X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/1e1ddfac79fbcd052f199500a6493c7f79cb8462..4613203eae8d2dae9b877f724c52825850c105b7:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 73624a7bc..464449d24 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -45,14 +45,16 @@ . Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.93" +.set previousversion "4.96" .include ./local_params .set ACL "access control lists (ACLs)" .set I "    " +.set drivernamemax "64" + .macro copyyear -2020 +2022 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -95,6 +97,34 @@ .itable none 0 0 2 $1 left $2 left .endmacro + +. --- A macro for a plain variable, including the .vitem and .vindex +.macro var +.vitem $1 +.vindex $1 +.endmacro + +. --- A macro for a "tainted" marker, done as a one-element table +.macro tmark +.itable none 0 0 1 10pt left +.row &'Tainted'& +.endtable +.endmacro + +. --- A macro for a tainted variable, adding a taint-marker +.macro tvar +.var $1 +.tmark +.endmacro + +. --- A macro for a cmdline option, including a .oindex +. --- 1st arg is the option name, undecorated (we do that here). +. --- 2nd arg, optional, text (decorated as needed) to be appended to the name +.macro cmdopt +.vitem &%$1%&$=2+&~$2+ +.oindex &%$1%& +.endmacro + . --- A macro that generates .row, but puts &I; at the start of the first . --- argument, thus indenting it. Assume a minimum of two arguments, and . --- allow up to four arguments, which is as many as we'll ever need. @@ -117,6 +147,8 @@ . --- style of entry, use .scindex for the start and .ecindex for the end. The . --- first argument of .scindex and the only argument of .ecindex must be the . --- ID that ties them together. +. --- The index entry points to the most-recent chapter head, section or subsection +. --- head, or list-item. .macro cindex && @@ -149,6 +181,9 @@ && .endmacro +. --- The index entry points to the most-recent chapter head, section or subsection +. --- head, or varlist item. + .macro vindex && &&$1&& @@ -161,6 +196,13 @@ .macro index .echo "** Don't use .index; use .cindex or .oindex or .vindex" .endmacro + + +. use this for a concept-index entry for a header line +.macro chindex +.cindex "&'$1'& header line" +.cindex "header lines" $1 +.endmacro . //////////////////////////////////////////////////////////////////////////// @@ -184,142 +226,69 @@ .copyyear - University of Cambridge + The Exim Maintainers .literal off . ///////////////////////////////////////////////////////////////////////////// -. This chunk of literal XML implements index entries of the form "x, see y" and -. "x, see also y". However, the DocBook DTD doesn't allow entries +. These implement index entries of the form "x, see y" and "x, see also y". +. However, the DocBook DTD doesn't allow entries . at the top level, so we have to put the .chapter directive first. . ///////////////////////////////////////////////////////////////////////////// .chapter "Introduction" "CHID1" -.literal xml - - $1, $2, etc. - numerical variables - - - address - rewriting - rewriting - - - Bounce Address Tag Validation - BATV - - - Client SMTP Authorization - CSA - - - CR character - carriage return - - - CRL - certificate revocation list - - - delivery - failure report - bounce message - - - dialup - intermittently connected hosts - - - exiscan - content scanning - - - failover - fallback - - - fallover - fallback - - - filter - Sieve - Sieve filter - - - ident - RFC 1413 - - - LF character - linefeed - - - maximum - limit - - - monitor - Exim monitor - - - no_xxx - entry for xxx - - - NUL - binary zero - - - passwd file - /etc/passwd - - - process id - pid - - - RBL - DNS list - - - redirection - address redirection - - - return path - envelope sender - - - scanning - content scanning - - - SSL - TLS - - - string - expansion - expansion - - - top bit - 8-bit characters - - - variables - expansion, variables - - - zero, binary - binary zero +.macro seeother +.literal xml + + $3 +.arg 5 + $5 +.endarg + <$1>$4 - .literal off +.endmacro + +. NB: for the 4-arg variant the ordering is awkward +.macro see +.seeother see "$1" "$2" "$3" "$4" +.endmacro +.macro seealso +.seeother seealso "$1" "$2" "$3" "$4" +.endmacro + +.see variable "$1, $2, etc." "numerical variables" +.see concept address rewriting rewriting +.see concept "Bounce Address Tag Validation" BATV +.see concept "Client SMTP Authorization" CSA +.see concept "CR character" "carriage return" +.see concept CRL "certificate revocation list" +.seealso concept de-tainting "tainted data" +.see concept delivery "bounce message" "failure report" +.see concept dialup "intermittently connected hosts" +.see concept exiscan "content scanning" +.see concept fallover fallback +.see concept filter "Sieve filter" Sieve +.see concept headers "header lines" +.see concept ident "RFC 1413" +.see concept "LF character" "linefeed" +.seealso concept maximum limit +.see concept monitor "Exim monitor" +.see concept "no_xxx" "entry for xxx" +.see concept NUL "binary zero" +.see concept "passwd file" "/etc/passwd" +.see concept "process id" pid +.see concept RBL "DNS list" +.see concept redirection "address redirection" +.see concept "return path" "envelope sender" +.see concept scanning "content scanning" +.see concept SSL TLS +.see concept string expansion expansion +.see concept "top bit" "8-bit characters" +.see concept variables "expansion, variables" +.see concept "zero, binary" "binary zero" . ///////////////////////////////////////////////////////////////////////////// @@ -743,17 +712,17 @@ the Exim documentation, &"spool"& is always used in the first sense. .chapter "Incorporated code" "CHID2" .cindex "incorporated code" .cindex "regular expressions" "library" -.cindex "PCRE" +.cindex "PCRE2" .cindex "OpenDMARC" 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 to PCRE is no longer shipped with -Exim, so you will need to use the version of PCRE shipped with your system, +Exim monitor using the freely-distributable PCRE2 library, copyright +© University of Cambridge. The source to PCRE2 is not longer shipped with +Exim, so you will need to use the version of PCRE2 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). +&url(https://github.com/PhilipHazel/pcre2/releases). .next .cindex "cdb" "acknowledgment" Support for the cdb (Constant DataBase) lookup method is provided by code @@ -1363,7 +1332,7 @@ The preconditions that are tested for each router are listed below, in the order in which they are tested. The individual configuration options are described in more detail in chapter &<>&. -.ilist +.olist .cindex affix "router precondition" The &%local_part_prefix%& and &%local_part_suffix%& options can specify that the local parts handled by the router may or must have certain prefixes and/or @@ -1394,9 +1363,21 @@ Again, cutthrough delivery counts as a verification. .next Individual routers can be explicitly skipped when running the routers to check an address given in the SMTP EXPN command (see the &%expn%& option). + .next If the &%domains%& option is set, the domain of the address must be in the set of domains that it defines. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using router domains option" +A match verifies the variable &$domain$& (which carries tainted data) +and assigns an untainted value to the &$domain_data$& variable. +Such an untainted value is often needed in the transport. +For specifics of the matching operation and the resulting untainted value, +refer to section &<>&. + +When an untainted value is wanted, use this option +rather than the generic &%condition%& option. + .next .vindex "&$local_part_prefix$&" .vindex "&$local_part_prefix_v$&" @@ -1405,15 +1386,24 @@ of domains that it defines. .vindex "&$local_part_suffix_v$&" .cindex affix "router precondition" If the &%local_parts%& option is set, the local part of the address must be in -the set of local parts that it defines. If &%local_part_prefix%& or +the set of local parts that it defines. +A match verifies the variable &$local_part$& (which carries tainted data) +and assigns an untainted value to the &$local_part_data$& variable. +Such an untainted value is often needed in the transport. +For specifics of the matching operation and the resulting untainted value, +refer to section &<>&. + +When an untainted value is wanted, use this option +rather than the generic &%condition%& option. + +If &%local_part_prefix%& or &%local_part_suffix%& is in use, the prefix or suffix is removed from the local part before this check. If you want to do precondition tests on local parts that include affixes, you can do so by using a &%condition%& option (see below) -.new that uses the variables &$local_part$&, &$local_part_prefix$&, &$local_part_prefix_v$&, &$local_part_suffix$& and &$local_part_suffix_v$& as necessary. -.wen + .next .vindex "&$local_user_uid$&" .vindex "&$local_user_gid$&" @@ -1423,23 +1413,35 @@ an account on the local host. If this check succeeds, the uid and gid of the local user are placed in &$local_user_uid$& and &$local_user_gid$& and the user's home directory is placed in &$home$&; these values can be used in the remaining preconditions. + .next If the &%router_home_directory%& option is set, it is expanded at this point, because it overrides the value of &$home$&. If this expansion were left till later, the value of &$home$& as set by &%check_local_user%& would be used in subsequent tests. Having two different values of &$home$& in the same router could lead to confusion. + .next If the &%senders%& option is set, the envelope sender address must be in the set of addresses that it defines. + .next If the &%require_files%& option is set, the existence or non-existence of specified files is tested. + .next .cindex "customizing" "precondition" If the &%condition%& option is set, it is evaluated and tested. This option uses an expanded string to allow you to set up your own custom preconditions. Expanded strings are described in chapter &<>&. + +Note that while using +this option for address matching technically works, +it does not set any de-tainted values. +Such values are often needed, either for router-specific options or +for transport options. +Using the &%domains%& and &%local_parts%& options is usually the most +convenient way to obtain them. .endlist @@ -1457,7 +1459,7 @@ example, &_.procmailrc_&). .cindex "delivery" "in detail" When a message is to be delivered, the sequence of events is as follows: -.ilist +.olist If a system-wide filter file is specified, the message is passed to it. The filter may add recipients to the message, replace the recipients, discard the message, cause a new message to be generated, or cause the message delivery to @@ -1568,7 +1570,7 @@ as permanent. -.section "Temporary delivery failure" "SECID20" +.subsection "Temporary delivery failure" SECID20 .cindex "delivery" "temporary failure" There are many reasons why a message may not be immediately deliverable to a particular address. Failure to connect to a remote machine (because it, or the @@ -1592,7 +1594,7 @@ one connection. -.section "Permanent delivery failure" "SECID21" +.subsection "Permanent delivery failure" SECID21 .cindex "delivery" "permanent failure" .cindex "bounce message" "when generated" When a message cannot be delivered to some or all of its intended recipients, a @@ -1620,7 +1622,7 @@ of the list. -.section "Failures to deliver bounce messages" "SECID22" +.subsection "Failures to deliver bounce messages" SECID22 .cindex "bounce message" "failure to deliver" If a bounce message (either locally generated or received from a remote host) itself suffers a permanent delivery failure, the message is left in the queue, @@ -1690,20 +1692,20 @@ overridden if necessary. A C99-capable compiler will be required for the build. -.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 package or the PCRE development package for your operating -system. If your system has a normal PCRE installation the Exim build +.section "PCRE2 library" "SECTpcre" +.cindex "PCRE2 library" +Exim no longer has an embedded regular-expression library as the vast majority of +modern systems include PCRE2 as a system library, although you may need to +install the PCRE2 package or the PCRE2 development package for your operating +system. If your system has a normal PCRE2 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 either set the PCRE_LIBS +headers are in an unusual location you will need to either set the PCRE2_LIBS and INCLUDE directives appropriately, -or set PCRE_CONFIG=yes to use the installed &(pcre-config)& command. +or set PCRE2_CONFIG=yes to use the installed &(pcre-config)& command. 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/). -More information on PCRE is available at &url(https://www.pcre.org/). +PCRE2 support then you will need to obtain and build the current PCRE2 +from &url(https://github.com/PhilipHazel/pcre2/releases). +More information on PCRE2 is available at &url(https://www.pcre.org/). .section "DBM libraries" "SECTdb" .cindex "DBM libraries" "discussion of" @@ -1756,9 +1758,11 @@ the traditional &'ndbm'& interface. .next To complicate things further, there are several very different versions of the Berkeley DB package. Version 1.85 was stable for a very long time, releases -2.&'x'& and 3.&'x'& were current for a while, but the latest versions when Exim last revamped support were numbered 4.&'x'&. -Maintenance of some of the earlier releases has ceased. All versions of -Berkeley DB could be obtained from +2.&'x'& and 3.&'x'& were current for a while, +but the latest versions when Exim last revamped support were numbered 5.&'x'&. +Maintenance of some of the earlier releases has ceased, +and Exim no longer supports versions before 3.&'x'&. +All versions of Berkeley DB could be obtained from &url(http://www.sleepycat.com/), which is now a redirect to their new owner's page with far newer versions listed. It is probably wise to plan to move your storage configurations away from @@ -1782,6 +1786,7 @@ USE_DB=yes .endd Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An error is diagnosed if you set more than one of these. +You can set USE_NDBM if needed to override an operating system default. At the lowest level, the build-time configuration sets none of these options, thereby assuming an interface of type (1). However, some operating system @@ -1796,7 +1801,9 @@ in one of these lines: .code DBMLIB = -ldb DBMLIB = -ltdb +DBMLIB = -lgdbm -lgdbm_compat .endd +The last of those was for a Linux having GDBM provide emulated NDBM facilities. Settings like that will work if the DBM library is installed in the standard place. Sometimes it is not, and the library's header file may also not be in the default path. You may need to set INCLUDE to specify where the header @@ -2532,6 +2539,25 @@ use of Exim's filtering capabilities, you should make the document entitled +.section "Running the daemon" SECTdaemonLaunch +The most common command line for launching the Exim daemon looks like +.code +exim -bd -q5m +.endd +This starts a daemon which +.ilist +listens for incoming smtp connections, launching handler processes for +each new one +.next +starts a queue-runner process every five minutes, to inspect queued messages +and run delivery attempts on any that have arrived at their retry time +.endlist +Should a queue run take longer than the time between queue-runner starts, +they will run in parallel. +Numbers of jobs of the various types are subject to policy controls +defined in the configuration. + + .section "Upgrading Exim" "SECID36" .cindex "upgrading Exim" If you are already running Exim on your host, building and installing a new @@ -2645,10 +2671,8 @@ Exim through the local interface (see the &%-bm%& and &%-f%& options below). See the &%untrusted_set_sender%& option for a way of permitting non-trusted users to set envelope senders. -.cindex "&'From:'& header line" -.cindex "&'Sender:'& header line" -.cindex "header lines" "From:" -.cindex "header lines" "Sender:" +.chindex From: +.chindex Sender: For a trusted user, there is never any check on the contents of the &'From:'& header line, and a &'Sender:'& line is never added. Furthermore, any existing &'Sender:'& line in incoming local (non-TCP/IP) messages is not removed. @@ -2711,21 +2735,18 @@ outputs a brief message about itself and exits. .vlist -.vitem &%--%& -.oindex "--" +.cmdopt "--" "--" .cindex "options" "command line; terminating" This is a pseudo-option whose only purpose is to terminate the options and therefore to cause subsequent command line items to be treated as arguments rather than options, even if they begin with hyphens. -.vitem &%--help%& -.oindex "&%--help%&" +.cmdopt --help This option causes Exim to output a few sentences stating what it is. The same output is generated if the Exim binary is called with no options and no arguments. -.vitem &%--version%& -.oindex "&%--version%&" +.cmdopt --version This option is an alias for &%-bV%& and causes version information to be displayed. @@ -2736,15 +2757,14 @@ displayed. These options are used by Sendmail for selecting configuration files and are ignored by Exim. -.vitem &%-B%&<&'type'&> +.cmdopt -B <&'type'&> .oindex "&%-B%&" .cindex "8-bit characters" .cindex "Sendmail compatibility" "8-bit characters" This is a Sendmail option for selecting 7 or 8 bit processing. Exim is 8-bit clean; it ignores this option. -.vitem &%-bd%& -.oindex "&%-bd%&" +.cmdopt -bd .cindex "daemon" .cindex "SMTP" "listener" .cindex "queue runner" @@ -2790,13 +2810,11 @@ of Exim is installed. It is not necessary to do this when other files that are referenced from the configuration (for example, alias files) are changed, because these are reread each time they are used. -.vitem &%-bdf%& -.oindex "&%-bdf%&" +.cmdopt -bdf This option has the same effect as &%-bd%& except that it never disconnects from the controlling terminal, even when no debugging is specified. -.vitem &%-be%& -.oindex "&%-be%&" +.cmdopt -be .cindex "testing" "string expansion" .cindex "expansion" "testing" Run Exim in expansion testing mode. Exim discards its root privilege, to @@ -2828,8 +2846,13 @@ defined and macros will be expanded. Because macros in the config file are often used for secrets, those are only available to admin users. -.vitem &%-bem%&&~<&'filename'&> -.oindex "&%-bem%&" +.new +The word &"set"& at the start of a line, followed by a single space, +is recognised specially as defining a value for a variable. +The syntax is otherwise the same as the ACL modifier &"set ="&. +.wen + +.cmdopt -bem <&'filename'&> .cindex "testing" "string expansion" .cindex "expansion" "testing" This option operates like &%-be%& except that it must be followed by the name @@ -2846,16 +2869,14 @@ recipients are read from the headers in the normal way, and are shown in the line, because further arguments are taken as strings to expand (just like &%-be%&). -.vitem &%-bF%&&~<&'filename'&> -.oindex "&%-bF%&" +.cmdopt -bF <&'filename'&> .cindex "system filter" "testing" .cindex "testing" "system filter" This option is the same as &%-bf%& except that it assumes that the filter being tested is a system filter. The additional commands that are available only in system filters are recognized. -.vitem &%-bf%&&~<&'filename'&> -.oindex "&%-bf%&" +.cmdopt -bf <&'filename'&> .cindex "filter" "testing" .cindex "testing" "filter file" .cindex "forward file" "testing" @@ -2901,37 +2922,32 @@ that would normally be taken from the envelope recipient address of the message can be set by means of additional command line options (see the next four options). -.vitem &%-bfd%&&~<&'domain'&> -.oindex "&%-bfd%&" +.cmdopt -bfd <&'domain'&> .vindex "&$qualify_domain$&" This sets the domain of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is the value of &$qualify_domain$&. -.vitem &%-bfl%&&~<&'local&~part'&> -.oindex "&%-bfl%&" +.cmdopt -bfl <&'local&~part'&> This sets the local part of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is the username of the process that calls Exim. A local part should be specified with any prefix or suffix stripped, because that is how it appears to the filter when a message is actually being delivered. -.vitem &%-bfp%&&~<&'prefix'&> -.oindex "&%-bfp%&" +.cmdopt -bfp <&'prefix'&> .cindex affix "filter testing" This sets the prefix of the local part of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is an empty prefix. -.vitem &%-bfs%&&~<&'suffix'&> -.oindex "&%-bfs%&" +.cmdopt -bfs <&'suffix'&> .cindex affix "filter testing" This sets the suffix of the local part of the recipient address when a filter file is being tested by means of the &%-bf%& option. The default is an empty suffix. -.vitem &%-bh%&&~<&'IP&~address'&> -.oindex "&%-bh%&" +.cmdopt -bh <&'IP&~address'&> .cindex "testing" "incoming SMTP" .cindex "SMTP" "testing incoming" .cindex "testing" "relay control" @@ -2983,14 +2999,12 @@ plain text, cannot easily be tested with &%-bh%&. Instead, you should use a specialized SMTP test program such as &url(https://www.jetmore.org/john/code/swaks/,swaks). -.vitem &%-bhc%&&~<&'IP&~address'&> -.oindex "&%-bhc%&" +.cmdopt -bhc <&'IP&~address'&> This option operates in the same way as &%-bh%&, except that address verification callouts are performed if required. This includes consulting and updating the callout cache database. -.vitem &%-bi%& -.oindex "&%-bi%&" +.cmdopt -bi .cindex "alias file" "building" .cindex "building alias file" .cindex "Sendmail compatibility" "&%-bi%& option" @@ -3009,8 +3023,7 @@ if this is required. If the &%bi_command%& option is not set, calling Exim with &%-bi%& is a no-op. . // Keep :help first, then the rest in alphabetical order -.vitem &%-bI:help%& -.oindex "&%-bI:help%&" +.cmdopt -bI:help .cindex "querying exim information" We shall provide various options starting &`-bI:`& for querying Exim for information. The output of many of these will be intended for machine @@ -3018,14 +3031,12 @@ consumption. This one is not. The &%-bI:help%& option asks Exim for a synopsis of supported options beginning &`-bI:`&. Use of any of these options shall cause Exim to exit after producing the requested output. -.vitem &%-bI:dscp%& -.oindex "&%-bI:dscp%&" +.cmdopt -bI:dscp .cindex "DSCP" "values" This option causes Exim to emit an alphabetically sorted list of all recognised DSCP names. -.vitem &%-bI:sieve%& -.oindex "&%-bI:sieve%&" +.cmdopt -bI:sieve .cindex "Sieve filter" "capabilities" This option causes Exim to emit an alphabetically sorted list of all supported Sieve protocol extensions on stdout, one per line. This is anticipated to be @@ -3034,8 +3045,7 @@ useful for ManageSieve (RFC 5804) implementations, in providing that protocol's compile-time build options, which this option will adapt to, this is the only way to guarantee a correct response. -.vitem &%-bm%& -.oindex "&%-bm%&" +.cmdopt -bm .cindex "local message reception" This option runs an Exim receiving process that accepts an incoming, locally-generated message on the standard input. The recipients are given as the @@ -3080,8 +3090,7 @@ The specified sender is treated as if it were given as the argument to the preference to the address taken from the message. The caller of Exim must be a trusted user for the sender of a message to be set in this way. -.vitem &%-bmalware%&&~<&'filename'&> -.oindex "&%-bmalware%&" +.cmdopt -bmalware <&'filename'&> .cindex "testing", "malware" .cindex "malware scan test" This debugging option causes Exim to scan the given file or directory @@ -3101,8 +3110,7 @@ The &%-bmalware%& option will not be extended to be more generally useful, there are better tools for file-scanning. This option exists to help administrators verify their Exim and AV scanner configuration. -.vitem &%-bnq%& -.oindex "&%-bnq%&" +.cmdopt -bnq .cindex "address qualification, suppressing" By default, Exim automatically qualifies unqualified addresses (those without domains) that appear in messages that are submitted locally (that @@ -3123,8 +3131,7 @@ addresses in the envelope provoke errors (causing message rejection) and unqualified addresses in header lines are left alone. -.vitem &%-bP%& -.oindex "&%-bP%&" +.cmdopt -bP .cindex "configuration options" "extracting" .cindex "options" "configuration &-- extracting" If this option is given with no arguments, it causes the values of all Exim's @@ -3200,8 +3207,7 @@ The output format is one item per line. For the "-bP macro " form, if no such macro is found the exit status will be nonzero. -.vitem &%-bp%& -.oindex "&%-bp%&" +.cmdopt -bp .cindex "queue" "listing messages in" .cindex "listing" "messages in the queue" This option requests a listing of the contents of the mail queue on the @@ -3238,48 +3244,41 @@ displayed with a D only when deliveries for all of its child addresses are complete. -.vitem &%-bpa%& -.oindex "&%-bpa%&" +.cmdopt -bpa This option operates like &%-bp%&, but in addition it shows delivered addresses that were generated from the original top level address(es) in each message by alias or forwarding operations. These addresses are flagged with &"+D"& instead of just &"D"&. -.vitem &%-bpc%& -.oindex "&%-bpc%&" +.cmdopt -bpc .cindex "queue" "count of messages on" This option counts the number of messages in the queue, and writes the total to the standard output. It is restricted to admin users, unless &%queue_list_requires_admin%& is set false. -.vitem &%-bpr%& -.oindex "&%-bpr%&" +.cmdopt -bpr This option operates like &%-bp%&, but the output is not sorted into chronological order of message arrival. This can speed it up when there are lots of messages in the queue, and is particularly useful if the output is going to be post-processed in a way that doesn't need the sorting. -.vitem &%-bpra%& -.oindex "&%-bpra%&" +.cmdopt -bpra This option is a combination of &%-bpr%& and &%-bpa%&. -.vitem &%-bpru%& -.oindex "&%-bpru%&" +.cmdopt -bpru This option is a combination of &%-bpr%& and &%-bpu%&. -.vitem &%-bpu%& -.oindex "&%-bpu%&" +.cmdopt -bpu This option operates like &%-bp%& but shows only undelivered top-level addresses for each message displayed. Addresses generated by aliasing or forwarding are not shown, unless the message was deferred after processing by a router with the &%one_time%& option set. -.vitem &%-brt%& -.oindex "&%-brt%&" +.cmdopt -brt .cindex "testing" "retry configuration" .cindex "retry" "configuration testing" This option is for testing retry rules, and it must be followed by up to three @@ -3303,8 +3302,7 @@ exim -brt haydn.comp.mus.example quota_3d Retry rule: *@haydn.comp.mus.example quota_3d F,1h,15m .endd -.vitem &%-brw%& -.oindex "&%-brw%&" +.cmdopt -brw .cindex "testing" "rewriting" .cindex "rewriting" "testing" This option is for testing address rewriting rules, and it must be followed by @@ -3313,8 +3311,7 @@ complete address with a fully qualified domain. Exim outputs how this address would be rewritten for each possible place it might appear. See chapter &<>& for further details. -.vitem &%-bS%& -.oindex "&%-bS%&" +.cmdopt -bS .cindex "SMTP" "batched incoming" .cindex "batched SMTP input" This option is used for batched SMTP input, which is an alternative interface @@ -3347,8 +3344,7 @@ was detected; otherwise it is 2. More details of input using batched SMTP are given in section &<>&. -.vitem &%-bs%& -.oindex "&%-bs%&" +.cmdopt -bs .cindex "SMTP" "local input" .cindex "local SMTP input" This option causes Exim to accept one or more messages by reading SMTP commands @@ -3376,8 +3372,7 @@ above concerning senders and qualification do not apply. In this situation, Exim behaves in exactly the same way as it does when receiving a message via the listening daemon. -.vitem &%-bt%& -.oindex "&%-bt%&" +.cmdopt -bt .cindex "testing" "addresses" .cindex "address" "testing" This option runs Exim in address testing mode, in which each argument is taken @@ -3422,8 +3417,7 @@ whose behaviour depends on the contents of an incoming message, you cannot test those conditions using &%-bt%&. The &%-N%& option provides a possible way of doing such tests. -.vitem &%-bV%& -.oindex "&%-bV%&" +.cmdopt -bV .cindex "version number of Exim" This option causes Exim to write the current version number, compilation number, and compilation date of the &'exim'& binary to the standard output. @@ -3439,8 +3433,7 @@ alone to discover (for example) all the typos in the configuration; some realistic testing is needed. The &%-bh%& and &%-N%& options provide more dynamic testing facilities. -.vitem &%-bv%& -.oindex "&%-bv%&" +.cmdopt -bv .cindex "verifying address" "using &%-bv%&" .cindex "address" "verification" This option runs Exim in address verification mode, in which each argument is @@ -3490,14 +3483,12 @@ address of a message, you should use the &%-f%& option to set an appropriate sender when running &%-bv%& tests. Without it, the sender is assumed to be the calling user at the default qualifying domain. -.vitem &%-bvs%& -.oindex "&%-bvs%&" +.cmdopt -bvs This option acts like &%-bv%&, but verifies the address as a sender rather than a recipient address. This affects any rewriting and qualification that might happen. -.vitem &%-bw%& -.oindex "&%-bw%&" +.cmdopt -bw .cindex "daemon" .cindex "inetd" .cindex "inetd" "wait mode" @@ -3513,8 +3504,7 @@ each port only when the first connection is received. If the option is given as &%-bw%&<&'time'&> then the time is a timeout, after which the daemon will exit, which should cause inetd to listen once more. -.vitem &%-C%&&~<&'filelist'&> -.oindex "&%-C%&" +.cmdopt -C <&'filelist'&> .cindex "configuration file" "alternate" .cindex "CONFIGURE_FILE" .cindex "alternate configuration file" @@ -3617,41 +3607,41 @@ of debugging data, respectively. For example, &%-d+filter%& adds filter debugging, whereas &%-d-all+filter%& selects only filter debugging. Note that no spaces are allowed in the debug setting. The available debugging categories are: -.display -&`acl `& ACL interpretation -&`auth `& authenticators -&`deliver `& general delivery logic -&`dns `& DNS lookups (see also resolver) -&`dnsbl `& DNS black list (aka RBL) code -&`exec `& arguments for &[execv()]& calls -&`expand `& detailed debugging for string expansions -&`filter `& filter handling -&`hints_lookup `& hints data lookups -&`host_lookup `& all types of name-to-IP address handling -&`ident `& ident lookup -&`interface `& lists of local interfaces -&`lists `& matching things in lists -&`load `& system load checks -&`local_scan `& can be used by &[local_scan()]& (see chapter &&& - &<>&) -&`lookup `& general lookup code and all lookups -&`memory `& memory handling -&`noutf8 `& modifier: avoid UTF-8 line-drawing -&`pid `& modifier: add pid to debug output lines -&`process_info `& setting info for the process log -&`queue_run `& queue runs -&`receive `& general message reception logic -&`resolver `& turn on the DNS resolver's debugging output -&`retry `& retry handling -&`rewrite `& address rewriting -&`route `& address routing -&`timestamp `& modifier: add timestamp to debug output lines -&`tls `& TLS logic -&`transport `& transports -&`uid `& changes of uid/gid and looking up uid/gid -&`verify `& address verification logic -&`all `& almost all of the above (see below), and also &%-v%& -.endd +.itable none 0 0 2 20* left 80* left +.irow acl "ACL interpretation" +.irow auth "authenticators" +.irow deliver "general delivery logic" +.irow dns "DNS lookups (see also resolver)" +.irow dnsbl "DNS black list (aka RBL) code" +.irow exec "arguments for &[execv()]& calls" +.irow expand "detailed debugging for string expansions" +.irow filter "filter handling" +.irow hints_lookup "hints data lookups" +.irow host_lookup "all types of name-to-IP address handling" +.irow ident "ident lookup" +.irow interface "lists of local interfaces" +.irow lists "matching things in lists" +.irow load "system load checks" +.irow local_scan "can be used by &[local_scan()]& (see chapter &&& + &<>&)" +.irow lookup "general lookup code and all lookups" +.irow memory "memory handling" +.irow noutf8 "modifier: avoid UTF-8 line-drawing" +.irow pid "modifier: add pid to debug output lines" +.irow process_info "setting info for the process log" +.irow queue_run "queue runs" +.irow receive "general message reception logic" +.irow resolver "turn on the DNS resolver's debugging output" +.irow retry "retry handling" +.irow rewrite "address rewriting"" +.irow route "address routing" +.irow timestamp "modifier: add timestamp to debug output lines" +.irow tls "TLS logic" +.irow transport "transports" +.irow uid "changes of uid/gid and looking up uid/gid" +.irow verify "address verification logic" +.irow all "almost all of the above (see below), and also &%-v%&" +.endtable The &`all`& option excludes &`memory`& when used as &`+all`&, but includes it for &`-all`&. The reason for this is that &`+all`& is something that people tend to use when generating debug output for Exim maintainers. If &`+memory`& @@ -3694,14 +3684,12 @@ starts a daemon process. In that case, debugging is turned off for the subprocesses that the daemon creates. Thus, it is useful for monitoring the behaviour of the daemon without creating as much output as full debugging does. -.vitem &%-dropcr%& -.oindex "&%-dropcr%&" +.cmdopt -dropcr This is an obsolete option that is now a no-op. It used to affect the way Exim handled CR and LF characters in incoming messages. What happens now is described in section &<>&. -.vitem &%-E%& -.oindex "&%-E%&" +.cmdopt -E .cindex "bounce message" "generating" This option specifies that an incoming message is a locally-generated delivery failure report. It is used internally by Exim when handling delivery failures @@ -3718,8 +3706,7 @@ called by various programs without the leading &%o%& in the option. For example, the &%vacation%& program uses &%-eq%&. Exim treats all options of the form &%-e%&&'x'& as synonymous with the corresponding &%-oe%&&'x'& options. -.vitem &%-F%&&~<&'string'&> -.oindex "&%-F%&" +.cmdopt -F <&'string'&> .cindex "sender" "name" .cindex "name" "of sender" This option sets the sender's full name for use when a locally-generated @@ -3728,8 +3715,7 @@ entry from the password data is used. As users are generally permitted to alter their &'gecos'& entries, no security considerations are involved. White space between &%-F%& and the <&'string'&> is optional. -.vitem &%-f%&&~<&'address'&> -.oindex "&%-f%&" +.cmdopt -f <&'address'&> .cindex "sender" "address" .cindex "address" "sender" .cindex "trusted users" @@ -3773,8 +3759,7 @@ locally-generated message can also be set (when permitted) by an initial &"From&~"& line in the message &-- see the description of &%-bm%& above &-- but if &%-f%& is also present, it overrides &"From&~"&. -.vitem &%-G%& -.oindex "&%-G%&" +.cmdopt -G .cindex "submission fixups, suppressing (command-line)" This option is equivalent to an ACL applying: .code @@ -3787,24 +3772,23 @@ in future. As this affects audit information, the caller must be a trusted user to use this option. -.vitem &%-h%&&~<&'number'&> -.oindex "&%-h%&" +.cmdopt -h <&'number'&> .cindex "Sendmail compatibility" "&%-h%& option ignored" This option is accepted for compatibility with Sendmail, but has no effect. (In Sendmail it overrides the &"hop count"& obtained by counting &'Received:'& headers.) -.vitem &%-i%& -.oindex "&%-i%&" +.cmdopt -i .cindex "Solaris" "&'mail'& command" .cindex "dot" "in incoming non-SMTP message" This option, which has the same effect as &%-oi%&, specifies that a dot on a -line by itself should not terminate an incoming, non-SMTP message. I can find -no documentation for this option in Solaris 2.4 Sendmail, but the &'mailx'& -command in Solaris 2.4 uses it. See also &%-ti%&. +line by itself should not terminate an incoming, non-SMTP message. +Solaris 2.4 (SunOS 5.4) Sendmail has a similar &%-i%& processing option +&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf), +p. 1M-529), and therefore a &%-oi%& command line option, which both are used +by its &'mailx'& command. -.vitem &%-L%&&~<&'tag'&> -.oindex "&%-L%&" +.cmdopt -L <&'tag'&> .cindex "syslog" "process name; set with flag" This option is equivalent to setting &%syslog_processname%& in the config file and setting &%log_file_path%& to &`syslog`&. @@ -3814,8 +3798,7 @@ effect, so early configuration file errors will not honour this flag. The tag should not be longer than 32 characters. -.vitem &%-M%&&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-M%&" +.cmdopt -M <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "forcing delivery" .cindex "delivery" "forcing attempt" .cindex "frozen messages" "forcing delivery" @@ -3837,8 +3820,7 @@ not terminate until all the delivery attempts have finished. No output is produced unless there is a serious error. If you want to see what is happening, use the &%-v%& option as well, or inspect Exim's main log. -.vitem &%-Mar%&&~<&'message&~id'&>&~<&'address'&>&~<&'address'&>&~... -.oindex "&%-Mar%&" +.cmdopt -Mar <&'message&~id'&>&~<&'address'&>&~<&'address'&>&~... .cindex "message" "adding recipients" .cindex "recipient" "adding" This option requests Exim to add the addresses to the list of recipients of the @@ -3847,7 +3829,9 @@ id, and the remaining ones must be email addresses. However, if the message is active (in the middle of a delivery attempt), it is not altered. This option can be used only by an admin user. -.vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&~<&'sequence&~number'&>&&& +.vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&&& + &~<&'host&~IP'&>&&& + &~<&'sequence&~number'&>&&& &~<&'message&~id'&>" .oindex "&%-MC%&" .cindex "SMTP" "passed connection" @@ -3859,46 +3843,50 @@ an existing SMTP connection, which is passed as the standard input. Details are given in chapter &<>&. This must be the final option, and the caller must be root or the Exim user in order to use it. -.vitem &%-MCA%& -.oindex "&%-MCA%&" +.cmdopt -MCA 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 connection to the remote host has been authenticated. -.vitem &%-MCD%& -.oindex "&%-MCD%&" +.cmdopt -MCD 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 &%-MCd%& -.oindex "&%-MCd%&" +.cmdopt -MCd This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-d%& option to pass on an information string on the purpose of the process. -.wen -.vitem &%-MCG%&&~<&'queue&~name'&> -.oindex "&%-MCG%&" +.cmdopt -MCG <&'queue&~name'&> 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 argument. -.vitem &%-MCK%& -.oindex "&%-MCK%&" +.cmdopt -MCK This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that a remote host supports the ESMTP &_CHUNKING_& extension. -.vitem &%-MCP%& -.oindex "&%-MCP%&" +.cmdopt -MCL +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 server to +which Exim is connected advertised limits on numbers of mails, recipients or +recipient domains. +The limits are given by the following three arguments. + +.cmdopt -MCP 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 server to which Exim is connected supports pipelining. -.vitem &%-MCQ%&&~<&'process&~id'&>&~<&'pipe&~fd'&> -.oindex "&%-MCQ%&" +.cmdopt -MCp +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 connection +t a remote server is via a SOCKS proxy, using addresses and ports given by +the following four arguments. + +.cmdopt -MCQ <&'process&~id'&>&~<&'pipe&~fd'&> This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option when the original delivery was started by a queue runner. It passes on the process id of the queue runner, @@ -3906,28 +3894,38 @@ together with the file descriptor number of an open pipe. Closure of the pipe signals the final completion of the sequence of processes that are passing messages through the same SMTP connection. -.vitem &%-MCS%& -.oindex "&%-MCS%&" +.cmdopt -MCq <&'recipient&~address'&>&~<&'size'&> +This option is not intended for use by external callers. It is used internally +by Exim to implement quota checking for local users. + +.cmdopt -MCS This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option, and passes on the fact that the -SMTP SIZE option should be used on messages delivered down the existing +ESMTP SIZE option should be used on messages delivered down the existing connection. -.vitem &%-MCT%& -.oindex "&%-MCT%&" +.cmdopt -MCT This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option, and passes on the fact that the host to which Exim is connected supports TLS encryption. -.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&> -.oindex "&%-MCt%&" +.vitem &%-MCr%&&~<&'SNI'&> &&& + &%-MCs%&&~<&'SNI'&> +.oindex "&%-MCs%&" +.oindex "&%-MCr%&" +These options are not intended for use by external callers. It is used internally +by Exim in conjunction with the &%-MCt%& option, and passes on the fact that +a TLS Server Name Indication was sent as part of the channel establishment. +The argument gives the SNI string. +The "r" variant indicates a DANE-verified connection. + +.cmdopt -MCt <&'IP&~address'&>&~<&'port'&>&~<&'cipher'&> This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option, and passes on the fact that the connection is being proxied by a parent process for handling TLS encryption. The arguments give the local address and port being proxied, and the TLS cipher. -.vitem &%-Mc%&&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-Mc%&" +.cmdopt -Mc <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "hints database" "not overridden by &%-Mc%&" .cindex "delivery" "manually started &-- not forced" This option requests Exim to run a delivery attempt on each message, in turn, @@ -3942,8 +3940,7 @@ If you want to run a specific delivery as if in a queue run, you should use &%-q%& with a message id argument. A distinction between queue run deliveries and other deliveries is made in one or two places. -.vitem &%-Mes%&&~<&'message&~id'&>&~<&'address'&> -.oindex "&%-Mes%&" +.cmdopt -Mes <&'message&~id'&>&~<&'address'&> .cindex "message" "changing sender" .cindex "sender" "changing" This option requests Exim to change the sender address in the message to the @@ -3953,8 +3950,7 @@ be a message id, and the second one an email address. However, if the message is active (in the middle of a delivery attempt), its status is not altered. This option can be used only by an admin user. -.vitem &%-Mf%&&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-Mf%&" +.cmdopt -Mf <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "freezing messages" .cindex "message" "manually freezing" This option requests Exim to mark each listed message as &"frozen"&. This @@ -3964,8 +3960,7 @@ However, if any of the messages are active (in the middle of a delivery attempt), their status is not altered. This option can be used only by an admin user. -.vitem &%-Mg%&&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-Mg%&" +.cmdopt -Mg <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "giving up on messages" .cindex "message" "abandoning delivery attempts" .cindex "delivery" "abandoning further attempts" @@ -3976,8 +3971,7 @@ is sent to the sender, containing the text &"cancelled by administrator"&. Bounce messages are just discarded. This option can be used only by an admin user. -.vitem &%-MG%&&~<&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-MG%&" +.cmdopt -MG <&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~... .cindex queue named .cindex "named queues" "moving messages" .cindex "queue" "moving messages" @@ -3988,16 +3982,14 @@ string to define the default queue. If the messages are not currently located in the default queue, a &%-qG%& option will be required to define the source queue. -.vitem &%-Mmad%&&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-Mmad%&" +.cmdopt -Mmad <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "delivery" "cancelling all" This option requests Exim to mark all the recipient addresses in the messages as already delivered (&"mad"& for &"mark all delivered"&). However, if any message is active (in the middle of a delivery attempt), its status is not altered. This option can be used only by an admin user. -.vitem &%-Mmd%&&~<&'message&~id'&>&~<&'address'&>&~<&'address'&>&~... -.oindex "&%-Mmd%&" +.cmdopt -Mmd <&'message&~id'&>&~<&'address'&>&~<&'address'&>&~... .cindex "delivery" "cancelling by address" .cindex "recipient" "removing" .cindex "removing recipients" @@ -4008,8 +4000,7 @@ addresses in the message in a case-sensitive manner. If the message is active (in the middle of a delivery attempt), its status is not altered. This option can be used only by an admin user. -.vitem &%-Mrm%&&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-Mrm%&" +.cmdopt -Mrm <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "removing messages" .cindex "abandoning mail" .cindex "message" "manually discarding" @@ -4028,8 +4019,7 @@ placed in the queue. . a bounce message. . .wen -.vitem &%-Mset%&&~<&'message&~id'&> -.oindex "&%-Mset%&" +.cmdopt -Mset <&'message&~id'&> .cindex "testing" "string expansion" .cindex "expansion" "testing" This option is useful only in conjunction with &%-be%& (that is, when testing @@ -4040,8 +4030,7 @@ available. This feature is provided to make it easier to test expansions that make use of these variables. However, this option can be used only by an admin user. See also &%-bem%&. -.vitem &%-Mt%&&~<&'message&~id'&>&~<&'message&~id'&>&~... -.oindex "&%-Mt%&" +.cmdopt -Mt <&'message&~id'&>&~<&'message&~id'&>&~... .cindex "thawing messages" .cindex "unfreezing messages" .cindex "frozen messages" "thawing" @@ -4051,43 +4040,38 @@ This option requests Exim to &"thaw"& any of the listed messages that are messages are active, their status is not altered. This option can be used only by an admin user. -.vitem &%-Mvb%&&~<&'message&~id'&> -.oindex "&%-Mvb%&" +.cmdopt -Mvb <&'message&~id'&> .cindex "listing" "message body" .cindex "message" "listing body of" 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. -.vitem &%-Mvc%&&~<&'message&~id'&> -.oindex "&%-Mvc%&" +.cmdopt -Mvc <&'message&~id'&> .cindex "message" "listing in RFC 2822 format" .cindex "listing" "message in RFC 2822 format" 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. -.vitem &%-Mvh%&&~<&'message&~id'&> -.oindex "&%-Mvh%&" +.cmdopt -Mvh <&'message&~id'&> .cindex "listing" "message headers" .cindex "header lines" "listing" .cindex "message" "listing header lines" This option causes the contents of the message headers (-H) spool file to be written to the standard output. This option can be used only by an admin user. -.vitem &%-Mvl%&&~<&'message&~id'&> -.oindex "&%-Mvl%&" +.cmdopt -Mvl <&'message&~id'&> .cindex "listing" "message log" .cindex "message" "listing message log" This option causes the contents of the message log spool file to be written to the standard output. This option can be used only by an admin user. -.vitem &%-m%& -.oindex "&%-m%&" -This is apparently a synonym for &%-om%& that is accepted by Sendmail, so Exim -treats it that way too. +.cmdopt -m +This is a synonym for &%-om%& that is accepted by Sendmail +(&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf) +p. 1M-258), so Exim treats it that way too. -.vitem &%-N%& -.oindex "&%-N%&" +.cmdopt -N .cindex "debugging" "&%-N%& option" .cindex "debugging" "suppressing delivery" This is a debugging option that inhibits delivery of a message at the transport @@ -4106,27 +4090,23 @@ routing problem. Once &%-N%& has been used for a delivery attempt, it sticks to the message, and applies to any subsequent delivery attempts that may happen for that message. -.vitem &%-n%& -.oindex "&%-n%&" +.cmdopt -n This option is interpreted by Sendmail to mean &"no aliasing"&. For normal modes of operation, it is ignored by Exim. When combined with &%-bP%& it makes the output more terse (suppresses option names, environment values and config pretty printing). -.vitem &%-O%&&~<&'data'&> -.oindex "&%-O%&" +.cmdopt -O <&'data'&> This option is interpreted by Sendmail to mean &`set option`&. It is ignored by Exim. -.vitem &%-oA%&&~<&'file&~name'&> -.oindex "&%-oA%&" +.cmdopt -oA <&'file&~name'&> .cindex "Sendmail compatibility" "&%-oA%& option" This option is used by Sendmail in conjunction with &%-bi%& to specify an alternative alias filename. Exim handles &%-bi%& differently; see the description above. -.vitem &%-oB%&&~<&'n'&> -.oindex "&%-oB%&" +.cmdopt -oB <&'n'&> .cindex "SMTP" "passed connection" .cindex "SMTP" "multiple deliveries" .cindex "multiple SMTP deliveries" @@ -4134,8 +4114,7 @@ This is a debugging option which limits the maximum number of messages that can be delivered down one SMTP connection, overriding the value set in any &(smtp)& transport. If <&'n'&> is omitted, the limit is set to 1. -.vitem &%-odb%& -.oindex "&%-odb%&" +.cmdopt -odb .cindex "background delivery" .cindex "delivery" "in the background" This option applies to all modes in which Exim accepts incoming messages, @@ -4154,8 +4133,7 @@ If one of the queueing options in the configuration file overrides it if &%queue_only_override%& is set true, which is the default setting. If &%queue_only_override%& is set false, &%-odb%& has no effect. -.vitem &%-odf%& -.oindex "&%-odf%&" +.cmdopt -odf .cindex "foreground delivery" .cindex "delivery" "in the foreground" This option requests &"foreground"& (synchronous) delivery when Exim has @@ -4176,13 +4154,11 @@ process exits. See chapter &<>& for a way of setting up a restricted configuration that never queues messages. -.vitem &%-odi%& -.oindex "&%-odi%&" +.cmdopt -odi This option is synonymous with &%-odf%&. It is provided for compatibility with Sendmail. -.vitem &%-odq%& -.oindex "&%-odq%&" +.cmdopt -odq .cindex "non-immediate delivery" .cindex "delivery" "suppressing immediate" .cindex "queueing incoming messages" @@ -4195,8 +4171,7 @@ process encounters them. There are several configuration options (such as conditions. This option overrides all of them and also &%-odqs%&. It always forces queueing. -.vitem &%-odqs%& -.oindex "&%-odqs%&" +.cmdopt -odqs .cindex "SMTP" "delaying delivery" .cindex "first pass routing" This option is a hybrid between &%-odb%&/&%-odi%& and &%-odq%&. @@ -4215,8 +4190,7 @@ host can be sent in a single SMTP connection. The &%queue_smtp_domains%& configuration option has the same effect for specific domains. See also the &%-qq%& option. -.vitem &%-oee%& -.oindex "&%-oee%&" +.cmdopt -oee .cindex "error" "reporting" If an error is detected while a non-SMTP message is being received (for example, a malformed address), the error is reported to the sender in a mail @@ -4229,36 +4203,31 @@ exits with a return code of zero. If not, the return code is 2 if the problem is that the original message has no recipients, or 1 for any other error. This is the default &%-oe%&&'x'& option if Exim is called as &'rmail'&. -.vitem &%-oem%& -.oindex "&%-oem%&" +.cmdopt -oem .cindex "error" "reporting" .cindex "return code" "for &%-oem%&" This is the same as &%-oee%&, except that Exim always exits with a non-zero return code, whether or not the error message was successfully sent. This is the default &%-oe%&&'x'& option, unless Exim is called as &'rmail'&. -.vitem &%-oep%& -.oindex "&%-oep%&" +.cmdopt -oep .cindex "error" "reporting" If an error is detected while a non-SMTP message is being received, the error is reported by writing a message to the standard error file (stderr). .cindex "return code" "for &%-oep%&" The return code is 1 for all errors. -.vitem &%-oeq%& -.oindex "&%-oeq%&" +.cmdopt -oeq .cindex "error" "reporting" This option is supported for compatibility with Sendmail, but has the same effect as &%-oep%&. -.vitem &%-oew%& -.oindex "&%-oew%&" +.cmdopt -oew .cindex "error" "reporting" This option is supported for compatibility with Sendmail, but has the same effect as &%-oem%&. -.vitem &%-oi%& -.oindex "&%-oi%&" +.cmdopt -oi .cindex "dot" "in incoming non-SMTP message" This option, which has the same effect as &%-i%&, specifies that a dot on a line by itself should not terminate an incoming, non-SMTP message. Otherwise, a @@ -4266,12 +4235,10 @@ single dot does terminate, though Exim does no special processing for other lines that start with a dot. This option is set by default if Exim is called as &'rmail'&. See also &%-ti%&. -.vitem &%-oitrue%& -.oindex "&%-oitrue%&" +.cmdopt -oitrue This option is treated as synonymous with &%-oi%&. -.vitem &%-oMa%&&~<&'host&~address'&> -.oindex "&%-oMa%&" +.cmdopt -oMa <&'host&~address'&> .cindex "sender" "host address, specifying for local message" A number of options starting with &%-oM%& can be used to set values associated with remote hosts on locally-submitted messages (that is, messages not received @@ -4294,8 +4261,7 @@ port, if present, in &$sender_host_port$&. If both &%-oMa%& and &%-bh%& are present on the command line, the sender host IP address is taken from whichever one is last. -.vitem &%-oMaa%&&~<&'name'&> -.oindex "&%-oMaa%&" +.cmdopt -oMaa <&'name'&> .cindex "authentication" "name, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMaa%& option sets the value of &$sender_host_authenticated$& (the authenticator @@ -4303,8 +4269,7 @@ name). See chapter &<>& for a discussion of SMTP authentication. This option can be used with &%-bh%& and &%-bs%& to set up an authenticated SMTP session without actually using the SMTP AUTH command. -.vitem &%-oMai%&&~<&'string'&> -.oindex "&%-oMai%&" +.cmdopt -oMai <&'string'&> .cindex "authentication" "id, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMai%& option sets the value of &$authenticated_id$& (the id that was authenticated). @@ -4312,8 +4277,7 @@ This overrides the default value (the caller's login id, except with &%-bh%&, where there is no default) for messages from local sources. See chapter &<>& for a discussion of authenticated ids. -.vitem &%-oMas%&&~<&'address'&> -.oindex "&%-oMas%&" +.cmdopt -oMas <&'address'&> .cindex "authentication" "sender, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMas%& option sets the authenticated sender value in &$authenticated_sender$&. It @@ -4323,16 +4287,14 @@ default. For both &%-bh%& and &%-bs%&, an authenticated sender that is specified on a MAIL command overrides this value. See chapter &<>& for a discussion of authenticated senders. -.vitem &%-oMi%&&~<&'interface&~address'&> -.oindex "&%-oMi%&" +.cmdopt -oMi <&'interface&~address'&> .cindex "interface" "address, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMi%& option sets the IP interface address value. A port number may be included, using the same syntax as for &%-oMa%&. The interface address is placed in &$received_ip_address$& and the port number, if present, in &$received_port$&. -.vitem &%-oMm%&&~<&'message&~reference'&> -.oindex "&%-oMm%&" +.cmdopt -oMm <&'message&~reference'&> .cindex "message reference" "message reference, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMm%& option sets the message reference, e.g. message-id, and is logged during @@ -4345,8 +4307,7 @@ The best example of a message reference is when Exim sends a bounce message. The message reference is the message-id of the original message for which Exim is sending the bounce. -.vitem &%-oMr%&&~<&'protocol&~name'&> -.oindex "&%-oMr%&" +.cmdopt -oMr <&'protocol&~name'&> .cindex "protocol, specifying for local message" .vindex "&$received_protocol$&" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMr%& @@ -4358,37 +4319,32 @@ SMTP protocol names (see the description of &$received_protocol$& in section one of those same names. For &%-bS%& (batched SMTP) however, the protocol can be set by &%-oMr%&. Repeated use of this option is not supported. -.vitem &%-oMs%&&~<&'host&~name'&> -.oindex "&%-oMs%&" +.cmdopt -oMs <&'host&~name'&> .cindex "sender" "host name, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMs%& option sets the sender host name in &$sender_host_name$&. When this option is present, Exim does not attempt to look up a host name from an IP address; it uses the name it is given. -.vitem &%-oMt%&&~<&'ident&~string'&> -.oindex "&%-oMt%&" +.cmdopt -oMt <&'ident&~string'&> .cindex "sender" "ident string, specifying for local message" See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMt%& option sets the sender ident value in &$sender_ident$&. The default setting for local callers is the login id of the calling process, except when &%-bh%& is used, when there is no default. -.vitem &%-om%& -.oindex "&%-om%&" +.cmdopt -om .cindex "Sendmail compatibility" "&%-om%& option ignored" In Sendmail, this option means &"me too"&, indicating that the sender of a message should receive a copy of the message if the sender appears in an alias expansion. Exim always does this, so the option does nothing. -.vitem &%-oo%& -.oindex "&%-oo%&" +.cmdopt -oo .cindex "Sendmail compatibility" "&%-oo%& option ignored" This option is ignored. In Sendmail it specifies &"old style headers"&, whatever that means. -.vitem &%-oP%&&~<&'path'&> -.oindex "&%-oP%&" +.cmdopt -oP <&'path'&> .cindex "pid (process id)" "of daemon" .cindex "daemon" "process id (pid)" This option is useful only in conjunction with &%-bd%& or &%-q%& with a time @@ -4397,27 +4353,22 @@ written. When &%-oX%& is used with &%-bd%&, or when &%-q%& with a time is used without &%-bd%&, this is the only way of causing Exim to write a pid file, because in those cases, the normal pid file is not used. -.new -.vitem &%-oPX%& -.oindex "&%-oPX%&" +.cmdopt -oPX .cindex "pid (process id)" "of daemon" .cindex "daemon" "process id (pid)" This option is not intended for general use. The daemon uses it when terminating due to a SIGTEM, possibly in combination with &%-oP%&&~<&'path'&>. It causes the pid file to be removed. -.wen -.vitem &%-or%&&~<&'time'&> -.oindex "&%-or%&" +.cmdopt -or <&'time'&> .cindex "timeout" "for non-SMTP input" This option sets a timeout value for incoming non-SMTP messages. If it is not set, Exim will wait forever for the standard input. The value can also be set by the &%receive_timeout%& option. The format used for specifying times is described in section &<>&. -.vitem &%-os%&&~<&'time'&> -.oindex "&%-os%&" +.cmdopt -os <&'time'&> .cindex "timeout" "for SMTP input" .cindex "SMTP" "input timeout" This option sets a timeout value for incoming SMTP messages. The timeout @@ -4425,12 +4376,10 @@ applies to each SMTP command and block of data. The value can also be set by the &%smtp_receive_timeout%& option; it defaults to 5 minutes. The format used for specifying times is described in section &<>&. -.vitem &%-ov%& -.oindex "&%-ov%&" +.cmdopt -ov This option has exactly the same effect as &%-v%&. -.vitem &%-oX%&&~<&'number&~or&~string'&> -.oindex "&%-oX%&" +.cmdopt -oX <&'number&~or&~string'&> .cindex "TCP/IP" "setting listening ports" .cindex "TCP/IP" "setting listening interfaces" .cindex "port" "receiving TCP/IP" @@ -4440,16 +4389,32 @@ of the syntax, and how it interacts with configuration file options, are given in chapter &<>&. When &%-oX%& is used to start a daemon, no pid file is written unless &%-oP%& is also present to specify a pid filename. -.vitem &%-pd%& -.oindex "&%-pd%&" +.cmdopt -oY +.cindex "daemon notifier socket" +This option controls the creation of an inter-process communications endpoint +by the Exim daemon. +It is only relevant when the &%-bd%& (start listening daemon) option is also +given. +Normally the daemon creates this socket, unless a &%-oX%& and &*no*& &%-oP%& +option is also present. +If this option is given then the socket will not be created. This could be +required if the system is running multiple daemons. + +The socket is currently used for +.ilist +fast ramp-up of queue runner processes +.next +obtaining a current queue size +.endlist + +.cmdopt -pd .cindex "Perl" "starting the interpreter" This option applies when an embedded Perl interpreter is linked with Exim (see chapter &<>&). It overrides the setting of the &%perl_at_start%& option, forcing the starting of the interpreter to be delayed until it is needed. -.vitem &%-ps%& -.oindex "&%-ps%&" +.cmdopt -ps .cindex "Perl" "starting the interpreter" This option applies when an embedded Perl interpreter is linked with Exim (see chapter &<>&). It overrides the setting of the &%perl_at_start%& @@ -4469,8 +4434,7 @@ to embedded Perl. It is therefore impossible to set a protocol value of &`d`& or &`s`& using this option (but that does not seem a real limitation). Repeated use of this option is not supported. -.vitem &%-q%& -.oindex "&%-q%&" +.cmdopt -q .cindex "queue runner" "starting manually" This option is normally restricted to admin users. However, there is a configuration option called &%prod_requires_admin%& which can be set false to @@ -4518,14 +4482,17 @@ appear in the correct order. Each flag is described in a separate item below. .cindex "queue" "routing" .cindex "routing" "whole queue before delivery" .cindex "first pass routing" +.cindex "queue runner" "two phase" An option starting with &%-qq%& requests a two-stage queue run. In the first stage, the queue is scanned as if the &%queue_smtp_domains%& option matched every domain. Addresses are routed, local deliveries happen, but no remote transports are run. -.new Performance will be best if the &%queue_run_in_order%& option is false. -.wen +If that is so and the &%queue_fast_ramp%& option is true then +in the first phase of the run, +once a threshold number of messages are routed for a given host, +a delivery process is forked in parallel with the rest of the scan. .cindex "hints database" "remembering routing" The hints database that remembers which messages are waiting for specific hosts @@ -4683,8 +4650,7 @@ command ETRN is accepted by its ACL (see chapter &<>&), its default effect is to run Exim with the &%-R%& option, but it can be configured to run an arbitrary command instead. -.vitem &%-r%& -.oindex "&%-r%&" +.cmdopt -r This is a documented (for Sendmail) obsolete alternative name for &%-f%&. .vitem &%-S%&<&'rsflags'&>&~<&'string'&> @@ -4696,18 +4662,16 @@ message's sender instead of against the recipients. If &%-R%& is also set, both conditions must be met for a message to be selected. If either of the options has &'f'& or &'ff'& in its flags, the associated action is taken. -.vitem &%-Tqt%&&~<&'times'&> -.oindex "&%-Tqt%&" +.cmdopt -Tqt <&'times'&> This is an option that is exclusively for use by the Exim testing suite. It is not recognized when Exim is run normally. It allows for the setting up of explicit &"queue times"& so that various warning/retry features can be tested. -.vitem &%-t%& -.oindex "&%-t%&" +.cmdopt -t .cindex "recipient" "extracting from header lines" -.cindex "&'Bcc:'& header line" -.cindex "&'Cc:'& header line" -.cindex "&'To:'& header line" +.chindex Bcc: +.chindex Cc: +.chindex To: When Exim is receiving a locally-generated, non-SMTP message on its standard input, the &%-t%& option causes the recipients of the message to be obtained from the &'To:'&, &'Cc:'&, and &'Bcc:'& header lines in the message instead of @@ -4743,13 +4707,11 @@ are often added at the end of the header, and if a message is resent more than once, it is common for the original set of &%Resent-%& headers to be renamed as &%X-Resent-%& when a new set is added. This removes any possible ambiguity. -.vitem &%-ti%& -.oindex "&%-ti%&" +.cmdopt -ti This option is exactly equivalent to &%-t%& &%-i%&. It is provided for compatibility with Sendmail. -.vitem &%-tls-on-connect%& -.oindex "&%-tls-on-connect%&" +.cmdopt -tls-on-connect .cindex "TLS" "use without STARTTLS" .cindex "TLS" "automatic start" This option is available when Exim is compiled with TLS support. It forces all @@ -4758,16 +4720,14 @@ incoming SMTP connections to behave as if the incoming port is listed in the &<>& for further details. -.vitem &%-U%& -.oindex "&%-U%&" +.cmdopt -U .cindex "Sendmail compatibility" "&%-U%& option ignored" Sendmail uses this option for &"initial message submission"&, and its documentation states that in future releases, it may complain about syntactically invalid messages rather than fixing them when this flag is not set. Exim ignores this option. -.vitem &%-v%& -.oindex "&%-v%&" +.cmdopt -v This option causes Exim to write information to the standard error stream, describing what it is doing. In particular, it shows the log lines for receiving and delivering a message, and if an SMTP connection is made, the SMTP @@ -4776,20 +4736,17 @@ the log if the setting of &%log_selector%& discards them. Any relevant selectors are shown with each log line. If none are shown, the logging is unconditional. -.vitem &%-x%& -.oindex "&%-x%&" +.cmdopt -x AIX uses &%-x%& for a private purpose (&"mail from a local mail program has National Language Support extended characters in the body of the mail item"&). It sets &%-x%& when calling the MTA from its &%mail%& command. Exim ignores this option. -.vitem &%-X%&&~<&'logfile'&> -.oindex "&%-X%&" +.cmdopt -X <&'logfile'&> This option is interpreted by Sendmail to cause debug information to be sent to the named file. It is ignored by Exim. -.vitem &%-z%&&~<&'log-line'&> -.oindex "&%-z%&" +.cmdopt -z <&'log-line'&> This option writes its argument to Exim's logfile. Use is restricted to administrators; the intent is for operational notes. Quotes should be used to maintain a multi-word item as a single argument, @@ -5399,8 +5356,8 @@ local_interfaces = 127.0.0.1 : ::::1 contains two IP addresses, the IPv4 address 127.0.0.1 and the IPv6 address ::1. &*Note*&: Although leading and trailing white space is ignored in individual -list items, it is not ignored when parsing the list. The space after the first -colon in the example above is necessary. If it were not there, the list would +list items, it is not ignored when parsing the list. The spaces around the first +colon in the example above are necessary. If they were not there, the list would be interpreted as the two items 127.0.0.1:: and 1. .section "Changing list separators" "SECTlistsepchange" @@ -5859,7 +5816,7 @@ Libraries you use may depend on specific environment settings. This imposes a security risk (e.g. PATH). There are two lists: &%keep_environment%& for the variables to import as they are, and &%add_environment%& for variables we want to set to a fixed value. -Note that TZ is handled separately, by the $%timezone%$ runtime +Note that TZ is handled separately, by the &%timezone%& runtime option and by the TIMEZONE_DEFAULT buildtime option. .code # keep_environment = ^LDAP @@ -5905,13 +5862,13 @@ messages that are submitted by SMTP from local processes using the standard input and output (that is, not using TCP/IP). A number of MUAs operate in this manner. .code -deny message = Restricted characters in address - domains = +local_domains +deny domains = +local_domains local_parts = ^[.] : ^.*[@%!/|] + message = Restricted characters in address -deny message = Restricted characters in address - domains = !