes Exim to scan the given file, +This debugging option causes Exim to scan the given file or directory +(depending on the used scanner interface), using the malware scanning framework. The option of &%av_scanner%& influences this option, so if &%av_scanner%&'s value is dependent upon an expansion then the expansion should have defaults which apply to this invocation. ACLs are @@ -3151,6 +3152,11 @@ using one of the words &%router_list%&, &%transport_list%&, or settings can be obtained by using &%routers%&, &%transports%&, or &%authenticators%&. +.cindex "environment" +If &%environment%& is given as an argument, the set of environment +variables is output, line by line. Using the &%-n%& flag suppresses the value of the +variables. + .cindex "options" "macro &-- extracting" If invoked by an admin user, then &%macro%&, &%macro_list%& and &%macros%& are available, similarly to the drivers. Because macros are sometimes used @@ -3552,9 +3558,7 @@ example: exim '-D ABC = something' ... .endd &%-D%& may be repeated up to 10 times on a command line. -.new Only macro names up to 22 letters long can be set. -.wen .vitem &%-d%&<&'debug&~options'&> @@ -4012,7 +4016,8 @@ for that message. .oindex "&%-n%&" This option is interpreted by Sendmail to mean &"no aliasing"&. For normal modes of operation, it is ignored by Exim. -When combined with &%-bP%& it suppresses the name of an option from being output. +When combined with &%-bP%& it makes the output more terse (suppresses +option names, environment values and config pretty printing). .vitem &%-O%&&~<&'data'&> .oindex "&%-O%&" @@ -5617,7 +5622,7 @@ It provides a list of domains for which the &"percent hack"& is to operate. This is an almost obsolete form of explicit email routing. If you do not know anything about it, you can safely ignore this topic. -The last two settings in the main part of the default configuration are +The next two settings in the main part of the default configuration are concerned with messages that have been &"frozen"& on Exim's queue. When a message is frozen, Exim no longer continues to try to deliver it. Freezing occurs when a bounce message encounters a permanent failure because the sender @@ -5635,6 +5640,44 @@ message (whether a bounce message or not) is to be timed out (and discarded) after a week. In this configuration, the first setting ensures that no failing bounce message ever lasts a week. +Exim queues it's messages in a spool directory. If you expect to have +large queues, you may consider using this option. It splits the spool +directory into subdirectories to avoid file system degradation from +many files in a single directory, resulting in better performance. +Manual manipulation of queued messages becomes more complex (though fortunately +not often needed). +.code +# split_spool_directory = true +.endd + +In an ideal world everybody follows the standards. For non-ASCII +messages RFC 2047 is a standard, allowing a maximum line length of 76 +characters. Exim adheres that standard and won't process messages which +violate this standard. (Even ${rfc2047:...} expansions will fail.) +In particular, the Exim maintainers have had multiple reports of +problems from Russian administrators of issues until they disable this +check, because of some popular, yet buggy, mail composition software. +.code +# check_rfc2047_length = false +.endd + +If you need to be strictly RFC compliant you may wish to disable the +8BITMIME advertisement. Use this, if you exchange mails with systems +that are not 8-bit clean. +.code +# accept_8bitmime = false +.endd + +Libraries you use may depend on specific environment settings. This +imposes a security risk (e.g. PATH). There are two lists: +&%keep_environment%& for the variables to import as they are, and +&%add_environment%& for variables we want to set to a fixed value. +Note that TZ is handled separately, by the $%timezone%$ runtime +option and by the TIMEZONE_DEFAULT buildtime option. +.code +# keep_environment = ^LDAP +# add_environment = PATH=/usr/bin::/bin +.endd .section "ACL configuration" "SECID54" @@ -6105,7 +6148,8 @@ errors: This causes any temporarily failing address to be retried every 15 minutes for 2 hours, then at intervals starting at one hour and increasing by a factor of 1.5 until 16 hours have passed, then every 6 hours up to 4 days. If an address -is not delivered after 4 days of temporary failure, it is bounced. +is not delivered after 4 days of temporary failure, it is bounced. The time is +measured from first failure, not from the time the message was received. If the retry section is removed from the configuration, or is empty (that is, if no retry rules are defined), Exim will not retry deliveries. This turns @@ -6567,7 +6611,7 @@ lookup types support only literal keys. .endlist ilist -.section "Query-style lookup types" "SECID62" +.section "Query-style lookup types" "SECTquerystylelookups" .cindex "lookup" "query-style types" .cindex "query-style lookup" "list of types" The supported query-style lookup types are listed below. Further details about @@ -6625,12 +6669,10 @@ password value. For example: PostgreSQL database. See section &<>&. .next -.new .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 &<>&. -.wen .next .cindex "sqlite lookup type" @@ -7008,14 +7050,12 @@ 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%&. -.new .cindex cacheing "of dns lookup" .cindex TTL "of dns lookup" .cindex DNS TTL Dnsdb lookup results are cached within a single process (and its children). The cache entry lifetime is limited to the smallest time-to-live (TTL) value of the set of returned DNS records. -.wen .section "Pseudo dnsdb record types" "SECID66" @@ -7568,7 +7608,6 @@ a query is successfully processed. The result of a query may be that no data is found, but that is still a successful query. In other words, the list of servers provides a backup facility, not a list of different places to look. -.new For Redis the global option need not be specified if all queries contain their own server information &-- see section &<>&. If specified, the option must be set to a colon-separated list of server @@ -7584,9 +7623,7 @@ The database number is optional; if present that number is selected in the backe .next The password is optional; if present it is used to authenticate to the backend .endlist -.wen -.new The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b respectively, and the characters single-quote, double-quote, and backslash @@ -7594,7 +7631,6 @@ itself are escaped with backslashes. The &%quote_redis%& expansion operator escapes whitespace and backslash characters with a backslash. -.wen .section "Specifying the server in the query" "SECTspeserque" For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase), @@ -7641,10 +7677,8 @@ ${lookup pgsql{servers=master/db/name/pw; UPDATE ...