X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/711df2d9898cf331b49a32e5b1ae9979c9c9cdcb..e2f032313876fb6a9f75a672383ab21948606064:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index dc441df2f..438db94b4 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -1,4 +1,4 @@ -. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.26 2007/10/24 17:47:31 fanf2 Exp $ +. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.56 2009/10/16 08:46:11 tom Exp $ . . ///////////////////////////////////////////////////////////////////////////// . This is the primary source of the Exim Manual. It is an xfpt document that is @@ -47,8 +47,8 @@ . the element must also be updated for each new edition. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.67" -.set version "4.68" +.set previousversion "4.69" +.set version "4.70" .set ACL "access control lists (ACLs)" .set I "    " @@ -172,17 +172,17 @@ Specification of the Exim Mail Transfer Agent The Exim MTA -23 August 2007 +09 June 2009 PhilipHazel PH University of Cambridge Computing Service
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England
- 4.68 - 23 August 2007 + 4.70 + 10 June 2009 PH -2007University of Cambridge +2009University of Cambridge .literal off @@ -367,6 +367,7 @@ 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. @@ -430,8 +431,6 @@ directory are: .row &_exim.8_& "a man page of Exim's command line options" .row &_experimental.txt_& "documentation of experimental features" .row &_filter.txt_& "specification of the filter language" -.row &_pcrepattern.txt_& "specification of PCRE regular expressions" -.row &_pcretest.txt_& "specification of the PCRE testing program" .row &_Exim3.upgrade_& "upgrade notes from release 2 to release 3" .row &_Exim4.upgrade_& "upgrade notes from release 3 to release 4" .endtable @@ -456,12 +455,12 @@ Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge. .cindex "FAQ" As well as Exim distribution tar files, the Exim web site contains a number of differently formatted versions of the documentation. A recent addition to the -online information is the Exim wiki &new("(&url(http://wiki.exim.org))"), +online information is the Exim wiki (&url(http://wiki.exim.org)), 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 &new("&url(http://bugs.exim.org)"). You can use +An Exim Bugzilla exists at &url(http://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. @@ -491,19 +490,17 @@ Please ask Debian-specific questions on this list and not on the general Exim lists. .section "Exim training" "SECID4" -.new .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/). -.wen .section "Bug reports" "SECID5" .cindex "bug reports" .cindex "reporting bugs" -Reports of obvious bugs &new("can be emailed to &'bugs@exim.org'& or reported -via the Bugzilla (&url(http://bugs.exim.org)).") However, if you are unsure +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 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. @@ -539,13 +536,13 @@ The &_.bz2_& file is usually a lot smaller than the &_.gz_& file. .cindex "distribution" "signing details" .cindex "distribution" "public key" .cindex "public key for signed distribution" -The distributions are currently signed with Philip Hazel's GPG key. The +The distributions are currently signed with Nigel Metheringham's GPG key. The corresponding public key is available from a number of keyservers, and there is -also a copy in the file &_Public-Key_&. The signatures for the tar bundles are +also a copy in the file &_nigel-pubkey.asc_&. The signatures for the tar bundles are in: .display -&_exim-n.nn.tar.gz.sig_& -&_exim-n.nn.tar.bz2.sig_& +&_exim-n.nn.tar.gz.asc_& +&_exim-n.nn.tar.bz2.asc_& .endd For each released version, the log of changes is made separately available in a separate file in the directory &_ChangeLogs_& so that it is possible to @@ -731,12 +728,11 @@ the Exim documentation, &"spool"& is always used in the first sense. A number of pieces of external code are included in the Exim distribution. .ilist -Regular expressions are supported in the main Exim program and in the Exim -monitor using the freely-distributable PCRE library, copyright © -University of Cambridge. The source is distributed in the directory -&_src/pcre_&. However, this is a cut-down version of PCRE. If you want to use -the PCRE library in other programs, you should obtain and install the full -version of the library from +Regular expressions are supported in the main Exim program and in the +Exim monitor using the freely-distributable PCRE library, copyright +© University of Cambridge. The source to PCRE is no longer shipped with +Exim, so you will need to use the version of PCRE shipped with your system, +or obtain and install the full version of the library from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre). .next .cindex "cdb" "acknowledgment" @@ -1656,6 +1652,18 @@ architecture and operating system for itself, but the defaults can be overridden if necessary. +.section "PCRE library" "SECTpcre" +.cindex "PCRE library" +Exim no longer has an embedded PCRE library as the vast majority of +modern systems include PCRE as a system library, although you may need +to install the PCRE or PCRE development package for your operating +system. If your system has a normal PCRE installation the Exim build +process will need no further configuration. If the library or the +headers are in an unusual location you will need to set the PCRE_LIBS +and INCLUDE directives appropriately. If your operating system has no +PCRE support then you will need to obtain and build the current PCRE +from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/). + .section "DBM libraries" "SECTdb" .cindex "DBM libraries" "discussion of" .cindex "hints database" "DBM files used for" @@ -2215,9 +2223,8 @@ but this usage is deprecated. .cindex "installing Exim" "what is not installed" Running &'make install'& does not copy the Exim 4 conversion script -&'convert4r4'&, or the &'pcretest'& test program. You will probably run the -first of these only once (if you are upgrading from Exim 3), and the second -isn't really part of Exim. None of the documentation files in the &_doc_& +&'convert4r4'&. You will probably run this only once if you are +upgrading from Exim 3. None of the documentation files in the &_doc_& directory are copied, except for the info files when you have set INFO_DIRECTORY, as described in section &<>& below. @@ -3731,7 +3738,6 @@ by an admin user. This option causes the contents of the message body (-D) spool file to be written to the standard output. This option can be used only by an admin user. -.new .vitem &%-Mvc%&&~<&'message&~id'&> .oindex "&%-Mvc%&" .cindex "message" "listing in RFC 2822 format" @@ -3739,7 +3745,6 @@ written to the standard output. This option can be used only by an admin user. This option causes a copy of the complete message (header lines plus body) to be written to the standard output in RFC 2822 format. This option can be used only by an admin user. -.wen .vitem &%-Mvh%&&~<&'message&~id'&> .oindex "&%-Mvh%&" @@ -4556,13 +4561,11 @@ addresses and determine how the message is to be delivered (see chapters define mechanisms for copying messages to destinations (see chapters &<>&&--&<>&). .next -.new &'retry'&: Retry rules, for use when a message cannot be delivered immediately. If there is no retry section, or if it is empty (that is, no retry rules are defined), Exim will not retry deliveries. In this situation, temporary errors are treated the same as permanent errors. Retry rules are discussed in chapter &<>&. -.wen .next &'rewrite'&: Global address rewriting rules, for use when a message arrives and when new addresses are generated during delivery. Rewriting is discussed in @@ -4715,7 +4718,7 @@ up in a MySQL database. It helps to keep the file less cluttered if long strings such as SQL statements are defined separately as macros, for example: .code ALIAS_QUERY = select mailbox from user where \ - login=${quote_mysql:$local_part}; + login='${quote_mysql:$local_part}'; .endd This can then be used in a &(redirect)& router setting like this: .code @@ -5821,11 +5824,9 @@ This causes any temporarily failing address to be retried every 15 minutes for 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. -.new 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 temporary errors into permanent errors. -.wen .section "Rewriting configuration" "SECID58" @@ -5884,6 +5885,10 @@ password are correct. In the examples it just produces an error message. To make the authenticators work, you can use a string expansion expression like one of the examples in &<>&. +Beware that the sequence of the parameters to PLAIN and LOGIN differ; the +usercode and password are in different positions. &<>& +covers both. + .ecindex IIDconfiwal @@ -5903,13 +5908,11 @@ Jeffrey Friedl's &'Mastering Regular Expressions'&, which is published by O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)). The documentation for the syntax and semantics of the