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Diffstat (limited to 'doc/doc-docbook/spec.xfpt')
| -rw-r--r-- | doc/doc-docbook/spec.xfpt | 76 |
1 files changed, 1 insertions, 75 deletions
diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 5324be398..ced906eaa 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -45,7 +45,7 @@ . Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.87" +.set previousversion "4.88" .include ./local_params .set ACL "access control lists (ACLs)" @@ -371,13 +371,11 @@ 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 @@ -3827,13 +3825,11 @@ 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. -.new .vitem &%-MCG%& .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. -.wen .vitem &%-MCP%& .oindex "&%-MCP%&" @@ -4381,9 +4377,7 @@ relax this restriction (and also the same requirement for the &%-M%&, &%-R%&, and &%-S%& options). .cindex "queue runner" "description of operation" -.new If other commandline options do not specify an action, -.wen the &%-q%& option starts one queue runner process. This scans the queue of waiting messages, and runs a delivery process for each one in turn. It waits for each delivery process to finish before starting the next one. A delivery @@ -4469,7 +4463,6 @@ The &'l'& (the letter &"ell"&) flag specifies that only local deliveries are to be done. If a message requires any remote deliveries, it remains on the queue for later delivery. -.new .vitem &%-q[q][i][f[f]][l][G<name>[/<time>]]]%& .oindex "&%-qG%&" .cindex queue named @@ -4489,7 +4482,6 @@ exim -bp -qGquarantine mailq -qGquarantime exim -qGoffpeak -Rf @special.domain.example .endd -.wen .vitem &%-q%&<&'qflags'&>&~<&'start&~id'&>&~<&'end&~id'&> When scanning the queue, Exim can be made to skip over messages whose ids are @@ -5033,7 +5025,6 @@ address lists. In Exim 4 these are handled better by named lists &-- see section &<<SECTnamedlists>>&. -.new .section "Builtin macros" "SECTbuiltinmacros" Exim defines some macros depending on facilities available, which may differ due to build-time definitions and from one release to another. @@ -5057,7 +5048,6 @@ The following classes of macros are defined: .endd Use an &"exim -bP macros"& command to get the list of macros. -.wen .section "Conditional skips in the configuration file" "SECID46" @@ -5164,9 +5154,7 @@ hexadecimal number. If an integer value is followed by the letter K, it is multiplied by 1024; if it is followed by the letter M, it is multiplied by 1024x1024; -.new if by the letter G, 1024x1024x1024. -.wen When the values of integer option settings are output, values which are an exact multiple of 1024 or 1024x1024 are sometimes, but not always, printed using the letters K @@ -6296,9 +6284,7 @@ Exim supports the use of regular expressions in many of its options. It uses the PCRE regular expression library; this provides regular expression matching that is compatible with Perl 5. The syntax and semantics of regular expressions is discussed in -.new online Perl manpages, in -.wen many Perl reference books, and also in Jeffrey Friedl's &'Mastering Regular Expressions'&, which is published by O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)). @@ -7846,10 +7832,8 @@ domain, host, address and local part lists. .cindex "expansion" "of lists" 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 @@ -10127,7 +10111,6 @@ Last:user@example.com user@example.com .endd -.new .vitem &*${base32:*&<&'digits'&>&*}*& .cindex "&%base32%& expansion item" .cindex "expansion" "conversion to base 32" @@ -10140,7 +10123,6 @@ Only lowercase letters are used. .cindex "expansion" "conversion to base 32" The string must consist entirely of base-32 digits. The number is converted to decimal and output as a string. -.wen .vitem &*${base62:*&<&'digits'&>&*}*& .cindex "&%base62%& expansion item" @@ -10193,14 +10175,12 @@ escape sequences starting with a backslash. Whether characters with the most significant bit set (so-called &"8-bit characters"&) count as printing or not is controlled by the &%print_topbitchars%& option. -.new .vitem &*${escape8bit:*&<&'string'&>&*}*& .cindex "expansion" "escaping 8-bit characters" .cindex "&%escape8bit%& expansion item" If the string contains and characters with the most significant bit set, they are converted to escape sequences starting with a backslash. Backslashes and DEL characters are also converted. -.wen .vitem &*${eval:*&<&'string'&>&*}*&&~and&~&*${eval10:*&<&'string'&>&*}*& @@ -10588,17 +10568,14 @@ returns the SHA-1 hash fingerprint of the certificate. .cindex certificate fingerprint .cindex "expansion" "SHA-256 hashing" .cindex "&%sha256%& expansion item" -.new The &%sha256%& operator computes the SHA-256 hash value of the string and returns it as a 64-digit hexadecimal number, in which any letters are in upper case. -.wen If the string is a single variable of