} } For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%& causes a connection to the server on the local host by means of a Unix domain socket. An alternate socket can be specified in parentheses. -.new An option group name for MySQL option files can be specified in square brackets; the default value is &"exim"&. -.wen The full syntax of each item in &%mysql_servers%& is: .display <&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&& @@ -7739,9 +7773,16 @@ domain, host, address and local part lists. -.section "Expansion of lists" "SECID75" +.section "Expansion of lists" "SECTlistexpand" .cindex "expansion" "of lists" -Each list is expanded as a single string before it is used. The result of +Each list is expanded as a single string before it is used. + +.new +&'Exception: the router headers_remove option, where list-item +splitting is done before string-expansion.'& +.wen + +The result of expansion must be a list, possibly containing empty items, which is split up into separate items for matching. By default, colon is the separator character, but this can be varied if necessary. See sections &<>& and @@ -9110,7 +9151,7 @@ configuration, you must add &%-export-dynamic%& to EXTRALIBS. .vitem "&*${env{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&" .cindex "expansion" "extracting value from environment" -.cindex "environment" "value from" +.cindex "environment" "values from" The key is first expanded separately, and leading and trailing white space removed. This is then searched for as a name in the environment. @@ -9130,6 +9171,9 @@ search failure. If {<&'string1'&>} is omitted the search result is substituted on search success. +The environment is adjusted by the &%keep_environment%& and +&%add_environment%& main section options. + .vitem "&*${extract{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&& {*&<&'string3'&>&*}}*&" @@ -9412,14 +9456,12 @@ condition = ${if >{$acl_m4}{3}} -.new .vitem &*${imapfolder{*&<&'foldername'&>&*}}*& .cindex expansion "imap folder" .cindex "&%imapfolder%& expansion item" This item converts a (possibly multilevel, or with non-ASCII characters) folder specification to a Maildir name for filesystem use. For information on internationalisation support see &<>&. -.wen @@ -9677,7 +9719,8 @@ ${readsocket{inet:[::1]:1234}{request string}} Only a single host name may be given, but if looking it up yields more than one IP address, they are each tried in turn until a connection is made. For both kinds of socket, Exim makes a connection, writes the request string -(unless it is an empty string) and reads from the socket until an end-of-file +unless it is an empty string; and no terminating NUL is ever sent) +and reads from the socket until an end-of-file is read. A timeout of 5 seconds is applied. Additional, optional arguments extend what can be done. Firstly, you can vary the timeout. For example: .code @@ -10033,7 +10076,6 @@ environments where Exim uses base 36 instead of base 62 for its message identifiers, base-36 digits. The number is converted to decimal and output as a string. -.new .vitem &*${base64:*&<&'string'&>&*}*& .cindex "expansion" "base64 encoding" .cindex "base64 encoding" "in string expansion" @@ -10050,7 +10092,6 @@ returns the base64 encoding of the DER form of the certificate. .cindex "base64 decoding" "in string expansion" .cindex "&%base64d%& expansion item" This operator converts a base64-encoded string into the un-coded form. -.wen .vitem &*${domain:*&<&'string'&>&*}*& @@ -10197,7 +10238,6 @@ as is, and other byte values are converted to &`\xNN`&, for example a byte value 127 is converted to &`\x7f`&. -.new .vitem &*${ipv6denorm:*&<&'string'&>&*}*& .cindex "&%ipv6denorm%& expansion item" .cindex "IP address" normalisation @@ -10215,7 +10255,6 @@ Leading zeroes of groups are omitted, and the longest set of zero-valued groups is replaced with a double colon. A trailing ipv4-style dotted-decimal set is converted to hex. Pure IPv4 addresses are converted to IPv4-mapped IPv6. -.wen .vitem &*${lc:*&<&'string'&>&*}*& @@ -10483,9 +10522,7 @@ systems for files larger than 2GB. .vitem &*${str2b64:*&<&'string'&>&*}*& .cindex "&%str2b64%& expansion item" -.new Now deprecated, a synonym for the &%base64%& expansion operator. -.wen @@ -10540,7 +10577,6 @@ This forces the letters in the string into upper-case. .cindex "&%utf8clean%& expansion item" This replaces any invalid utf-8 sequence in the string by the character &`?`&. -.new .vitem "&*${utf8_domain_to_alabel:*&<&'string'&>&*}*&" &&& "&*${utf8_domain_from_alabel:*&<&'string'&>&*}*&" &&& "&*${utf8_localpart_to_alabel:*&<&'string'&>&*}*&" &&& @@ -10555,7 +10591,6 @@ This replaces any invalid utf-8 sequence in the string by the character &`?`&. .cindex "&%utf8_localpart_from_alabel%& expansion item" These convert EAI mail name components between UTF-8 and a-label forms. For information on internationalisation support see &<>&. -.wen .endlist @@ -11483,18 +11518,6 @@ contain the trailing slash. If &$config_file$& does not contain a slash, .vindex "&$config_file$&" The name of the main configuration file Exim is using. -.vitem &$demime_errorlevel$& -.vindex "&$demime_errorlevel$&" -This variable is available when Exim is compiled with -the content-scanning extension and the obsolete &%demime%& condition. For -details, see section &<>&. - -.vitem &$demime_reason$& -.vindex "&$demime_reason$&" -This variable is available when Exim is compiled with the -content-scanning extension and the obsolete &%demime%& condition. For details, -see section &<>&. - .vitem &$dkim_cur_signer$& &&& &$dkim_verify_status$& &&& &$dkim_verify_reason$& &&& @@ -11626,12 +11649,6 @@ The first character is a major version number, currently 4. Then after a dot, the next group of digits is a