regular expressions that -are supported by PCRE is included in plain text in the file -&_doc/pcrepattern.txt_& in the Exim distribution, and also in the HTML -tarbundle of Exim documentation. It describes in detail the features of the -regular expressions that PCRE supports, so no further description is included -here. The PCRE functions are called from Exim using the default option settings -(that is, with no PCRE options set), except that the PCRE_CASELESS option is -set when the matching is required to be case-insensitive. +are supported by PCRE is included in the PCRE distribution, and no further +description is included here. The PCRE functions are called from Exim using +the default option settings (that is, with no PCRE options set), except that +the PCRE_CASELESS option is set when the matching is required to be +case-insensitive. In most cases, when a regular expression is required in an Exim configuration, it has to start with a circumflex, in order to distinguish it from plain text @@ -5948,47 +5951,6 @@ $ is needed because string expansion also interprets dollar characters. -.section "Testing regular expressions" "SECID59" -.cindex "testing" "regular expressions" -.cindex "regular expressions" "testing" -.cindex "&'pcretest'&" -A program called &'pcretest'& forms part of the PCRE distribution and is built -with PCRE during the process of building Exim. It is primarily intended for -testing PCRE itself, but it can also be used for experimenting with regular -expressions. After building Exim, the binary can be found in the build -directory (it is not installed anywhere automatically). There is documentation -of various options in &_doc/pcretest.txt_&, but for simple testing, none are -needed. This is the output of a sample run of &'pcretest'&: -.display -&` re> `&&*&`/^([@]+)@.+\.(ac|edu)\.(?!kr)[a-z]{2}$/`&*& -&`data> `&&*&`x@y.ac.uk`&*& -&` 0: x@y.ac.uk`& -&` 1: x`& -&` 2: ac`& -&`data> `&&*&`x@y.ac.kr`&*& -&`No match`& -&`data> `&&*&`x@y.edu.com`&*& -&`No match`& -&`data> `&&*&`x@y.edu.co`&*& -&` 0: x@y.edu.co`& -&` 1: x`& -&` 2: edu`& -.endd -Input typed by the user is shown in bold face. After the &"re>"& prompt, a -regular expression enclosed in delimiters is expected. If this compiles without -error, &"data>"& prompts are given for strings against which the expression is -matched. An empty data line causes a new regular expression to be read. If the -match is successful, the captured substring values (that is, what would be in -the variables &$0$&, &$1$&, &$2$&, etc.) are shown. The above example tests for -an email address whose domain ends with either &"ac"& or &"edu"& followed by a -two-character top-level domain that is not &"kr"&. The local part is captured -in &$1$& and the &"ac"& or &"edu"& in &$2$&. - - - - - - . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -6151,7 +6113,6 @@ calls using the passwords from Courier's &_/etc/userdbshadow.dat_& file. Exim's utility program for creating DBM files (&'exim_dbmbuild'&) includes the zeros by default, but has an option to omit them (see section &<>&). .next -.new .cindex "lookup" "dsearch" .cindex "dsearch lookup type" &(dsearch)&: The given file must be a directory; this is searched for an entry @@ -6161,7 +6122,6 @@ the lookup is the name of the entry, which may be a file, directory, symbolic link, or any other kind of directory entry. An example of how this lookup can be used to support virtual domains is given in section &<>&. -.wen .next .cindex "lookup" "iplsearch" .cindex "iplsearch lookup type" @@ -7154,9 +7114,9 @@ If any MySQL, PostgreSQL, Oracle, or InterBase lookups are used, the &%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, or &%ibase_servers%& option (as appropriate) must be set to a colon-separated list of server information. -&new("(For MySQL and PostgreSQL only, the global option need not be set if all +(For MySQL and PostgreSQL only, the global option need not be set if all queries contain their own server information &-- see section -&<>&.)") Each item in the list is a slash-separated list of four +&<>&.) Each item in the list is a slash-separated list of four items: host name, database name, user name, and password. In the case of Oracle, the host name field is used for the &"service name"&, and the database name field is not used and should be empty. For example: @@ -7170,14 +7130,12 @@ option. Here is an example where two MySQL servers are listed: hide mysql_servers = localhost/users/root/secret:\ otherhost/users/root/othersecret .endd -.new For MySQL and PostgreSQL, a host may be specified as <&'name'&>:<&'port'&> but because this is a colon-separated list, the colon has to be doubled. For each query, these parameter groups are tried in order until a connection is made and 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. -.wen The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b @@ -7187,7 +7145,6 @@ addition, escapes the percent and underscore characters. This cannot be done for MySQL because these escapes are not recognized in contexts where these characters are not special. -.new .section "Specifying the server in the query" "SECTspeserque" For MySQL and PostgreSQL lookups (but not currently for Oracle and InterBase), it is possible to specify a list of servers with an individual query. This is @@ -7219,15 +7176,14 @@ mysql_servers = slave1/db/name/pw:\ .endd In an updating lookup, you could then write: .code -${lookup mysql{servers=master; UPDATE ...} +${lookup mysql{servers=master; UPDATE ...} } .endd That query would then be sent only to the master server. If, on the other hand, the master is not to be used for reading, and so is not present in the global option, you can still update it by a query of this form: .code -${lookup pgsql{servers=master/db/name/pw; UPDATE ...} +${lookup pgsql{servers=master/db/name/pw; UPDATE ...} } .endd -.wen .section "Special MySQL features" "SECID73" @@ -7594,7 +7550,6 @@ as set by the &%primary_hostname%& option (or defaulted). This makes it possible to use the same configuration file on several different hosts that differ only in their names. .next -.new .cindex "@[] in a domain list" .cindex "domain list" "matching local IP interfaces" .cindex "domain literal" @@ -7604,7 +7559,6 @@ only if that IP address is recognized as local for email routing purposes. The &%local_interfaces%& and &%extra_local_interfaces%& options can be used to control which of a host's several IP addresses are treated as local. In today's Internet, the use of domain literals is controversial. -.wen .next .cindex "@mx_any" .cindex "@mx_primary" @@ -7666,7 +7620,6 @@ list item such as &`*key.ex`& matches &'donkey.ex'& as well as &'cipher.key.ex'&. .next -.new .cindex "regular expressions" "in domain list" .cindex "domain list" "matching regular expression" If a pattern starts with a circumflex character, it is treated as a regular @@ -7676,7 +7629,6 @@ Email domains are case-independent, so this regular expression match is by default case-independent, but you can make it case-dependent by starting it with &`(?-i)`&. References to descriptions of the syntax of regular expressions are given in chapter &<>&. -.wen &*Warning*&: Because domain lists are expanded before being processed, you must escape any backslash and dollar characters in the regular expression, or @@ -7919,7 +7871,6 @@ mask, and this is used as the lookup key. For example, if the host's IP address is 192.168.34.6, the key that is looked up for the above example is &"192.168.34.0/24"&. -.new When an IPv6 address is converted to a string, dots are normally used instead of colons, so that keys in &(lsearch)& files need not contain colons (which terminate &(lsearch)& keys). This was implemented some time before the ability @@ -7934,7 +7885,6 @@ Ideally, it would be nice to tidy up this anomalous situation by changing to colons in all cases, given that quoting is now available for &(lsearch)&. However, this would be an incompatible change that might break some existing configurations. -.wen &*Warning*&: Specifying &%net32-%& (for an IPv4 address) or &%net128-%& (for an IPv6 address) is not the same as specifying just &%net-%& without a number. In @@ -7990,7 +7940,6 @@ the host name. For example, &`*.b.c`& matches all hosts whose names end in requirement. Other kinds of wildcarding require the use of a regular expression. .next -.new .cindex "regular expressions" "in host list" .cindex "host list" "regular expression in" If the item starts with &"^"& it is taken to be a regular expression which is @@ -7999,7 +7948,6 @@ expression match is by default case-independent, but you can make it case-dependent by starting it with &`(?