+local_domains +deny domains = !+local_domains local_parts = ^[./|] : ^.*[@%!] : ^.*/\\.\\./ + message = Restricted characters in address .endd These statements are concerned with local parts that contain any of the characters &"@"&, &"%"&, &"!"&, &"/"&, &"|"&, or dots in unusual places. @@ -6015,10 +5972,10 @@ require verify = recipient This statement requires the recipient address to be verified; if verification fails, the address is rejected. .code -# deny message = rejected because $sender_host_address \ +# deny dnslists = black.list.example +# message = rejected because $sender_host_address \ # is in a black list at $dnslist_domain\n\ # $dnslist_text -# dnslists = black.list.example # # warn dnslists = black.list.example # add_header = X-Warning: $sender_host_address is in \ @@ -6334,9 +6291,9 @@ smarthost_smtp: # request with your smarthost provider to get things fixed: hosts_require_tls = * tls_verify_hosts = * - # As long as tls_verify_hosts is enabled, this won't matter, but if you - # have to comment it out then this will at least log whether you succeed - # or not: + # As long as tls_verify_hosts is enabled, this this will have no effect, + # but if you have to comment it out then this will at least log whether + # you succeed or not: tls_try_verify_hosts = * # # The SNI name should match the name which we'll expect to verify; @@ -6381,7 +6338,7 @@ All other options are defaulted. .code local_delivery: driver = appendfile - file = /var/mail/$local_part_verified + file = /var/mail/$local_part_data delivery_date_add envelope_to_add return_path_add @@ -6391,13 +6348,11 @@ local_delivery: This &(appendfile)& transport is used for local delivery to user mailboxes in traditional BSD mailbox format. -.new We prefer to avoid using &$local_part$& directly to define the mailbox filename, as it is provided by a potential bad actor. -Instead we use &$local_part_verified$&, +Instead we use &$local_part_data$&, the result of looking up &$local_part$& in the user database (done by using &%check_local_user%& in the the router). -.wen By default &(appendfile)& runs under the uid and gid of the local user, which requires the sticky bit to be set on the &_/var/mail_& @@ -6531,9 +6486,9 @@ Chapter &<>& covers both. .chapter "Regular expressions" "CHAPregexp" .cindex "regular expressions" "library" -.cindex "PCRE" +.cindex "PCRE2" Exim supports the use of regular expressions in many of its options. It -uses the PCRE regular expression library; this provides regular expression +uses the PCRE2 regular expression library; this provides regular expression matching that is compatible with Perl 5. The syntax and semantics of regular expressions is discussed in online Perl manpages, in @@ -6545,10 +6500,10 @@ O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)). . --- to the old URL for now. 2018-09-07. The documentation for the syntax and semantics of the regular expressions that -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 +are supported by PCRE2 is included in the PCRE2 distribution, and no further +description is included here. The PCRE2 functions are called from Exim using +the default option settings (that is, with no PCRE2 options set), except that +the PCRE2_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, @@ -6604,14 +6559,17 @@ cause parts of the string to be replaced by data that is obtained from the lookup. Lookups of this type are conditional expansion items. Different results can be defined for the cases of lookup success and failure. See chapter &<>&, where string expansions are described in detail. -The key for the lookup is specified as part of the string expansion. +The key for the lookup is &*specified*& as part of the string to be expanded. .next Lists of domains, hosts, and email addresses can contain lookup requests as a way of avoiding excessively long linear lists. In this case, the data that is returned by the lookup is often (but not always) discarded; whether the lookup succeeds or fails is what really counts. These kinds of list are described in chapter &<>&. -The key for the lookup is given by the context in which the list is expanded. +Depending on the lookup type (see below) +the key for the lookup may need to be &*specified*& as above +or may be &*implicit*&, +given by the context in which the list is being checked. .endlist String expansions, lists, and lookups interact with each other in such a way @@ -6630,7 +6588,9 @@ Be careful to distinguish between the following two examples: domains = ${lookup{$sender_host_address}lsearch{/some/file}} domains = lsearch;/some/file .endd +.ilist The first uses a string expansion, the result of which must be a domain list. +The key for an expansion-style lookup must be given explicitly. No strings have been specified for a successful or a failing lookup; the defaults in this case are the looked-up data and an empty string, respectively. The expansion takes place before the string is processed as a list, and the @@ -6641,10 +6601,15 @@ file that is searched could contain lines like this: .endd When the lookup succeeds, the result of the expansion is a list of domains (and possibly other types of item that are allowed in domain lists). +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using a lookup expansion"" +The result of the expansion is not tainted. +.next In the second example, the lookup is a single item in a domain list. It causes Exim to use a lookup to see if the domain that is being processed can be found -in the file. The file could contains lines like this: +in the file. +The file could contains lines like this: .code domain1: domain2: @@ -6652,6 +6617,11 @@ domain2: Any data that follows the keys is not relevant when checking that the domain matches the list item. +The key for a list-style lookup is implicit, from the lookup context, if +the lookup is a single-key type (see below). +For query-style lookup types the query must be given explicitly. +.endlist + It is possible, though no doubt confusing, to use both kinds of lookup at once. Consider a file containing lines like this: .code @@ -6661,6 +6631,16 @@ If the value of &$sender_host_address$& is 192.168.5.6, expansion of the first &%domains%& setting above generates the second setting, which therefore causes a second lookup to occur. +The lookup type may optionally be followed by a comma +and a comma-separated list of options. +Each option is a &"name=value"& pair. +Whether an option is meaningful depends on the lookup type. + +All lookups support the option &"cache=no_rd"&. +If this is given then the cache that Exim manages for lookup results +is not checked before doing the lookup. +The result of the lookup is still written to the cache. + The rest of this chapter describes the different lookup types that are available. Any of them can be used in any part of the configuration where a lookup is permitted. @@ -6675,15 +6655,26 @@ Two different types of data lookup are implemented: The &'single-key'& type requires the specification of a file in which to look, and a single key to search for. The key must be a non-empty string for the lookup to succeed. The lookup type determines how the file is searched. -.new .cindex "tainted data" "single-key lookups" -The file string may not be tainted -.wen +The file string may not be tainted. + +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using a single-key lookup" +All single-key lookups support the option &"ret=key"&. +If this is given and the lookup +(either underlying implementation or cached value) +returns data, the result is replaced with a non-tainted +version of the lookup key. + .next .cindex "query-style lookup" "definition of" The &'query-style'& type accepts a generalized database query. No particular key value is assumed by Exim for query-style lookups. You can use whichever Exim variables you need to construct the database query. +.cindex "tainted data" "quoting for lookups" +If tainted data is used in the query then it should be quuted by +using the &*${quote_*&<&'lookup-type'&>&*:*&<&'string'&>&*}*& expansion operator +appropriate for the lookup. .endlist The code for each lookup type is in a separate source file that is included in @@ -6705,11 +6696,11 @@ libraries and header files before building Exim. .cindex "single-key lookup" "list of types" The following single-key lookup types are implemented: -.ilist +.subsection cdb .cindex "cdb" "description of" .cindex "lookup" "cdb" .cindex "binary zero" "in lookup key" -&(cdb)&: The given file is searched as a Constant DataBase file, using the key +The given file is searched as a Constant DataBase file, using the key string without a terminating binary zero. The cdb format is designed for indexed files that are read frequently and never updated, except by total re-creation. As such, it is particularly suitable for large files containing @@ -6725,11 +6716,12 @@ A cdb distribution is not needed in order to build Exim with cdb support, because the code for reading cdb files is included directly in Exim itself. However, no means of building or testing cdb files is provided with Exim, so you need to obtain a cdb distribution in order to do this. -.next + +.subsection dbm .cindex "DBM" "lookup type" .cindex "lookup" "dbm" .cindex "binary zero" "in lookup key" -&(dbm)&: Calls to DBM library functions are used to extract data from the given +Calls to DBM library functions are used to extract data from the given DBM file by looking up the record with the given key. A terminating binary zero is included in the key that is passed to the DBM library. See section &<>& for a discussion of DBM libraries. @@ -6741,25 +6733,27 @@ using Berkeley DB versions 3 or 4, it opens existing databases for reading with the DB_UNKNOWN option. This enables it to handle any of the types of database that the library supports, and can be useful for accessing DBM files created by other applications. (For earlier DB versions, DB_HASH is always used.) -.next + +.subsection dbmjz .cindex "lookup" "dbmjz" .cindex "lookup" "dbm &-- embedded NULs" .cindex "sasldb2" .cindex "dbmjz lookup type" -&(dbmjz)&: This is the same as &(dbm)&, except that the lookup key is +This is the same as &(dbm)&, except that the lookup key is interpreted as an Exim list; the elements of the list are joined together with ASCII NUL characters to form the lookup key. An example usage would be to authenticate incoming SMTP calls using the passwords from Cyrus SASL's &_/etc/sasldb2_& file with the &(gsasl)& authenticator or Exim's own &(cram_md5)& authenticator. -.next + +.subsection dbmnz .cindex "lookup" "dbmnz" .cindex "lookup" "dbm &-- terminating zero" .cindex "binary zero" "in lookup key" .cindex "Courier" .cindex "&_/etc/userdbshadow.dat_&" .cindex "dbmnz lookup type" -&(dbmnz)&: This is the same as &(dbm)&, except that a terminating binary zero +This is the same as &(dbm)&, except that a terminating binary zero is not included in the key that is passed to the DBM library. You may need this if you want to look up data in files that are created by or shared with some other application that does not use terminating zeros. For example, you need to @@ -6767,19 +6761,14 @@ use &(dbmnz)& rather than &(dbm)& if you want to authenticate incoming SMTP 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 + +.subsection dsearch .cindex "lookup" "dsearch" .cindex "dsearch lookup type" -&(dsearch)&: The given file must be an -.new -absolute -.wen -directory path; this is searched for an entry +The given file must be an absolute directory path; this is searched for an entry whose name is the key by calling the &[lstat()]& function. -The key may not -contain any forward slash characters. +The key may not contain any forward slash characters. If &[lstat()]& succeeds then so does the lookup. -.new .cindex "tainted data" "dsearch result" The result is regarded as untainted. @@ -6803,15 +6792,15 @@ ${lookup {passwd} dsearch,filter=file {/etc}} .endd The default matching is for any entry type, including directories and symlinks. -.wen An example of how this lookup can be used to support virtual domains is given in section &<>&. -.next + +.subsection iplsearch .cindex "lookup" "iplsearch" .cindex "iplsearch lookup type" -&(iplsearch)&: The given file is a text file containing keys and data. A key is +The given file is a text file containing keys and data. A key is terminated by a colon or white space or the end of the line. The keys in the file must be IP addresses, or IP addresses with CIDR masks. Keys that involve IPv6 addresses must be enclosed in quotes to prevent the first internal colon @@ -6839,11 +6828,16 @@ the implicit key is the host's IP address rather than its name (see section &*Warning 3*&: Do not use an IPv4-mapped IPv6 address for a key; use the IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this notation before executing the lookup.) -.next + +One option is supported, "ret=full", to request the return of the entire line +rather than omitting the key portion. +Note however that the key portion will have been de-quoted. + +.subsection json .cindex lookup json .cindex json "lookup type" .cindex JSON expansions -&(json)&: The given file is a text file with a JSON structure. +The given file is a text file with a JSON structure. An element of the structure is extracted, defined by the search key. The key is a list of subelement selectors (colon-separated by default but changeable in the usual way) @@ -6853,15 +6847,36 @@ If a selector is numeric, it must apply to a JSON array; the (zero-based) nunbered array element is selected. Otherwise it must apply to a JSON object; the named element is selected. The final resulting element can be a simple JSON type or a JSON object -or array; for the latter two a string-representation os the JSON +or array; for the latter two a string-representation of the JSON is returned. For elements of type string, the returned value is de-quoted. -.next + + +.subsection lmdb +.cindex LMDB +.cindex lookup lmdb +.cindex database lmdb +The given file is an LMDB database. +LMDB is a memory-mapped key-value store, +with API modeled loosely on that of BerkeleyDB. +See &url(https://symas.com/products/lightning-memory-mapped-database/) +for the feature set and operation modes. + +Exim provides read-only access via the LMDB C library. +The library can be obtained from &url(https://github.com/LMDB/lmdb) +or your operating system package repository. +To enable LMDB support in Exim set LOOKUP_LMDB=yes in &_Local/Makefile_&. + +You will need to separately create the LMDB database file, +possibly using the &"mdb_load"& utility. + + +.subsection lsearch .cindex "linear search" .cindex "lookup" "lsearch" .cindex "lsearch lookup type" .cindex "case sensitivity" "in lsearch lookup" -&(lsearch)&: The given file is a text file that is searched linearly for a +The given file is a text file that is searched linearly for a line beginning with the search key, terminated by a colon or white space or the end of the line. The search is case-insensitive; that is, upper and lower case letters are treated as the same. The first occurrence of the key that is found @@ -6891,17 +6906,17 @@ contents (see section &<>&). An optional colon is permitted after quoted keys (exactly as for unquoted keys). There is no special handling of quotes for the data part of an &(lsearch)& line. -.next +.subsection nis .cindex "NIS lookup type" .cindex "lookup" "NIS" .cindex "binary zero" "in lookup key" -&(nis)&: The given file is the name of a NIS map, and a NIS lookup is done with +The given file is the name of a NIS map, and a NIS lookup is done with the given key, without a terminating binary zero. There is a variant called &(nis0)& which does include the terminating binary zero in the key. This is reportedly needed for Sun-style alias files. Exim does not recognize NIS aliases; the full map names must be used. -.next +.subsection (n)wildlsearch .cindex "wildlsearch lookup type" .cindex "lookup" "wildlsearch" .cindex "nwildlsearch lookup type" @@ -6917,32 +6932,29 @@ Like &(lsearch)&, the testing is done case-insensitively. However, keys in the file that are regular expressions can be made case-sensitive by the use of &`(-i)`& within the pattern. The following forms of wildcard are recognized: -. ==== As this is a nested list, any displays it contains must be indented -. ==== as otherwise they are too far to the left. - .olist The string may begin with an asterisk to mean &"ends with"&. For example: .code - *.a.b.c data for anything.a.b.c - *fish data for anythingfish +*.a.b.c data for anything.a.b.c +*fish data for anythingfish .endd .next The string may begin with a circumflex to indicate a regular expression. For example, for &(wildlsearch)&: .code - ^\N\d+\.a\.b\N data for .a.b +^\N\d+\.a\.b\N data for .a.b .endd Note the use of &`\N`& to disable expansion of the contents of the regular expression. If you are using &(nwildlsearch)&, where the keys are not string-expanded, the equivalent entry is: .code - ^\d+\.a\.b data for .a.b +^\d+\.a\.b data for .a.b .endd The case-insensitive flag is set at the start of compiling the regular expression, but it can be turned off by using &`(-i)`& at an appropriate point. For example, to make the entire pattern case-sensitive: .code - ^(?-i)\d+\.a\.b data for .a.b +^(?-i)\d+\.a\.b data for .a.b .endd If the regular expression contains white space or colon characters, you must @@ -6963,7 +6975,7 @@ is used to implement &((n)wildlsearch)& means that the string may begin with a lookup name terminated by a semicolon, and followed by lookup data. For example: .code - cdb;/some/file data for keys that match the file +cdb;/some/file data for keys that match the file .endd The data that is obtained from the nested lookup is discarded. .endlist olist @@ -6976,12 +6988,12 @@ be followed by optional colons. &((n)wildlsearch)& can &'not'& be turned into a DBM or cdb file, because those lookup types support only literal keys. -.next +.subsection spf +.cindex "spf lookup type" .cindex "lookup" "spf" If Exim is built with SPF support, manual lookups can be done -(as opposed to the standard ACL condition method. +(as opposed to the standard ACL condition method). For details see section &<>&. -.endlist ilist .section "Query-style lookup types" "SECTquerystylelookups" @@ -6990,44 +7002,50 @@ For details see section &<>&. The supported query-style lookup types are listed below. Further details about many of them are given in later sections. -.ilist +.subsection dnsdb .cindex "DNS" "as a lookup type" .cindex "lookup" "DNS" -&(dnsdb)&: This does a DNS search for one or more records whose domain names +This does a DNS search for one or more records whose domain names are given in the supplied query. The resulting data is the contents of the records. See section &<>&. -.next + +.subsection ibase .cindex "InterBase lookup type" .cindex "lookup" "InterBase" -&(ibase)&: This does a lookup in an InterBase database. -.next +This does a lookup in an InterBase database. + +.subsection ldap .cindex "LDAP" "lookup type" .cindex "lookup" "LDAP" -&(ldap)&: This does an LDAP lookup using a query in the form of a URL, and +This does an LDAP lookup using a query in the form of a URL, and returns attributes from a single entry. There is a variant called &(ldapm)& that permits values from multiple entries to be returned. A third variant called &(ldapdn)& returns the Distinguished Name of a single entry instead of any attribute values. See section &<>&. -.next + +.subsection mysql .cindex "MySQL" "lookup type" .cindex "lookup" "MySQL" -&(mysql)&: The format of the query is an SQL statement that is passed to a +The format of the query is an SQL statement that is passed to a MySQL database. See section &<>&. -.next + +.subsection nisplus .cindex "NIS+ lookup type" .cindex "lookup" "NIS+" -&(nisplus)&: This does a NIS+ lookup using a query that can specify the name of +This does a NIS+ lookup using a query that can specify the name of the field to be returned. See section &<>&. -.next + +.subsection oracle .cindex "Oracle" "lookup type" .cindex "lookup" "Oracle" -&(oracle)&: The format of the query is an SQL statement that is passed to an +The format of the query is an SQL statement that is passed to an Oracle database. See section &<>&. -.next + +.subsection passwd .cindex "lookup" "passwd" .cindex "passwd lookup type" .cindex "&_/etc/passwd_&" -&(passwd)& is a query-style lookup with queries that are just user names. The +This is a query-style lookup with queries that are just user names. The lookup calls &[getpwnam()]& to interrogate the system password data, and on success, the result string is the same as you would get from an &(lsearch)& lookup on a traditional &_/etc/passwd file_&, though with &`*`& for the @@ -7035,36 +7053,33 @@ password value. For example: .code *:42:42:King Rat:/home/kr:/bin/bash .endd -.next + +.subsection pgsql .cindex "PostgreSQL lookup type" .cindex "lookup" "PostgreSQL" -&(pgsql)&: The format of the query is an SQL statement that is passed to a +The format of the query is an SQL statement that is passed to a PostgreSQL database. See section &<>&. -.next +.subsection redis .cindex "Redis lookup type" .cindex lookup Redis -&(redis)&: The format of the query is either a simple get or simple set, +The format of the query is either a simple get or simple set, passed to a Redis database. See section &<>&. -.next +.subsection sqlite .cindex "sqlite lookup type" .cindex "lookup" "sqlite" -&(sqlite)&: The format of the query is -new -an optional filename -.wen -followed by an SQL statement -that is passed to an SQLite database. See section &<>&. +The format of the query is +an SQL statement that is passed to an SQLite database. See section &<>&. -.next -&(testdb)&: This is a lookup type that is used for testing Exim. It is +.subsection testdb +This is a lookup type that is used for testing Exim. It is not likely to be useful in normal operation. -.next + +.subsection whoson .cindex "whoson lookup type" .cindex "lookup" "whoson" -. --- still http:-only, 2018-09-07 -&(whoson)&: &'Whoson'& (&url(http://whoson.sourceforge.net)) is a protocol that +&'Whoson'& (&url(http://whoson.sourceforge.net)) is a protocol that allows a server to check whether a particular (dynamically allocated) IP address is currently allocated to a known (trusted) user and, optionally, to obtain the identity of the said user. For SMTP servers, &'Whoson'& was popular @@ -7079,7 +7094,6 @@ The query consists of a single IP address. The value returned is the name of the authenticated user, which is stored in the variable &$value$&. However, in this example, the data in &$value$& is not used; the result of the lookup is one of the fixed strings &"yes"& or &"no"&. -.endlist @@ -7258,6 +7272,10 @@ lookups. However, because (apart from the daemon) Exim operates as a collection of independent, short-lived processes, this caching applies only within a single Exim process. There is no inter-process lookup caching facility. +If an option &"cache=no_rd"& is used on the lookup then +the cache is only written to, cached data is not used for the operation +and a real lookup is done. + For single-key lookups, Exim keeps the relevant files open in case there is another lookup that needs them. In some types of configuration this can lead to many files being kept open for messages with many recipients. To avoid hitting @@ -7378,7 +7396,7 @@ specified. ${lookup dnsdb{>:,; soa=a.b.example.com}} .endd -.section "Dnsdb lookup modifiers" "SECTdnsdb_mod" +.subsection "Dnsdb lookup modifiers" SECTdnsdb_mod .cindex "dnsdb modifiers" .cindex "modifiers" "dnsdb" .cindex "options" "dnsdb" @@ -7436,7 +7454,7 @@ The cache entry lifetime is limited to the smallest time-to-live (TTL) value of the set of returned DNS records. -.section "Pseudo dnsdb record types" "SECID66" +.subsection "Pseudo dnsdb record types" SECID66 .cindex "MX record" "in &(dnsdb)& lookup" By default, both the preference value and the host name are returned for each MX record, separated by a space. If you want only host names, you can use @@ -7492,7 +7510,7 @@ ${lookup dnsdb {>; a+=$sender_helo_name}} .endd -.section "Multiple dnsdb lookups" "SECID67" +.subsection "Multiple dnsdb lookups" SECID67 In the previous sections, &(dnsdb)& lookups for a single domain are described. However, you can specify a list of domains or IP addresses in a single &(dnsdb)& lookup. The list is specified in the normal Exim way, with colon as @@ -7557,7 +7575,7 @@ the data returned by a successful lookup is described in the next section. First we explain how LDAP queries are coded. -.section "Format of LDAP queries" "SECTforldaque" +.subsection "Format of LDAP queries" SECTforldaque .cindex "LDAP" "query format" An LDAP query takes the form of a URL as defined in RFC 2255. For example, in the configuration of a &(redirect)& router one might have this setting: @@ -7586,7 +7604,7 @@ methods become optional, only taking effect if not specifically set in &_exim.conf_&. -.section "LDAP quoting" "SECID68" +.subsection "LDAP quoting" SECID68 .cindex "LDAP" "quoting" Two levels of quoting are required in LDAP queries, the first for LDAP itself and the second because the LDAP query is represented as a URL. Furthermore, @@ -7643,7 +7661,7 @@ There are some further comments about quoting in the section on LDAP authentication below. -.section "LDAP connections" "SECID69" +.subsection "LDAP connections" SECID69 .cindex "LDAP" "connections" The connection to an LDAP server may either be over TCP/IP, or, when OpenLDAP is in use, via a Unix domain socket. The example given above does not specify @@ -7717,7 +7735,7 @@ Using &`ldapi`& with no host or path in the query, and no setting of -.section "LDAP authentication and control information" "SECID70" +.subsection "LDAP authentication and control information" SECID70 .cindex "LDAP" "authentication" The LDAP URL syntax provides no way of passing authentication and other control information to the server. To make this possible, the URL in an LDAP query may @@ -7725,16 +7743,16 @@ be preceded by any number of <&'name'&>=<&'value'&> settings, separated by spaces. If a value contains spaces it must be enclosed in double quotes, and when double quotes are used, backslash is interpreted in the usual way inside them. The following names are recognized: -.display -&`DEREFERENCE`& set the dereferencing parameter -&`NETTIME `& set a timeout for a network operation -&`USER `& set the DN, for authenticating the LDAP bind -&`PASS `& set the password, likewise -&`REFERRALS `& set the referrals parameter -&`SERVERS `& set alternate server list for this query only -&`SIZE `& set the limit for the number of entries returned -&`TIME `& set the maximum waiting time for a query -.endd +.itable none 0 0 2 20* left 80* left +.irow DEREFERENCE "set the dereferencing parameter" +.irow NETTIME "set a timeout for a network operation" +.irow USER "set the DN, for authenticating the LDAP bind" +.irow PASS "set the password, likewise" +.irow REFERRALS "set the referrals parameter" +.irow SERVERS "set alternate server list for this query only" +.irow SIZE "set the limit for the number of entries returned" +.irow TIME "set the maximum waiting time for a query" +.endtable The value of the DEREFERENCE parameter must be one of the words &"never"&, &"searching"&, &"finding"&, or &"always"&. The value of the REFERRALS parameter must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP @@ -7811,7 +7829,7 @@ SMTP authentication. See the &%ldapauth%& expansion string condition in chapter -.section "Format of data returned by LDAP" "SECID71" +.subsection "Format of data returned by LDAP" SECID71 .cindex "LDAP" "returned data formats" The &(ldapdn)& lookup type returns the Distinguished Name from a single entry as a sequence of values, for example @@ -7945,7 +7963,7 @@ If the result of the query yields more than one row, it is all concatenated, with a newline between the data for each row. -.section "More about MySQL, PostgreSQL, Oracle, InterBase, and Redis" "SECID72" +.subsection "More about MySQL, PostgreSQL, Oracle, InterBase, and Redis" SECID72 .cindex "MySQL" "lookup type" .cindex "PostgreSQL lookup type" .cindex "lookup" "MySQL" @@ -8015,15 +8033,13 @@ itself are escaped with backslashes. The &%quote_redis%& expansion operator escapes whitespace and backslash characters with a backslash. -.section "Specifying the server in the query" "SECTspeserque" -.new +.subsection "Specifying the server in the query" SECTspeserque For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase), it is possible to specify a list of servers with an individual query. This is done by appending a comma-separated option to the query type: .display -.endd &`,servers=`&&'server1:server2:server3:...'& -.wen +.endd Each item in the list may take one of two forms: .olist If it contains no slashes it is assumed to be just a host name. The appropriate @@ -8057,8 +8073,7 @@ option, you can still update it by a query of this form: ${lookup pgsql,servers=master/db/name/pw {UPDATE ...} } .endd -.new -An older syntax places the servers speciification before the qury, +An older syntax places the servers specification before the query, semicolon separated: .code ${lookup mysql{servers=master; UPDATE ...} } @@ -8066,10 +8081,9 @@ ${lookup mysql{servers=master; UPDATE ...