minor version number. There may be other characters following the minor version. -.vitem &$found_extension$& -.vindex "&$found_extension$&" -This variable is available when Exim is compiled with the -content-scanning extension and the obsolete &%demime%& condition. For details, -see section &<>&. - .vitem &$header_$&<&'name'&> This is not strictly an expansion variable. It is expansion syntax for inserting the message header line with the given name. Note that the name must @@ -11653,7 +11670,8 @@ explicitly set a home directory for use by a transport; this can be overridden by a setting on the transport itself. When running a filter test via the &%-bf%& option, &$home$& is set to the value -of the environment variable HOME. +of the environment variable HOME, which is subject to the +&%keep_environment%& and &%add_environment%& main config options. .vitem &$host$& .vindex "&$host$&" @@ -11729,6 +11747,12 @@ See &$host_lookup_deferred$&. This variable is set to the remote host's TCP port whenever &$host$& is set for an outbound connection. +.vitem &$initial_cwd$& +.vindex "&$initial_cwd$& +This variable contains the full path name of the initial working +directory of the current Exim process. This may differ from the current +working directory, as Exim changes this to "/" during early startup, and +to &$spool_directory$& later. .vitem &$inode$& .vindex "&$inode$&" @@ -12125,22 +12149,20 @@ qualified host name. See also &$smtp_active_hostname$&. .new -.vitem &$proxy_host_address$& &&& - &$proxy_host_port$& &&& - &$proxy_target_address$& &&& - &$proxy_target_port$& &&& +.vitem &$proxy_external_address$& &&& + &$proxy_external_port$& &&& + &$proxy_local_address$& &&& + &$proxy_local_port$& &&& &$proxy_session$& These variables are only available when built with Proxy Protocol or Socks5 support For details see chapter &<>&. .wen -.new .vitem &$prdr_requested$& .cindex "PRDR" "variable for" This variable is set to &"yes"& if PRDR was requested by the client for the current message, otherwise &"no"&. -.wen .vitem &$prvscheck_address$& This variable is used in conjunction with the &%prvscheck%& expansion item, @@ -12966,6 +12988,17 @@ overriding the setting of &%perl_at_start%&. There is also a command line option &%-pd%& (for delay) which suppresses the initial startup, even if &%perl_at_start%& is set. +.new +.ilist +.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 +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. +.wen + .section "Calling Perl subroutines" "SECID86" When the configuration file includes a &%perl_startup%& option you can make use @@ -13494,6 +13527,7 @@ listed in more than one group. .table2 .row &%perl_at_start%& "always start the interpreter" .row &%perl_startup%& "code to obey when starting Perl" +.row &%perl_taintmode%& "enable taint mode in Perl" .endtable @@ -13786,6 +13820,7 @@ See also the &'Policy controls'& section above. .row &%bounce_message_file%& "content of bounce" .row &%bounce_message_text%& "content of bounce" .row &%bounce_return_body%& "include body if returning message" +.row &%bounce_return_linesize_limit%& "limit on returned message line length" .row &%bounce_return_message%& "include original message in bounce" .row &%bounce_return_size_limit%& "limit on returned message" .row &%bounce_sender_authentication%& "send authenticated sender with bounce" @@ -13945,6 +13980,12 @@ received. See chapter &<>& for further details. This option defines the ACL that is run when an SMTP VRFY command is received. See chapter &<>& for further details. +.option add_environment main "string list" empty +.cindex "environment" "set values" +This option allows to set individual environment variables that the +currently linked libraries and programs in child processes use. +See &<>& for the environment of &(pipe)& transports. + .option admin_groups main "string list&!!" unset .cindex "admin user" This option is expanded just once, at the start of Exim's processing. If the @@ -14094,6 +14135,24 @@ error that is detected during reception, only those header lines preceding the point at which the error was detected are returned. .cindex "bounce message" "including original" +.option bounce_return_linesize_limit main integer 998 +.cindex "size" "of bounce lines, limit" +.cindex "bounce message" "line length limit" +.cindex "limit" "bounce message line length" +This option sets a limit in bytes on the line length of messages +that are returned to senders due to delivery problems, +when &%bounce_return_message%& is true. +The default value corresponds to RFC limits. +If the message being returned has lines longer than this value it is +treated as if the &%bounce_return_size_limit%& (below) restriction was exceeded. + +The option also applies to bounces returned when an error is detected +during reception of a message. +In this case lines from the original are truncated. + +The option does not apply to messages generated by an &(autoreply)& transport. + + .option bounce_return_message main boolean true If this option is set false, none of the original message is included in bounce messages generated by Exim. See also &%bounce_return_size_limit%& and @@ -14587,12 +14646,10 @@ own &'Reply-To:'& header line, the value of the &%errors_reply_to%& option is not used. -.new .option event_action main string&!! unset .cindex events This option declares a string to be expanded for Exim's events mechanism. For details see &<>&. -.wen .option exim_group main string "compile-time configured" @@ -14940,12 +14997,10 @@ If the &%smtp_connection%& log selector is not set, this option has no effect. -.new .