-i)`&. References to descriptions of the syntax of regular expressions are given in chapter &<>&. For example, -.wen .code ^(a|b)\.c\.d$ .endd @@ -8027,10 +7975,8 @@ name (see section &<>&), or it may need to look up a host name from an IP address (see section &<>&). In either case, the behaviour when it fails to find the information it is seeking is the same. -.new &*Note*&: This section applies to permanent lookup failures. It does &'not'& apply to temporary DNS errors, whose handling is described in the next section. -.wen .cindex "&`+include_unknown`&" .cindex "&`+ignore_unknown`&" @@ -8066,7 +8012,6 @@ list. The effect of each one lasts until the next, or until the end of the list. -.new .section "Temporary DNS errors when looking up host information" &&& "SECTtemdnserr" .cindex "host" "lookup failures, temporary" @@ -8078,7 +8023,6 @@ host lists can include &`+ignore_defer`& and &`+include_defer`&, analagous to &`+ignore_unknown`& and &`+include_unknown`&, as described in the previous section. These options should be used with care, probably only in non-critical host lists such as whitelists. -.wen @@ -9658,11 +9602,9 @@ bytes are replaced by question marks. Characters are converted into the character set defined by &%headers_charset%&. Overlong RFC 2047 &"words"& are not recognized unless &%check_rfc2047_length%& is set false. -.new &*Note*&: If you use &%$header%&_&'xxx'&&*:*& (or &%$h%&_&'xxx'&&*:*&) to access a header line, RFC 2047 decoding is done automatically. You do not need to use this operator as well. -.wen @@ -9794,6 +9736,22 @@ lower case), signifying multiplication by 1024 or 1024*1024, respectively. As a special case, the numerical value of an empty string is taken as zero. +.vitem &*bool&~{*&<&'string'&>&*}*& +.cindex "expansion" "boolean parsing" +.cindex "&%bool%& expansion condition" +This condition turns a string holding a true or false representation into +a boolean state. It parses &"true"&, &"false"&, &"yes"& and &"no"& +(case-insensitively); also positive integer numbers map to true if non-zero, +false if zero. Leading whitespace is ignored. +All other string values will result in expansion failure. + +When combined with ACL variables, this expansion condition will let you +make decisions in one place and act on those decisions in another place. +For example, +.code +${if bool{$acl_m_privileged_sender} ... +.endd + .vitem &*crypteq&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "expansion" "encrypted comparison" .cindex "encrypted strings, comparing" @@ -9992,7 +9950,6 @@ The substring is first expanded, and then tested to see if it has the form of an IP address. Both IPv4 and IPv6 addresses are valid for &%isip%&, whereas &%isip4%& and &%isip6%& test specifically for IPv4 or IPv6 addresses. -.new For an IPv4 address, the test is for four dot-separated components, each of which consists of from one to three digits. For an IPv6 address, up to eight colon-separated components are permitted, each containing from one to four @@ -10007,7 +9964,6 @@ host names, or between IPv4 and IPv6 addresses. For example, you could use ${if isip4{$sender_host_address}... .endd to test which IP version an incoming SMTP connection is using. -.wen .vitem &*ldapauth&~{*&<&'ldap&~query'&>&*}*& .cindex "LDAP" "use for authentication" @@ -10247,6 +10203,10 @@ configuration, you might have this: .code server_condition = ${if pwcheck{$auth1:$auth2}} .endd +Again, for a PLAIN authenticator configuration, this would be: +.code +server_condition = ${if pwcheck{$auth2:$auth3}} +.endd .vitem &*queue_running*& .cindex "queue runner" "detecting when delivering from" .cindex "expansion" "queue runner test" @@ -10574,7 +10534,6 @@ This variable is available when Exim is compiled with the content-scanning extension and the obsolete &%demime%& condition. For details, see section &<>&. -.new .vitem &$dnslist_domain$& &&& &$dnslist_matched$& &&& &$dnslist_text$& &&& @@ -10588,7 +10547,6 @@ When a DNS (black) list lookup succeeds, these variables are set to contain the following data from the lookup: the list's domain name, the key that was looked up, the contents of any associated TXT record, and the value from the main A record. See section &<>& for more details. -.wen .vitem &$domain$& .vindex "&$domain$&" @@ -10782,7 +10740,7 @@ This is an obsolete name for &$received_port$&. .vitem &$item$& .vindex "&$item$&" This variable is used during the expansion of &*forall*& and &*forany*& -conditions (see section &<>&), and &*filter*&, &*man*&, and +conditions (see section &<>&), and &*filter*&, &*map*&, and &*reduce*& items (see section &<>&). In other circumstances, it is empty. @@ -10930,7 +10888,6 @@ This variable is available when Exim is compiled with the content-scanning extension. It is set to the name of the virus that was found when the ACL &%malware%& condition is true (see section &<>&). -.new .vitem &$max_received_linelength$& .vindex "&$max_received_linelength$&" .cindex "maximum" "line length" @@ -10938,7 +10895,6 @@ when the ACL &%malware%& condition is true (see section &<>&). This variable contains the number of bytes in the longest line that was received as part of the message, not counting the line termination character(s). -.wen .vitem &$message_age$& .cindex "message" "age of" @@ -10958,13 +10914,11 @@ being delivered, and is intended mainly for use in filter files. The maximum number of characters of the body that are put into the variable is set by the &%message_body_visible%& configuration option; the default is 500. -.new .oindex "&%message_body_newlines%&" By default, newlines are converted into spaces in &$message_body$&, to make it easier to search for phrases that might be split over a line break. However, this can be disabled by setting &%message_body_newlines%& to be true. Binary zeros are always converted into spaces. -.wen .vitem &$message_body_end$& .cindex "body of message" "expansion variable" @@ -11645,7 +11599,6 @@ This variable is set to &"1"& if a TLS certificate was verified when the message was received, and &"0"& otherwise. .vitem &$tls_cipher$& -.new .vindex "&$tls_cipher$&" When a message is received from a remote host over an encrypted SMTP connection, this variable is set to the cipher suite that was negotiated, for @@ -11660,16 +11613,15 @@ case, &$tls_cipher$& is cleared before any outgoing SMTP connection is made, and then set to the outgoing cipher suite if one is negotiated. See chapter &<>& for details of TLS support and chapter &<>& for details of the &(smtp)& transport. -.wen .vitem &$tls_peerdn$& .vindex "&$tls_peerdn$&" When a message is received from a remote host over an encrypted SMTP connection, and Exim is configured to request a certificate from the client, the value of the Distinguished Name of the certificate is made available in the -&$tls_peerdn$& during subsequent processing. &new("Like &$tls_cipher$&, the +&$tls_peerdn$& during subsequent processing. Like &$tls_cipher$&, the value is retained during message delivery, except during outbound SMTP -deliveries.") +deliveries. .vitem &$tod_bsdinbox$& .vindex "&$tod_bsdinbox$&" @@ -12212,7 +12164,7 @@ listed in more than one group. .row &%disable_ipv6%& "do no IPv6 processing" .row &%keep_malformed%& "for broken files &-- should not happen" .row &%localhost_number%& "for unique message ids in clusters" -.row &new(&%message_body_newlines%&) "retain newlines in &$message_body$&" +.row &%message_body_newlines%& "retain newlines in &$message_body$&" .row &%message_body_visible%& "how much to show in &$message_body$&" .row &%mua_wrapper%& "run in &""MUA wrapper""& mode" .row &%print_topbitchars%& "top-bit characters are printing" @@ -12279,13 +12231,13 @@ listed in more than one group. .section "Data lookups" "SECID101" .table2 -.row &new(&%ibase_servers%&) "InterBase servers" +.row &%ibase_servers%& "InterBase servers" .row &%ldap_default_servers%& "used if no server in query" .row &%ldap_version%& "set protocol version" .row &%lookup_open_max%& "lookup files held open" -.row &new(&%mysql_servers%&) "default MySQL servers" -.row &new(&%oracle_servers%&) "Oracle servers" -.row &new(&%pgsql_servers%&) "default PostgreSQL servers" +.row &%mysql_servers%& "default MySQL servers" +.row &%oracle_servers%& "Oracle servers" +.row &%pgsql_servers%& "default PostgreSQL servers" .row &%sqlite_lock_timeout%& "as it says" .endtable @@ -12328,7 +12280,7 @@ listed in more than one group. .row &%check_spool_space%& "before accepting a message" .row &%deliver_queue_load_max%& "no queue deliveries if load high" .row &%queue_only_load%& "queue incoming if load high" -.row &new(&%queue_only_load_latch%&) "don't re-evaluate load for each message" +.row &%queue_only_load_latch%& "don't re-evaluate load for each message" .row &%queue_run_max%& "maximum simultaneous queue runners" .row &%remote_max_parallel%& "parallel SMTP delivery per message" .row &%smtp_accept_max%& "simultaneous incoming connections" @@ -12563,7 +12515,7 @@ See also the &'Policy controls'& section above. .row &%queue_only%& "no immediate delivery at all" .row &%queue_only_file%& "no immediate delivery if file exists" .row &%queue_only_load%& "no immediate delivery if load is high" -.row &new(&%queue_only_load_latch%&) "don't re-evaluate load for each message" +.row &%queue_only_load_latch%& "don't re-evaluate load for each message" .row &%queue_only_override%& "allow command line to override" .row &%queue_run_in_order%& "order of arrival" .row &%queue_run_max%& "of simultaneous queue runners" @@ -13144,7 +13096,7 @@ dns_check_names_pattern = \ (?i)^(?