} } The new version avoids potential issues with tainted arguments in the query, for explicit expansion. &*Note*&: server specifications in list-style lookups are still problematic. -.wen -.section "Special MySQL features" "SECID73" +.subsection "Special MySQL features" SECID73 For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%& causes a connection to the server on the local host by means of a Unix domain socket. An alternate socket can be specified in parentheses. @@ -8094,7 +8108,7 @@ anything (for example, setting a field to the value it already has), the result is zero because no rows are affected. -.section "Special PostgreSQL features" "SECID74" +.subsection "Special PostgreSQL features" SECID74 PostgreSQL lookups can also use Unix domain socket connections to the database. This is usually faster and costs less CPU time than a TCP/IP connection. However it can be used only if the mail server runs on the same machine as the @@ -8111,28 +8125,33 @@ If a PostgreSQL query is issued that does not request any data (an insert, update, or delete command), the result of the lookup is the number of rows affected. -.section "More about SQLite" "SECTsqlite" +.subsection "More about SQLite" SECTsqlite .cindex "lookup" "SQLite" .cindex "sqlite lookup type" SQLite is different to the other SQL lookups because a filename is required in addition to the SQL query. An SQLite database is a single file, and there is no daemon as in the other SQL databases. -.new .oindex &%sqlite_dbfile%& -The preferred way of specifying the file is by using the -&%sqlite_dbfile%& option, set to -an absolute path. -.wen +There are two ways of +specifying the file. +The first is is by using the &%sqlite_dbfile%& main option. +The second, which allows separate files for each query, +is to use an option appended, comma-separated, to the &"sqlite"& +lookup type word. The option is the word &"file"&, then an equals, +then the filename. +The filename in this case cannot contain whitespace or open-brace charachters. + A deprecated method is available, prefixing the query with the filename separated by white space. -This means that the path name cannot contain white space. +This means that .cindex "tainted data" "sqlite file" -It also means that the query cannot use any tainted values, as that taints +the query cannot use any tainted values, as that taints the entire query including the filename - resulting in a refusal to open the file. -.new +In all the above cases the filename must be an absolute path. + Here is a lookup expansion example: .code sqlite_dbfile = /some/thing/sqlitedb @@ -8144,7 +8163,6 @@ In a list, the syntax is similar. For example: domainlist relay_to_domains = sqlite;\ select * from relays where ip='$sender_host_address'; .endd -.wen The only character affected by the &%quote_sqlite%& operator is a single quote, which it doubles. @@ -8158,7 +8176,7 @@ waits for the lock to be released. In Exim, the default timeout is set to 5 seconds, but it can be changed by means of the &%sqlite_lock_timeout%& option. -.section "More about Redis" "SECTredis" +.subsection "More about Redis" SECTredis .cindex "lookup" "Redis" .cindex "redis lookup type" Redis is a non-SQL database. Commands are simple get and set. @@ -8207,6 +8225,34 @@ domain, host, address and local part lists. +.section "Results of list checking" SECTlistresults +The primary result of doing a list check is a truth value. +In some contexts additional information is stored +about the list element that matched: +.vlist +.vitem hosts +A &%hosts%& ACL condition +will store a result in the &$host_data$& variable. +.vitem local_parts +A &%local_parts%& router option or &%local_parts%& ACL condition +will store a result in the &$local_part_data$& variable. +.vitem domains +A &%domains%& router option or &%domains%& ACL condition +will store a result in the &$domain_data$& variable. +.vitem senders +A &%senders%& router option or &%senders%& ACL condition +will store a result in the &$sender_data$& variable. +.vitem recipients +A &%recipients%& ACL condition +will store a result in the &$recipient_data$& variable. +.endlist + +The detail of the additional information depends on the +type of match and is given below as the &*value*& information. + + + + .section "Expansion of lists" "SECTlistexpand" .cindex "expansion" "of lists" Each list is expanded as a single string before it is used. @@ -8242,7 +8288,7 @@ senders based on the receiving domain. -.section "Negated items in lists" "SECID76" +.subsection "Negated items in lists" SECID76 .cindex "list" "negation" .cindex "negation" "in lists" Items in a list may be positive or negative. Negative items are indicated by a @@ -8275,7 +8321,7 @@ item. -.section "File names in lists" "SECTfilnamlis" +.subsection "File names in lists" SECTfilnamlis .cindex "list" "filename in" If an item in a domain, host, address, or local part list is an absolute filename (beginning with a slash character), each line of the file is read and @@ -8317,7 +8363,7 @@ any domain matching &`*.b.c`& is not. -.section "An lsearch file is not an out-of-line list" "SECID77" +.subsection "An lsearch file is not an out-of-line list" SECID77 As will be described in the sections that follow, lookups can be used in lists to provide indexed methods of checking list membership. There has been some confusion about the way &(lsearch)& lookups work in lists. Because @@ -8334,7 +8380,7 @@ in the previous section. You could also use the &(wildlsearch)& or -.section "Named lists" "SECTnamedlists" +.subsection "Named lists" SECTnamedlists .cindex "named lists" .cindex "list" "named" A list of domains, hosts, email addresses, or local parts can be given a name @@ -8392,7 +8438,6 @@ domainlist dom2 = !a.b : *.b where &'x.y'& does not match. It's best to avoid negation altogether in referenced lists if you can. -.new .cindex "hiding named list values" .cindex "named lists" "hiding value of" Some named list definitions may contain sensitive data, for example, passwords for @@ -8402,7 +8447,6 @@ word &"hide"&. For example: .code hide domainlist filter_for_domains = ldap;PASS=secret ldap::/// ... .endd -.wen Named lists may have a performance advantage. When Exim is routing an @@ -8425,7 +8469,7 @@ hosts. The default configuration is set up like this. -.section "Named lists compared with macros" "SECID78" +.subsection "Named lists compared with macros" SECID78 .cindex "list" "named compared with macro" .cindex "macro" "compared with named list" At first sight, named lists might seem to be no different from macros in the @@ -8451,7 +8495,7 @@ auth_advertise_hosts = !host1 : !host2 .endd -.section "Named list caching" "SECID79" +.subsection "Named list caching" SECID79 .cindex "list" "caching of named" .cindex "caching" "named lists" While processing a message, Exim caches the result of checking a named list if @@ -8496,6 +8540,10 @@ If a pattern consists of a single @ character, it matches the local host name, 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. + +The value for a match will be the primary host name. + + .next .cindex "@[] in a domain list" .cindex "domain list" "matching local IP interfaces" @@ -8505,7 +8553,12 @@ in square brackets (as in an email address that contains a domain literal), but 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. +In today's Internet, the use of domain literals is controversial; +see the &%allow_domain_literals%& main option. + +The value for a match will be the string &`@[]`&. + + .next .cindex "@mx_any" .cindex "@mx_primary" @@ -8554,6 +8607,9 @@ involved, it is easiest to change the delimiter for the main list as well: domains = >&) to specify that it is not to be expanded (unless you really do want to build a regular expression by expansion, of course). + +The value for a match will be the list element string (starting with the circumflex). +Additionally, &$0$& will be set to the string matching the regular expression, +and &$1$& (onwards) to any submatches identified by parentheses. + + + .next .cindex "lookup" "in domain list" .cindex "domain list" "matching by lookup" @@ -8593,12 +8660,21 @@ must be a filename in a suitable format for the lookup type. For example, for domains = cdb;/etc/mail/local_domains.cdb .endd The appropriate type of lookup is done on the file using the domain name as the -key. In most cases, the data that is looked up is not used; Exim is interested +key. In most cases, the value resulting from the lookup is not used; Exim is interested only in whether or not the key is present in the file. However, when a lookup is used for the &%domains%& option on a router -or a &%domains%& condition in an ACL statement, the data is preserved in the +or a &%domains%& condition in an ACL statement, the value is preserved in the &$domain_data$& variable and can be referred to in other router options or other statements in the same ACL. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using ACL domains condition" +The value will be untainted. + +&*Note*&: If the data result of the lookup (as opposed to the key) +is empty, then this empty value is stored in &$domain_data$&. +The option to return the key for the lookup, as the value, +may be what is wanted. + .next Any of the single-key lookup type names may be preceded by @@ -8617,6 +8693,7 @@ original lookup fails. This is not a useful feature when using a domain list to select particular domains (because any domain would match), but it might have value if the result of the lookup is being used via the &$domain_data$& expansion variable. + .next If the pattern starts with the name of a query-style lookup type followed by a semicolon (for example, &"nisplus;"& or &"ldap;"&), the remainder of the @@ -8626,25 +8703,41 @@ chapter &<>&. For example: hold_domains = mysql;select domain from holdlist \ where domain = '${quote_mysql:$domain}'; .endd -In most cases, the data that is looked up is not used (so for an SQL query, for +In most cases, the value resulting from the lookup is not used (so for an SQL query, for example, it doesn't matter what field you select). Exim is interested only in whether or not the query succeeds. However, when a lookup is used for the -&%domains%& option on a router, the data is preserved in the &$domain_data$& +&%domains%& option on a router, the value is preserved in the &$domain_data$& variable and can be referred to in other options. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using router domains option" +The value will be untainted. + .next -.new If the pattern starts with the name of a lookup type of either kind (single-key or query-style) it may be -followed by a command and options, +followed by a comma and options, The options are lookup-type specific and consist of a comma-separated list. -Each item starts with a tag and and equals "=". -.wen +Each item starts with a tag and and equals "=" sign. + .next .cindex "domain list" "matching literal domain name" If none of the above cases apply, a caseless textual comparison is made between the pattern and the domain. + +The value for a match will be the list element string. +.cindex "tainted data" "de-tainting" +Note that this is commonly untainted +(depending on the way the list was created). +Specifically, explicit text in the configuration file in not tainted. +This is a useful way of obtaining an untainted equivalent to +the domain, for later operations. + +However if the list (including one-element lists) +is created by expanding a variable containing tainted data, +it is tainted and so will the match value be. .endlist + Here is an example that uses several different kinds of pattern: .code domainlist funny_domains = \ @@ -8677,7 +8770,7 @@ You need to be particularly careful with this when single-key lookups are involved, to ensure that the right value is being used as the key. -.section "Special host list patterns" "SECID80" +.subsection "Special host list patterns" SECID80 .cindex "empty item in hosts list" .cindex "host list" "empty string in" If a host list item is the empty string, it matches only when no remote host is @@ -8691,7 +8784,7 @@ the IP address nor the name is actually inspected. -.section "Host list patterns that match by IP address" "SECThoslispatip" +.subsection "Host list patterns that match by IP address" SECThoslispatip .cindex "host list" "matching IP addresses" If an IPv4 host calls an IPv6 host and the call is accepted on an IPv6 socket, the incoming address actually appears in the IPv6 host as @@ -8743,9 +8836,13 @@ accept hosts = @[] .endd .next .cindex "CIDR notation" -If the pattern is an IP address followed by a slash and a mask length (for -example 10.11.42.0/24), it is matched against the IP address of the subject -host under the given mask. This allows, an entire network of hosts to be +If the pattern is an IP address followed by a slash and a mask length, for +example +.code +10.11.42.0/24 +.endd +, it is matched against the IP address of the subject +host under the given mask. This allows an entire network of hosts to be included (or excluded) by a single item. The mask uses CIDR notation; it specifies the number of address bits that must match, starting from the most significant end of the address. @@ -8790,8 +8887,8 @@ list. -.section "Host list patterns for single-key lookups by host address" &&& - "SECThoslispatsikey" +.subsection "Host list patterns for single-key lookups by host address" &&& + SECThoslispatsikey .cindex "host list" "lookup of IP address" When a host is to be identified by a single-key lookup of its complete IP address, the pattern takes this form: @@ -8850,7 +8947,7 @@ case the IP address is used on its own. -.section "Host list patterns that match by host name" "SECThoslispatnam" +.subsection "Host list patterns that match by host name" SECThoslispatnam .cindex "host" "lookup failures" .cindex "unknown host name" .cindex "host list" "matching host name" @@ -8925,7 +9022,7 @@ required. -.section "Behaviour when an IP address or name cannot be found" "SECTbehipnot" +.subsection "Behaviour when an IP address or name cannot be found" SECTbehipnot .cindex "host" "lookup failures, permanent" While processing a host list, Exim may need to look up an IP address from a name (see section &<>&), or it may need to look up a host name @@ -8971,8 +9068,8 @@ Both &`+include_unknown`& and &`+ignore_unknown`& may appear in the same list. The effect of each one lasts until the next, or until the end of the list. -.section "Mixing wildcarded host names and addresses in host lists" &&& - "SECTmixwilhos" +.subsection "Mixing wildcarded host names and addresses in host lists" &&& + SECTmixwilhos .cindex "host list" "mixing names and addresses in" This section explains the host/ip processing logic with the same concepts @@ -9008,8 +9105,8 @@ this section. .endlist -.section "Temporary DNS errors when looking up host information" &&& - "SECTtemdnserr" +.subsection "Temporary DNS errors when looking up host information" &&& + SECTtemdnserr .cindex "host" "lookup failures, temporary" .cindex "&`+include_defer`&" .cindex "&`+ignore_defer`&" @@ -9022,8 +9119,8 @@ host lists such as whitelists. -.section "Host list patterns for single-key lookups by host name" &&& - "SECThoslispatnamsk" +.subsection "Host list patterns for single-key lookups by host name" &&& + SECThoslispatnamsk .cindex "unknown host name" .cindex "host list" "matching host name" If a pattern is of the form @@ -9047,7 +9144,7 @@ lookup, both using the same file. -.section "Host list patterns for query-style lookups" "SECID81" +.subsection "Host list patterns for query-style lookups" SECID81 If a pattern is of the form .display <&'query-style-search-type'&>;<&'query'&> @@ -9279,7 +9376,7 @@ example it is a named domain list. -.section "Case of letters in address lists" "SECTcasletadd" +.subsection "Case of letters in address lists" SECTcasletadd .cindex "case of local parts" .cindex "address list" "case forcing" .cindex "case forcing in address lists" @@ -9314,6 +9411,9 @@ become case-sensitive after &"+caseful"& has been seen. .section "Local part lists" "SECTlocparlis" .cindex "list" "local part list" .cindex "local part" "list" +These behave in the same way as domain and host lists, with the following +changes: + Case-sensitivity in local part lists is handled in the same way as for address lists, as just described. The &"+caseful"& item can be used if required. In a setting of the &%local_parts%& option in a router with &%caseful_local_part%& @@ -9358,9 +9458,19 @@ the data type. ACL rules always expand strings. A couple of expansion conditions do not expand some of the brace-delimited branches, for security reasons, .cindex "tainted data" expansion +.cindex "tainted data" definition .cindex expansion "tainted data" and expansion of data deriving from the sender (&"tainted data"&) -is not permitted. +is not permitted (including acessing a file using a tainted name). + +Common ways of obtaining untainted equivalents of variables with +tainted values +.cindex "tainted data" "de-tainting" +come down to using the tainted value as a lookup key in a trusted database. +This database could be the filesystem structure, +or the password file, +or accessed via a DBMS. +Specific methods are indexed under &"de-tainting"&. @@ -9413,6 +9523,17 @@ value. Nevertheless the &%-be%& option can be useful for checking out file and database lookups, and the use of expansion operators such as &%sg%&, &%substr%& and &%nhash%&. +.new +When reading lines from the standard input, +macros can be defined and ACL variables can be set. +For example: +.code +MY_MACRO = foo +set acl_m_myvar = bar +.endd +Such macros and variables can then be used in later input lines. +.wen + Exim gives up its root privilege when it is called with the &%-be%& option, and instead runs under the uid and gid it was called with, to prevent users from using &%-be%& for reading files to which they do not have access. @@ -9507,7 +9628,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&" .cindex authentication "results header" -.cindex headers "authentication-results:" +.chindex Authentication-Results: .cindex authentication "expansion item" This item returns a string suitable for insertion as an &'Authentication-Results:'& @@ -9786,7 +9907,11 @@ After expansion, <&'string'&> is interpreted as a list, colon-separated by default, but the separator can be changed in the usual way (&<>&). For each item in this list, its value is place in &$item$&, and then the condition is -evaluated. If the condition is true, &$item$& is added to the output as an +evaluated. +.new +Any modification of &$value$& by this evaluation is discarded. +.wen +If the condition is true, &$item$& is added to the output as an item in a new list; if the condition is false, the item is discarded. The separator used for the output list is the same as the one used for the input, but a separator setting is not included in the output. For example: @@ -9794,7 +9919,8 @@ input, but a separator setting is not included in the output. For example: ${filter{a:b:c}{!eq{$item}{b}}} .endd yields &`a:c`&. At the end of the expansion, the value of &$item$& is restored -to what it was before. See also the &%map%& and &%reduce%& expansion items. +to what it was before. +See also the &%map%& and &%reduce%& expansion items. .vitem &*${hash{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*& @@ -9917,7 +10043,7 @@ They are visible in DKIM, PRDR and DATA ACLs. Header lines that are added in a RCPT ACL (for example) are saved until the message's incoming header lines are available, at which point they are added. -When any of the above ACLs ar +When any of the above ACLs are running, however, header lines added by earlier ACLs are visible. Upper case and lower case letters are synonymous in header names. If the @@ -9938,11 +10064,9 @@ newline at the very end. For the &%header%& and &%bheader%& expansion, for those headers that contain lists of addresses, a comma is also inserted at the junctions between headers. This does not happen for the &%rheader%& expansion. -.new -.cindex "tainted data" +.cindex "tainted data" "message headers" When the headers are from an incoming message, the result of expanding any of these variables is tainted. -.wen .vitem &*${hmac{*&<&'hashname'&>&*}{*&<&'secret'&>&*}{*&<&'string'&>&*}}*& @@ -10075,12 +10199,19 @@ extracted is used. You can use &`fail`& instead of {<&'string3'&>} as in a string extract. -.vitem "&*${lookup{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& - {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" -This is the first of one of two different types of lookup item, which are both -described in the next item. +.vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*& +.cindex quoting "for list" +.cindex list quoting +This item doubles any occurrence of the separator character +in the given string. +An empty string is replaced with a single space. +This converts the string into a safe form for use as a list element, +in a list using the given separator. + -.vitem "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&& +.vitem "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& + {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" &&& + "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&& {*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" .cindex "expansion" "lookup in" .cindex "file" "lookups" @@ -10186,10 +10317,11 @@ additional arguments need be given; the maximum number permitted, including the name of the subroutine, is nine. The return value of the subroutine is inserted into the expanded string, unless -the return value is &%undef%&. In that case, the expansion fails in the same -way as an explicit &"fail"& on a lookup item. The return value is a scalar. -Whatever you return is evaluated in a scalar context. For example, if you -return the name of a Perl vector, the return value is the size of the vector, +the return value is &%undef%&. In that case, the entire expansion is +forced to fail, in the same way as an explicit &"fail"& on a lookup item +does (see section &<>&). Whatever you return is evaluated +in a scalar context, thus the return value is a scalar. For example, if you +return a Perl vector, the return value is the size of the vector, not its contents. If the subroutine exits by calling Perl's &%die%& function, the expansion fails @@ -10239,7 +10371,7 @@ For more discussion and an example, see section &<>&. .cindex "expansion" "inserting an entire file" .cindex "file" "inserting into expansion" .cindex "&%readfile%& expansion item" -The filename and end-of-line string are first expanded separately. The file is +The filename and end-of-line (eol) string are first expanded separately. The file is then read, and its contents replace the entire item. All newline characters in the file are replaced by the end-of-line string if it is present. Otherwise, newlines are left in the string. @@ -10276,7 +10408,7 @@ ${readsocket{inet:[::1]:1234}{request string}} Only a single host name may be given, but if looking it up yields more than one IP address, they are each tried in turn until a connection is made. For both kinds of socket, Exim makes a connection, writes the request string -unless it is an empty string; and no terminating NUL is ever sent) +(unless it is an empty string; no terminating NUL is ever sent) and reads from the socket until an end-of-file is read. A timeout of 5 seconds is applied. Additional, optional arguments extend what can be done. Firstly, you can vary the timeout. For example: @@ -10292,7 +10424,6 @@ Example: ${readsocket{/socket/name}{request string}{3s:shutdown=no}} .endd -.new The following option names are recognised: .ilist &*cache*& @@ -10312,9 +10443,8 @@ sending the request. Values are &"yes"& (the default) or &"no"& &*tls*& Controls the use of TLS on the connection. Values are &"yes"& or &"no"& (the default). -If it is enabled, a shutdown as descripbed above is never done. +If it is enabled, a shutdown as described above is never done. .endlist -.wen A fourth argument allows you to change any newlines that are in the data @@ -10381,20 +10511,45 @@ At the end of a &*reduce*& expansion, the values of &$item$& and &$value$& are restored to what they were before. See also the &%filter%& and &%map%& expansion items. +. A bit of a special-case logic error in writing an expansion; +. probably not worth including in the mainline of documentation. +. If only we had footnotes (the html output variant is the problem). +. +. .new +. &*Note*&: if an &'expansion condition'& is used in <&'string3'&> +. and that condition modifies &$value$&, +. then the string expansions dependent on the condition cannot use +. the &$value$& of the reduce iteration. +. .wen + .vitem &*$rheader_*&<&'header&~name'&>&*:*&&~or&~&*$rh_*&<&'header&~name'&>&*:*& This item inserts &"raw"& header lines. It is described with the &%header%& expansion item in section &<>& above. -.vitem "&*${run{*&<&'command'&>&*&~*&<&'args'&>&*}{*&<&'string1'&>&*}&&& +.vitem "&*${run <&'options'&> {*&<&'command&~arg&~list'&>&*}{*&<&'string1'&>&*}&&& {*&<&'string2'&>&*}}*&" .cindex "expansion" "running a command" .cindex "&%run%& expansion item" -The command and its arguments are first expanded as one string. The string is -split apart into individual arguments by spaces, and then the command is run +This item runs an external command, as a subprocess. +One option is supported after the word &'run'&, comma-separated. + +If the option &'preexpand'& is not used, +the command string is split into individual arguments by spaces +and then each argument is expanded. +Then the command is run in a separate process, but under the same uid and gid. As in other command executions from Exim, a shell is not used by default. If the command requires a shell, you must explicitly code it. +The command name may not be tainted, but the remaining arguments can be. +&*Note*&: if tainted arguments are used, they are supplied by a +potential attacker; +a careful assessment for security vulnerabilities should be done. + +If the option &'preexpand'& is used, +the command and its arguments are first expanded as one string. The result is +split apart into individual arguments by spaces, and then the command is run +as above. Since the arguments are split by spaces, when there is a variable expansion which has an empty result, it will cause the situation that the argument will simply be omitted when the program is actually executed by Exim. If the @@ -10405,6 +10560,7 @@ in a string containing quotes, because it would interfere with the quotes around the command arguments. A possible guard against this is to wrap the variable in the &%sg%& operator to change any quote marks to some other character. +Neither the command nor any argument may be tainted. The standard input for the command exists, but is empty. The standard output and standard error are set to the same file descriptor. @@ -10516,16 +10672,22 @@ ${sort {${lookup dnsdb{>:,,mx=example.com}}} {<} {${listextract{1}{<,$item}}}} will sort an MX lookup into priority order. -.vitem &*${substr{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*& + +.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*& +SRS encoding. See SECT &<>& for details. + + + +.vitem &*${substr{*&<&'start'&>&*}{*&<&'len'&>&*}{*&<&'subject'&>&*}}*& .cindex "&%substr%& expansion item" .cindex "substring extraction" .cindex "expansion" "substring extraction" The three strings are expanded; the first two must yield numbers. Call them <&'n'&> and <&'m'&>. If you are using fixed values for these numbers, that is, -if <&'string1'&> and <&'string2'&> do not change when they are expanded, you +if <&'start'&> and <&'len'&> do not change when they are expanded, you can use the simpler operator notation that avoids some of the braces: .code -${substr__:} +${substr__:} .endd The second number is optional (in both notations). If it is absent in the simpler format, the preceding underscore must also be @@ -10736,7 +10898,7 @@ is controlled by the &%print_topbitchars%& option. .vitem &*${escape8bit:*&<&'string'&>&*}*& .cindex "expansion" "escaping 8-bit characters" .cindex "&%escape8bit%& expansion item" -If the string contains and characters with the most significant bit set, +If the string contains any characters with the most significant bit set, they are converted to escape sequences starting with a backslash. Backslashes and DEL characters are also converted. @@ -10790,8 +10952,7 @@ a decimal representation of the answer (without &"K"&, &"M"& or &"G"&). For exam As a more realistic example, in an ACL you might have .code -deny message = Too many bad recipients - condition = \ +deny condition = \ ${if and { \ {>{$rcpt_count}{10}} \ { \ @@ -10800,6 +10961,7 @@ deny message = Too many bad recipients {${eval:$rcpt_count/2}} \ } \ }{yes}{no}} + message = Too many bad recipients .endd The condition is true if there have been more than 10 RCPT commands and fewer than half of them have resulted in a valid recipient. @@ -10932,6 +11094,8 @@ If the optional type is given it must be one of "a", "d", "h" or "l" and selects address-, domain-, host- or localpart- lists to search among respectively. Otherwise all types are searched in an undefined order and the first matching list is returned. +&*Note*&: Neither string-expansion of lists referenced by named-list syntax elements, +nor expansion of lookup elements, is done by the &%listnamed%& operator. .vitem &*${local_part:*&<&'string'&>&*}*& @@ -10943,7 +11107,8 @@ empty. The parsing correctly handles SMTPUTF8 Unicode in the string. -.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& +.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& &&& + &*${mask_n:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& .cindex "masked IP address" .cindex "IP address" "masking" .cindex "CIDR notation" @@ -10957,8 +11122,12 @@ the result back to text, with mask appended. For example, .code ${mask:10.111.131.206/28} .endd -returns the string &"10.111.131.192/28"&. Since this operation is expected to -be mostly used for looking up masked addresses in files, the result for an IPv6 +returns the string &"10.111.131.192/28"&. + +Since this operation is expected to +be mostly used for looking up masked addresses in files, the +normal +result for an IPv6 address uses dots to separate components instead of colons, because colon terminates a key string in lsearch files. So, for example, .code @@ -10968,6 +11137,8 @@ returns the string .code 3ffe.ffff.836f.0a00.000a.0800.2000.0000/99 .endd +If the optional form &*mask_n*& is used, IPv6 address result are instead +returned in normailsed form, using colons and with zero-compression. Letters in IPv6 addresses are always output in lower case. @@ -11199,7 +11370,7 @@ Now deprecated, a synonym for the &%base64%& expansion operator. .cindex "expansion" "string length" .cindex "string" "length in expansion" .cindex "&%strlen%& expansion item" -The item is replace by the length of the expanded string, expressed as a +The item is replaced by the length of the expanded string, expressed as a decimal number. &*Note*&: Do not confuse &%strlen%& with &%length%&. All measurement is done in bytes and is not UTF-8 aware. @@ -11299,14 +11470,14 @@ condition. .cindex "expansion" "numeric comparison" There are a number of symbolic operators for doing numeric comparisons. They are: -.display -&`= `& equal -&`== `& equal -&`> `& greater -&`>= `& greater or equal -&`< `& less -&`<= `& less or equal -.endd +.itable none 0 0 2 10* left 90* left +.irow "= " "equal" +.irow "== " "equal" +.irow "> " "greater" +.irow ">= " "greater or equal" +.irow "< " "less" +.irow "<= " "less or equal" +.endtable For example: .code ${if >{$message_size}{10M} ... @@ -11494,11 +11665,16 @@ condition is true if the named file (or directory) exists. The existence test is done by calling the &[stat()]& function. The use of the &%exists%& test in users' filter files may be locked out by the system administrator. +&*Note:*& Testing a path using this condition is not a sufficient way of +de-tainting it. +Consider using a dsearch lookup. + .vitem &*first_delivery*& .cindex "delivery" "first" .cindex "first delivery" .cindex "expansion" "first delivery test" .cindex "&%first_delivery%& expansion condition" +.cindex retry condition This condition, which has no data, is true during a message's first delivery attempt. It is false during any subsequent delivery attempts. @@ -11578,6 +11754,11 @@ includes the case of letters, whereas for &%gti%& the comparison is case-independent. Case and collation order are defined per the system C locale. + +.vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*& +SRS decode. See SECT &<>& for details. + + .vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& &*inlisti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "string" "comparison" @@ -11596,6 +11777,18 @@ ${if inlisti{Needle}{fOo:NeeDLE:bAr}} ${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}} .endd +The variable &$value$& will be set for a successful match and can be +used in the success clause of an &%if%& expansion item using the condition. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using an inlist expansion condition" +It will have the same taint status as the list; expansions such as +.code +${if inlist {$h_mycode:} {0 : 1 : 42} {$value}} +.endd +can be used for de-tainting. +Any previous &$value$& is restored after the if. + + .vitem &*isip&~{*&<&'string'&>&*}*& &&& &*isip4&~{*&<&'string'&>&*}*& &&& &*isip6&~{*&<&'string'&>&*}*& @@ -11792,6 +11985,17 @@ item can be used, as in all address lists, to cause subsequent items to have their local parts matched casefully. Domains are always matched caselessly. +The variable &$value$& will be set for a successful match and can be +used in the success clause of an &%if%& expansion item using the condition. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using a match_local_part expansion condition" +It will have the same taint status as the list; expansions such as +.code +${if match_local_part {$local_part} {alice : bill : charlotte : dave} {$value}} +.endd +can be used for de-tainting. +Any previous &$value$& is restored after the if. + Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. @@ -11808,8 +12012,9 @@ matched using &%match_ip%&. .cindex "&%pam%& expansion condition" &'Pluggable Authentication Modules'& (&url(https://mirrors.edge.kernel.org/pub/linux/libs/pam/)) are a facility that is -available in the latest releases of Solaris and in some GNU/Linux -distributions. The Exim support, which is intended for use in conjunction with +available in Solaris +and in some GNU/Linux distributions. +The Exim support, which is intended for use in conjunction with the SMTP AUTH command, is available only if Exim is compiled with .code SUPPORT_PAM=yes @@ -11827,15 +12032,12 @@ request, for a password, so the data consists of just two strings. There can be problems if any of the strings are permitted to contain colon characters. In the usual way, these have to be doubled to avoid being taken as -separators. If the data is being inserted from a variable, the &%sg%& expansion -item can be used to double any existing colons. For example, the configuration +separators. +The &%listquote%& expansion item can be used for this. +For example, the configuration of a LOGIN authenticator might contain this setting: .code -server_condition = ${if pam{$auth1:${sg{$auth2}{:}{::}}}} -.endd -For a PLAIN authenticator you could use: -.code -server_condition = ${if pam{$auth2:${sg{$auth3}{:}{::}}}} +server_condition = ${if pam{$auth1:${listquote{:}{$auth2}}}} .endd In some operating systems, PAM authentication can be done only from a process running as root. Since Exim is running as the Exim user when receiving @@ -11989,6 +12191,14 @@ parsed but not evaluated. This section contains an alphabetical list of all the expansion variables. Some of them are available only when Exim is compiled with specific options such as support for TLS or the content scanning extension. +.cindex "tainted data" +Variables marked as &'tainted'& are likely to carry data supplied by +a potential attacker. +Variables without such marking may also, depending on how their +values are created. +Such variables should not be further expanded, +used as filenames +or used as command-line arguments for external commands. .vlist .vitem "&$0$&, &$1$&, etc" @@ -12003,6 +12213,7 @@ variables may also be set externally by some other matching process which precedes the expansion of the string. For example, the commands available in Exim filter files include an &%if%& command with its own regular expression matching condition. +If the subject string was tainted then any captured substring will also be. .vitem "&$acl_arg1$&, &$acl_arg2$&, etc" Within an acl condition, expansion condition or expansion item @@ -12037,8 +12248,8 @@ this variable has the number of arguments. .vitem &$acl_verify_message$& .vindex "&$acl_verify_message$&" After an address verification has failed, this variable contains the failure -message. It retains its value for use in subsequent modifiers. The message can -be preserved by coding like this: +message. It retains its value for use in subsequent modifiers of the verb. +The message can be preserved by coding like this: .code warn !verify = sender set acl_m0 = $acl_verify_message @@ -12046,6 +12257,7 @@ warn !verify = sender You can use &$acl_verify_message$& during the expansion of the &%message%& or &%log_message%& modifiers, to include information about the verification failure. +&*Note*&: The variable is cleared at the end of processing the ACL verb. .vitem &$address_data$& .vindex "&$address_data$&" @@ -12093,7 +12305,7 @@ to the relevant file. When, as a result of aliasing or forwarding, a message is directed to a pipe, this variable holds the pipe command when the transport is running. -.vitem "&$auth1$& &-- &$auth3$&" +.vitem "&$auth1$& &-- &$auth4$&" .vindex "&$auth1$&, &$auth2$&, etc" These variables are used in SMTP authenticators (see chapters &<>&&--&<>&). Elsewhere, they are empty. @@ -12127,11 +12339,10 @@ authentication, which means this variable could also be visible in all of the ACL's as well. -.vitem &$authenticated_sender$& +.tvar &$authenticated_sender$& .cindex "sender" "authenticated" .cindex "authentication" "sender" .cindex "AUTH" "on MAIL command" -.vindex "&$authenticated_sender$&" When acting as a server, Exim takes note of the AUTH= parameter on an incoming SMTP MAIL command if it believes the sender is sufficiently trusted, as described in section &<>&. Unless the data is the string @@ -12154,9 +12365,10 @@ command that does not succeed. Otherwise it is set to &"0"&. This makes it possible to distinguish between &"did not try to authenticate"& (&$sender_host_authenticated$& is empty and &$authentication_failed$& is set to &"0"&) and &"tried to authenticate but failed"& (&$sender_host_authenticated$& -is empty and &$authentication_failed$& is set to &"1"&). Failure includes any -negative response to an AUTH command, including (for example) an attempt to use -an undefined mechanism. +is empty and &$authentication_failed$& is set to &"1"&). +Failure includes cancellation of a authentication attempt, +and any negative response to an AUTH command, +(including, for example, an attempt to use an undefined mechanism). .vitem &$av_failed$& .cindex "content scanning" "AV scanner failure" @@ -12230,13 +12442,6 @@ contain the trailing slash. If &$config_file$& does not contain a slash, .vindex "&$config_file$&" The name of the main configuration file Exim is using. -.vitem &$dmarc_domain_policy$& &&& - &$dmarc_status$& &&& - &$dmarc_status_text$& &&& - &$dmarc_used_domains$& -Results of DMARC verification. -For details see section &<>&. - .vitem &$dkim_verify_status$& Results of DKIM verification. For details see section &<>&. @@ -12269,6 +12474,13 @@ When a message has been received this variable contains a colon-separated list of signer domains and identities for the message. For details see section &<>&. +.vitem &$dmarc_domain_policy$& &&& + &$dmarc_status$& &&& + &$dmarc_status_text$& &&& + &$dmarc_used_domains$& +Results of DMARC verification. +For details see section &<>&. + .vitem &$dnslist_domain$& &&& &$dnslist_matched$& &&& &$dnslist_text$& &&& @@ -12283,8 +12495,7 @@ the following data from the lookup: the list's domain name, the key that was looked up, the contents of any associated TXT record, and the value from the main A record. See section &<>& for more details. -.vitem &$domain$& -.vindex "&$domain$&" +.tvar &$domain$& When an address is being routed, or delivered on its own, this variable contains the domain. Uppercase letters in the domain are converted into lower case for &$domain$&. @@ -12337,27 +12548,32 @@ When the &%smtp_etrn_command%& option is being expanded, &$domain$& contains the complete argument of the ETRN command (see section &<>&). .endlist -.new .cindex "tainted data" If the origin of the data is an incoming message, -the result of expanding this variable is tainted. -See also &$domain_verified$&. -.wen +the result of expanding this variable is tainted and may not +be further expanded or used as a filename. +When an untainted version is needed, one should be obtained from +looking up the value in a local (therefore trusted) database. +Often &$domain_data$& is usable in this role. .vitem &$domain_data$& .vindex "&$domain_data$&" -When the &%domains%& option on a router matches a domain by -means of a lookup, the data read by the lookup is available during the running -of the router as &$domain_data$&. In addition, if the driver routes the +When the &%domains%& condition on a router +or an ACL +matches a domain +against a list, the match value is copied to &$domain_data$&. +This is an enhancement over previous versions of Exim, when it only +applied to the data read by a lookup. +For details on match values see section &<>& et. al. + +If the router routes the address to a transport, the value is available in that transport. If the transport is handling multiple addresses, the value from the first address is used. -&$domain_data$& is also set when the &%domains%& condition in an ACL matches a -domain by means of a lookup. The data read by the lookup is available during -the rest of the ACL statement. In all other situations, this variable expands -to nothing. +&$domain_data$& set in an ACL is available during +the rest of the ACL statement. .vitem &$exim_gid$& .vindex "&$exim_gid$&" @@ -12380,6 +12596,7 @@ There may be other characters following the minor version. This value may be overridden by the &%exim_version%& main config option. .vitem &$header_$&<&'name'&> +.tmark This is not strictly an expansion variable. It is expansion syntax for inserting the message header line with the given name. Note that the name must be terminated by colon or white space, because it may contain a wide variety of @@ -12438,8 +12655,9 @@ result of the lookup is made available in the &$host_data$& variable. This allows you, for example, to do things like this: .code deny hosts = net-lsearch;/some/file -message = $host_data + message = $host_data .endd + .vitem &$host_lookup_deferred$& .cindex "host name" "lookup, failure of" .vindex "&$host_lookup_deferred$&" @@ -12497,13 +12715,11 @@ option in the &(appendfile)& transport. The variable contains the inode number of the temporary file which is about to be renamed. It can be used to construct a unique name for the file. -.vitem &$interface_address$& +.vitem &$interface_address$& &&& + &$interface_port$& .vindex "&$interface_address$&" -This is an obsolete name for &$received_ip_address$&. - -.vitem &$interface_port$& .vindex "&$interface_port$&" -This is an obsolete name for &$received_port$&. +These are obsolete names for &$received_ip_address$& and &$received_port$&. .vitem &$item$& .vindex "&$item$&" @@ -12524,8 +12740,7 @@ This variable contains the system load average, multiplied by 1000 so that it is an integer. For example, if the load average is 0.21, the value of the variable is 210. The value is recomputed every time the variable is referenced. -.vitem &$local_part$& -.vindex "&$local_part$&" +.tvar &$local_part$& When an address is being routed, or delivered on its own, this variable contains the local part. When a number of addresses are being delivered together (for example, multiple RCPT commands in an SMTP @@ -12537,10 +12752,10 @@ Global address rewriting happens when a message is received, so the value of because a message may have many recipients and the system filter is called just once. -.new .cindex "tainted data" If the origin of the data is an incoming message, -the result of expanding this variable is tainted. +the result of expanding this variable is tainted and +may not be further expanded or used as a filename. &*Warning*&: the content of this variable is usually provided by a potential attacker. @@ -12548,28 +12763,13 @@ Consider carefully the implications of using it unvalidated as a name for file access. This presents issues for users' &_.forward_& and filter files. For traditional full user accounts, use &%check_local_users%& and the -&$local_part_verified$& variable rather than this one. +&$local_part_data$& variable rather than this one. For virtual users, store a suitable pathname component in the database which is used for account name validation, and use that retrieved value rather than this variable. +Often &$local_part_data$& is usable in this role. If needed, use a router &%address_data%& or &%set%& option for the retrieved data. -.wen - -.vindex "&$local_part_prefix$&" -.vindex "&$local_part_prefix_v$&" -.vindex "&$local_part_suffix$&" -.vindex "&$local_part_suffix_v$&" -.cindex affix variables -If a local part prefix or suffix has been recognized, it is not included in the -value of &$local_part$& during routing and subsequent delivery. The values of -any prefix or suffix are in &$local_part_prefix$& and -&$local_part_suffix$&, respectively. -.new -If the affix specification included a wildcard then the portion of -the affix matched by the wildcard is in -&$local_part_prefix_v$& or &$local_part_suffix_v$& as appropriate. -.wen When a message is being delivered to a file, pipe, or autoreply transport as a result of aliasing or forwarding, &$local_part$& is set to the local part of @@ -12605,51 +12805,32 @@ to process local parts in a case-dependent manner in a router, you can set the .vitem &$local_part_data$& .vindex "&$local_part_data$&" -When the &%local_parts%& option on a router matches a local part by means of a -lookup, the data read by the lookup is available during the running of the -router as &$local_part_data$&. In addition, if the driver routes the address -to a transport, the value is available in that transport. If the transport is -handling multiple addresses, the value from the first address is used. - -&$local_part_data$& is also set when the &%local_parts%& condition in an ACL -matches a local part by means of a lookup. The data read by the lookup is -available during the rest of the ACL statement. In all other situations, this -variable expands to nothing. - -.vitem &$local_part_prefix$& -.vindex "&$local_part_prefix$&" +When the &%local_parts%& condition on a router or ACL +matches a local part list +the match value is copied to &$local_part_data$&. +This is an enhancement over previous versions of Exim, when it only +applied to the data read by a lookup. +For details on match values see section &<>& et. al. + +The &%check_local_user%& router option also sets this variable. + +.vindex &$local_part_prefix$& &&& + &$local_part_prefix_v$& &&& + &$local_part_suffix$& &&& + &$local_part_suffix_v$& .cindex affix variables -When an address is being routed or delivered, and a -specific prefix for the local part was recognized, it is available in this -variable, having been removed from &$local_part$&. - -.new -.vitem &$local_part_prefix_v$& -.vindex "&$local_part_prefix_v$&" -When &$local_part_prefix$& is valid and the prefix match used a wildcard, -the portion matching the wildcard is available in this variable. -.wen - -.vitem &$local_part_suffix$& -.vindex "&$local_part_suffix$&" -When an address is being routed or delivered, and a -specific suffix for the local part was recognized, it is available in this -variable, having been removed from &$local_part$&. - -.new -.vitem &$local_part_suffix_v$& -.vindex "&$local_part_suffix_v$&" -When &$local_part_suffix$& is valid and the suffix match used a wildcard, -the portion matching the wildcard is available in this variable. -.wen +If a local part prefix or suffix has been recognized, it is not included in the +value of &$local_part$& during routing and subsequent delivery. The values of +any prefix or suffix are in &$local_part_prefix$& and +&$local_part_suffix$&, respectively. +.cindex "tainted data" +If the specification did not include a wildcard then +the affix variable value is not tainted. -.new -.vitem &$local_part_verified$& -.vindex "&$local_part_verified$&" -If the router generic option &%check_local_part%& has run successfully, -this variable has the user database version of &$local_part$&. -Such values are not tainted and hence usable for building file names. -.wen +If the affix specification included a wildcard then the portion of +the affix matched by the wildcard is in +&$local_part_prefix_v$& or &$local_part_suffix_v$& as appropriate, +and both the whole and varying values are tainted. .vitem &$local_scan_data$& .vindex "&$local_scan_data$&" @@ -12725,7 +12906,7 @@ when the ACL &%malware%& condition is true (see section &<>&). This variable contains the number of bytes in the longest line that was received as part of the message, not counting the line termination character(s). -It is not valid if the &%spool_files_wireformat%& option is used. +It is not valid if the &%spool_wireformat%& option is used. .vitem &$message_age$& .cindex "message" "age of" @@ -12734,11 +12915,10 @@ This variable is set at the start of a delivery attempt to contain the number of seconds since the message was received. It does not change during a single delivery attempt. -.vitem &$message_body$& +.tvar &$message_body$& .cindex "body of message" "expansion variable" .cindex "message body" "in expansion" .cindex "binary zero" "in message body" -.vindex "&$message_body$&" .oindex "&%message_body_visible%&" This variable contains the initial portion of a message's body while it is being delivered, and is intended mainly for use in filter files. The maximum @@ -12751,10 +12931,9 @@ easier to search for phrases that might be split over a line break. However, this can be disabled by setting &%message_body_newlines%& to be true. Binary zeros are always converted into spaces. -.vitem &$message_body_end$& +.tvar &$message_body_end$& .cindex "body of message" "expansion variable" .cindex "message body" "in expansion" -.vindex "&$message_body_end$&" This variable contains the final portion of a message's body while it is being delivered. The format and maximum size are as for &$message_body$&. @@ -12769,7 +12948,7 @@ separates the body from the header. Newlines are included in the count. See also &$message_size$&, &$body_linecount$&, and &$body_zerocount$&. If the spool file is wireformat -(see the &%spool_files_wireformat%& main option) +(see the &%spool_wireformat%& main option) the CRLF line-terminators are included in the count. .vitem &$message_exim_id$& @@ -12781,15 +12960,13 @@ received. &*Note*&: This is &'not'& the contents of the &'Message-ID:'& header line; it is the local id that Exim assigns to the message, for example: &`1BXTIK-0001yO-VA`&. -.vitem &$message_headers$& -.vindex &$message_headers$& +.tvar &$message_headers$& This variable contains a concatenation of all the header lines when a message is being processed, except for lines added by routers or transports. The header lines are separated by newline characters. Their contents are decoded in the same way as a header line that is inserted by &%bheader%&. -.vitem &$message_headers_raw$& -.vindex &$message_headers_raw$& +.tvar &$message_headers_raw$& This variable is like &$message_headers$& except that no processing of the contents of header lines is done. @@ -12815,14 +12992,14 @@ header and the body). Here is an example of the use of this variable in a DATA ACL: .code -deny message = Too many lines in message header - condition = \ +deny condition = \ ${if <{250}{${eval:$message_linecount - $body_linecount}}} + message = Too many lines in message header .endd In the MAIL and RCPT ACLs, the value is zero because at that stage the message has not yet been received. -This variable is not valid if the &%spool_files_wireformat%& option is used. +This variable is not valid if the &%spool_wireformat%& option is used. .vitem &$message_size$& .cindex "size" "of message" @@ -12842,7 +13019,22 @@ While running a per message ACL (mail/rcpt/predata), &$message_size$& contains the size supplied on the MAIL command, or -1 if no size was given. The value may not, of course, be truthful. -.vitem &$mime_$&&'xxx'& +.vitem &$mime_anomaly_level$& &&& + &$mime_anomaly_text$& &&& + &$mime_boundary$& &&& + &$mime_charset$& &&& + &$mime_content_description$& &&& + &$mime_content_disposition$& &&& + &$mime_content_id$& &&& + &$mime_content_size$& &&& + &$mime_content_transfer_encoding$& &&& + &$mime_content_type$& &&& + &$mime_decoded_filename$& &&& + &$mime_filename$& &&& + &$mime_is_coverletter$& &&& + &$mime_is_multipart$& &&& + &$mime_is_rfc822$& &&& + &$mime_part_count$& A number of variables whose names start with &$mime$& are available when Exim is compiled with the content-scanning extension. For details, see section &<>&. @@ -12851,9 +13043,8 @@ details, see section &<>&. These variables are counters that can be incremented by means of the &%add%& command in filter files. -.vitem &$original_domain$& +.tvar &$original_domain$& .vindex "&$domain$&" -.vindex "&$original_domain$&" When a top-level address is being processed for delivery, this contains the same value as &$domain$&. However, if a &"child"& address (for example, generated by an alias, forward, or filter file) is being processed, this @@ -12866,9 +13057,8 @@ If a new address is created by means of a &%deliver%& command in a system filter, it is set up with an artificial &"parent"& address. This has the local part &'system-filter'& and the default qualify domain. -.vitem &$original_local_part$& +.tvar &$original_local_part$& .vindex "&$local_part$&" -.vindex "&$original_local_part$&" When a top-level address is being processed for delivery, this contains the same value as &$local_part$&, unless a prefix or suffix was removed from the local part, because &$original_local_part$& always contains the full local @@ -12906,13 +13096,11 @@ messages received via the command line, this is the uid of the sending user. For messages received by SMTP over TCP/IP, this is normally the uid of the Exim user. -.vitem &$parent_domain$& -.vindex "&$parent_domain$&" +.tvar &$parent_domain$& This variable is similar to &$original_domain$& (see above), except that it refers to the immediately preceding parent address. -.vitem &$parent_local_part$& -.vindex "&$parent_local_part$&" +.tvar &$parent_local_part$& This variable is similar to &$original_local_part$& (see above), except that it refers to the immediately preceding parent address. @@ -12931,6 +13119,9 @@ This is not an expansion variable, but is mentioned here because the string (described under &%transport_filter%& in chapter &<>&). It cannot be used in general expansion strings, and provokes an &"unknown variable"& error if encountered. +&*Note*&: This value permits data supplied by a potential attacker to +be used in the command for a &(pipe)& transport. +Such configurations should be carefully assessed for security vulnerbilities. .vitem &$primary_hostname$& .vindex "&$primary_hostname$&" @@ -12955,18 +13146,10 @@ For details see chapter &<>&. This variable is set to &"yes"& if PRDR was requested by the client for the current message, otherwise &"no"&. -.vitem &$prvscheck_address$& -This variable is used in conjunction with the &%prvscheck%& expansion item, -which is described in sections &<>& and -&<>&. - -.vitem &$prvscheck_keynum$& -This variable is used in conjunction with the &%prvscheck%& expansion item, -which is described in sections &<>& and -&<>&. - -.vitem &$prvscheck_result$& -This variable is used in conjunction with the &%prvscheck%& expansion item, +.vitem &$prvscheck_address$& &&& + &$prvscheck_keynum$& &&& + &$prvscheck_result$& +These variables are used in conjunction with the &%prvscheck%& expansion item, which is described in sections &<>& and &<>&. @@ -12991,6 +13174,8 @@ The name of the spool queue in use; empty for the default queue. .cindex "spool" "number of messages" This variable contains the number of messages queued. It is evaluated on demand, but no more often than once every minute. +If there is no daemon notifier socket open, the value will be +an empty string. .vitem &$r_...$& .vindex &$r_...$& @@ -13026,18 +13211,19 @@ including the one added by Exim (so its value is always greater than zero). It is available in the DATA ACL, the non-SMTP ACL, and while routing and delivering. -.vitem &$received_for$& -.vindex "&$received_for$&" +.tvar &$received_for$& If there is only a single recipient address in an incoming message, this variable contains that address when the &'Received:'& header line is being built. The value is copied after recipient rewriting has happened, but before the &[local_scan()]& function is run. -.vitem &$received_ip_address$& +.vitem &$received_ip_address$& &&& + &$received_port$& .vindex "&$received_ip_address$&" -As soon as an Exim server starts processing an incoming TCP/IP connection, this -variable is set to the address of the local IP interface, and &$received_port$& -is set to the local port number. (The remote IP address and port are in +.vindex "&$received_port$&" +As soon as an Exim server starts processing an incoming TCP/IP connection, these +variables are set to the address and port on the local IP interface. +(The remote IP address and port are in &$sender_host_address$& and &$sender_host_port$&.) When testing with &%-bh%&, the port value is -1 unless it has been set using the &%-oMi%& command line option. @@ -13050,10 +13236,6 @@ messages that are received, thus making these variables available at delivery time. For outbound connections see &$sending_ip_address$&. -.vitem &$received_port$& -.vindex "&$received_port$&" -See &$received_ip_address$&. - .vitem &$received_protocol$& .vindex "&$received_protocol$&" When a message is being processed, this variable contains the name of the @@ -13121,8 +13303,7 @@ MAIL). The main use of this variable is expected to be to distinguish between rejections of MAIL and rejections of RCPT. -.vitem &$recipients$& -.vindex "&$recipients$&" +.tvar &$recipients$& This variable contains a list of envelope recipients for a message. A comma and a space separate the addresses in the replacement text. However, the variable is not generally available, to prevent exposure of Bcc recipients in @@ -13159,10 +13340,10 @@ This variable is set to contain the matching regular expression after a When a &%regex%& or &%mime_regex%& ACL condition succeeds, these variables contain the captured substrings identified by the regular expression. +If the subject string was tainted then so will any captured substring. -.vitem &$reply_address$& -.vindex "&$reply_address$&" +.tvar &$reply_address$& When a message is being processed, this variable contains the contents of the &'Reply-To:'& header line if one exists and it is not empty, or otherwise the contents of the &'From:'& header line. Apart from the removal of leading @@ -13211,8 +13392,7 @@ One of its values causes the address to be passed to another router. When this happens, &$self_hostname$& is set to the name of the local host that the original router encountered. In other circumstances its contents are null. -.vitem &$sender_address$& -.vindex "&$sender_address$&" +.tvar &$sender_address$& When a message is being processed, this variable contains the sender's address that was received in the message's envelope. The case of letters in the address is retained, in both the local part and the domain. For bounce messages, the @@ -13227,12 +13407,10 @@ distinguish it from data from a recipient address. The value does not persist after the end of the current ACL statement. If you want to preserve it for longer, you can save it in an ACL variable. -.vitem &$sender_address_domain$& -.vindex "&$sender_address_domain$&" +.tvar &$sender_address_domain$& The domain portion of &$sender_address$&. -.vitem &$sender_address_local_part$& -.vindex "&$sender_address_local_part$&" +.tvar &$sender_address_local_part$& The local part portion of &$sender_address$&. .vitem &$sender_data$& @@ -13270,8 +13448,7 @@ This boolean variable is true if a successful HELO verification was .cindex "DNS" "DNSSEC" done using DNS information the resolver library stated was authenticated data. -.vitem &$sender_helo_name$& -.vindex "&$sender_helo_name$&" +.tvar &$sender_helo_name$& When a message is received from a remote host that has issued a HELO or EHLO command, the argument of that command is placed in this variable. It is also set if HELO or EHLO is used when a message is received using SMTP locally via @@ -13306,7 +13483,6 @@ library, by setting: dns_dnssec_ok = 1 .endd -.new In addition, on Linux with glibc 2.31 or newer the resolver library will default to stripping out a successful validation status. This will break a previously working Exim installation. @@ -13316,7 +13492,6 @@ glibc to pass through any successful validation with a new option in .code options trust-ad .endd -.wen Exim does not perform DNSSEC validation itself, instead leaving that to a validating resolver (e.g. unbound, or bind with suitable configuration). @@ -13330,8 +13505,7 @@ all EDNS0 options, then this will have no effect. OpenBSD's asr resolver is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3). -.vitem &$sender_host_name$& -.vindex "&$sender_host_name$&" +.tvar &$sender_host_name$& When a message is received from a remote host, this variable contains the host's name as obtained by looking up its IP address. For messages received by other means, this variable is empty. @@ -13449,8 +13623,7 @@ host name, as specified by the &%smtp_active_hostname%& option. The value of &$smtp_active_hostname$& is saved with any message that is received, so its value can be consulted during routing and delivery. -.vitem &$smtp_command$& -.vindex "&$smtp_command$&" +.tvar &$smtp_command$& During the processing of an incoming SMTP command, this variable contains the entire command. This makes it possible to distinguish between HELO and EHLO in the HELO ACL, and also to distinguish between commands such as these: @@ -13463,9 +13636,8 @@ command, the address in &$smtp_command$& is the original address before any rewriting, whereas the values in &$local_part$& and &$domain$& are taken from the address after SMTP-time rewriting. -.vitem &$smtp_command_argument$& +.tvar &$smtp_command_argument$& .cindex "SMTP" "command, argument for" -.vindex "&$smtp_command_argument$&" While an ACL is running to check an SMTP command, this variable contains the argument, that is, the text that follows the command name, with leading white space removed. Following the introduction of &$smtp_command$&, this variable is @@ -13497,7 +13669,11 @@ filter file to set values that can be tested in users' filter files. For example, a system filter could set a value indicating how likely it is that a message is junk mail. -.vitem &$spam_$&&'xxx'& +.vitem &$spam_score$& &&& + &$spam_score_int$& &&& + &$spam_bar$& &&& + &$spam_report$& &&& + &$spam_action$& A number of variables whose names start with &$spam$& are available when Exim is compiled with the content-scanning extension. For details, see section &<>&. @@ -13693,10 +13869,20 @@ the value of the Distinguished Name of the certificate is made available in the If certificate verification fails it may refer to a failing chain element which is not the leaf. -.vitem &$tls_in_sni$& -.vindex "&$tls_in_sni$&" + +.vitem &$tls_in_resumption$& &&& + &$tls_out_resumption$& +.vindex &$tls_in_resumption$& +.vindex &$tls_out_resumption$& +.cindex TLS resumption +Observability for TLS session resumption. See &<>& for details. + + +.tvar &$tls_in_sni$& .vindex "&$tls_sni$&" .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI "observability on server" When a TLS session is being established, if the client sends the Server Name Indication extension, the value will be placed in this variable. If the variable appears in &%tls_certificate%& then this option and @@ -13712,6 +13898,8 @@ the outbound. .vitem &$tls_out_sni$& .vindex "&$tls_out_sni$&" .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI "observability in client" During outbound SMTP deliveries, this variable reflects the value of the &%tls_sni%& option on the transport. @@ -13872,6 +14060,8 @@ taint mode of the Perl interpreter. You are encouraged to set this option to a true value. To avoid breaking existing installations, it defaults to false. +&*Note*&: This is entirely separate from Exim's tainted-data tracking. + .section "Calling Perl subroutines" "SECID86" When the configuration file includes a &%perl_startup%& option you can make use @@ -14306,9 +14496,11 @@ listed in more than one group. .section "Miscellaneous" "SECID96" .table2 +.row &%add_environment%& "environment variables" .row &%bi_command%& "to run for &%-bi%& command line option" .row &%debug_store%& "do extra internal checks" .row &%disable_ipv6%& "do no IPv6 processing" +.row &%keep_environment%& "environment variables" .row &%keep_malformed%& "for broken files &-- should not happen" .row &%localhost_number%& "for unique message ids in clusters" .row &%message_body_newlines%& "retain newlines in &$message_body$&" @@ -14359,6 +14551,7 @@ listed in more than one group. .row &%log_timezone%& "add timezone to log lines" .row &%message_logs%& "create per-message logs" .row &%preserve_message_logs%& "after message completion" +.row &%panic_coredump%& "request coredump on fatal errors" .row &%process_log_path%& "for SIGUSR1 and &'exiwhat'&" .row &%slow_lookup_log%& "control logging of slow DNS lookups" .row &%syslog_duplication%& "controls duplicate log lines on syslog" @@ -14429,6 +14622,7 @@ listed in more than one group. .row &%notifier_socket%& "override compiled-in value" .row &%pid_file_path%& "override compiled-in value" .row &%queue_run_max%& "maximum simultaneous queue runners" +.row &%smtp_backlog_monitor%& "level to log listen backlog" .endtable @@ -14504,8 +14698,10 @@ listed in more than one group. .row &%local_scan_timeout%& "timeout for &[local_scan()]&" .row &%message_size_limit%& "for all messages" .row &%percent_hack_domains%& "recognize %-hack for these domains" +.row &%proxy_protocol_timeout%& "timeout for proxy protocol negotiation" .row &%spamd_address%& "set interface to SpamAssassin" .row &%strict_acl_vars%& "object to unset ACL variables" +.row &%spf_smtp_comment_template%& "template for &$spf_smtp_comment$&" .endtable @@ -14527,8 +14723,11 @@ listed in more than one group. .table2 .row &%gnutls_compat_mode%& "use GnuTLS compatibility mode" .row &%gnutls_allow_auto_pkcs11%& "allow GnuTLS to autoload PKCS11 modules" +.row &%hosts_require_alpn%& "mandatory ALPN" +.row &%hosts_require_helo%& "mandatory HELO/EHLO" .row &%openssl_options%& "adjust OpenSSL compatibility options" .row &%tls_advertise_hosts%& "advertise TLS to these hosts" +.row &%tls_alpn%& "acceptable protocol names" .row &%tls_certificate%& "location of server certificate" .row &%tls_crl%& "certificate revocation list" .row &%tls_dh_max_bits%& "clamp D-H bit count suggestion" @@ -14592,6 +14791,9 @@ See also the &'Policy controls'& section above. .row &%dkim_verify_keytypes%& "DKIM key types accepted for signatures" .row &%dkim_verify_min_keysizes%& "DKIM key sizes accepted for signatures" .row &%dkim_verify_signers%& "DKIM domains for which DKIM ACL is run" +.row &%dmarc_forensic_sender%& "DMARC sender for report messages" +.row &%dmarc_history_file%& "DMARC results log" +.row &%dmarc_tld_file%& "DMARC toplevel domains file" .row &%host_lookup%& "host name looked up for these hosts" .row &%host_lookup_order%& "order of DNS and local name lookups" .row &%recipient_unqualified_hosts%& "may send unqualified recipients" @@ -14693,6 +14895,7 @@ See also the &'Policy controls'& section above. .row &%hold_domains%& "hold delivery for these domains" .row &%local_interfaces%& "for routing checks" .row &%queue_domains%& "no immediate delivery for these" +.row &%queue_fast_ramp%& "parallel delivery with 2-phase queue run" .