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 &<>&. -.wen .option hosts_treat_as_local main "domain list&!!" unset @@ -15014,6 +15069,34 @@ process rather than a remote host, and is using &%-bs%& to inject the messages, .option ignore_fromline_local main boolean false See &%ignore_fromline_hosts%& above. +.option keep_environment main "string list" unset +.cindex "environment" "values from" +This option contains a string list of environment variables to keep. +You have to trust these variables or you have to be sure that +these variables do not impose any security risk. Keep in mind that +during the startup phase Exim is running with an effective UID 0 in most +installations. As the default value is an empty list, the default +environment for using libraries, running embedded Perl code, or running +external binaries is empty, and does not not even contain PATH or HOME. + +Actually the list is interpreted as a list of patterns +(&<>&), except that it is not expanded first. + +WARNING: Macro substitution is still done first, so having a macro +FOO and having FOO_HOME in your &%keep_environment%& option may have +unexpected results. You may work around this using a regular expression +that does not match the macro name: ^[F]OO_HOME$. + +Current versions of Exim issue a warning during startup if you do not mention +&%keep_environment%& in your runtime configuration file and if your +current environment is not empty. Future versions may not issue that warning +anymore. + +See the &%add_environment%& main config option for a way to set +environment variables to a fixed value. The environment for &(pipe)& +transports is handled separately, see section &<>& for +details. + .option keep_malformed main time 4d This option specifies the length of time to keep messages whose spool files @@ -15431,7 +15514,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.option openssl_options main "string list" "+no_sslv2" +.option openssl_options main "string list" "+no_sslv2 +single_dh_use" .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, @@ -15562,14 +15645,20 @@ local parts. Exim's default configuration does this. .option perl_at_start main boolean false +.cindex "Perl" This option is available only when Exim is built with an embedded Perl interpreter. See chapter &<>& for details of its use. .option perl_startup main string unset +.cindex "Perl" This option is available only when Exim is built with an embedded Perl interpreter. See chapter &<>& for details of its use. +.option perl_startup main boolean false +.cindex "Perl" +This Option enables the taint mode of the embedded Perl interpreter. + .option pgsql_servers main "string list" unset .cindex "PostgreSQL lookup type" "server list" @@ -16052,6 +16141,12 @@ it qualifies them only if the message came from a host that matches &%sender_unqualified_hosts%&, or if the message was submitted locally (not using TCP/IP), and the &%-bnq%& option was not set. +.option set_environment main "string list" empty +.cindex "environment" +This option allows to set individual environment variables that the +currently linked libraries and programs in child processes use. The +default list is empty, + .option slow_lookup_log main integer 0 .cindex "logging" "slow lookups" @@ -16487,14 +16582,12 @@ example, instead of &"Administrative prohibition"&, it might give: .endd -.new .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 response to EHLO only to those client hosts that match this option. See chapter &<>& for details of Exim's support for internationalisation. -.wen .option spamd_address main string "see below" @@ -16725,6 +16818,7 @@ messages that are released by &%ignore_bounce_errors_after%&). .option timezone main string unset .cindex "timezone, setting" +.cindex "environment" "values from" The value of &%timezone%& is used to set the environment variable TZ while running Exim (if it is different on entry). This ensures that all timestamps created by Exim are in the required timezone. If you want all your timestamps @@ -16740,9 +16834,7 @@ runs. This is appropriate behaviour for obtaining wall-clock time on some, but unfortunately not all, operating systems. -.new .option tls_advertise_hosts main "host list&!!" * -.wen .cindex "TLS" "advertising" .cindex "encryption" "on SMTP connection" .cindex "SMTP" "encrypted connection" @@ -16750,11 +16842,9 @@ When Exim is built with support for TLS encrypted connections, the availability of the STARTTLS command to set up an encrypted session is advertised in response to EHLO only to those client hosts that match this option. See chapter &<>& for details of Exim's support for TLS. -.new Note that the default value requires that a certificate be supplied -using the &%tls_certificate%& option. If no certificate is available then -the &%tls_advertise_hosts%& option should be set empty. -.wen +using the &%tls_certificate%& option. If TLS support for incoming connections +is not required the &%tls_advertise_hosts%& option should be set empty. .option tls_certificate main string&!! unset @@ -16775,6 +16865,11 @@ if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in &<>& will be re-expanded. +.new +If this option is unset or empty a fresh self-signed certificate will be +generated for every connection. +.wen + .option tls_crl main string&!! unset .cindex "TLS" "server certificate revocation list" .cindex "certificate" "revocation list for server" @@ -16868,7 +16963,7 @@ this option selects a EC curve for use by Exim. Curve names of the form &'prime256v1'& are accepted. For even more-recent library versions, names of the form &'P-512'& are also accepted, plus the special value &'auto'& -which tell the library to choose. +which tells the library to choose. If the option is set to an empty string, no EC curves will be enabled. @@ -16881,9 +16976,7 @@ must if set expand to the absolute path to a file which contains a current status proof for the server's certificate, as obtained from the Certificate Authority. -.new Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later). -.wen .option tls_on_connect_ports main "string list" unset @@ -20371,7 +20464,7 @@ See &%skip_syntax_errors%& above. .chapter "Environment for running local transports" "CHAPenvironment" &&& "Environment for local transports" .scindex IIDenvlotra1 "local transports" "environment for" -.scindex IIDenvlotra2 "environment for local transports" +.scindex IIDenvlotra2 "environment" "local transports" .scindex IIDenvlotra3 "transport" "local; environment for" Local transports handle deliveries to files and pipes. (The &(autoreply)& transport can be thought of as similar to a pipe.) Exim always runs transports @@ -20637,7 +20730,6 @@ resent to other recipients. .cindex events This option declares a string to be expanded for Exim's events mechanism. For details see &<>&. -.wen .option group transports string&!! "Exim group" @@ -20741,7 +20833,6 @@ transport, the &[initgroups()]& function is called when running the transport to ensure that any additional groups associated with the uid are set up. -.new .option max_parallel transports integer&!! unset .cindex limit "transport parallelism" .cindex transport "parallel processes" @@ -20764,7 +20855,6 @@ relevant hints database whenever your system reboots. The names of the files start with &_misc_& and they are kept in the &_spool/db_& directory. There may be one or two files, depending on the type of DBM in use. The same files are used for ETRN and smtp transport serialization. -.wen .option message_size_limit transports string&!! 