>(?(1)\.|())[^\W_](?>[a-z0-9/-]*[^\W_])?)+$ .endd which permits only letters, digits, slashes, and hyphens in components, but -they must start and end with a letter or digit. &new(Slashes) are not, in fact, +they must start and end with a letter or digit. Slashes are not, in fact, permitted in host names, but they are found in certain NS records (which can be accessed in Exim by using a &%dnsdb%& lookup). If you set &%allow_utf8_domains%&, you must modify this pattern, or set the option to an @@ -13628,13 +13580,11 @@ chapter &<>&, which contains a discussion about local network interfaces and recognizing the local host. -.new .option ibase_servers main "string list" unset .cindex "InterBase" "server list" This option provides a list of InterBase servers and associated connection data, to be used in conjunction with &(ibase)& lookups (see section &<>&). The option is available only if Exim has been built with InterBase support. -.wen @@ -13888,7 +13838,6 @@ this option is set greater than zero, any attempt to call &[getpwnam()]& with an argument that is longer behaves as if &[getpwnam()]& failed. -.new .option message_body_newlines main bool false .cindex "message body" "newlines in variables" .cindex "newline" "in message body variables" @@ -13897,7 +13846,6 @@ an argument that is longer behaves as if &[getpwnam()]& failed. By default, newlines in the message body are replaced by spaces when setting the &$message_body$& and &$message_body_end$& expansion variables. If this option is set true, this no longer happens. -.wen .option message_body_visible main integer 500 @@ -14234,7 +14182,6 @@ causes Exim to behave as if &%queue_smtp_domains%& were set to &"*"& whenever .option queue_only_load main fixed-point unset -.new .cindex "load average" .cindex "queueing incoming messages" .cindex "message" "queueing by load" @@ -14244,7 +14191,6 @@ happens during local or remote SMTP input, all subsequent messages received on the same SMTP connection are queued by default, whatever happens to the load in the meantime, but this can be changed by setting &%queue_only_load_latch%& false. -.wen Deliveries will subsequently be performed by queue runner processes. This option has no effect on ancient operating systems on which Exim cannot @@ -14252,7 +14198,6 @@ determine the load average. See also &%deliver_queue_load_max%& and &%smtp_load_reserve%&. -.new .option queue_only_load_latch main boolean true .cindex "load average" "re-evaluating per message" When this option is true (the default), once one message has been queued @@ -14265,7 +14210,6 @@ circumstances such as very long-lived connections from scanning appliances where this is not the best strategy. In such cases, &%queue_only_load_latch%& should be set false. This causes the value of the load average to be re-evaluated for each message. -.wen .option queue_only_override main boolean true @@ -14628,7 +14572,6 @@ doing this processing, it cannot accept any other incoming connections. .option smtp_accept_queue main integer 0 -.new .cindex "SMTP" "incoming connection count" .cindex "queueing incoming messages" .cindex "message" "queueing by SMTP connection count" @@ -14638,7 +14581,6 @@ on the queue; no delivery processes are started automatically. The count is fixed at the start of an SMTP connection. It cannot be updated in the subprocess that receives messages, and so the queueing or not queueing applies to all messages received in the same connection. -.wen A value of zero implies no limit, and clearly any non-zero value is useful only if it is less than the &%smtp_accept_max%& value (unless that is zero). See @@ -15295,7 +15237,6 @@ certificates from clients. The expected certificates are defined by either &%tls_verify_hosts%& or &%tls_try_verify_hosts%& is set and &%tls_verify_certificates%& is not set. -.new Any client that matches &%tls_verify_hosts%& is constrained by &%tls_verify_certificates%&. When the client initiates a TLS session, it must present one of the listed certificates. If it does not, the connection is @@ -15303,7 +15244,6 @@ aborted. &*Warning*&: Including a host in &%tls_verify_hosts%& does not require the host to use TLS. It can still send SMTP commands through unencrypted connections. Forcing a client to use TLS has to be done separately using an ACL to reject inappropriate commands when the connection is not encrypted. -.wen A weaker form of checking is provided by &%tls_try_verify_hosts%&. If a client matches this option (but not &%tls_verify_hosts%&), Exim requests a @@ -15954,14 +15894,12 @@ real_localuser: check_local_user transport = local_delivery .endd -.new For security, it would probably be a good idea to restrict the use of this router to locally-generated messages, using a condition such as this: .code condition = ${if match {$sender_host_address}\ {\N^(|127\.0\.0\.1)$\N}} .endd -.wen If both &%local_part_prefix%& and &%local_part_suffix%& are set for a router, both conditions must be met if not optional. Care must be taken if wildcards @@ -16071,7 +16009,6 @@ applies to all of them. .option pass_router routers string unset -.new .cindex "router" "go to after &""pass""&" Routers that recognize the generic &%self%& option (&(dnslookup)&, &(ipliteral)&, and &(manualroute)&) are able to return &"pass"&, forcing @@ -16082,7 +16019,6 @@ of another router. However (unlike &%redirect_router%&) the named router must be below the current router, to avoid loops. Note that this option applies only to the special case of &"pass"&. It does not apply when a router returns &"decline"& because it cannot handle an address. -.wen @@ -18503,14 +18439,12 @@ real_localuser: local_part_prefix = real- transport = local_delivery .endd -.new For security, it would probably be a good idea to restrict the use of this router to locally-generated messages, using a condition such as this: .code condition = ${if match {$sender_host_address}\ {\N^(|127\.0\.0\.1)$\N}} .endd -.wen .option syntax_errors_text redirect string&!! unset @@ -19048,11 +18982,9 @@ filter itself, and the original process that reads the result and delivers it are all run in parallel, like a shell pipeline. The filter can perform any transformations it likes, but of course should take -care not to break RFC 2822 syntax. A demonstration Perl script is provided in -&_util/transport-filter.pl_&; this makes a few arbitrary modifications just to -show the possibilities. Exim does not check the result, except to test for a -final newline when SMTP is in use. All messages transmitted over SMTP must end -with a newline, so Exim supplies one if it is missing. +care not to break RFC 2822 syntax. Exim does not check the result, except to +test for a final newline when SMTP is in use. All messages transmitted over +SMTP must end with a newline, so Exim supplies one if it is missing. .cindex "content scanning" "per user" A transport filter can be used to provide content-scanning on a per-user basis @@ -19805,10 +19737,8 @@ in which case it is: message_prefix = "From ${if def:return_path{$return_path}\ {MAILER-DAEMON}} $tod_bsdinbox\n" .endd -.new &*Note:*& If you set &%use_crlf%& true, you must change any occurrences of &`\n`& to &`\r\n`& in &%message_prefix%&. -.wen .option message_suffix appendfile string&!! "see below" The string specified here is expanded and output at the end of every message. @@ -19818,10 +19748,8 @@ setting .code message_suffix = .endd -.new &*Note:*& If you set &%use_crlf%& true, you must change any occurrences of &`\n`& to &`\r\n`& in &%message_suffix%&. -.wen .option mode appendfile "octal integer" 0600 If the output file is created, it is given this mode. If it already exists and @@ -20003,14 +19931,12 @@ This option causes lines to be terminated with the two-character CRLF sequence of batched SMTP, the byte sequence written to the file is then an exact image of what would be sent down a real SMTP connection. -.new &*Note:*& The contents of the &%message_prefix%& and &%message_suffix%& options (which are used to supply the traditional &"From&~"& and blank line separators in Berkeley-style mailboxes) are written verbatim, so must contain their own carriage return characters if these are needed. In cases where these options have non-empty defaults, the values end with a single linefeed, so they must be changed to end with &`\r\n`& if &%use_crlf%& is set. -.wen .option use_fcntl_lock appendfile boolean "see below" @@ -20701,8 +20627,8 @@ delivers the message to it using the LMTP protocol. .option timeout lmtp time 5m The transport is aborted if the created process or Unix domain socket does not -respond to LMTP commands or message input within this timeout. &new("Delivery -is deferred, and will be tried again later.") Here is an example of a typical +respond to LMTP commands or message input