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" @@ -14739,6 +14942,7 @@ Those options that undergo string expansion before use are marked with .cindex "8-bit characters" .cindex "log" "selectors" .cindex "log" "8BITMIME" +.cindex "ESMTP extensions" 8BITMIME This option causes Exim to send 8BITMIME in its response to an SMTP EHLO command, and to accept the BODY= parameter on MAIL commands. However, though Exim is 8-bit clean, it is not a protocol converter, and it @@ -14908,7 +15112,6 @@ domains (defined in the named domain list &%local_domains%& in the default configuration). This &"magic string"& matches the domain literal form of all the local host's IP addresses. - .option allow_mx_to_ip main boolean false .cindex "MX record" "pointing to IP address" It appears that more and more DNS zone administrators are breaking the rules @@ -14952,6 +15155,7 @@ That is, set the option to an empty string so that no check is done. .option auth_advertise_hosts main "host list&!!" * .cindex "authentication" "advertising" .cindex "AUTH" "advertising" +.cindex "ESMTP extensions" AUTH If any server authentication mechanisms are configured, Exim advertises them in response to an EHLO command only if the calling host matches this list. Otherwise, Exim does not advertise AUTH. @@ -15013,12 +15217,16 @@ just the command name, it is not a complete command line. If an argument is required, it must come from the &%-oA%& command line option. -.option bounce_message_file main string unset +.option bounce_message_file main string&!! unset .cindex "bounce message" "customizing" .cindex "customizing" "bounce message" This option defines a template file containing paragraphs of text to be used for constructing bounce messages. Details of the file's contents are given in -chapter &<>&. See also &%warn_message_file%&. +chapter &<>&. +.cindex bounce_message_file "tainted data" +The option is expanded to give the file path, which must be +absolute and untainted. +See also &%warn_message_file%&. .option bounce_message_text main string unset @@ -15207,6 +15415,7 @@ may wish to deliberately disable them. .option chunking_advertise_hosts main "host list&!!" * .cindex CHUNKING advertisement .cindex "RFC 3030" "CHUNKING" +.cindex "ESMTP extensions" 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. @@ -15343,11 +15552,9 @@ etc. are ignored. If IP literals are enabled, the &(ipliteral)& router declines to handle IPv6 literal addresses. -.new .option dkim_verify_hashes main "string list" "sha256 : sha512" .cindex DKIM "selecting signature algorithms" This option gives a list of hash types which are acceptable in signatures, -.wen and an order of processing. Signatures with algorithms not in the list will be ignored. @@ -15366,14 +15573,12 @@ and an order of processing. Signatures with algorithms not in the list will be ignored. -.new .option dkim_verify_min_keysizes main "string list" "rsa=1024 ed25519=250" This option gives a list of key sizes which are acceptable in signatures. The list is keyed by the algorithm type for the key; the values are in bits. Signatures with keys smaller than given by this option will fail verification. The default enforces the RFC 8301 minimum key size for RSA signatures. -.wen .option dkim_verify_minimal main boolean false If set to true, verification of signatures will terminate after the @@ -15387,6 +15592,14 @@ the ACL once for each signature in the message. See section &<>&. +.option dmarc_forensic_sender main string&!! unset +.option dmarc_history_file main string unset +.option dmarc_tld_file main string unset +.cindex DMARC "main section options" +These options control DMARC processing. +See section &<>& for details. + + .option dns_again_means_nonexist main "domain list&!!" unset .cindex "DNS" "&""try again""& response; overriding" DNS lookups give a &"try again"& response for the DNS errors @@ -15457,7 +15670,6 @@ default. A value of 0 coerces DNSSEC off, a value of 1 coerces DNSSEC on. If the resolver library does not support DNSSEC then this option has no effect. -.new On Linux with glibc 2.31 or newer this is insufficient, the resolver library will default to stripping out a successful validation status. This will break a previously working Exim installation. @@ -15467,7 +15679,6 @@ glibc to pass through any successful validation with a new option in .code options trust-ad .endd -.wen .option dns_ipv4_lookup main "domain list&!!" unset @@ -15558,13 +15769,16 @@ described in section &<>&. .cindex "bounce messages" "success" .cindex "DSN" "success" .cindex "Delivery Status Notification" "success" +.cindex "ESMTP extensions" DSN DSN extensions (RFC3461) will be advertised in the EHLO message to, and accepted from, these hosts. -Hosts may use the NOTIFY and ENVID options on RCPT TO commands, -and RET and ORCPT options on MAIL FROM commands. +Hosts may use the NOTIFY and ORCPT options on RCPT TO commands, +and RET and ENVID options on MAIL FROM commands. A NOTIFY=SUCCESS option requests success-DSN messages. A NOTIFY= option with no argument requests that no delay or failure DSNs are sent. +&*Note*&: Supplying success-DSN messages has been criticised +on privacy grounds; it can leak details of internal forwarding. .option dsn_from main "string&!!" "see below" .cindex "&'From:'& header line" "in bounces" @@ -15998,8 +16212,29 @@ local processes, you must create a host list with an empty item. For example: .code hosts_connection_nolog = : .endd -If the &%smtp_connection%& log selector is not set, this option has no effect. +.new +The hosts affected by this option also do not log "no MAIL in SMTP connection" +lines, as may commonly be produced by a monitoring system. +.wen + +.option hosts_require_alpn main "host list&!!" unset +.cindex ALPN "require negotiation in server" +.cindex TLS ALPN +.cindex TLS "Application Layer Protocol Names" +If the TLS library supports ALPN +then a successful negotiation of ALPN will be required for any client +matching the list, for TLS to be used. +See also the &%tls_alpn%& option. + +&*Note*&: prevention of fallback to in-clear connection is not +managed by this option, and should be done separately. + + +.option hosts_require_helo main "host list&!!" * +.cindex "HELO/EHLO" requiring +Exim will require an accepted HELO or EHLO command from a host matching +this list, before accepting a MAIL command. .option hosts_proxy main "host list&!!" unset @@ -16446,6 +16681,11 @@ to depend on the IP address of the remote host for messages arriving via TCP/IP. After expansion, the value must be a sequence of decimal digits, optionally followed by K or M. +.cindex "SIZE" "ESMTP extension, advertising" +.cindex "ESMTP extensions" SIZE +If nonzero the value will be advertised as a parameter to the ESMTP SIZE +service extension keyword. + &*Note*&: This limit cannot be made to depend on a message's sender or any other properties of an individual message, because it has to be advertised in the server's response to EHLO. String expansion failure causes a temporary @@ -16523,7 +16763,6 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.new .option notifier_socket main string "$spool_directory/exim_daemon_notify" This option gives the name for a unix-domain socket on which the daemon listens for work and information-requests. @@ -16533,12 +16772,14 @@ should need to modify the default. The option is expanded before use. If the platform supports Linux-style abstract socket names, the result is used with a nul byte prefixed. -Otherwise, it should be a full path name and use a directory accessible +Otherwise, +it should be a full path name and use a directory accessible to Exim. -If the Exim command line uses a &%-oX%& option and does not use &%-oP%& +If this option is set as empty, +or the command line &%-oY%& option is used, or +the command line uses a &%-oX%& option and does not use &%-oP%&, then a notifier socket is not created. -.wen .option openssl_options main "string list" "+no_sslv2 +no_sslv3 +single_dh_use +no_ticket +no_renegotiation" @@ -16650,6 +16891,19 @@ to be used in conjunction with &(oracle)& lookups (see section &<>&). The option is available only if Exim has been built with Oracle support. +.new +.option panic_coredump main boolean false +This option is rarely needed but can help for some debugging investigations. +If set, when an internal error is detected by Exim which is sufficient +to terminate the process +(all such are logged in the paniclog) +then a coredump is requested. + +Note that most systems require additional administrative configuration +to permit write a core file for a setuid program, which is Exim's +common installed configuration. +.wen + .option percent_hack_domains main "domain list&!!" unset .cindex "&""percent hack""&" .cindex "source routing" "in email address" @@ -16713,6 +16967,7 @@ of the &%-oX%& option, unless a path is explicitly supplied by &%-oP%&. .option pipelining_advertise_hosts main "host list&!!" * .cindex "PIPELINING" "suppressing advertising" +.cindex "ESMTP extensions" PIPELINING This option can be used to suppress the advertisement of the SMTP PIPELINING extension to specific hosts. See also the &*no_pipelining*& control in section &<>&. When PIPELINING is not advertised and @@ -16723,8 +16978,9 @@ not count as protocol errors (see &%smtp_max_synprot_errors%&). .option pipelining_connect_advertise_hosts main "host list&!!" * .cindex "pipelining" "early connection" -.cindex "pipelining" PIPE_CONNECT -If Exim is built with the SUPPORT_PIPE_CONNECT build option +.cindex "pipelining" PIPECONNECT +.cindex "ESMTP extensions" PIPECONNECT +If Exim is built without the DISABLE_PIPE_CONNECT build option this option controls which hosts the facility is advertised to and from which pipeline early-connection (before MAIL) SMTP commands are acceptable. @@ -16732,11 +16988,16 @@ When used, the pipelining saves on roundtrip times. See also the &%hosts_pipe_connect%& smtp transport option. -Currently the option name &"X_PIPE_CONNECT"& is used. +The SMTP service extension keyword advertised is &"PIPECONNECT"&; +it permits the client to pipeline +TCP connection and hello command (inclear phase), +or TLS-establishment and hello command (encrypted phase), +on later connections to the same host. .option prdr_enable main boolean false .cindex "PRDR" "enabling on server" +.cindex "ESMTP extensions" PRDR This option can be used to enable the Per-Recipient Data Response extension to SMTP, defined by Eric Hall. If the option is set, PRDR is advertised by Exim when operating as a server. @@ -16812,6 +17073,12 @@ admin user unless &%prod_requires_admin%& is set false. See also &%queue_list_requires_admin%& and &%commandline_checks_require_admin%&. +.option proxy_protocol_timeout main time 3s +.cindex proxy "proxy protocol" +This option sets the timeout for proxy protocol negotiation. +For details see section &<>&. + + .option qualify_domain main string "see below" .cindex "domain" "for qualifying addresses" .cindex "address" "qualification" @@ -16847,6 +17114,15 @@ domains that do not match are processed. All other deliveries wait until the next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&. +.option queue_fast_ramp main boolean true +.cindex "queue runner" "two phase" +.cindex "queue" "double scanning" +If set to true, two-phase queue runs, initiated using &%-qq%& on the +command line, may start parallel delivery processes during their first +phase. This will be done when a threshold number of messages have been +routed for a single host. + + .option queue_list_requires_admin main boolean true .cindex "restricting access to features" .oindex "&%-bp%&" @@ -17058,7 +17334,7 @@ or if the message was submitted locally (not using TCP/IP), and the &%-bnq%& option was not set. -.option recipients_max main integer 0 +.option recipients_max main integer 50000 .cindex "limit" "number of recipients" .cindex "recipient" "maximum number" If this option is set greater than zero, it specifies the maximum number of @@ -17082,7 +17358,7 @@ initial set of recipients. The remote server should then re-send the message for the remaining recipients at a later time. -.option remote_max_parallel main integer 2 +.option remote_max_parallel main integer 4 .cindex "delivery" "parallelism for remote" This option controls parallel delivery of one message to a number of remote hosts. If the value is less than 2, parallel delivery is disabled, and Exim @@ -17103,6 +17379,9 @@ manager, there is no way of controlling the total number of simultaneous deliveries if the configuration allows a delivery attempt as soon as a message is received. +See also the &%max_parallel%& generic transport option, +and the &%serialize_hosts%& smtp transport option. + .cindex "number of deliveries" .cindex "delivery" "maximum number of" If you want to control the total number of deliveries on the system, you @@ -17271,7 +17550,7 @@ live with. . searchable. NM changed this occurrence for bug 1197 to no longer allow . the option name to split. -.option "smtp_accept_max_per_connection" main integer 1000 &&& +.option "smtp_accept_max_per_connection" main integer&!! 1000 &&& smtp_accept_max_per_connection .cindex "SMTP" "limiting incoming message count" .cindex "limit" "messages per SMTP connection" @@ -17281,6 +17560,9 @@ results in the transfer of a message. After the limit is reached, a 421 response is given to subsequent MAIL commands. This limit is a safety precaution against a client that goes mad (incidents of this type have been seen). +The option is expanded after the HELO or EHLO is received +and may depend on values available at that time. +An empty or zero value after expansion removes the limit. .option smtp_accept_max_per_host main string&!! unset @@ -17388,6 +17670,14 @@ messages, it is also used as the default for HELO commands in callout verification if there is no remote transport from which to obtain a &%helo_data%& value. +.option smtp_backlog_monitor main integer 0 +.cindex "connection backlog" monitoring +If this option is set to greater than zero, and the backlog of available +TCP connections on a socket listening for SMTP is larger than it, a line +is logged giving the value and the socket address and port. +The value is retrived jsut before an accept call. +This facility is only available on Linux. + .option smtp_banner main string&!! "see below" .cindex "SMTP" "welcome banner" .cindex "banner for SMTP" @@ -17418,7 +17708,7 @@ is zero). If there isn't enough space, a temporary error code is returned. .option smtp_connect_backlog main integer 20 -.cindex "connection backlog" +.cindex "connection backlog" "set maximum" .cindex "SMTP" "connection backlog" .cindex "backlog of connections" This option specifies a maximum number of waiting SMTP connections. Exim passes @@ -17456,6 +17746,7 @@ hosts), you can do so by an appropriate use of a &%control%& modifier in an ACL .option smtp_etrn_command main string&!! unset .cindex "ETRN" "command to be run" +.cindex "ESMTP extensions" ETRN .vindex "&$domain$&" If this option is set, the given command is run whenever an SMTP ETRN command is received from a host that is permitted to issue such commands (see @@ -17467,12 +17758,10 @@ example: smtp_etrn_command = /etc/etrn_command $domain \ $sender_host_address .endd -.new If the option is not set, the argument for the ETRN command must be a &'#'& followed by an address string. In this case an &'exim -R '& command is used; if the ETRN ACL has set up a named-queue then &'-MCG '& is appended. -.wen A new process is created to run the command, but Exim does not wait for it to complete. Consequently, its status cannot be checked. If the command cannot be @@ -17636,7 +17925,8 @@ example, instead of &"Administrative prohibition"&, it might give: .option smtputf8_advertise_hosts main "host list&!!" * -.cindex "SMTPUTF8" "advertising" +.cindex "SMTPUTF8" "ESMTP extension, advertising" +.cindex "ESMTP extensions" SMTPUTF8 When Exim is built with support for internationalised mail names, the availability thereof is advertised in response to EHLO only to those client hosts that match this option. See @@ -17654,6 +17944,46 @@ See section &<>& for more details. This option is available when Exim is compiled with SPF support. See section &<>& for more details. +.option spf_smtp_comment_template main string&!! "Please%_see%_http://www.open-spf.org/Why" +This option is available when Exim is compiled with SPF support. It +allows the customisation of the SMTP comment that the SPF library +generates. You are strongly encouraged to link to your own explanative +site. The template must not contain spaces. If you need spaces in the +output, use the proper placeholder. If libspf2 can not parse the +template, it uses a built-in default broken link. The following placeholders +(along with Exim variables (but see below)) are allowed in the template: +.ilist +&*%_*&: A space. +.next +&*%{L}*&: Envelope sender's local part. +.next +&*%{S}*&: Envelope sender. +.next +&*%{O}*&: Envelope sender's domain. +.next +&*%{D}*&: Current(?) domain. +.next +&*%{I}*&: SMTP client Ip. +.next +&*%{C}*&: SMTP client pretty IP. +.next +&*%{T}*&: Epoch time (UTC). +.next +&*%{P}*&: SMTP client domain name. +.next +&*%{V}*&: IP version. +.next +&*%{H}*&: EHLO/HELO domain. +.next +&*%{R}*&: Receiving domain. +.endlist +The capitalized placeholders do proper URL encoding, if you use them +lowercased, no encoding takes place. This list was compiled from the +libspf2 sources. + +A note on using Exim variables: As +currently the SPF library is initialized before the SMTP EHLO phase, +the variables useful for expansion are quite limited. .option split_spool_directory main boolean false @@ -17805,6 +18135,7 @@ syslog. The value must be no longer than 32 characters. See chapter .option syslog_timestamp main boolean true .cindex "syslog" "timestamps" +.cindex timestamps syslog If &%syslog_timestamp%& is set false, the timestamps on Exim's log lines are omitted when these lines are sent to syslog. See chapter &<>& for details of Exim's logging. @@ -17927,6 +18258,7 @@ unfortunately not all, operating systems. .cindex "TLS" "advertising" .cindex "encryption" "on SMTP connection" .cindex "SMTP" "encrypted connection" +.cindex "ESMTP extensions" STARTTLS When Exim is built with support for TLS encrypted connections, the availability of the STARTTLS command to set up an encrypted session is advertised in response to EHLO only to those client hosts that match this option. See @@ -17936,7 +18268,18 @@ using the &%tls_certificate%& option. If TLS support for incoming connections is not required the &%tls_advertise_hosts%& option should be set empty. -.option tls_certificate main string list&!! unset +.option tls_alpn main "string list&!!" "smtp : esmtp" +.cindex TLS "Application Layer Protocol Names" +.cindex TLS ALPN +.cindex ALPN "set acceptable names for server" +If this option is set, +the TLS library supports ALPN, +and the client offers either more than +ALPN name or a name which does not match the list, +the TLS connection is declined. + + +.option tls_certificate main "string list&!!" unset .cindex "TLS" "server certificate; location of" .cindex "certificate" "server, location of" The value of this option is expanded, and must then be a list of absolute paths to @@ -17959,13 +18302,16 @@ when a list of more than one file is used, the &$tls_in_ourcert$& variable is unreliable. The macro "_TLS_BAD_MULTICERT_IN_OURCERT" will be defined for those versions. +.cindex SNI "selecting server certificate based on" If the option contains &$tls_out_sni$& and Exim is built against OpenSSL, then if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in &<>& will be re-expanded. -If this option is unset or empty a fresh self-signed certificate will be -generated for every connection. +If this option is unset or empty a self-signed certificate will be +used. +Under Linux this is generated at daemon startup; on other platforms it will be +generated fresh for every connection. .option tls_crl main string&!! unset .cindex "TLS" "server certificate revocation list" @@ -18008,12 +18354,7 @@ larger prime than requested. The value of this option is expanded and indicates the source of DH parameters to be used by Exim. -This option is ignored for GnuTLS version 3.6.0 and later. -The library manages parameter negotiation internally. - -&*Note: The Exim Maintainers strongly recommend, -for other TLS library versions, -using a filename with site-generated +&*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. @@ -18064,8 +18405,15 @@ of the later IKE values, which led into RFC7919 providing new fixed constants (the "ffdhe" identifiers). At this point, all of the "ike" values should be considered obsolete; -they're still in Exim to avoid breaking unusual configurations, but are +they are still in Exim to avoid breaking unusual configurations, but are candidates for removal the next time we have backwards-incompatible changes. +Two of them in particular (&`ike1`& and &`ike22`&) are called out by RFC 8247 +as MUST NOT use for IPSEC, and two more (&`ike23`& and &`ike24`&) as +SHOULD NOT. +Because of this, Exim regards them as deprecated; if either of the first pair +are used, warnings will be logged in the paniclog, and if any are used then +warnings will be logged in the mainlog. +All four will be removed in a future Exim release. 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, @@ -18142,7 +18490,7 @@ further details, see section &<>&. -.option tls_privatekey main string list&!! unset +.option tls_privatekey main "string list&!!" unset .cindex "TLS" "server private key; location of" The value of this option is expanded, and must then be a list of absolute paths to files which contains the server's private keys. @@ -18176,6 +18524,12 @@ preference order of the available ciphers. Details are given in sections &<>& and &<>&. +.option tls_resumption_hosts main "host list&!!" unset +.cindex TLS resumption +This option controls which connections to offer the TLS resumption feature. +See &<>& for details. + + .option tls_try_verify_hosts main "host list&!!" unset .cindex "TLS" "client certificate verification" .cindex "certificate" "verification of client" @@ -18210,7 +18564,9 @@ than the public cert of individual clients. With both OpenSSL and GnuTLS, if the value is a file then the certificates are sent by Exim as a server to connecting clients, defining the list of accepted certificate authorities. Thus the values defined should be considered public data. To avoid this, -use the explicit directory version. +use the explicit directory version. (If your peer is Exim up to 4.85, +using GnuTLS, you may need to send the CAs (thus using the file +variant). Otherwise the peer doesn't send its certificate.) See &<>& for discussion of when this option might be re-expanded. @@ -18230,7 +18586,8 @@ either &%tls_verify_hosts%& or &%tls_try_verify_hosts%& is set and 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 -aborted. &*Warning*&: Including a host in &%tls_verify_hosts%& does not require +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. @@ -18364,14 +18721,18 @@ regular expression by a parenthesized subpattern. The default value for See &%uucp_from_pattern%& above. -.option warn_message_file main string unset +.option warn_message_file main string&!! unset .cindex "warning of delay" "customizing the message" .cindex "customizing" "warning message" This option defines a template file containing paragraphs of text to be used for constructing the warning message which is sent by Exim when a message has been in the queue for a specified amount of time, as specified by &%delay_warning%&. Details of the file's contents are given in chapter -&<>&. See also &%bounce_message_file%&. +&<>&. +.cindex warn_message_file "tainted data" +The option is expanded to give the file path, which must be +absolute and untainted. +See also &%bounce_message_file%&. .option write_rejectlog main boolean true @@ -18399,6 +18760,9 @@ which the preconditions are tested. The order of expansion of the options that provide data for a transport is: &%errors_to%&, &%headers_add%&, &%headers_remove%&, &%transport%&. +The name of a router is limited to be &drivernamemax; ASCII characters long; +prior to Exim 4.95 names would be silently truncated at this length, but now +it is enforced. .option address_data routers string&!! unset @@ -18525,7 +18889,11 @@ address (with affixes removed if relevant) is the name of an account on the local system. The check is done by calling the &[getpwnam()]& function rather than trying to read &_/etc/passwd_& directly. This means that other methods of holding password data (such as NIS) are supported. If the local part is a local -user, &$home$& is set from the password data, and can be tested in other +user, +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using router check_local_user option" +&$local_part_data$& is set to an untainted version of the local part and +&$home$& is set from the password data. The latter can be tested in other preconditions that are evaluated after this one (the order of evaluation is given in section &<>&). However, the value of &$home$& can be overridden by &%router_home_directory%&. If the local part is not a local user, @@ -18652,7 +19020,7 @@ transport option of the same name. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_request_domains%& will be done with -the dnssec request bit set. +the DNSSEC request bit set. This applies to all of the SRV, MX, AAAA, A lookup sequence. .option dnssec_require_domains routers "domain list&!!" unset @@ -18661,7 +19029,7 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_require_domains%& will be done with -the dnssec request bit set. Any returns not having the Authenticated Data bit +the DNSSEC request bit set. Any returns not having the Authenticated Data bit (AD bit) set will be ignored and logged as a host-lookup failure. This applies to all of the SRV, MX, AAAA, A lookup sequence. @@ -18672,7 +19040,8 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence. If this option is set, the router is skipped unless the current domain matches the list. If the match is achieved by means of a file lookup, the data that the lookup returned for the domain is placed in &$domain_data$& for use in string -expansions of the driver's private options. See section &<>& for +expansions of the driver's private options and in the transport. +See section &<>& for a list of the order in which preconditions are evaluated. @@ -18856,9 +19225,7 @@ colon-separated (by default, changeable in the usual way &<>& that is associated with any addresses that are accepted by the router. However, the option has no effect when an address is just being verified. Each list item is separately expanded, at transport time. -.new If an item ends in *, it will match any header with the given prefix. -.wen The way in which the text is used to remove header lines at transport time is described in section &<>&. Header lines are not actually removed until @@ -18971,11 +19338,9 @@ command for LMTP, SMTP, and BSMTP deliveries has the prefix removed by default. This behaviour can be overridden by setting &%rcpt_include_affixes%& true on the relevant transport. -.new .vindex &$local_part_prefix_v$& If wildcarding (above) was used then the part of the prefix matching the wildcard is available in &$local_part_prefix_v$&. -.wen When an address is being verified, &%local_part_prefix%& affects only the behaviour of the router. If the callout feature of verification is in use, this @@ -19039,12 +19404,13 @@ section &<>& for a discussion of local part lists. Because the string is expanded, it is possible to make it depend on the domain, for example: .code -local_parts = dbm;/usr/local/specials/$domain +local_parts = dbm;/usr/local/specials/$domain_data .endd .vindex "&$local_part_data$&" If the match is achieved by a lookup, the data that the lookup returned for the local part is placed in the variable &$local_part_data$& for use in -expansions of the router's private options. You might use this option, for +expansions of the router's private options or in the transport. +You might use this option, for example, if you have a large number of local virtual domains, and you want to send all postmaster mail to the same place without having to set up an alias in each virtual domain: @@ -19182,7 +19548,7 @@ but the user is specified symbolically, the gid associated with the uid is used. For example: .code require_files = mail:/some/file -require_files = $local_part:$home/.procmailrc +require_files = $local_part_data:$home/.procmailrc .endd If a user or group name in a &%require_files%& list does not exist, the &%require_files%& condition fails. @@ -19389,6 +19755,8 @@ Values containing a list-separator should have them doubled. When a router runs, the strings are evaluated in order, to create variables which are added to the set associated with the address. +This is done immediately after all the preconditions, before the +evaluation of the &%address_data%& option. The variable is set with the expansion of the value. The variables can be used by the router options (not including any preconditions) @@ -20810,7 +21178,6 @@ is not the case when the file contains syntactically valid items that happen to yield empty addresses, for example, items containing only RFC 2822 address comments. -.new .cindex "tainted data" "in filenames" .cindex redirect "tainted data" Tainted data may not be used for a filename. @@ -20821,7 +21188,6 @@ as they are provided by a potential attacker. In the examples above, &$local_part$& is used for looking up data held locally on the system, and not used directly (the second example derives &$home$& via the passsword file or database, using &$local_part$&). -.wen @@ -21048,11 +21414,9 @@ It must be given as .code list1: :include:/opt/lists/list1 .endd -.new .cindex "tainted data" "in filenames" .cindex redirect "tainted data" Tainted data may not be used for a filename. -.wen .next .cindex "address redirection" "to black hole" .cindex "delivery" "discard" @@ -21104,7 +21468,7 @@ The text is not included in the response to an EXPN command. In non-SMTP cases the text is included in the error message that Exim generates. .cindex "SMTP" "error codes" -By default, Exim sends a 451 SMTP code for a &':defer:'&, and 550 for +By default for verify, Exim sends a 451 SMTP code for a &':defer:'&, and 550 for &':fail:'&. However, if the message starts with three digits followed by a space, optionally followed by an extended code of the form &'n.n.n'&, also followed by a space, and the very first digit is the same as the default error @@ -21813,7 +22177,7 @@ local_users: # This transport overrides the group group_delivery: driver = appendfile - file = /var/spool/mail/$local_part + file = /var/spool/mail/$local_part_data group = mail .endd If &%user%& is set for a transport, its value overrides what is set in the @@ -21941,6 +22305,10 @@ and &$original_domain$& is never set. .scindex IIDgenoptra1 "generic options" "transport" .scindex IIDgenoptra2 "options" "generic; for transports" .scindex IIDgenoptra3 "transport" "generic options for" +The name of a transport is limited to be &drivernamemax; ASCII characters long; +prior to Exim 4.95 names would be silently truncated at this length, but now +it is enforced. + The following generic options apply to all transports: @@ -22010,6 +22378,12 @@ header, Exim has a configuration option (&%envelope_to_remove%&) which requests its removal from incoming messages, so that delivered messages can safely be resent to other recipients. +&*Note:*& If used on a transport handling multiple recipients +(the smtp transport unless &%rcpt_max%& is 1, the appendfile, pipe or lmtp +transport if &%batch_max%& is greater than 1) +then information about Bcc recipients will be leaked. +Doing so is generally not advised. + .option event_action transports string&!! unset .cindex events @@ -22061,9 +22435,7 @@ Each list item is separately expanded. If the result of the expansion is an empty string, or if the expansion is forced to fail, no action is taken. Other expansion failures are treated as errors and cause the delivery to be deferred. -.new If an item ends in *, it will match any header with the given prefix. -.wen Matching headers are omitted from the message as it is transported, as described in section &<>&. Header removal can also be specified by @@ -22242,7 +22614,7 @@ This defaults to the incoming sender address, but can be changed by setting .option return_path_add transports boolean false -.cindex "&'Return-path:'& header line" +.chindex Return-path: If this option is true, a &'Return-path:'& header is added to the message. Although the return path is normally available in the prefix line of BSD mailboxes, this is commonly not displayed by MUAs, and so the user does not @@ -22328,7 +22700,7 @@ message. For example, a content scan could insert a new header line containing a spam score. This could be interpreted by a filter in the user's MUA. It is not possible to discard a message at this stage. -.cindex "SMTP" "SIZE" +.cindex "SIZE" "ESMTP extension" A problem might arise if the filter increases the size of a message that is being sent down an SMTP connection. If the receiving SMTP server has indicated support for the SIZE parameter, Exim will have sent the size of the message @@ -22353,9 +22725,10 @@ an ideal name for this feature here, but as it was already implemented for the The expansion variables &$host$& and &$host_address$& are available when the transport is a remote one. They contain the name and IP address of the host to which the message is being sent. For example: +. used to have $sender_address in this cmdline, but it's tainted .code transport_filter = /some/directory/transport-filter.pl \ - $host $host_address $sender_address $pipe_addresses + $host $host_address $pipe_addresses .endd Two problems arise if you want to use more complicated expansion items to @@ -22618,14 +22991,17 @@ If &%file%& or &%directory%& is set for a delivery from a redirection, it is used to determine the file or directory name for the delivery. Normally, the contents of &$address_file$& are used in some way in the string expansion. .endlist -.new +If the &%create_file%& option is set to a path which +matches (see the option definition below for details) +a file or directory name +for the delivery, that name becomes de-tainted. + .cindex "tainted data" "in filenames" .cindex appendfile "tainted data" Tainted data may not be used for a file or directory name. This means that, for instance, &$local_part$& cannot be used directly as a component of a path. It can however be used as the key for a lookup which returns a path (or component). -.wen .cindex "Sieve filter" "configuring &(appendfile)&" @@ -22648,7 +23024,7 @@ is used as a result of a &"keep"& action in the filter. This example shows one way of handling this requirement: .code file = ${if eq{$address_file}{inbox} \ - {/var/mail/$local_part} \ + {/var/mail/$local_part_data} \ {${if eq{${substr_0_1:$address_file}}{/} \ {$address_file} \ {$home/mail/$address_file} \ @@ -22768,13 +23144,30 @@ delivery, it applies to the top level directory, not the maildir directories beneath. The option must be set to one of the words &"anywhere"&, &"inhome"&, or -&"belowhome"&. In the second and third cases, a home directory must have been -set for the transport. This option is not useful when an explicit filename is +&"belowhome"&, or to an absolute path. + +In the second and third cases, a home directory must have been +set for the transport, and the file or directory being created must +reside within it. +The "belowhome" checking additionally checks for attempts to use "../" +to evade the testing. +This option is not useful when an explicit filename is given for normal mailbox deliveries. It is intended for the case when filenames are generated from users' &_.forward_& files. These are usually handled by an &(appendfile)& transport called &%address_file%&. See also &%file_must_exist%&. +In the fourth case, +the value given for this option must be an absolute path for an +existing directory. +The value is used for checking instead of a home directory; +checking is done in "belowhome" mode. + +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using appendfile create_file option" +If "belowhome" checking is used, the file or directory path +becomes de-tainted. + .option directory appendfile string&!! unset This option is mutually exclusive with the &%file%& option, but one of &%file%& @@ -22787,6 +23180,9 @@ appended to a single mailbox file. A number of different formats are provided (see &%maildir_format%& and &%mailstore_format%&), and see section &<>& for further details of this form of delivery. +The result of expansion must not be tainted, unless the &%create_file%& option +specifies a path. + .option directory_file appendfile string&!! "see below" .cindex "base62" @@ -22819,6 +23215,9 @@ specifies a single file, to which the message is appended. One or more of &%use_fcntl_lock%&, &%use_flock_lock%&, or &%use_lockfile%& must be set with &%file%&. +The result of expansion must not be tainted, unless the &%create_file%& option +specifies a path. + .cindex "NFS" "lock file" .cindex "locking files" .cindex "lock files" @@ -22829,8 +23228,8 @@ The string value is expanded for each delivery, and must yield an absolute path. The most common settings of this option are variations on one of these examples: .code -file = /var/spool/mail/$local_part -file = /home/$local_part/inbox +file = /var/spool/mail/$local_part_data +file = /home/$local_part_data/inbox file = $home/inbox .endd .cindex "&""sticky""& bit" @@ -23586,7 +23985,7 @@ and directories in a maildir mailbox, including subdirectories for maildir++ folders. Consider this example: .code maildir_format = true -directory = /var/mail/$local_part\ +directory = /var/mail/$local_part_data\ ${if eq{$local_part_suffix}{}{}\ {/.