type certificate, returns the SHA-256 hash fingerprint of the certificate. -.new .vitem &*${sha3:*&<&'string'&>&*}*& &&& &*${sha3_<n>:*&<&'string'&>&*}*& .cindex "SHA3 hash" @@ -10614,7 +10591,6 @@ with 256 being the default. The &%sha3%& expansion item is only supported if Exim has been compiled with GnuTLS 3.5.0 or later. -.wen .vitem &*${stat:*&<&'string'&>&*}*& @@ -12263,7 +12239,6 @@ a single-component name, Exim calls &[gethostbyname()]& (or qualified host name. See also &$smtp_active_hostname$&. -.new .vitem &$proxy_external_address$& &&& &$proxy_external_port$& &&& &$proxy_local_address$& &&& @@ -12272,7 +12247,6 @@ qualified host name. See also &$smtp_active_hostname$&. These variables are only available when built with Proxy Protocol or Socks5 support For details see chapter &<<SECTproxyInbound>>&. -.wen .vitem &$prdr_requested$& .cindex "PRDR" "variable for" @@ -12303,13 +12277,11 @@ The value set for the &%qualify_domain%& option in the configuration file. The value set for the &%qualify_recipient%& option in the configuration file, or if not set, the value of &$qualify_domain$&. -.new .vitem &$queue_name$& .vindex &$queue_name$& .cindex "named queues" .cindex queues named The name of the spool queue in use; empty for the default queue. -.wen .vitem &$rcpt_count$& .vindex "&$rcpt_count$&" @@ -13110,7 +13082,6 @@ 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" @@ -13119,7 +13090,6 @@ 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" @@ -14352,15 +14322,11 @@ $primary_hostname-$tod_epoch-testing See section &<<CALLaddparcall>>& for details of how this value is used. -.new .option check_log_inodes main integer 100 -.wen See &%check_spool_space%& below. -.new .option check_log_space main integer 10M -.wen See &%check_spool_space%& below. .oindex "&%check_rfc2047_length%&" @@ -14375,15 +14341,11 @@ of the RFC, generates overlong encoded words. If &%check_rfc2047_length%& is set false, Exim recognizes encoded words of any length. -.new .option check_spool_inodes main integer 100 -.wen See &%check_spool_space%& below. -.new .option check_spool_space main integer 10M -.wen .cindex "checking disk space" .cindex "disk space, checking" .cindex "spool directory" "checking space" @@ -14429,21 +14391,17 @@ For non-SMTP input and for batched SMTP input, the test is done at start-up; on failure a message is written to stderr and Exim exits with a non-zero code, as it obviously cannot send an error message of any kind. -.new 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 may wish to deliberately disable them. -.wen -.new .option chunking_advertise_hosts main "host list&!!" * .cindex CHUNKING advertisement .cindex "RFC 3030" "CHUNKING" 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. -.wen .option daemon_smtp_ports main string &`smtp`& .cindex "port" "for daemon" @@ -16063,12 +16021,10 @@ the limit, allowing any number of simultaneous queue runner processes to be run. If you do not want queue runs to occur, omit the &%-q%&&'xx'& setting on the daemon's command line. -.new .cindex queues named .cindex "named queues" To set limits for different named queues use an expansion depending on the &$queue_name$& variable. -.wen .option queue_smtp_domains main "domain list&!!" unset .cindex "queueing incoming messages" @@ -17031,10 +16987,8 @@ if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in &<<SECTtlssni>>& 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" @@ -17071,12 +17025,10 @@ larger prime than requested. The value of this option is expanded and indicates the source of DH parameters to be used by Exim. -.new &*Note: The Exim Maintainers strongly recommend using a filename with site-generated local DH parameters*&, which has been supported across all versions of Exim. The other specific constants available are a fallback so that even when "unconfigured", Exim can offer Perfect Forward Secrecy in older ciphersuites in TLS. -.wen If &%tls_dhparam%& is a filename starting with a &`/`&, then it names a file from which DH @@ -17095,7 +17047,6 @@ Exim will attempt to load a file from inside the spool directory. If the file does not exist, Exim will attempt to create it. See section &<<SECTgnutlsparam>>& for further details. -.new If Exim is using OpenSSL and this option is empty or unset, then Exim will load a default DH prime; the default is Exim-specific but lacks verifiable provenance. @@ -17127,7 +17078,6 @@ of the later IKE values, which led into RFC7919 providing new fixed constants At this point, all of the "ike" values should be considered obsolete; they're still in Exim to avoid breaking unusual configurations, but are candidates for removal the next time we have backwards-incompatible changes. -.wen The TLS protocol does not negotiate an acceptable size for this; clients tend to hard-drop connections if what is offered by the server is