within this timeout. Delivery +is deferred, and will be tried again later. Here is an example of a typical LMTP transport: .code lmtp: @@ -21058,10 +20984,8 @@ setting .code message_prefix = .endd -.new &*Note:*& If you set &%use_crlf%& true, you must change any occurrences of &`\n`& to &`\r\n`& in &%message_prefix%&. -.wen .option message_suffix pipe string&!! "see below" @@ -21071,10 +20995,8 @@ The suffix can be suppressed by setting .code message_suffix = .endd -.new &*Note:*& If you set &%use_crlf%& true, you must change any occurrences of &`\n`& to &`\r\n`& in &%message_suffix%&. -.wen .option path pipe string "see below" @@ -21184,13 +21106,11 @@ This option causes lines to be terminated with the two-character CRLF sequence of batched SMTP, the byte sequence written to the pipe is then an exact image of what would be sent down a real SMTP connection. -.new The contents of the &%message_prefix%& and &%message_suffix%& options are written verbatim, so must contain their own carriage return characters if these are needed. When &%use_bsmtp%& is not set, the default values for both &%message_prefix%& and &%message_suffix%& end with a single linefeed, so their values must be changed to end with &`\r\n`& if &%use_crlf%& is set. -.wen .option use_shell pipe boolean false @@ -21337,7 +21257,6 @@ that are in force when the &%helo_data%&, &%hosts_try_auth%&, &%interface%&, &%serialize_hosts%&, and the various TLS options are expanded. -.new .section "Use of $tls_cipher and $tls_peerdn" "usecippeer" .vindex &$tls_cipher$& .vindex &$tls_peerdn$& @@ -21349,7 +21268,6 @@ variables are emptied. If TLS is subsequently started, they are set to the appropriate values for the outgoing connection, and these are the values that are in force when any authenticators are run and when the &%authenticated_sender%& option is expanded. -.wen .section "Private options for smtp" "SECID146" @@ -21386,12 +21304,10 @@ forced to fail, the option is ignored. Other expansion failures cause delivery to be deferred. If the result of expansion is an empty string, that is also ignored. -.new The expansion happens after the outgoing connection has been made and TLS started, if required. This means that the &$host$&, &$host_address$&, &$tls_cipher$&, and &$tls_peerdn$& variables are set according to the particular connection. -.wen If the SMTP session is not authenticated, the expansion of &%authenticated_sender%& still happens (and can cause the delivery to be @@ -21715,8 +21631,8 @@ unauthenticated. See also &%hosts_require_auth%&, and chapter .vindex "&$host$&" .vindex "&$host_address$&" This option specifies which interface to bind to when making an outgoing SMTP -call. &new("The value is an IP address, not an interface name such as -&`eth0`&.") Do not confuse this with the interface address that was used when a +call. The value is an IP address, not an interface name such as +&`eth0`&. Do not confuse this with the interface address that was used when a message was received, which is in &$received_ip_address$&, formerly known as &$interface_address$&. The name was changed to minimize confusion with the outgoing interface address. There is no variable that contains an outgoing @@ -22479,7 +22395,6 @@ can be done on the rewritten addresses. .chapter "Retry configuration" "CHAPretry" .scindex IIDretconf1 "retry" "configuration, description of" .scindex IIDregconf2 "configuration file" "retry section" -.new The &"retry"& section of the runtime configuration file contains a list of retry rules that control how often Exim tries to deliver messages that cannot be delivered at the first attempt. If there are no retry rules (the section is @@ -22488,7 +22403,6 @@ errors are treated as permanent. The default configuration contains a single, general-purpose retry rule (see section &<>&). The &%-brt%& command line option can be used to test which retry rule will be used for a given address, domain and error. -.wen The most common cause of retries is temporary failure to deliver to a remote host because the host is down, or inaccessible because of a network problem. @@ -23134,7 +23048,6 @@ in Exim. .cindex "authentication" "generic options" .cindex "options" "generic; for authenticators" -.new .option client_condition authenticators string&!! unset When Exim is authenticating as a client, it skips any authenticator whose &%client_condition%& expansion yields &"0"&, &"no"&, or &"false"&. This can be @@ -23146,7 +23059,6 @@ client_condition = ${if !eq{$tls_cipher}{}} (Older documentation incorrectly states that &$tls_cipher$& contains the cipher used for incoming messages. In fact, during SMTP delivery, it contains the cipher used for the delivery.) -.wen .option driver authenticators string unset @@ -23634,17 +23546,20 @@ login: driver = plaintext public_name = LOGIN server_prompts = Username:: : Password:: - server_condition = ${if ldapauth \ - {user="cn=${quote_ldap_dn:$auth1},ou=people,o=example.org" \ - pass=${quote:$auth2} \ - ldap://ldap.example.org/}} + server_condition = ${if and{{ + !eq{}{$auth1} }{ \ + ldapauth{user="cn=${quote_ldap_dn:$auth1},ou=people,o=example.org" \ + pass=${quote:$auth2} \ + ldap://ldap.example.org/} }} } server_set_id = uid=$auth1,ou=people,o=example.org .endd -Note the use of the &%quote_ldap_dn%& operator to correctly quote the DN for -authentication. However, the basic &%quote%& operator, rather than any of the -LDAP quoting operators, is the correct one to use for the password, because -quoting is needed only to make the password conform to the Exim syntax. At the -LDAP level, the password is an uninterpreted string. +We have to check that the username is not empty before using it, because LDAP +does not permit empty DN components. We must also use the &%quote_ldap_dn%& +operator to correctly quote the DN for authentication. However, the basic +&%quote%& operator, rather than any of the LDAP quoting operators, is the +correct one to use for the password, because quoting is needed only to make +the password conform to the Exim syntax. At the LDAP level, the password is an +uninterpreted string. @@ -23906,7 +23821,7 @@ sasl_cram_md5: sasl_plain: driver = cyrus_sasl public_name = PLAIN - server_set_id = $auth1 + server_set_id = $auth2 .endd Cyrus SASL does implement the LOGIN authentication method, even though it is not a standard method. It is disabled by default in the source distribution, @@ -23939,7 +23854,7 @@ dovecot_plain: driver = dovecot public_name = PLAIN server_socket = /var/run/dovecot/auth-client - server_set_id = $auth1 + server_set_id = $auth2 dovecot_ntlm: driver = dovecot @@ -24164,11 +24079,11 @@ sections &<>& and &<>&. .section "GnuTLS parameter computation" "SECID181" -GnuTLS uses RSA and D-H parameters that may take a substantial amount of time +GnuTLS uses D-H parameters that may take a substantial amount of time to compute. It is unreasonable to re-compute them for every TLS session. Therefore, Exim keeps this data in a file in its spool directory, called &_gnutls-params_&. The file is owned by the Exim user and is readable only by -its owner. Every Exim process that start up GnuTLS reads the RSA and D-H +its owner. Every Exim process that start up GnuTLS reads the D-H parameters from this file. If the file does not exist, the first Exim process that needs it computes the data and writes it to a temporary file which is renamed once it is complete. It does not matter if several Exim processes do @@ -24413,17 +24328,15 @@ incoming message (by default &-- you can, of course, change this), and it is also included in the log line that records a message's arrival, keyed by &"X="&, unless the &%tls_cipher%& log selector is turned off. The &%encrypted%& condition can be used to test for specific cipher suites in ACLs. -&new("(For outgoing SMTP deliveries, &$tls_cipher$& is reset &-- see section -&<>&.)") +(For outgoing SMTP deliveries, &$tls_cipher$& is reset &-- see section +&<>&.) -.new Once TLS has been established, the ACLs that run for subsequent SMTP commands can check the name of the cipher suite and vary their actions accordingly. The cipher suite names vary, depending on which TLS library is being used. For example, OpenSSL uses the name DES-CBC3-SHA for the cipher suite which in other contexts is known as TLS_RSA_WITH_3DES_EDE_CBC_SHA. Check the OpenSSL or GnuTLS documentation for more details. -.wen .section "Requesting and verifying client certificates" "SECID183" @@ -24549,7 +24462,6 @@ All the TLS options in the &(smtp)& transport are expanded before use, with which the client is connected. Forced failure of an expansion causes Exim to behave as if the relevant option were unset. -.new .vindex &$tls_cipher$& .vindex &$tls_peerdn$& Before an SMTP connection is established, the &$tls_cipher$& and &$tls_peerdn$& @@ -24557,7 +24469,6 @@ variables are emptied. (Until the first connection, they contain the values that were set when the message was received.) If STARTTLS is subsequently successfully obeyed, these variables are set