0 @@ -20913,9 +21003,7 @@ headers that some sites insist on. This option sets up a filtering (in the Unix shell sense) process for messages at transport time. It should not be confused with mail filtering as set up by individual users or via a system filter. -.new If unset, or expanding to an empty string, no filtering is done. -.wen When the message is about to be written out, the command specified by &%transport_filter%& is started up in a separate, parallel process, and @@ -22667,10 +22755,8 @@ If two messages arrive at almost the same time, and both are routed to a pipe delivery, the two pipe transports may be run concurrently. You must ensure that any pipe commands you set up are robust against this happening. If the commands write to a file, the &%exim_lock%& utility might be of use. -.new Alternatively the &%max_parallel%& option could be used with a value of "1" to enforce serialization. -.wen @@ -22790,11 +22876,12 @@ with &%use_shell%&, and the whole mechanism is inherently less secure. .section "Environment variables" "SECTpipeenv" .cindex "&(pipe)& transport" "environment for command" -.cindex "environment for pipe transport" +.cindex "environment" "&(pipe)& transport" The environment variables listed below are set up when the command is invoked. This list is a compromise for maximum compatibility with other MTAs. Note that the &%environment%& option can be used to add additional variables to this -environment. +environment. The environment for the &(pipe)& transport is not subject +to the &%add_environment%& and &%keep_environment%& main config options. .display &`DOMAIN `& the domain of the address &`HOME `& the home directory, if set @@ -22889,7 +22976,7 @@ Exim, and each argument is separately expanded, as described in section .option environment pipe string&!! unset .cindex "&(pipe)& transport" "environment for command" -.cindex "environment for &(pipe)& transport" +.cindex "environment" "&(pipe)& transport" This option is used to add additional variables to the environment in which the command runs (see section &<>& for the default list). Its value is a string which is expanded, and then interpreted as a colon-separated list of @@ -23398,6 +23485,15 @@ 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_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 &<>&. + + .option delay_after_cutoff smtp boolean true This option controls what happens when all remote IP addresses for a given domain have been inaccessible for so long that they have passed their retry @@ -23853,9 +23949,7 @@ start with &_misc_& and they are kept in the &_spool/db_& directory. There may be one or two files, depending on the type of DBM in use. The same files are used for ETRN serialization. -.new See also the &%max_parallel%& generic transport option. -.wen .option size_addition smtp integer 1024 @@ -23875,12 +23969,10 @@ Alternatively, if the value of &%size_addition%& is set negative, it disables the use of the SIZE option altogether. -.new .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 &<>&. -.wen .option tls_certificate smtp string&!! unset @@ -24040,7 +24132,7 @@ and certificate verification fails the TLS connection is closed. .option tls_verify_hosts smtp "host list&!!" unset .cindex "TLS" "server certificate verification" .cindex "certificate" "verification of server" -This option gives a list of hosts for which. on encrypted connections, +This option gives a list of hosts for which, on encrypted connections, certificate verification must succeed. The &%tls_verify_certificates%& option must also be set. If both this option and &%tls_try_verify_hosts%& are unset @@ -26506,7 +26598,7 @@ whereas a plaintext SMTP AUTH done inside TLS is not. . to require one of a set of specific certs that define a given account . (the verification is still required, but mostly irrelevant). . This would help for per-device use. -. +. . However, for the future we really need support for checking a . user cert in LDAP - which probably wants a base-64 DER. @@ -26825,7 +26917,8 @@ Documentation of the strings accepted may be found in the GnuTLS manual, under &url(http://www.gnutls.org/manual/html_node/Priority-Strings.html), but beware that this relates to GnuTLS 3, which may be newer than the version installed on your system. If you are using GnuTLS 3, -&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string, then the example code) +then the example code +&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string) on that site can be used to test a given string. For example: @@ -26870,10 +26963,17 @@ with the error If a STARTTLS command is issued within an existing TLS session, it is rejected with a 554 error code. -To enable TLS operations on a server, you must set &%tls_advertise_hosts%& to -match some hosts. You can, of course, set it to * to match all hosts. -However, this is not all you need to do. TLS sessions to a server won't work -without some further configuration at the server end. +To enable TLS operations on a server, the &%tls_advertise_hosts%& option +must be set to match some hosts. The default is * which matches all hosts. + +.new +If this is all you do, TLS encryption will be enabled but not authentication - +meaning that the peer has no assurance it is actually you he is talking to. +You gain protection from a passive sniffer listening on the wire but not +from someone able to intercept the communication. +.wen + +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, @@ -27041,9 +27141,7 @@ starts retrying to fetch an OCSP proof some time before its current proof expires. The downside is that it requires server support. Unless Exim is built with the support disabled, -.new or with GnuTLS earlier than version 3.3.16 / 3.4.8 -.wen support for OCSP