unacceptable, @@ -23999,7 +23949,6 @@ connects. If authentication fails, Exim will try to transfer the message unauthenticated. See also &%hosts_require_auth%&, and chapter &<<CHAPSMTPAUTH>>& for details of authentication. -.new .option hosts_try_chunking smtp "host list&!!" * .cindex CHUNKING "enabling, in client" .cindex BDAT "SMTP command" @@ -24007,9 +23956,7 @@ unauthenticated. See also &%hosts_require_auth%&, and chapter 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. -.wen -.new .option hosts_try_fastopen smtp "host list!!" unset .option "fast open, TCP" "enabling, in client" .option "TCP Fast Open" "enabling, in client" @@ -24026,7 +23973,6 @@ 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. -.wen .option hosts_try_prdr smtp "host list&!!" * .cindex "PRDR" "enabling, optional in client" @@ -27192,12 +27138,10 @@ rejected with a 554 error code. 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. @@ -27576,11 +27520,9 @@ 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. -.new Further, the initial cerificate 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. -.wen The Exim developers are proceeding cautiously and so far no other TLS options are re-expanded. @@ -27903,7 +27845,6 @@ received, before the final response to the DATA command is sent. This is the ACL specified by &%acl_smtp_data%&, which is the second ACL that is associated with the DATA command. -.new .cindex CHUNKING "BDAT command" .cindex BDAT "SMTP command" .cindex "RFC 3030" CHUNKING @@ -27912,7 +27853,6 @@ the &%acl_smtp_predata%& ACL is not run. . XXX why not? It should be possible, for the first BDAT. The &%acl_smtp_data%& is run after the last BDAT command and all of the data specified is received. -.wen For both of these ACLs, it is not possible to reject individual recipients. An error response rejects the entire message. Unfortunately, it is known that some @@ -28810,7 +28750,6 @@ all the conditions are true, wherever it appears in an ACL command, whereas effect. -.new .vitem &*queue*&&~=&~<&'text'&> This modifier specifies the use of a named queue for spool files for the message. @@ -28820,7 +28759,6 @@ This could be used, for example, for known high-volume burst sources of traffic, or for quarantine of messages. Separate queue-runner processes will be needed for named queues. If the text after expansion is empty, the default queue is used. -.wen .vitem &*remove_header*&&~=&~<&'text'&> @@ -28953,7 +28891,6 @@ If the item is successfully delivered in cutthrough mode the delivery log lines are tagged with ">>" rather than "=>" and appear before the acceptance "<=" line. -.new If there is a temporary error the item is queued for later delivery in the usual fashion. This behaviour can be adjusted by appending the option &*defer=*&<&'value'&> @@ -28961,7 +28898,6 @@ 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. -.wen Delivery in this mode avoids the generation of a bounce mail to a (possibly faked) @@ -28977,9 +28913,7 @@ with &`-d`&, with the output going to a new logfile, by default called 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. -.new Logging may be stopped, and the file removed, with the &'kill'& option. -.wen Some examples (which depend on variables that don't exist in all contexts): .code @@ -31842,11 +31776,9 @@ spam bar is 50 characters. A multiline text table, containing the full SpamAssassin report for the message. Useful for inclusion in headers or reject messages. This variable is only usable in a DATA-time ACL. -.new Beware that SpamAssassin may return non-ASCII characters, especially when running in country-specific locales, which are not legal unencoded in headers. -.wen .vitem &$spam_action$& For SpamAssassin either 'reject' or 'no action' depending on the @@ -38438,11 +38370,9 @@ The header canonicalization method. One of 'relaxed' or 'simple'. .vitem &%$dkim_copiedheaders%& A transcript of headers and their values which are included in the signature (copied from the 'z=' tag of the signature). -.new Note that RFC6376 requires that verification fail if the From: header is not included in the signature. Exim does not enforce this; sites wishing strict enforcement should code the check explicitly. -.wen .vitem &%$dkim_bodylength%& The number of signed body bytes. If zero ("0"), the body is unsigned. If no @@ -38500,10 +38430,8 @@ warn log_message = GMail sender without gmail.com DKIM signature dkim_status = none .endd -.new Note that the above does not check for a total lack of DKIM signing; for that check for empty &$h_DKIM-Signature:$& in the data ACL. -.wen .vitem &%dkim_status%& ACL condition that checks a colon-separated list of possible DKIM verification @@ -38563,7 +38491,6 @@ 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): @@ -38576,7 +38503,6 @@ of the proxy): .endd 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 |