to the relevant values for the outgoing connection. -.wen @@ -24738,7 +24649,7 @@ options in the main part of the configuration. These options are: .irow &%acl_smtp_mail%& "ACL for MAIL" .irow &%acl_smtp_mailauth%& "ACL for the AUTH parameter of MAIL" .irow &%acl_smtp_mime%& "ACL for content-scanning MIME parts" -.irow &new(&%acl_smtp_notquit%&) "ACL for non-QUIT terminations" +.irow &%acl_smtp_notquit%& "ACL for non-QUIT terminations" .irow &%acl_smtp_predata%& "ACL at start of DATA command" .irow &%acl_smtp_quit%& "ACL for QUIT" .irow &%acl_smtp_rcpt%& "ACL for RCPT" @@ -24879,9 +24790,9 @@ connection is closed. In these special cases, the QUIT ACL does not run. -.new .section "The not-QUIT ACL" "SECTNOTQUITACL" -The not-QUIT ACL, specified by &%smtp_notquit_acl%&, is run in most cases when +.vindex &$acl_smtp_notquit$& +The not-QUIT ACL, specified by &%acl_smtp_notquit%&, is run in most cases when an SMTP session ends without sending QUIT. However, when Exim itself is is bad trouble, such as being unable to write to its log files, this ACL is not run, because it might try to do things (such as write to log files) that make the @@ -24914,7 +24825,6 @@ With the exception of the &`acl-drop`& case, the default message can be overridden by the &%message%& modifier in the not-QUIT ACL. In the case of a &%drop%& verb in another ACL, it is the message from the other ACL that is used. -.wen .section "Finding an ACL to use" "SECID195" @@ -25194,7 +25104,7 @@ the sending entity receives a &"success"& response. However, &%discard%& causes recipients to be discarded. If it is used in an ACL for RCPT, just the one recipient is discarded; if used for MAIL, DATA or in the non-SMTP ACL, all the message's recipients are discarded. Recipients that are discarded before DATA -do not appear in the log line when the &%log_recipients%& log selector is set. +do not appear in the log line when the &%received_recipients%& log selector is set. If the &%log_message%& modifier is set when &%discard%& operates, its contents are added to the line that is automatically written to the log. @@ -25584,7 +25494,8 @@ ACL fragment writes no logging information when access is denied: &` log_reject_target =`& .endd This modifier can be used in SMTP and non-SMTP ACLs. It applies to both -permanent and temporary rejections. +permanent and temporary rejections. Its effect lasts for the rest of the +current ACL. .vitem &*logwrite*&&~=&~<&'text'&> @@ -26430,7 +26341,9 @@ verified as a sender. .cindex "&ACL;" "testing a DNS list" In its simplest form, the &%dnslists%& condition tests whether the calling host is on at least one of a number of DNS lists by looking up the inverted IP -address in one or more DNS domains. For example, if the calling host's IP +address in one or more DNS domains. (Note that DNS list domains are not mail +domains, so the &`+`& syntax for named lists doesn't work - it is used for +special options instead.) For example, if the calling host's IP address is 192.168.62.43, and the ACL statement is .code deny dnslists = blackholes.mail-abuse.org : \ @@ -26591,10 +26504,8 @@ dnslists = sbl.spahmaus.org/<|192.168.2.3|192.168.5.6|... Thus, this example checks whether or not the IP addresses of the sender domain's mail servers are on the Spamhaus black list. -.new The key that was used for a successful DNS list lookup is put into the variable &$dnslist_matched$& (see section &<>&). -.wen @@ -26620,7 +26531,6 @@ see section &<>& for details of how they are checked. .section "Variables set from DNS lists" "SECID204" -.new .cindex "expansion" "variables, set from DNS list" .cindex "DNS list" "variables set from" .vindex "&$dnslist_domain$&" @@ -26646,7 +26556,6 @@ deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|... .endd If this condition succeeds, the value in &$dnslist_matched$& might be &`192.168.6.7`& (for example). -.wen If more than one address record is returned by the DNS lookup, all the IP addresses are included in &$dnslist_value$&, separated by commas and spaces. @@ -26926,7 +26835,7 @@ parameter &'m'& is the maximum number of messages that a client is permitted to send in each time interval. It also specifies the number of messages permitted in a fast burst. By increasing both &'m'& and &'p'& but keeping &'m/p'& constant, you can allow a client to send more messages in a burst without -changing its overall sending rate limit. Conversely, if &'m'& and &'p'& are +changing its long-term sending rate limit. Conversely, if &'m'& and &'p'& are both small, messages must be sent at an even rate. There is a script in &_util/ratelimit.pl_& which extracts sending rates from @@ -26935,36 +26844,33 @@ when deploying the &%ratelimit%& ACL condition. The script prints usage instructions when it is run with no arguments. The key is used to look up the data for calculating the client's average -sending rate. This data is stored in a database maintained by Exim in its spool -directory, alongside the retry and other hints databases. The default key is -&$sender_host_address$&, which applies the limit to each client host IP address. +sending rate. This data is stored in Exim's spool directory, alongside the +retry and other hints databases. The default key is &$sender_host_address$&, +which means Exim computes the sending rate of each client host IP address. By changing the key you can change how Exim identifies clients for the purpose of ratelimiting. For example, to limit the sending rate of each authenticated user, independent of the computer they are sending from, set the key to &$authenticated_id$&. You must ensure that the lookup key is meaningful; for example, &$authenticated_id$& is only meaningful if the client has -authenticated, and you can check with the &%authenticated%& ACL condition. +authenticated (which you can check with the &%authenticated%& ACL condition). -.new -If you want to limit the rate at which a recipient receives messages, you can -use the key &`$local_part@$domain`& with the &%per_rcpt%& option (see below) in -a RCPT ACL. -.wen +The lookup key does not have to identify clients: If you want to limit the +rate at which a recipient receives messages, you can use the key +&`$local_part@$domain`& with the &%per_rcpt%& option (see below) in a RCPT +ACL. -Internally, Exim includes the smoothing constant &'p'& and the options in the +Internally, Exim appends the smoothing constant &'p'& and the options onto the lookup key because they alter the meaning of the stored data. This is not true for the limit &'m'&, so you can alter the configured maximum rate and Exim will still remember clients' past behaviour, but if you alter the other ratelimit parameters Exim forgets past behaviour. -.new Each &%ratelimit%& condition can have up to three options. One option specifies what Exim measures the rate of, and the second specifies how Exim handles excessively fast clients. The third option can be &`noupdate`&, to disable updating of the ratelimiting database (see section &<>&). The options are separated by a slash, like the other parameters. They may appear in any order. -.wen .section "Ratelimit options for what is being measured" "ratoptmea" The &%per_conn%& option limits the client's connection rate. @@ -26974,16 +26880,17 @@ the default if none of the &%per_*%& options is specified. The &%per_byte%& option limits the sender's email bandwidth. Note that it is best to use this option in the DATA ACL; if it is used in an earlier ACL it -relies on the SIZE parameter on the MAIL command, which may be inaccurate or -completely missing. You can follow the limit &'m'& in the configuration with K, -M, or G to specify limits in kilobytes, megabytes, or gigabytes, respectively. +relies on the SIZE parameter specified by the client in its MAIL command, +which may be inaccurate or completely missing. You can follow the limit &'m'& +in the configuration with K, M, or G to specify limits in kilobytes, +megabytes, or gigabytes, respectively. The &%per_rcpt%& option causes Exim to limit the rate at which recipients are accepted. To be effective, it would need to be used in either the &%acl_smtp_rcpt%& or the &%acl_not_smtp%& ACL. In the &%acl_smtp_rcpt%& ACL, the number of recipients is incremented by one. In the case of a locally submitted message in the &%acl_not_smtp%& ACL, -the number of recipients incremented is equal to &%$recipients_count%& +the number of recipients is incremented by the &%$recipients_count%& for the entire message. Note that in either case the rate limiting engine will see a message with many recipients as a large high-speed burst. @@ -27002,17 +26909,18 @@ counter-measures (such as rejecting the message) that may be specified by the rest of the ACL. The default mode is leaky, which avoids a sender's over-aggressive retry rate preventing it from getting any email through. -The &%strict%& option means that the client's recorded rate is always updated. -The effect of this is that Exim measures the client's average rate of attempts -to send email, which