stapling is included. There is a global option called &%tls_ocsp_file%&. @@ -27431,9 +27529,6 @@ a realistic ACL for checking RCPT commands. This is discussed in chapter .section "Testing ACLs" "SECID188" The &%-bh%& command line option provides a way of testing your ACL configuration locally by running a fake SMTP session with which you interact. -The host &'relay-test.mail-abuse.org'& provides a service for checking your -relaying configuration (see section &<>& for more details). - .section "Specifying when ACLs are used" "SECID189" @@ -27548,6 +27643,10 @@ Note that a client may issue more than one EHLO or HELO command in an SMTP session, and indeed is required to issue a new EHLO or HELO after successfully setting up encryption following a STARTTLS command. +Note also that a deny neither forces the client to go away nor means that +mail will be refused on the connection. Consider checking for +&$sender_helo_name$& being defined in a MAIL or RCPT ACL to do that. + If the command is accepted by an &%accept%& verb that has a &%message%& modifier, the message may not contain more than one line (it will be truncated at the first newline and a panic logged if it does). Such a message cannot @@ -27625,11 +27724,9 @@ for some or all recipients. PRDR may be used to support per-user content filtering. Without it one must defer any recipient after the first that has a different content-filter configuration. With PRDR, the RCPT-time check -.new .cindex "PRDR" "variable for" for this can be disabled when the variable &$prdr_requested$& is &"yes"&. -.wen Any required difference in behaviour of the main DATA-time ACL should however depend on the PRDR-time ACL having run, as Exim will avoid doing so in some situations (e.g. single-recipient mails). @@ -28571,7 +28668,9 @@ and data is copied from one to the other. An attempt to set this option for any recipient but the first for a mail will be quietly ignored. -If a recipient-verify callout connection is subsequently +If a recipient-verify callout +(with use_sender) +connection is subsequently requested in the same ACL it is held open and used for any subsequent recipients and the data, otherwise one is made after the initial RCPT ACL completes. @@ -28582,6 +28681,12 @@ 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. +All the usual ACLs are called; if one results in the message being +rejected, all effort spent in delivery (including the costs on +the ultimate destination) will be wasted. +Note that in the case of data-time ACLs this includes the entire +message body. + Cutthrough delivery is not supported via transport-filters or when DKIM signing of outgoing messages is done, because it sends data to the ultimate destination before the entire message has been received from the source. @@ -28810,12 +28915,10 @@ data is read. &*Note:*& This control applies only to the current message, not to any others that are being submitted at the same time using &%-bs%& or &%-bS%&. -.new .vitem &*control&~=&~utf8_downconvert*& This control enables conversion of UTF-8 in message addresses to a-label form. For details see &<>&. -.wen .endlist vlist @@ -29094,12 +29197,6 @@ If all goes well, the condition is true. It is false only if there are problems such as a syntax error or a memory shortage. For more details, see chapter &<>&. -.vitem &*demime&~=&~*&<&'extension&~list'&> -.cindex "&%demime%& ACL condition" -This condition is available only when Exim is compiled with the -content-scanning extension. Its use is described in section -&<>&. - .vitem &*dnslists&~=&~*&<&'list&~of&~domain&~names&~and&~other&~data'&> .cindex "&%dnslists%& ACL condition" .cindex "DNS list" "in ACL" @@ -29496,9 +29593,7 @@ warn message = X-Warn: sending host is on dialups list .cindex cacheing "of dns lookup" .cindex DNS TTL DNS list lookups are cached by Exim for the duration of the SMTP session -.new (but limited by the DNS return TTL value), -.wen so a lookup based on the IP address is done at most once for any incoming connection (assuming long-enough TTL). Exim does not share information between multiple incoming @@ -30870,14 +30965,6 @@ in chapter &<>&. You can check the relay characteristics of your configuration in the same way that you can test any ACL behaviour for an incoming SMTP connection, by using the &%-bh%& option to run a fake SMTP session with which you interact. - -For specifically testing for unwanted relaying, the host -&'relay-test.mail-abuse.org'& provides a useful service. If you telnet to this -host from the host on which Exim is running, using the normal telnet port, you -will see a normal telnet connection message and then quite a long delay. Be -patient. The remote host is making an SMTP connection back to your host, and -trying a number of common probes to test for open relay vulnerability. The -results of the tests will eventually appear on your terminal. .ecindex IIDacl @@ -30920,10 +31007,6 @@ conditions. Two new main configuration options: &%av_scanner%& and &%spamd_address%&. .endlist -There is another content-scanning configuration option for &_Local/Makefile_&, -called WITH_OLD_DEMIME. If this is set, the old, deprecated &%demime%& ACL -condition is compiled, in addition to all the other content-scanning features. - Content-scanning is continually evolving, and new features are still being added. While such features are still unstable and liable to incompatible changes, they are made available in Exim by setting options whose names begin @@ -31173,7 +31256,7 @@ This is a daemon type scanner that is aimed mainly at Polish users, though some parts of documentation are now available in English. You can get it at &url(http://linux.mks.com.pl/). The only option for this scanner type is the maximum number of processes used simultaneously to scan the attachments, -provided that the demime facility is employed and also provided that mksd has +provided that mksd has been run with at least the same number of child processes. For example: .code av_scanner = mksd:2 @@ -31264,23 +31347,17 @@ When a virus is found, the condition sets up an expansion variable called &%message%& modifier that specifies the error returned to the sender, and/or in logging data. -If your virus scanner cannot unpack MIME and TNEF containers itself, you should -use the &%demime%& condition (see section &<>&) before the -&%malware%& condition. - Beware the interaction of Exim's &%message_size_limit%& with any size limits imposed by your anti-virus scanner. Here is a very simple scanning example: .code deny message = This message contains malware ($malware_name) - demime = * malware = * .endd The next example accepts messages when there is a problem with the scanner: .code deny message = This message contains malware ($malware_name) - demime = * malware = */defer_ok .endd The next example shows how to use an ACL variable to scan with both sophie and @@ -31776,90 +31853,6 @@ are set to any substrings captured by the regular expression. &*Warning*&: With large messages, these conditions can be fairly CPU-intensive. - - - -.section "The demime condition" "SECTdemimecond" -.cindex "content scanning" "MIME checking" -.cindex "MIME content scanning" -The &%demime%& ACL condition provides MIME unpacking, sanity checking and file -extension blocking. It is usable only in the DATA and non-SMTP ACLs. The -&%demime%& condition uses a simpler interface to MIME decoding than the MIME -ACL functionality, but provides no additional facilities. Please note that this -condition is deprecated and kept only for backward compatibility. You must set -the WITH_OLD_DEMIME option in &_Local/Makefile_& at build time to be able to -use the &%demime%& condition. - -The &%demime%& condition unpacks MIME containers in the message. It detects -errors in MIME containers and can match file extensions found in the message -against a list. Using this facility produces files containing the unpacked MIME -parts of the message in the temporary scan directory. If you do antivirus -scanning, it is recommended that you use the &%demime%& condition before the -antivirus (&%malware%&) condition. - -On the right-hand side of the &%demime%& condition you can pass a -colon-separated list of file extensions that it should match against. For -example: -.code -deny message = Found blacklisted file attachment - demime = vbs:com:bat:pif:prf:lnk -.endd -If one of the file extensions is found, the condition is true, otherwise it is -false. If there is a temporary error while demimeing (for example, &"disk -full"&), the condition defers, and the message is temporarily rejected (unless -the condition is on a &%warn%& verb). - -The right-hand side is expanded before being treated as a list, so you can have -conditions and lookups there. If it expands to an empty string, &"false"&, or -zero (&"0"&), no demimeing is done and the condition is false. - -The &%demime%& condition set the following variables: - -.vlist -.vitem &$demime_errorlevel$& -.vindex "&$demime_errorlevel$&" -When an error is detected in a MIME container, this variable contains the -severity of the error, as an integer number. The higher the value, the more -severe the error (the current maximum value is 3). If this variable is unset or -zero, no error occurred. - -.vitem &$demime_reason$& -.vindex "&$demime_reason$&" -When &$demime_errorlevel$& is greater than zero, this variable contains a -human-readable text string describing the MIME error that occurred. -.endlist - -.vlist -.vitem &$found_extension$& -.vindex "&$found_extension$&" -When the &%demime%& condition is true, this variable contains the file -extension it found. -.endlist - -Both &$demime_errorlevel$& and &$demime_reason$& are set by the first call of -the &%demime%& condition, and are not changed on subsequent calls. - -If you do not want to check for file extensions, but rather use the &%demime%& -condition for unpacking or error checking purposes, pass &"*"& as the -right-hand side value. Here is a more elaborate example of how to use this -facility: -.code -# Reject messages with serious MIME container errors -deny message = Found MIME error ($demime_reason). - demime = * - condition = ${if >{$demime_errorlevel}{2}{1}{0}} - -# Reject known virus spreading file extensions. -# Accepting these is pretty much braindead. -deny message = contains $found_extension file (blacklisted). - demime = com:vbs:bat:pif:scr - -# Freeze .exe and .doc files. Postmaster can -# examine them and eventually thaw them. -deny log_message = Another $found_extension file. - demime = exe:doc - control = freeze -.endd .ecindex IIDcosca @@ -34040,13 +34033,18 @@ specific badly-behaved hosts that you have to live with. When Exim receives a VRFY or EXPN command on a TCP/IP connection, it runs the ACL specified by &%acl_smtp_vrfy%& or &%acl_smtp_expn%& (as appropriate) in order to decide whether the command should be accepted or not. -If no ACL is defined, the command is rejected. .cindex "VRFY" "processing" +When no ACL is defined for VRFY, or if it rejects without +setting an explicit response code, the command is accepted +(with a 252 SMTP response code) +in order to support awkward clients that do a VRFY before every RCPT. When VRFY is accepted, it runs exactly the same code as when Exim is -called with the &%-bv%& option. +called with the &%-bv%& option, and returns 250/451/550 +SMTP response codes. .cindex "EXPN" "processing" +If no ACL for EXPN is defined, the command is rejected. When EXPN is accepted, a single-level expansion of the address is done. EXPN is treated as an &"address test"& (similar to the &%-bt%& option) rather than a verification (the &%-bv%& option). If an unqualified local part is given @@ -35541,8 +35539,8 @@ the following table: &`QT `& on &`=>`& lines: time spent on queue so far &` `& on &"Completed"& lines: time spent on queue &`R `& on &`<=`& lines: reference for local bounce -&` `& on &`=>`& &`**`& and &`==`& lines: router name -&`S `& size of message +&` `& on &`=>`& &`>>`& &`**`& and &`==`& lines: router name +&`S `& size of message in bytes &`SNI `& server name indication from TLS client hello &`ST `& shadow transport name &`T `& on &`<=`& lines: message subject (topic) @@ -35626,17 +35624,13 @@ 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) -.new &` outgoing_interface `& local interface on => lines -.wen &` outgoing_port `& add remote port to => lines &`*queue_run `& start and end queue runs &` queue_time `& time on queue for one recipient &` queue_time_overall `& time on queue for whole message &` pid `& Exim process id -.new &` proxy `& proxy address on <= and => lines -.wen &` received_recipients `& recipients on <= lines &` received_sender `& sender on <= lines &`*rejected_header `& header contents on reject log @@ -35759,11 +35753,8 @@ to the &"<="& line as an IP address in square brackets, tagged by I= and followed by a colon and the port number. The local interface and port are also added to other SMTP log lines, for example &"SMTP connection from"&, to rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines. -.new The latter can be disabled by turning off the &%outgoing_interface%& option. -.wen .next -.new .cindex log "incoming proxy address" .cindex proxy "logging proxy address" .cindex "TCP/IP" "logging proxy address" @@ -35772,7 +35763,6 @@ of the proxy, tagged by PRX=, on the &"<="& line for a message accepted on a proxied connection or the &"=>"& line for a message delivered on a proxied connection.. See &<>& for more information. -.wen .next .cindex "log" "incoming remote port" .cindex "port" "logging remote" @@ -35795,22 +35785,18 @@ connection is unexpectedly dropped. .cindex "log" "local address and port" .cindex "TCP/IP" "logging local address and port" .cindex "interface" "logging" -.new &%outgoing_interface%&: If &%incoming_interface%& is turned on, then the interface on which a message was sent is added to delivery lines as an I= tag followed by IP address in square brackets. You can disable this by turning off the &%outgoing_interface%& option. -.wen .next .cindex "log" "outgoing remote port" .cindex "port" "logging outgoint remote" .cindex "TCP/IP" "logging ougtoing remote port" &%outgoing_port%&: The remote port number is added to delivery log lines (those containing => tags) following the IP address. -.new The local port is also added if &%incoming_interface%& and &%outgoing_interface%& are both enabled. -.wen This option is not included in the default setting, because for most ordinary configurations, the remote port number is always 25 (the SMTP port), and the local port is a random ephemeral port. @@ -37935,9 +37921,7 @@ linked to a domain which that entity controls. It permits reputation to be tracked on a per-domain basis, rather than merely upon source IP address. DKIM is documented in RFC 4871. -.new DKIM support is compiled into Exim by default if TLS support is present. -.wen It can be disabled by setting DISABLE_DKIM=yes in &_Local/Makefile_&. Exim's DKIM implementation allows to @@ -37973,7 +37957,7 @@ where you accept mail from relay sources (internal hosts or authenticated senders). -.section "Signing outgoing messages" "SECID513" +.section "Signing outgoing messages" "SECDKIMSIGN" .cindex "DKIM" "signing" Signing is implemented by setting private options on the SMTP transport. @@ -37988,7 +37972,7 @@ option is put into the &%$dkim_domain%& expansion variable. MANDATORY: This sets the key selector string. You can use the &%$dkim_domain%& expansion variable to look up a matching selector. The result is put in the expansion -variable &%$dkim_selector%& which should be used in the &%dkim_private_key%& +variable &%$dkim_selector%& which may be used in the &%dkim_private_key%& option along with &%$dkim_domain%&. .option dkim_private_key smtp string&!! unset @@ -38210,7 +38194,6 @@ for more information of what they mean. .cindex "proxy support" .cindex "proxy" "access via" -.new A proxy is an intermediate system through which communication is passed. Proxies may provide a security, availability or load-distribution function. @@ -38244,18 +38227,20 @@ 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. +.new The following expansion variables are usable (&"internal"& and &"external"& here refer to the interfaces of the proxy): .display -&'proxy_host_address '& internal IP address of the proxy -&'proxy_host_port '& internal TCP port of the proxy -&'proxy_target_address '& external IP address of the proxy -&'proxy_target_port '& external TCP port of the proxy +&'proxy_external_address '& IP of host being proxied or IP of remote interface of proxy +&'proxy_external_port '& Port of host being proxied or Port on remote interface of proxy +&'proxy_local_address '& IP of proxy server inbound or IP of local interface of proxy +&'proxy_local_port '& Port of proxy server inbound or Port on local interface of proxy &'proxy_session '& boolean: SMTP connection via proxy .endd -If &$proxy_session$& is set but &$proxy_host_address$& is empty +If &$proxy_session$& is set but &$proxy_external_address$& is empty there was a protocol error. +.wen Since the real connections are all coming from the proxy, and the per host connection tracking is done before Proxy Protocol is @@ -38296,7 +38281,7 @@ Each proxy specifier is a list (space-separated by default) where the initial element is an IP address and any subsequent elements are options. -Options are a string =. +Options are a string =. The list of options is in the following table: .display &'auth '& authentication method @@ -38348,7 +38333,6 @@ overall connection applies to the set of proxied attempts. To log the (local) IP of a proxy in the incoming or delivery logline, add &"+proxy"& to the &%log_selector%& option. This will add a component tagged with &"PRX="& to the line. -.wen . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -38360,7 +38344,6 @@ This will add a component tagged with &"PRX="& to the line. .cindex i18n .cindex UTF-8 "mail name handling" -.new 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. @@ -38469,7 +38452,6 @@ Examples: Note that the source charset setting is vital, and also that characters must be representable in UTF-16. -.wen . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -38478,7 +38460,6 @@ must be representable in UTF-16. "Events" .cindex events -.new The events mechanism in Exim can be used to intercept processing at a number of points. It was originally invented to giave a way to do customised logging actions (for example, to a database) but can also be used to modify some @@ -38584,7 +38565,6 @@ For tls:cert events, if GnuTLS is in use this will trigger only per chain element received on the connection. For OpenSSL it will trigger for every chain element including those loaded locally. -.wen . //////////////////////////////////////////////////////////////////////////// . ////////////////////////////////////////////////////////////////////////////