${substr_1:$local_part_suffix}}} maildirfolder_create_regex = /\.[^/]+$ @@ -24063,11 +24462,9 @@ directories are also controllable. See chapter &<>& for details of the local delivery environment and chapter &<>& for a discussion of local delivery batching. -.new .cindex "tainted data" "in pipe command" .cindex pipe "tainted data" Tainted data may not be used for the command name. -.wen .section "Concurrent delivery" "SECID140" @@ -24203,6 +24600,9 @@ This list is a compromise for maximum compatibility with other MTAs. Note that the &%environment%& option can be used to add additional variables to this environment. The environment for the &(pipe)& transport is not subject to the &%add_environment%& and &%keep_environment%& main config options. +&*Note*&: Using enviroment variables loses track of tainted data. +Writers of &(pipe)& transport commands should be wary of data supplied +by potential attackers. .display &`DOMAIN `& the domain of the address &`HOME `& the home directory, if set @@ -24294,6 +24694,9 @@ the &%path%& option below). The command is split up into separate arguments by Exim, and each argument is separately expanded, as described in section &<>& above. +.cindex "tainted data" +No part of the resulting command may be tainted. + .option environment pipe string&!! unset .cindex "&(pipe)& transport" "environment for command" @@ -24576,14 +24979,14 @@ configuration for &%procmail%&: # transport procmail_pipe: driver = pipe - command = /usr/local/bin/procmail -d $local_part + command = /usr/local/bin/procmail -d $local_part_data return_path_add delivery_date_add envelope_to_add check_string = "From " escape_string = ">From " umask = 077 - user = $local_part + user = $local_part_data group = mail # router @@ -24609,12 +25012,15 @@ use a shell to run pipe commands. .cindex "Cyrus" The next example shows a transport and a router for a system where local deliveries are handled by the Cyrus IMAP server. +. Used to have R: local_part_suffix = .* + T: -m $local_part_suffix_v +. but that suffix is tainted so cannot be used in a command arg +. Really, you'd want to use a lookup for acceptable suffixes to do real detainting .code # transport local_delivery_cyrus: driver = pipe command = /usr/cyrus/bin/deliver \ - -m ${substr_1:$local_part_suffix} -- $local_part + -- $local_part_data user = cyrus group = mail return_output @@ -24626,7 +25032,6 @@ local_delivery_cyrus: local_user_cyrus: driver = accept check_local_user - local_part_suffix = .* transport = local_delivery_cyrus .endd Note the unsetting of &%message_prefix%& and &%message_suffix%&, and the use of @@ -24774,12 +25179,14 @@ authenticated as a client. .option command_timeout smtp time 5m +.cindex timeout "smtp transport command" This sets a timeout for receiving a response to an SMTP command that has been sent out. It is also used when waiting for the initial banner line from the remote host. Its value must not be zero. .option connect_timeout smtp time 5m +.cindex timeout "smtp transport connect" This sets a timeout for the &[connect()]& function, which sets up a TCP/IP call to a remote host. A setting of zero allows the system timeout (typically several minutes) to act. To have any effect, the value of this option must be @@ -24815,6 +25222,7 @@ be treated as unset and &%tls_require_ciphers%& will be used instead. .option data_timeout smtp time 5m +.cindex timeout "for transmitted SMTP data blocks" This sets a timeout for the transmission of each block in the data portion of the message. As a result, the overall timeout for a message depends on the size of the message. Its value must not be zero. See also &%final_timeout%&. @@ -24822,7 +25230,7 @@ of the message. Its value must not be zero. See also &%final_timeout%&. .option dkim_canon smtp string&!! unset DKIM signing option. For details see section &<>&. -.option dkim_domain smtp string list&!! unset +.option dkim_domain smtp "string list&!!" unset DKIM signing option. For details see section &<>&. .option dkim_hash smtp string&!! sha256 DKIM signing option. For details see section &<>&. @@ -24885,7 +25293,7 @@ details. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_request_domains%& will be done with -the dnssec request bit set. Setting this transport option is only useful if the +the DNSSEC request bit set. Setting this transport option is only useful if the transport overrides or sets the host names. See the &%dnssec_request_domains%& router option. @@ -24897,7 +25305,7 @@ router option. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_require_domains%& will be done with -the dnssec request bit set. Setting this transport option is only +the DNSSEC request bit set. Setting this transport option is only useful if the transport overrides or sets the host names. See the &%dnssec_require_domains%& router option. @@ -24953,6 +25361,7 @@ fails"& facility. .option final_timeout smtp time 10m +.cindex timeout "for transmitted SMTP data accept" This is the timeout that applies while waiting for the response to the final line containing just &"."& that terminates a message. Its value must not be zero. @@ -24988,12 +25397,43 @@ servers or different local IP addresses. For example, if you want the string that is used for &%helo_data%& to be obtained by a DNS lookup of the outgoing interface address, you could use this: .code -helo_data = ${lookup dnsdb{ptr=$sending_ip_address}{$value}\ +helo_data = ${lookup dnsdb{ptr=$sending_ip_address} \ + {${listextract{1}{<\n $value}}} \ {$primary_hostname}} .endd The use of &%helo_data%& applies both to sending messages and when doing callouts. +.option host_name_extract smtp "string list&!!" "see below" +.cindex "load balancer" "hosts behind" +.cindex TLS resumption +Some mail-accepting sites +(notably Microsoft) +operate many servers behind a network load-balancer. When this is done, +with separated TLS session caches, TLS session resuption becomes problematic. +It will only succeed when the same server happens to be selected by the +load-balancer, matching the session stored in the client's cache. + +Exim can pull out a server name, if there is one, from the response to the +client's SMTP EHLO command. +The default value of this option: +.code + ${if and { {match {$host} {.outlook.com\$}} \ + {match {$item} {\N^250-([\w.]+)\s\N}} \ + } {$1}} +.endd +suffices for one known case. +During the expansion of this option the &$item$& variable will have the +server's EHLO response. +The result of the option expansion is included in the key used to store and +retrieve the TLS session, for session resumption. + +Operators of high-load sites may wish to evaluate their logs for indications +of other destination sites operating load-balancers, and develop a suitable +expression for this option. +The smtp:ehlo event and the &$tls_out_resumption$& variable +will be useful for such work. + .option hosts smtp "string list&!!" unset Hosts are associated with an address by a router such as &(dnslookup)&, which finds the hosts by looking up the address domain in the DNS, or by @@ -25041,12 +25481,13 @@ facilities such as AUTH, PIPELINING, SIZE, and STARTTLS. .option hosts_avoid_pipelining smtp "host list&!!" unset .cindex "PIPELINING" "avoiding the use of" -Exim will not use the SMTP PIPELINING extension when delivering to any host +.cindex "ESMTP extensions" PIPELINING +Exim will not use the ESMTP PIPELINING extension when delivering to any host that matches this list, even if the server host advertises PIPELINING support. .option hosts_pipe_connect smtp "host list&!!" unset .cindex "pipelining" "early connection" -.cindex "pipelining" PIPE_CONNECT +.cindex "pipelining" PIPECONNECT If Exim is built with the SUPPORT_PIPE_CONNECT build option this option controls which to hosts the facility watched for and recorded, and used for subsequent connections. @@ -25060,7 +25501,8 @@ so combines well with TCP Fast Open. See also the &%pipelining_connect_advertise_hosts%& main option. Note: -When the facility is used, the transport &%helo_data%& option +When the facility is used, if the transport &%interface%& option is unset +the &%helo_data%& option will be expanded before the &$sending_ip_address$& variable is filled in. A check is made for the use of that variable, without the @@ -25165,20 +25607,38 @@ hard failure if required. See also &%hosts_try_auth%&, and chapter &<>& for details of authentication. -.option hosts_request_ocsp smtp "host list&!!" * +.option hosts_request_ocsp smtp "host list&!!" "see below" .cindex "TLS" "requiring for certain servers" Exim will request a Certificate Status on a TLS session for any host that matches this list. &%tls_verify_certificates%& should also be set for the transport. +.new +The default is &"**"& if DANE is not in use for the connection, +or if DANE-TA us used. +It is empty if DANE-EE is used. +.wen + +.option hosts_require_alpn smtp "host list&!!" unset +.cindex ALPN "require negotiation in client" +.cindex TLS ALPN +.cindex TLS "Application Layer Protocol Names" +If the TLS library supports ALPN +then a successful negotiation of ALPN will be required for any host +matching the list, for TLS to be used. +See also the &%tls_alpn%& option. + +&*Note*&: prevention of fallback to in-clear connection is not +managed by this option; see &%hosts_require_tls%&. + .option hosts_require_dane smtp "host list&!!" unset .cindex DANE "transport options" .cindex DANE "requiring for certain servers" If built with DANE support, Exim will require that a DNSSEC-validated TLSA record is present for any host matching the list, -and that a DANE-verified TLS connection is made. See -the &%dnssec_request_domains%& router and transport options. +and that a DANE-verified TLS connection is made. There will be no fallback to in-clear communication. +See the &%dnssec_request_domains%& router and transport options. See section &<>&. .option hosts_require_ocsp smtp "host list&!!" unset @@ -25198,9 +25658,10 @@ incoming messages, use an appropriate ACL. .cindex "authentication" "optional in client" This option provides a list of servers to which, provided they announce authentication support, Exim will attempt to authenticate as a client when it -connects. If authentication fails, Exim will try to transfer the message -unauthenticated. See also &%hosts_require_auth%&, and chapter -&<>& for details of authentication. +connects. If authentication fails +and &%hosts_require_auth%& permits, +Exim will try to transfer the message unauthenticated. +See also chapter &<>& for details of authentication. .option hosts_try_chunking smtp "host list&!!" * .cindex CHUNKING "enabling, in client" @@ -25208,19 +25669,18 @@ unauthenticated. See also &%hosts_require_auth%&, and chapter .cindex "RFC 3030" "CHUNKING" This option provides a list of servers to which, provided they announce CHUNKING support, Exim will attempt to use BDAT commands rather than DATA. -.new Unless DKIM signing is being done, -.wen BDAT will not be used in conjunction with a transport filter. .option hosts_try_dane smtp "host list&!!" * .cindex DANE "transport options" .cindex DANE "attempting for certain servers" -If built with DANE support, Exim will require that a DNSSEC-validated -TLSA record is present for any host matching the list, -and that a DANE-verified TLS connection is made. See -the &%dnssec_request_domains%& router and transport options. -There will be no fallback to in-clear communication. +If built with DANE support, Exim will look up a +TLSA record for any host matching the list, +If one is found and that lookup was DNSSEC-validated, +then Exim requires that a DANE-verified TLS connection is made for that host; +there will be no fallback to in-clear communication. +See the &%dnssec_request_domains%& router and transport options. See section &<>&. .option hosts_try_fastopen smtp "host list&!!" * @@ -25245,6 +25705,7 @@ such as DNSBL lookups, will still delay the emission of the SMTP banner. .option hosts_try_prdr smtp "host list&!!" * .cindex "PRDR" "enabling, optional in client" +.cindex "ESMTP extensions" PRDR This option provides a list of servers to which, provided they announce PRDR support, Exim will attempt to negotiate PRDR for multi-recipient messages. @@ -25304,7 +25765,19 @@ has advertised support for IGNOREQUOTA in its response to the LHLO command. This option limits the number of RCPT commands that are sent in a single SMTP message transaction. Each set of addresses is treated independently, and so can cause parallel connections to the same host if &%remote_max_parallel%& -permits this. +permits this. A value setting of zero disables the limit. + + +.option message_linelength_limit smtp integer 998 +.cindex "line length" limit +This option sets the maximum line length, in bytes, that the transport +will send. Any messages with lines exceeding the given value +will fail and a failure-DSN ("bounce") message will if possible be returned +to the sender. +The default value is that defined by the SMTP standards. + +It is generally wise to also check in the data ACL so that messages +received via SMTP can be refused without producing a bounce. .option multi_domain smtp boolean&!! true @@ -25320,6 +25793,10 @@ It is expanded per-address and can depend on any of &$address_data$&, &$domain_data$&, &$local_part_data$&, &$host$&, &$host_address$& and &$host_port$&. +If the connection is DANE-enabled then this option is ignored; +only messages having the domain used for the DANE TLSA lookup are +sent on the connection. + .option port smtp string&!! "see below" .cindex "port" "sending TCP/IP" .cindex "TCP/IP" "setting outgoing port" @@ -25357,7 +25834,7 @@ If this option is set to &"smtps"&, the default value for the &%port%& option changes to &"smtps"&, and the transport initiates TLS immediately after connecting, as an outbound SSL-on-connect, instead of using STARTTLS to upgrade. The Internet standards bodies used to strongly discourage use of this mode, -but as of RFC 8314 it is perferred over STARTTLS for message submission +but as of RFC 8314 it is preferred over STARTTLS for message submission (as distinct from MTA-MTA communication). @@ -25402,7 +25879,7 @@ See also the &%max_parallel%& generic transport option. .option size_addition smtp integer 1024 -.cindex "SMTP" "SIZE" +.cindex "SIZE" "ESMTP extension" .cindex "message" "size issue for transport filter" .cindex "size" "of message" .cindex "transport" "filter" @@ -25424,6 +25901,19 @@ This option enables use of SOCKS proxies for connections made by the transport. For details see section &<>&. +.option tls_alpn smtp string&!! unset +.cindex TLS "Application Layer Protocol Names" +.cindex TLS ALPN +.cindex ALPN "set name in client" +If this option is set +and the TLS library supports ALPN, +the value given is used. + +As of writing no value has been standardised for email use. +The authors suggest using &"smtp"&. + + + .option tls_certificate smtp string&!! unset .cindex "TLS" "client certificate, location of" .cindex "certificate" "client, location of" @@ -25488,11 +25978,21 @@ is used in different ways by OpenSSL and GnuTLS (see sections ciphers is a preference order. +.option tls_resumption_hosts smtp "host list&!!" unset +.cindex TLS resumption +This option controls which connections to use the TLS resumption feature. +See &<>& for details. + + .option tls_sni smtp string&!! unset .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI "setting in client" .vindex "&$tls_sni$&" -If this option is set then it sets the $tls_out_sni variable and causes any +If this option is set +and the connection is not DANE-validated +then it sets the $tls_out_sni variable and causes any TLS session to pass this value as the Server Name Indication extension to the remote side, which can be used by the remote side to select an appropriate certificate and private key for the session. @@ -25586,14 +26086,22 @@ certificate verification must succeed. The &%tls_verify_certificates%& option must also be set. If both this option and &%tls_try_verify_hosts%& are unset operation is as if this option selected all hosts. +&*Warning*&: Including a host in &%tls_verify_hosts%& does not require +that connections use TLS. +Fallback to in-clear communication will be done unless restricted by +the &%hosts_require_tls%& option. -.option utf8_downconvert smtp integer!! unset +.option utf8_downconvert smtp integer&!! -1 .cindex utf8 "address downconversion" .cindex i18n "utf8 address downconversion" If built with internationalization support, -this option controls conversion of UTF-8 in message addresses +this option controls conversion of UTF-8 in message envelope addresses to a-label form. -For details see section &<>&. +If, after expansion, the value is 1, 0, or -1 then this value overrides +any value previously set for the message. Otherwise, any previously +set value is used. To permit use of a previous value, +set this option to an empty string. +For details on the values see section &<>&. @@ -25756,7 +26264,7 @@ message's processing. .vindex "&$sender_address$&" At the start of an ACL for MAIL, the sender address may have been rewritten -by a special SMTP-time rewrite rule (see section &<>&), but no +by a special SMTP-time rewrite rule (see section &<>&), but no ordinary rewrite rules have yet been applied. If, however, the sender address is verified in the ACL, it is rewritten before verification, and remains rewritten thereafter. The subsequent value of &$sender_address$& is the @@ -25963,7 +26471,7 @@ entry written to the panic log. -.section "Rewriting flags" "SECID153" +.subsection "Rewriting flags" "SSECID153" There are three different kinds of flag that may appear on rewriting rules: .ilist @@ -25980,11 +26488,11 @@ E, F, T, and S are not permitted. -.section "Flags specifying which headers and envelope addresses to rewrite" &&& - "SECID154" -.cindex "rewriting" "flags" +.subsection "Flags specifying which headers and envelope addresses to rewrite" &&& + "SSECID154" +.cindex rewriting flags If none of the following flag letters, nor the &"S"& flag (see section -&<>&) are present, a main rewriting rule applies to all headers +&<>&) are present, a main rewriting rule applies to all headers and to both the sender and recipient fields of the envelope, whereas a transport-time rewriting rule just applies to all headers. Otherwise, the rewriting rule is skipped unless the relevant addresses are being processed. @@ -26008,10 +26516,10 @@ You should be particularly careful about rewriting &'Sender:'& headers, and restrict this to special known cases in your own domains. -.section "The SMTP-time rewriting flag" "SECTrewriteS" -.cindex "SMTP" "rewriting malformed addresses" -.cindex "RCPT" "rewriting argument of" -.cindex "MAIL" "rewriting argument of" +.subsection "The SMTP-time rewriting flag" SSECTrewriteS +.cindex SMTP "rewriting malformed addresses" +.cindex RCPT "rewriting argument of" +.cindex MAIL "rewriting argument of" The rewrite flag &"S"& specifies a rewrite of incoming envelope addresses at SMTP time, as soon as an address is received in a MAIL or RCPT command, and before any other processing; even before syntax checking. The pattern is @@ -26028,7 +26536,7 @@ expansion of the replacement string. The result of rewriting replaces the original address in the MAIL or RCPT command. -.section "Flags controlling the rewriting process" "SECID155" +.subsection "Flags controlling the rewriting process" SSECID155 There are four flags which control the way the rewriting process works. These take effect only when a rule is invoked, that is, when the address is of the correct type (matches the flags) and matches the pattern: @@ -26700,10 +27208,15 @@ permitted to use it as a relay. SMTP authentication is not of relevance to the transfer of mail between servers that have no managerial connection with each other. +The name of an authenticator is limited to be &drivernamemax; ASCII characters long; +prior to Exim 4.95 names would be silently truncated at this length, but now +it is enforced. + .cindex "AUTH" "description of" +.cindex "ESMTP extensions" AUTH Very briefly, the way SMTP authentication works is as follows: -.ilist +.olist The server advertises a number of authentication &'mechanisms'& in response to the client's EHLO command. .next @@ -26991,7 +27504,7 @@ conditions: .ilist The client host must match &%auth_advertise_hosts%& (default *). .next -It the &%server_advertise_condition%& option is set, its expansion must not +If the &%server_advertise_condition%& option is set, its expansion must not yield the empty string, &"0"&, &"no"&, or &"false"&. .endlist @@ -27059,7 +27572,18 @@ no successful authentication. Successful authentication sets up information used by the &%authresults%& expansion item. - +.new +.cindex authentication "failure event, server" +If an authenticator is run and does not succeed, +an event (see &<>&) of type "auth:fail" is raised. +While the event is being processed the variables +&$sender_host_authenticated$& (with the authenticator name) +and &$authenticated_fail_id$& (as set by the authenticator &%server_set_id%& option) +will be valid. +If the event is serviced and a string is returned then the string will be logged +instead of the default log line. +See <> for details on events. +.wen .section "Testing server authentication" "SECID169" @@ -27099,7 +27623,7 @@ encode '\0user@domain.com\0pas$$word' .endd gives an incorrect answer because of the unescaped &"@"& and &"$"& characters. -If you have the &%mimencode%& command installed, another way to do produce +If you have the &%mimencode%& command installed, another way to produce base64-encoded strings is to run the command .code echo -e -n `\0user\0password' | mimencode @@ -27137,6 +27661,19 @@ If the result of the authentication attempt is a temporary error or a timeout, Exim abandons trying to send the message to the host for the moment. It will try again later. If there are any backup hosts available, they are tried in the usual way. + +.new +.next +.cindex authentication "failure event, client" +If the response to authentication is a permanent error (5&'xx'& code), +an event (see &<>&) of type "auth:fail" is raised. +While the event is being processed the variable +&$sender_host_authenticated$& (with the authenticator name) +will be valid. +If the event is serviced and a string is returned then the string will be logged. +See <> for details on events. +.wen + .next If the response to authentication is a permanent error (5&'xx'& code), Exim carries on searching the list of authenticators and tries another one if @@ -27441,7 +27978,12 @@ fixed_plain: client_send = ^username^mysecret .endd The lack of colons means that the entire text is sent with the AUTH -command, with the circumflex characters converted to NULs. A similar example +command, with the circumflex characters converted to NULs. +Note that due to the ambiguity of parsing three consectutive circumflex characters +there is no way to provide a password having a leading circumflex. + + +A similar example that uses the LOGIN mechanism is: .code fixed_login: @@ -27715,8 +28257,7 @@ connection, a client certificate has been verified, the &"valid-client-cert"& option is passed. When authentication succeeds, the identity of the user who authenticated is placed in &$auth1$&. -.new -The Dovecot configuration to match the above wil look +The Dovecot configuration to match the above will look something like: .code conf.d/10-master.conf :- @@ -27735,7 +28276,6 @@ conf.d/10-auth.conf :- auth_mechanisms = plain login ntlm .endd -.wen .ecindex IIDdcotauth1 .ecindex IIDdcotauth2 @@ -27762,12 +28302,15 @@ scale to handle future authentication mechanisms, so no guarantee can be made that any particular new authentication mechanism will be supported without code changes in Exim. -.new The library is expected to add support in an upcoming realease for the SCRAM-SHA-256 method. The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined when this happens. +To see the list of mechanisms supported by the library run Exim with "auth" debug +enabled and look for a line containing "GNU SASL supports". +Note however that some may not have been tested from Exim. + .option client_authz gsasl string&!! unset This option can be used to supply an &'authorization id'& @@ -27786,25 +28329,41 @@ the password to be used, in clear. .option client_username gsasl string&!! unset This option is exapanded before use, and should result in the account name to be used. -.wen -.new + .option client_spassword gsasl string&!! unset +This option is only supported for library versions 1.9.1 and greater. +The macro _HAVE_AUTH_GSASL_SCRAM_S_KEY will be defined when this is so. + If a SCRAM mechanism is being used and this option is set +and correctly sized it is used in preference to &%client_password%&. The value after expansion should be a 40 (for SHA-1) or 64 (for SHA-256) character string with the PBKDF2-prepared password, hex-encoded. + Note that this value will depend on the salt and iteration-count supplied by the server. -.wen +The option is expanded before use. +During the expansion &$auth1$& is set with the client username, +&$auth2$& with the iteration count, and +&$auth3$& with the salt. +The intent of this option +is to support clients that can cache thes salted password +to save on recalculation costs. +The cache lookup should return an unusable value +(eg. an empty string) +if the salt or iteration count has changed +If the authentication succeeds then the above variables are set, +.vindex "&$auth4$&" +plus the calculated salted password value value in &$auth4$&, +during the expansion of the &%client_set_id%& option. +A side-effect of this expansion can be used to prime the cache. -.option server_channelbinding gsasl boolean false -Do not set this true and rely on the properties -without consulting a cryptographic engineer. +.option server_channelbinding gsasl boolean false Some authentication mechanisms are able to use external context at both ends of the session to bind the authentication to that context, and fail the authentication process if that context differs. Specifically, some TLS @@ -27815,20 +28374,23 @@ This should have meant that certificate identity and verification becomes a non-issue, as a man-in-the-middle attack will cause the correct client and server to see different identifiers and authentication will fail. -.new This is only usable by mechanisms which support "channel binding"; at time of writing, that's the SCRAM family. When using this feature the "-PLUS" variants of the method names need to be used. -.wen This defaults off to ensure smooth upgrade across Exim releases, in case this option causes some clients to start failing. Some future release of Exim might have switched the default to be true. -However, Channel Binding in TLS has proven to be vulnerable in current versions. -Do not plan to rely upon this feature for security, ever, without consulting -with a subject matter expert (a cryptographic engineer). +. However, Channel Binding in TLS has proven to be vulnerable in current versions. +. Do not plan to rely upon this feature for security, ever, without consulting +. with a subject matter expert (a cryptographic engineer). + +This option was deprecated in previous releases due to doubts over +the "Triple Handshake" vulnerability. +Exim takes suitable precausions (requiring Extended Master Secret if TLS +Session Resumption was used) for safety. .option server_hostname gsasl string&!! "see below" @@ -27876,7 +28438,6 @@ Some mechanisms will use this data. .option server_scram_iter gsasl string&!! 