can be much higher than the maximum &new("it is actually -allowed. If the client is over the limit it may be subjected to -counter-measures in the ACL until it slows down below the maximum rate.") The -smoothing period determines the time it takes for a high sending rate to decay -exponentially to 37% of its peak value, which means that you can work out the -time (the number of smoothing periods) that a client is subjected to -counter-measures after an over-limit burst with this formula: +The &%strict%& option means that the client's recorded rate is always +updated. The effect of this is that Exim measures the client's average rate +of attempts to send email, which can be much higher than the maximum it is +actually allowed. If the client is over the limit it may be subjected to +counter-measures by the ACL until it slows down below the maximum rate. If +the client stops attempting to send email for the time specified in the &'p'& +parameter then its computed rate will decay exponentially to 37% of its peak +value. You can work out the time (the number of smoothing periods) that a +client is subjected to counter-measures after an over-limit burst with this +formula: .code -ln(peakrate/maxrate) + ln(peakrate/maxrate) .endd The &%leaky%& (default) option means that the client's recorded rate is not updated if it is above the limit. The effect of this is that Exim measures the @@ -27064,7 +26972,6 @@ this means that Exim will lose its hints data after a reboot (including retry hints, the callout cache, and ratelimit data). -.new .section "Reading ratelimit data without updating" "rearatdat" .cindex "rate limitint" "reading data without updating" If the &%noupdate%& option is present on a &%ratelimit%& ACL condition, Exim @@ -27093,7 +27000,6 @@ acl_check_mail: In this example, the rate is tested and used to deny access (when it is too high) in the connect ACL, but the actual computation of the remembered rate happens later, on a per-command basis, in another ACL. -.wen @@ -27672,19 +27578,8 @@ the third string (in this case &"1"&), whether or not the cryptographic and timeout checks succeed. The &$prvscheck_result$& variable contains the result of the checks (empty for failure, &"1"& for success). -There are two more issues you must consider when implementing prvs-signing. -Firstly, you need to ensure that prvs-signed addresses are not blocked by your -ACLs. A prvs-signed address contains a slash character, but the default Exim -configuration contains this statement in the RCPT ACL: -.code -deny message = Restricted characters in address - domains = +local_domains - local_parts = ^[.] : ^.*[@%!/|] -.endd -This is a conservative rule that blocks local parts that contain slashes. You -should remove the slash in the last line. - -Secondly, you have to ensure that the routers accept prvs-signed addresses and +There is one more issue you must consider when implementing prvs-signing: +you have to ensure that the routers accept prvs-signed addresses and deliver them correctly. The easiest way to handle this is to use a &(redirect)& router to remove the signature with a configuration along these lines: .code @@ -28123,6 +28018,10 @@ condition defers. &*Warning*&: It is not possible to use the UNIX socket connection method with multiple &%spamd%& servers. +The &%spamd_address%& variable is expanded before use if it starts with +a dollar sign. In this case, the expansion may return a string that is +used as the list so that multiple spamd servers can be the result of an +expansion. .section "Calling SpamAssassin from an Exim ACL" "SECID206" Here is a simple example of the use of the &%spam%& condition in a DATA ACL: @@ -28176,7 +28075,9 @@ for inclusion in log or reject messages. .vitem &$spam_score_int$& The spam score of the message, multiplied by ten, as an integer value. For -example &"34"& or &"305"&. This is useful for numeric comparisons in +example &"34"& or &"305"&. It may appear to disagree with &$spam_score$& +because &$spam_score$& is rounded and &$spam_score_int$& is truncated. +The integer value is useful for numeric comparisons in conditions. This variable is special; its value is saved with the message, and written to Exim's spool file. This means that it can be used during the whole life of the message on your Exim system, in particular, in routers or @@ -28193,14 +28094,15 @@ A multiline text table, containing the full SpamAssassin report for the message. Useful for inclusion in headers or reject messages. .endlist -The &%spam%& condition caches its results. If you call it again with the same -user name, it does not scan again, but rather returns the same values as -before. +The &%spam%& condition caches its results unless expansion in +spamd_address was used. If you call it again with the same user name, it +does not scan again, but rather returns the same values as before. -The &%spam%& condition returns DEFER if there is any error while running the -message through SpamAssassin. If you want to treat DEFER as FAIL (to pass on to -the next ACL statement block), append &`/defer_ok`& to the right-hand side of -the spam condition, like this: +The &%spam%& condition returns DEFER if there is any error while running +the message through SpamAssassin or if the expansion of spamd_address +failed. If you want to treat DEFER as FAIL (to pass on to the next ACL +statement block), append &`/defer_ok`& to the right-hand side of the +spam condition, like this: .code deny message = This message was classified as SPAM spam = joe/defer_ok @@ -28243,7 +28145,7 @@ cases. These ACLs are called (possibly many times) just before the &%acl_smtp_data%& ACL in the case of an SMTP message, or just before the &%acl_not_smtp%& ACL in the case of a non-SMTP message. However, a MIME ACL is called only if the -message contains a &new(&'Content-Type:'&) header line. When a call to a MIME +message contains a &'Content-Type:'& header line. When a call to a MIME ACL does not yield &"accept"&, ACL processing is aborted and the appropriate result code is sent to the client. In the case of an SMTP message, the &%acl_smtp_data%& ACL is not called when this happens. @@ -28796,23 +28698,19 @@ out the values of all the &[local_scan()]& options. .section "Available Exim variables" "SECID208" -.new .cindex "&[local_scan()]& function" "available Exim variables" The header &_local_scan.h_& gives you access to a number of C variables. These are the only ones that are guaranteed to be maintained from release to release. Note, however, that you can obtain the value of any Exim expansion variable, including &$recipients$&, by calling &'expand_string()'&. The exported C variables are as follows: -.wen .vlist .vitem &*int&~body_linecount*& -.new This variable contains the number of lines in the message's body. .vitem &*int&~body_zerocount*& This variable contains the number of binary zero bytes in the message's body. -.wen .vitem &*unsigned&~int&~debug_selector*& This variable is set to zero when no debugging is taking place. Otherwise, it @@ -34393,13 +34291,263 @@ unqualified domain &'foundation'&. .ecindex IIDforspo2 .ecindex IIDforspo3 +. //////////////////////////////////////////////////////////////////////////// +. //////////////////////////////////////////////////////////////////////////// + +.chapter "Support for DKIM (DomainKeys Identified Mail) - RFC4871" "CHID12" &&& + "DKIM Support" +.cindex "DKIM" + +Since version 4.70, DKIM support is compiled into Exim by default. It can be +disabled by setting DISABLE_DKIM=yes in Local/Makefile. + +Exim's DKIM implementation allows to +.olist +Sign outgoing messages: This function is implemented in the SMTP transport. +It can co-exist with all other Exim features, including transport filters. +.next +Verify signatures in incoming messages: This is implemented by an additional +ACL (acl_smtp_dkim), which can be called several times per message, with +different signature context. +.endlist + +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. + +Please note that verification of DKIM signatures in incoming mail is turned +on by default for logging purposes. 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: +.code +2009-09-09 10:22:28 1MlIRf-0003LU-U3 DKIM: d=facebookmail.com s=q1-2009b c=relaxed/relaxed a=rsa-sha1 i=@facebookmail.com t=1252484542 [verification succeeded] +.endd +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 +where you accept mail from relay sources (internal hosts or authenticated +senders). + + +.section "Signing outgoing messages" "SECID513" +.cindex "DKIM" "signing" + +Signing is implemented by setting private options on the SMTP transport. +These options take (expandable) strings as arguments. +.option dkim_domain smtp string&!! unset +MANDATORY +The domain you want to sign with. The result of this expanded +option is put into the &%$dkim_domain%& expansion variable. + +.option dkim_selector smtp string&!! unset +MANDATORY +This sets the key selector string. You can use the &%$dkim_domain%& expansion +variable to look up a matching selector. The result is put in the expansion +variable &%$dkim_selector%& which should be used in the &%dkim_private_key%& +option along with &%$dkim_domain%&. + +.option dkim_private_key smtp string&!! unset +MANDATORY +This sets the private key to use. You can use the &%$dkim_domain%& and +&%$dkim_selector%& expansion variables to determine the private key to use. +The result can either +.ilist +be a valid RSA private key in ASCII armor, including line breaks. +.next +start with a slash, in which case it is treated as a file that contains +the private key. +.next +be "0", "false" or the empty string, in which case the message will not +be signed. This case will not result in an error, even if &%dkim_strict%& +is set. +.endlist + +.option dkim_canon smtp string&!! unset +OPTIONAL +This option sets the canonicalization method used when signing a message. +The DKIM RFC currently supports two methods: "simple" and "relaxed". +The option defaults to "relaxed" when unset. Note: the current implementation +only supports using the same canonicalization method for both headers and body. + +.option dkim_strict smtp string&!! unset +OPTIONAL +This option defines how Exim behaves when signing a message that +should be signed fails for some reason. When the expansion evaluates to +either "1" or "true", Exim will defer. Otherwise Exim will send the message +unsigned. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion +variables here. + +.option dkim_sign_headers smtp string&!! unset +OPTIONAL +When set, this option must expand to (or be specified as) a colon-separated +list of header names. Headers with these names will be included in the message +signature. When unspecified, the header names recommended in RFC4871 will be +used. + + +.section "Verifying DKIM signatures in incoming mail" "SECID514" +.cindex "DKIM" "verification" + +Verification of DKIM signatures in incoming email is implemented via the +&%acl_smtp_dkim%& ACL. By default, this ACL is called once for each +syntactically(!) correct signature in the incoming message. + +To evaluate the signature in the ACL a large number of expansion variables +containing the signature status and its details are set up during the +runtime of the ACL. + +Calling the ACL only for existing signatures is not sufficient to build +more advanced policies. For that reason, the global option +&%dkim_verify_signers%&, and a global expansion variable +&%$dkim_signing_domains%& exist. + +The global option &%dkim_verify_signers%& can be set to a colon-separated +list of DKIM domains or identities for which the ACL &%acl_smtp_dkim%& is +called. It is expanded when the message has been received. At this point, +the expansion variable &%$dkim_signing_domains%& already contains a colon- +separated list of signer domains for the message. When &%dkim_verify_signers%& +is not specified in the main configuration, it defaults as: +.code +dkim_verify_signers = $dkim_signing_domains +.endd +This leads to the default behaviour of calling &%acl_smtp_dkim%& for each +DKIM signature in the message. Current DKIM verifiers may want to explicitly +call the ACL for known domains or identities. This would be achieved as follows: +.code +dkim_verify_signers = paypal.com:ebay.com:$dkim_signing_domains +.endd +This would result in &%acl_smtp_dkim%& always being called for "paypal.com" +and "ebay.com", plus all domains that have signatures in the message. You can +also be more creative in constructing your policy. Example: +.code +dkim_verify_signers = $sender_address_domain:$dkim_signing_domains +.endd + +Inside the &%acl_smtp_dkim%&, the following expansion variables are +available (from most to least important): + +.vlist +.vitem &%$dkim_verify_status%& +A string describing the general status of the signature. One of +.ilist +&%none%&: There is no signature in the message for the current domain or +identity. +.next +&%invalid%&: The signature could not be verified due to a processing error. +More detail is available in &%$dkim_verify_reason%&. +.next +&%fail%&: Verification of the signature failed. More detail is +available in &%$dkim_verify_reason%&. +.next +&%pass%&: The signature passed verification. It is valid. +.endlist +.vitem &%$dkim_verify_reason%& +A string giving a litte bit more detail when &%$dkim_verify_status%& is either +"fail" or "invalid". One of +.ilist +&%pubkey_unavailable%& (when &%$dkim_verify_status%&="invalid"): The public +key for the domain could not be retrieved. This may be a temporary problem. +.next +&%pubkey_syntax%& (when &%$dkim_verify_status%&="invalid"): The public key +record for the domain is syntactically invalid. +.next +&%bodyhash_mismatch%& (when &%$dkim_verify_status%&="fail"): The calculated +body hash does not match the one specified in the signature header. This +means that the message body was modified in transit. +.next +&%signature_incorrect%& (when &%$dkim_verify_status%&="fail"): The signature +could not be verified. This may mean that headers were modified, +re-written or otherwise changed in a way which is incompatible with +DKIM verification. It may of course also mean that the signature is forged. +.endlist +.vitem &%$dkim_domain%& +The signing domain. IMPORTANT: This variable is only populated if there is +ab actual signature in the message. It does NOT neccessarily carry the +domain that is currently being evaluated. Please use the &%dkim_signers%& ACL +condition for that. +.vitem &%$dkim_identity%& +The signing identity. IMPORTANT: This variable is only populated if there is +ab actual signature in the message. It does NOT neccessarily carry the +identity that is currently being evaluated. Please use the &%dkim_signers%& ACL +condition for that. +.vitem &%$dkim_selector%& +The key record selector string +.vitem &%$dkim_algo%& +The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'. +.vitem &%$dkim_canon_body%& +The body canonicalization method. One of 'relaxed' or 'simple'. +.vitem &%dkim_canon_headers%& +The header canonicalization method. One of 'relaxed' or 'simple'. +.vitem &%$dkim_copiedheaders%& +A transcript of headers and their values which are included in the signature +(copied from the 'z=' tag of the signature). +.vitem &%$dkim_bodylength%& +The number of signed body bytes. If zero ("0"), the body is unsigned. If no +limit was set by the signer, "9999999999999" is returned. This makes sure +that this variable always expands to an integer value. +.vitem &%$dkim_created%& +UNIX timestamp reflecting the date and time when the signature was created. +When this was not specified by the signer, "0" is returned. +.vitem &%$dkim_expires%& +UNIX timestamp reflecting the date and time when the signer wants the +signature to be treated as "expired". When this was not specified by the +signer, "9999999999999" is returned. This makes it possible to do useful +integer size comparisons against this value. +.vitem &%$dkim_headernames%& +A colon-separated list of names of headers included in the signature. +.vitem &%$dkim_key_testing%& +"1" if the key record has the "testing" flag set, "0" if not. +.vitem &%$dkim_key_nosubdomaining%& +"1" if the key record forbids subdomaining, "0" otherwise. +.vitem &%$dkim_key_srvtype%& +Service type (tag s=) from the key record. Defaults to "*" if not specified +in the key record. +.vitem &%$dkim_key_granularity%& +Key granularity (tag g=) from the key record. Defaults to "*" if not specified +in the key record. +.vitem &%$dkim_key_notes%& +Notes from the key record (tag n=) +.endlist + +In addition, two ACL conditions are provided: + +.vlist +.vitem &%dkim_signers%& +ACL condition that checks a colon-separated list of domains or identities +for a match against the domain or identity that the ACL is currently verifying. +This is typically used to restrict an ACL verb to a group of domains or identities, like: + +.code +# Warn when message apparently from GMail has no signature at all +warn log_message = GMail sender without DKIM signature + sender_domains = gmail.com + dkim_signers = gmail.com + dkim_status = none +.endd + +.vitem &%dkim_status%& +ACL condition that checks a colon-separated list of possible DKIM verification +results agains the actual result of verification. This is typically used +to restrict an ACL verb to a list of verification outcomes, like: + +.code +deny message = Message from Paypal with invalid or missing signature + sender_domains = paypal.com:paypal.de + dkim_signers = paypal.com:paypal.de + dkim_status = none:invalid:fail +.endd + +The possible status keywords are: 'none','invalid','fail' and 'pass'. Please +see the documentation of the &%$dkim_verify_status%& expansion variable above +for more information of what they mean. +.endlist . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.chapter "Adding new drivers or lookup types" "CHID12" &&& +.chapter "Adding new drivers or lookup types" "CHID13" &&& "Adding drivers or lookups" .cindex "adding drivers" .cindex "new drivers, adding"