4096 This option provides data for the SCRAM family of mechanisms. -.new The &$auth1$&, &$auth2$& and &$auth3$& variables are available when this option is expanded. @@ -27887,21 +28448,17 @@ a compute cost factor imposed on the client either the iteration count or the salt). A minimum value of 4096 is required by the standards for all current SCRAM mechanism variants. -.wen .option server_scram_salt gsasl string&!! unset This option provides data for the SCRAM family of mechanisms. -.new The &$auth1$&, &$auth2$& and &$auth3$& variables are available when this option is expanded. The value should be a base64-encoded string, of random data typically 4-to-16 bytes long. If unset or empty after expansion the library will provides a value for the protocol conversation. -.wen -.new .option server_key gsasl string&!! unset .option server_skey gsasl string&!! unset These options can be used for the SCRAM family of mechanisms @@ -27927,7 +28484,6 @@ If unset or not of the right length, &%server_password%& will be used. The libgsasl library release includes a utility &'gsasl'& which can be used to generate these values. -.wen .option server_service gsasl string &`smtp`& @@ -28154,7 +28710,7 @@ and for clients to only attempt, this authentication method on a secure (eg. under TLS) connection. One possible use, compatible with the -K-9 Mail Andoid client (&url(https://k9mail.github.io/)), +K-9 Mail Android client (&url(https://k9mail.github.io/)), is for using X509 client certificates. It thus overlaps in function with the TLS authenticator @@ -28507,6 +29063,10 @@ Some other recently added features may only be available in one or the other. This should be documented with the feature. If the documentation does not explicitly state that the feature is infeasible in the other TLS implementation, then patches are welcome. +.next +The output from "exim -bV" will show which (if any) support was included +in the build. +Also, the macro "_HAVE_OPENSSL" or "_HAVE_GNUTLS" will be defined. .endlist @@ -28732,6 +29292,7 @@ tls_require_ciphers = ${if =={$received_port}{25}\ .section "Configuring an Exim server to use TLS" "SECID182" .cindex "TLS" "configuring an Exim server" +.cindex "ESMTP extensions" STARTTLS When Exim has been built with TLS support, it advertises the availability of the STARTTLS command to client hosts that match &%tls_advertise_hosts%&, but not to any others. The default value of this option is *, which means @@ -28847,7 +29408,7 @@ For outgoing SMTP deliveries, &$tls_out_cipher$& is used and logged (again depending on the &%tls_cipher%& log selector). -.section "Requesting and verifying client certificates" "SECID183" +.subsection "Requesting and verifying client certificates" .cindex "certificate" "verification of client" .cindex "TLS" "client certificate verification" If you want an Exim server to request a certificate when negotiating a TLS @@ -28900,83 +29461,57 @@ Because it is often a long text string, it is not included in the log line or certificate is supplied, &$tls_in_peerdn$& is empty. -.section "Revoked certificates" "SECID184" -.cindex "TLS" "revoked certificates" -.cindex "revocation list" -.cindex "certificate" "revocation list" -.cindex "OCSP" "stapling" -Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when -certificates are revoked. If you have such a list, you can pass it to an Exim -server using the global option called &%tls_crl%& and to an Exim client using -an identically named option for the &(smtp)& transport. In each case, the value -of the option is expanded and must then be the name of a file that contains a -CRL in PEM format. -The downside is that clients have to periodically re-download a potentially huge -file from every certificate authority they know of. - -The way with most moving parts at query time is Online Certificate -Status Protocol (OCSP), where the client verifies the certificate -against an OCSP server run by the CA. This lets the CA track all -usage of the certs. It requires running software with access to the -private key of the CA, to sign the responses to the OCSP queries. OCSP -is based on HTTP and can be proxied accordingly. - -The only widespread OCSP server implementation (known to this writer) -comes as part of OpenSSL and aborts on an invalid request, such as -connecting to the port and then disconnecting. This requires -re-entering the passphrase each time some random client does this. - -The third way is OCSP Stapling; in this, the server using a certificate -issued by the CA periodically requests an OCSP proof of validity from -the OCSP server, then serves it up inline as part of the TLS -negotiation. This approach adds no extra round trips, does not let the -CA track users, scales well with number of certs issued by the CA and is -resilient to temporary OCSP server failures, as long as the server -starts retrying to fetch an OCSP proof some time before its current -proof expires. The downside is that it requires server support. - -Unless Exim is built with the support disabled, -or with GnuTLS earlier than version 3.3.16 / 3.4.8 -support for OCSP stapling is included. - -There is a global option called &%tls_ocsp_file%&. -The file specified therein is expected to be in DER format, and contain -an OCSP proof. Exim will serve it as part of the TLS handshake. This -option will be re-expanded for SNI, if the &%tls_certificate%& option -contains &`tls_in_sni`&, as per other TLS options. - -Exim does not at this time implement any support for fetching a new OCSP -proof. The burden is on the administrator to handle this, outside of -Exim. The file specified should be replaced atomically, so that the -contents are always valid. Exim will expand the &%tls_ocsp_file%& option -on each connection, so a new file will be handled transparently on the -next connection. - -When built with OpenSSL Exim will check for a valid next update timestamp -in the OCSP proof; if not present, or if the proof has expired, it will be -ignored. - -For the client to be able to verify the stapled OCSP the server must -also supply, in its stapled information, any intermediate -certificates for the chain leading to the OCSP proof from the signer -of the server certificate. There may be zero or one such. These -intermediate certificates should be added to the server OCSP stapling -file named by &%tls_ocsp_file%&. - -Note that the proof only covers the terminal server certificate, -not any of the chain from CA to it. - -There is no current way to staple a proof for a client certificate. - -.code - A helper script "ocsp_fetch.pl" for fetching a proof from a CA - OCSP server is supplied. The server URL may be included in the - server certificate, if the CA is helpful. - - One failure mode seen was the OCSP Signer cert expiring before the end - of validity of the OCSP proof. The checking done by Exim/OpenSSL - noted this as invalid overall, but the re-fetch script did not. -.endd +.subsection "Caching of static server configuration items" "SSECTserverTLScache" +.cindex certificate caching +.cindex privatekey caching +.cindex crl caching +.cindex ocsp caching +.cindex ciphers caching +.cindex "CA bundle" caching +.cindex "certificate authorities" caching +.cindex tls_certificate caching +.cindex tls_privatekey caching +.cindex tls_crl caching +.cindex tls_ocsp_file caching +.cindex tls_require_ciphers caching +.cindex tls_verify_certificate caching +.cindex caching certificate +.cindex caching privatekey +.cindex caching crl +.cindex caching ocsp +.cindex caching ciphers +.cindex caching "certificate authorities +If any of the main configuration options &%tls_certificate%&, &%tls_privatekey%&, +&%tls_crl%& and &%tls_ocsp_file%& have values with no +expandable elements, +then the associated information is loaded at daemon startup. +It is made available +to child processes forked for handling received SMTP connections. + +This caching is currently only supported under Linux and FreeBSD. + +If caching is not possible, for example if an item has to be dependent +on the peer host so contains a &$sender_host_name$& expansion, the load +of the associated information is done at the startup of the TLS connection. + +The cache is invalidated and reloaded after any changes to the directories +containing files specified by these options. + +The information specified by the main option &%tls_verify_certificates%& +is similarly cached so long as it specifies files explicitly +or (under GnuTLS) is the string &"system,cache"&. +The latter case is not automatically invalidated; +it is the operator's responsibility to arrange for a daemon restart +any time the system certificate authority bundle is updated. +A HUP signal is sufficient for this. +The value &"system"& results in no caching under GnuTLS. + +The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system" +is acceptable in configurations for the Exim executavble. + +Caching of the system Certificate Authorities bundle can +save siginificant time and processing on every TLS connection +accepted by Exim. @@ -28991,6 +29526,7 @@ deliveries as well as to incoming, the latter one causing logging of the server certificate's DN. The remaining client configuration for TLS is all within the &(smtp)& transport. +.cindex "ESMTP extensions" STARTTLS It is not necessary to set any options to have TLS work in the &(smtp)& transport. If Exim is built with TLS support, and TLS is advertised by a server, the &(smtp)& transport always tries to start a TLS session. However, @@ -29018,7 +29554,10 @@ unencrypted. The &%tls_certificate%& and &%tls_privatekey%& options of the &(smtp)& transport provide the client with a certificate, which is passed to the server -if it requests it. If the server is Exim, it will request a certificate only if +if it requests it. +This is an optional thing for TLS connections, although either end +may insist on it. +If the server is Exim, it will request a certificate only if &%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client. &*Note*&: Do not use a certificate which has the OCSP-must-staple extension, @@ -29043,8 +29582,12 @@ certificate verification to the listed servers. Verification either must or need not succeed respectively. The &%tls_verify_cert_hostnames%& option lists hosts for which additional -checks are made: that the host name (the one in the DNS A record) -is valid for the certificate. +name checks are made on the server certificate. +The match against this list is, as per other Exim usage, the +IP for the host. That is most closely associated with the +name on the DNS A (or AAAA) record for the host. +However, the name that needs to be in the certificate +is the one at the head of any CNAME chain leading to the A record. The option defaults to always checking. The &(smtp)& transport has two OCSP-related options: @@ -29092,8 +29635,64 @@ outgoing connection. +.subsection "Caching of static client configuration items" SECTclientTLScache +.cindex certificate caching +.cindex privatekey caching +.cindex crl caching +.cindex ciphers caching +.cindex "CA bundle" caching +.cindex "certificate authorities" caching +.cindex tls_certificate caching +.cindex tls_privatekey caching +.cindex tls_crl caching +.cindex tls_require_ciphers caching +.cindex tls_verify_certificate caching +.cindex caching certificate +.cindex caching privatekey +.cindex caching crl +.cindex caching ciphers +.cindex caching "certificate authorities +If any of the transport configuration options &%tls_certificate%&, &%tls_privatekey%& +and &%tls_crl%& have values with no +expandable elements, +then the associated information is loaded per smtp transport +at daemon startup, at the start of a queue run, or on a +command-line specified message delivery. +It is made available +to child processes forked for handling making SMTP connections. + +This caching is currently only supported under Linux. + +If caching is not possible, the load +of the associated information is done at the startup of the TLS connection. + +The cache is invalidated in the daemon +and reloaded after any changes to the directories +containing files specified by these options. + +The information specified by the main option &%tls_verify_certificates%& +is similarly cached so long as it specifies files explicitly +or (under GnuTLS) is the string &"system,cache"&. +The latter case is not automatically invaludated; +it is the operator's responsibility to arrange for a daemon restart +any time the system certificate authority bundle is updated. +A HUP signal is sufficient for this. +The value &"system"& results in no caching under GnuTLS. + +The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system" +is acceptable in configurations for the Exim executavble. + +Caching of the system Certificate Authorities bundle can +save siginificant time and processing on every TLS connection +initiated by Exim. + + + + .section "Use of TLS Server Name Indication" "SECTtlssni" .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI .vindex "&$tls_in_sni$&" .oindex "&%tls_in_sni%&" With TLS1.0 or above, there is an extension mechanism by which extra @@ -29125,6 +29724,9 @@ nothing more to it. Choosing a sensible value not derived insecurely is the only point of caution. The &$tls_out_sni$& variable will be set to this string for the lifetime of the client connection (including during authentication). +If DANE validated the connection attempt then the value of the &%tls_sni%& option +is forced to the name of the destination host, after any MX- or CNAME-following. + Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string received from a client. It can be logged with the &%log_selector%& item &`+tls_sni`&. @@ -29165,6 +29767,34 @@ When Exim is built against GnuTLS, SNI support is available as of GnuTLS 0.5.10. (Its presence predates the current API which Exim uses, so if Exim built, then you have SNI support). +.subsection ALPN +.cindex TLS ALPN +.cindex ALPN "general information" +.cindex TLS "Application Layer Protocol Names" +There is a TLS feature related to SNI +called Application Layer Protocol Name (ALPN). +This is intended to declare, or select, what protocol layer will be using a TLS +connection. +The client for the connection proposes a set of protocol names, and +the server responds with a selected one. +It is not, as of 2021, commonly used for SMTP connections. +However, to guard against misirected or malicious use of web clients +(which often do use ALPN) against MTA ports, Exim by default check that +there is no incompatible ALPN specified by a client for a TLS connection. +If there is, the connection is rejected. + +As a client Exim does not supply ALPN by default. +The behaviour of both client and server can be configured using the options +&%tls_alpn%& and &%hosts_require_alpn%&. +There are no variables providing observability. +Some feature-specific logging may appear on denied connections, but this +depends on the behavious of the peer +(not all peers can send a feature-specific TLS Alert). + +This feature is available when Exim is built with +OpenSSL 1.1.0 or later or GnuTLS 3.2.0 or later; +the macro _HAVE_TLS_ALPN will be defined when this is so. + .section "Multiple messages on the same encrypted TCP/IP connection" &&& @@ -29237,8 +29867,8 @@ Ivan is the author of the popular TLS testing tools at &url(https://www.ssllabs.com/). -.section "Certificate chains" "SECID186" -The file named by &%tls_certificate%& may contain more than one +.subsection "Certificate chains" SECID186 +A file named by &%tls_certificate%& may contain more than one certificate. This is useful in the case where the certificate that is being sent is validated by an intermediate certificate which the other end does not have. Multiple certificates must be in the correct order in the file. @@ -29258,7 +29888,7 @@ diagnostics in such a case can be frustratingly vague. -.section "Self-signed certificates" "SECID187" +.subsection "Self-signed certificates" SECID187 .cindex "certificate" "self-signed" You can create a self-signed certificate using the &'req'& command provided with OpenSSL, like this: @@ -29307,10 +29937,190 @@ For information on creating self-signed CA certificates and using them to sign user certificates, see the &'General implementation overview'& chapter of the Open-source PKI book, available online at &url(https://sourceforge.net/projects/ospkibook/). + + +.subsection "Revoked certificates" +.cindex "TLS" "revoked certificates" +.cindex "revocation list" +.cindex "certificate" "revocation list" +.cindex "OCSP" "stapling" +There are three ways for a certificate to be made unusable +before its expiry. + +.ilist +Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when +certificates are revoked. If you have such a list, you can pass it to an Exim +server using the global option called &%tls_crl%& and to an Exim client using +an identically named option for the &(smtp)& transport. In each case, the value +of the option is expanded and must then be the name of a file that contains a +CRL in PEM format. +The downside is that clients have to periodically re-download a potentially huge +file from every certificate authority they know of. + +.next +The way with most moving parts at query time is Online Certificate +Status Protocol (OCSP), where the client verifies the certificate +against an OCSP server run by the CA. This lets the CA track all +usage of the certs. It requires running software with access to the +private key of the CA, to sign the responses to the OCSP queries. OCSP +is based on HTTP and can be proxied accordingly. + +The only widespread OCSP server implementation (known to this writer) +comes as part of OpenSSL and aborts on an invalid request, such as +connecting to the port and then disconnecting. This requires +re-entering the passphrase each time some random client does this. + +.next +The third way is OCSP Stapling; in this, the server using a certificate +issued by the CA periodically requests an OCSP proof of validity from +the OCSP server, then serves it up inline as part of the TLS +negotiation. This approach adds no extra round trips, does not let the +CA track users, scales well with number of certs issued by the CA and is +resilient to temporary OCSP server failures, as long as the server +starts retrying to fetch an OCSP proof some time before its current +proof expires. The downside is that it requires server support. + +Unless Exim is built with the support disabled, +or with GnuTLS earlier than version 3.3.16 / 3.4.8 +support for OCSP stapling is included. + +There is a global option called &%tls_ocsp_file%&. +The file specified therein is expected to be in DER format, and contain +an OCSP proof. Exim will serve it as part of the TLS handshake. This +option will be re-expanded for SNI, if the &%tls_certificate%& option +contains &`tls_in_sni`&, as per other TLS options. + +Exim does not at this time implement any support for fetching a new OCSP +proof. The burden is on the administrator to handle this, outside of +Exim. The file specified should be replaced atomically, so that the +contents are always valid. Exim will expand the &%tls_ocsp_file%& option +on each connection, so a new file will be handled transparently on the +next connection. + +When built with OpenSSL Exim will check for a valid next update timestamp +in the OCSP proof; if not present, or if the proof has expired, it will be +ignored. + +For the client to be able to verify the stapled OCSP the server must +also supply, in its stapled information, any intermediate +certificates for the chain leading to the OCSP proof from the signer +of the server certificate. There may be zero or one such. These +intermediate certificates should be added to the server OCSP stapling +file named by &%tls_ocsp_file%&. + +Note that the proof only covers the terminal server certificate, +not any of the chain from CA to it. + +There is no current way to staple a proof for a client certificate. + +.code + A helper script "ocsp_fetch.pl" for fetching a proof from a CA + OCSP server is supplied. The server URL may be included in the + server certificate, if the CA is helpful. + + One failure mode seen was the OCSP Signer cert expiring before the end + of validity of the OCSP proof. The checking done by Exim/OpenSSL + noted this as invalid overall, but the re-fetch script did not. +.endd +.endlist + + .ecindex IIDencsmtp1 .ecindex IIDencsmtp2 +.section "TLS Resumption" "SECTresumption" +.cindex TLS resumption +TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined +in RFC 5077 for 1.2). The support for this requires GnuTLS 3.6.3 or OpenSSL 1.1.1 +(or later). + +Session resumption (this is the "stateless" variant) involves the server sending +a "session ticket" to the client on one connection, which can be stored by the +client and used for a later session. The ticket contains sufficient state for +the server to reconstruct the TLS session, avoiding some expensive crypto +calculation and (on TLS1.2) one full packet roundtrip time. + +.ilist +Operational cost/benefit: + + The extra data being transmitted costs a minor amount, and the client has + extra costs in storing and retrieving the data. + + In the Exim/Gnutls implementation the extra cost on an initial connection + which is TLS1.2 over a loopback path is about 6ms on 2017-laptop class hardware. + The saved cost on a subsequent connection is about 4ms; three or more + connections become a net win. On longer network paths, two or more + connections will have an average lower startup time thanks to the one + saved packet roundtrip. TLS1.3 will save the crypto cpu costs but not any + packet roundtrips. + +.cindex "hints database" tls + Since a new hints DB is used on the TLS client, + the hints DB maintenance should be updated to additionally handle "tls". + +.next +Security aspects: + + The session ticket is encrypted, but is obviously an additional security + vulnarability surface. An attacker able to decrypt it would have access + all connections using the resumed session. + The session ticket encryption key is not committed to storage by the server + and is rotated regularly (OpenSSL: 1hr, and one previous key is used for + overlap; GnuTLS 6hr but does not specify any overlap). + Tickets have limited lifetime (2hr, and new ones issued after 1hr under + OpenSSL. GnuTLS 2hr, appears to not do overlap). + + There is a question-mark over the security of the Diffie-Helman parameters + used for session negotiation. + +.next +Observability: + + The &%log_selector%& "tls_resumption" appends an asterisk to the tls_cipher "X=" + element. + + The variables &$tls_in_resumption$& and &$tls_out_resumption$& + have bits 0-4 indicating respectively + support built, client requested ticket, client offered session, + server issued ticket, resume used. A suitable decode list is provided + in the builtin macro _RESUME_DECODE for in &%listextract%& expansions. + +.next +Control: + +The &%tls_resumption_hosts%& main option specifies a hostlist for which +exim, operating as a server, will offer resumption to clients. +Current best practice is to not offer the feature to MUA connection. +Commonly this can be done like this: +.code +tls_resumption_hosts = ${if inlist {$received_port}{587:465} {:}{*}} +.endd +If the peer host matches the list after expansion then resumption +is offered and/or accepted. + +The &%tls_resumption_hosts%& smtp transport option performs the +equivalent function for operation as a client. +If the peer host matches the list after expansion then resumption +is attempted (if a stored session is available) or the information +stored (if supplied by the peer). + + +.next +Issues: + + In a resumed session: +.ilist + The variables &$tls_{in,out}_cipher$& will have values different + to the original (under GnuTLS). +.next + The variables &$tls_{in,out}_ocsp$& will be "not requested" or "no response", + and the &%hosts_require_ocsp%& smtp trasnport option will fail. +. XXX need to do something with that hosts_require_ocsp +.endlist + +.endlist + .section DANE "SECDANE" .cindex DANE @@ -29328,22 +30138,28 @@ by (a) is thought to be smaller than that of the set of root CAs. It also allows the server to declare (implicitly) that connections to it should use TLS. An MITM could simply fail to pass on a server's STARTTLS. -DANE scales better than having to maintain (and side-channel communicate) copies of server certificates +DANE scales better than having to maintain (and communicate via side-channel) copies of server certificates for every possible target server. It also scales (slightly) better than having to maintain on an SMTP client a copy of the standard CAs bundle. It also means not having to pay a CA for certificates. -DANE requires a server operator to do three things: 1) run DNSSEC. This provides assurance to clients +DANE requires a server operator to do three things: +.olist +Run DNSSEC. This provides assurance to clients that DNS lookups they do for the server have not been tampered with. The domain MX record applying to this server, its A record, its TLSA record and any associated CNAME records must all be covered by DNSSEC. -2) add TLSA DNS records. These say what the server certificate for a TLS connection should be. -3) offer a server certificate, or certificate chain, in TLS connections which is is anchored by one of the TLSA records. +.next +Add TLSA DNS records. These say what the server certificate for a TLS connection should be. +.next +Offer a server certificate, or certificate chain, in TLS connections which is is anchored by one of the TLSA records. +.endlist There are no changes to Exim specific to server-side operation of DANE. Support for client-side operation of DANE can be included at compile time by defining SUPPORT_DANE=yes in &_Local/Makefile_&. If it has been included, the macro "_HAVE_DANE" will be defined. +.subsection "DNS records" A TLSA record consist of 4 fields, the "Certificate Usage", the "Selector", the "Matching type", and the "Certificate Association Data". For a detailed description of the TLSA record see @@ -29424,6 +30240,7 @@ libraries. This means no MD5 and no SHA-1. SHA2-256 is the minimum for reliable interoperability (and probably the maximum too, in 2018). +.subsection "Interaction with OCSP" The use of OCSP-stapling should be considered, allowing for fast revocation of certificates (which would otherwise be limited by the DNS TTL on the TLSA records). However, this is likely to only be usable with DANE-TA. NOTE: the default of requesting OCSP for all hosts is modified iff DANE is in use, to: @@ -29444,6 +30261,7 @@ This modification of hosts_request_ocsp is only done if it has the default value those who use &%hosts_require_ocsp%&, should consider the interaction with DANE in their OCSP settings. +.subsection "Client configuration" For client-side DANE there are three new smtp transport options, &%hosts_try_dane%&, &%hosts_require_dane%& and &%dane_require_tls_ciphers%&. The &"require"& variant will result in failure if the target host is not @@ -29452,7 +30270,7 @@ the &%dnssec_request_domains%& router or transport option. DANE will only be usable if the target host has DNSSEC-secured MX, A and TLSA records. -A TLSA lookup will be done if either of the above options match and the host-lookup succeeded using dnssec. +A TLSA lookup will be done if either of the above options match and the host-lookup succeeded using DNSSEC. If a TLSA lookup is done and succeeds, a DANE-verified TLS connection will be required for the host. If it does not, the host will not be used; there is no fallback to non-DANE or non-TLS. @@ -29473,6 +30291,7 @@ If DANE is requested and useable (see above) the following transport options are tls_verify_certificates tls_crl tls_verify_cert_hostnames + tls_sni .endd If DANE is not usable, whether requested or not, and CA-anchored @@ -29481,6 +30300,7 @@ verification evaluation is wanted, the above variables should be set appropriate The router and transport option &%dnssec_request_domains%& must not be set to &"never"&, and &%dnssec_require_domains%& is ignored. +.subsection Observability If verification was successful using DANE then the "CV" item in the delivery log line will show as "CV=dane". There is a new variable &$tls_out_dane$& which will have "yes" if @@ -29496,11 +30316,13 @@ required. This is intended to support TLS-reporting as defined in The &$event_data$& will be one of the Result Types defined in Section 4.3 of that document. +.subsection General Under GnuTLS, DANE is only supported from version 3.0.0 onwards. DANE is specified in published RFCs and decouples certificate authority trust selection from a "race to the bottom" of "you must trust everything for mail -to get through". There is an alternative technology called MTA-STS, which +to get through". +There is an alternative technology called MTA-STS, which instead publishes MX trust anchor information on an HTTPS website. At the time this text was last updated, MTA-STS was still a draft, not yet an RFC. Exim has no support for MTA-STS as a client, but Exim mail server operators @@ -29614,7 +30436,7 @@ trying to deliver the message. It is therefore recommended that you do as much testing as possible at RCPT time. -.section "The non-SMTP ACLs" "SECID190" +.subsection "The non-SMTP ACLs" SECID190 .cindex "non-SMTP messages" "ACLs for" The non-SMTP ACLs apply to all non-interactive incoming messages, that is, they apply to batched SMTP as well as to non-SMTP messages. (Batched SMTP is not @@ -29648,7 +30470,7 @@ kind of rejection is treated as permanent, because there is no way of sending a temporary error for these kinds of message. -.section "The SMTP connect ACL" "SECID191" +.subsection "The SMTP connect ACL" SECID191 .cindex "SMTP" "connection, ACL for" .oindex &%smtp_banner%& The ACL test specified by &%acl_smtp_connect%& happens at the start of an SMTP @@ -29658,8 +30480,11 @@ accepted by an &%accept%& verb that has a &%message%& modifier, the contents of the message override the banner message that is otherwise specified by the &%smtp_banner%& option. +For tls-on-connect connections, the ACL is run after the TLS connection +is accepted (however, &%host_reject_connection%& is tested before). -.section "The EHLO/HELO ACL" "SECID192" + +.subsection "The EHLO/HELO ACL" SECID192 .cindex "EHLO" "ACL for" .cindex "HELO" "ACL for" The ACL test specified by &%acl_smtp_helo%& happens when the client issues an @@ -29680,7 +30505,7 @@ affect the EHLO options that are listed on the second and subsequent lines of an EHLO response. -.section "The DATA ACLs" "SECID193" +.subsection "The DATA ACLs" SECID193 .cindex "DATA" "ACLs for" Two ACLs are associated with the DATA command, because it is two-stage command, with two responses being sent to the client. @@ -29719,7 +30544,7 @@ the &%acl_smtp_data_prdr%&, the &%acl_smtp_dkim%& and the &%acl_smtp_mime%& ACLs. -.section "The SMTP DKIM ACL" "SECTDKIMACL" +.subsection "The SMTP DKIM ACL" SECTDKIMACL The &%acl_smtp_dkim%& ACL is available only when Exim is compiled with DKIM support enabled (which is the default). @@ -29732,14 +30557,14 @@ This ACL is evaluated before &%acl_smtp_mime%& and &%acl_smtp_data%&. For details on the operation of DKIM, see section &<>&. -.section "The SMTP MIME ACL" "SECID194" +.subsection "The SMTP MIME ACL" SECID194 The &%acl_smtp_mime%& option is available only when Exim is compiled with the content-scanning extension. For details, see chapter &<>&. This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&. -.section "The SMTP PRDR ACL" "SECTPRDRACL" +.subsection "The SMTP PRDR ACL" SECTPRDRACL .cindex "PRDR" "ACL for" .oindex "&%prdr_enable%&" The &%acl_smtp_data_prdr%& ACL is available only when Exim is compiled @@ -29773,7 +30598,7 @@ This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&. If the ACL is not defined, processing completes as if the feature was not requested by the client. -.section "The QUIT ACL" "SECTQUITACL" +.subsection "The QUIT ACL" SECTQUITACL .cindex "QUIT, ACL for" The ACL for the SMTP QUIT command is anomalous, in that the outcome of the ACL does not affect the response code to QUIT, which is always 221. Thus, the ACL @@ -29800,7 +30625,7 @@ client are given temporary error responses until QUIT is received or the connection is closed. In these special cases, the QUIT ACL does not run. -.section "The not-QUIT ACL" "SECTNOTQUITACL" +.subsection "The not-QUIT ACL" SECTNOTQUITACL .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 in bad @@ -30129,8 +30954,8 @@ The &%message%& modifier operates exactly as it does for &%accept%&. &%drop%&: This verb behaves like &%deny%&, except that an SMTP connection is forcibly closed after the 5&'xx'& error message has been sent. For example: .code -drop message = I don't take more than 20 RCPTs - condition = ${if > {$rcpt_count}{20}} +drop condition = ${if > {$rcpt_count}{20}} + message = I don't take more than 20 RCPTs .endd There is no difference between &%deny%& and &%drop%& for the connect-time ACL. The connection is always dropped after sending a 550 response. @@ -30586,8 +31411,9 @@ anyway. If the message contains newlines, this gives rise to a multi-line SMTP response. .vindex "&$acl_verify_message$&" -For ACLs that are called by an &%acl =%& ACL condition, the message is -stored in &$acl_verify_message$&, from which the calling ACL may use it. +While the text is being expanded, the &$acl_verify_message$& variable +contains any message previously set. +Afterwards, &$acl_verify_message$& is cleared. If &%message%& is used on a statement that verifies an address, the message specified overrides any message that is generated by the verification process. @@ -30774,12 +31600,43 @@ sender when the destination system is doing content-scan based rejection. This control turns on debug logging, almost as though Exim had been invoked with &`-d`&, with the output going to a new logfile in the usual logs directory, by default called &'debuglog'&. -The filename can be adjusted with the &'tag'& option, which -may access any variables already defined. The logging may be adjusted with -the &'opts'& option, which takes the same values as the &`-d`& command-line -option. -Logging started this way may be stopped, and the file removed, -with the &'kill'& option. + +Logging set up by the control will be maintained across spool residency. + +Options are a slash-separated list. +If an option takes an argument, the option name and argument are separated by +an equals character. +Several options are supported: +.display +tag=<&'suffix'&> The filename can be adjusted with thise option. + The argument, which may access any variables already defined, + is appended to the default name. + +opts=<&'debug&~options'&> The argument specififes what is to be logged, + using the same values as the &`-d`& command-line option. + +stop Logging started with this control may be + stopped by using this option. + +kill Logging started with this control may be + stopped by using this option. + Additionally the debug file will be removed, + providing one means for speculative debug tracing. + +pretrigger=<&'size'&> This option specifies a memory buffuer to be used + for pre-trigger debug capture. + Debug lines are recorded in the buffer until + and if) a trigger occurs; at which time they are + dumped to the debug file. Newer lines displace the + oldest if the buffer is full. After a trigger, + immediate writes to file are done as normal. + +trigger=<&'reason'&> This option selects cause for the pretrigger buffer + see above) to be copied to file. A reason of $*now* + take effect immediately; one of &*paniclog*& triggers + on a write to the panic log. +.endd + Some examples (which depend on variables that don't exist in all contexts): .code @@ -30788,6 +31645,8 @@ contexts): control = debug/opts=+expand+acl control = debug/tag=.$message_exim_id/opts=+expand control = debug/kill + control = debug/opts=+all/pretrigger=1024/trigger=paniclog + control = debug/trigger=now .endd @@ -30933,13 +31792,13 @@ calling host. Its effect lasts until the end of the SMTP connection. .vitem &*control&~=&~no_pipelining*& .cindex "PIPELINING" "suppressing advertising" +.cindex "ESMTP extensions" PIPELINING This control turns off the advertising of the PIPELINING extension to SMTP in the current session. To be useful, it must be obeyed before Exim sends its response to an EHLO command. Therefore, it should normally appear in an ACL controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also &%pipelining_advertise_hosts%&. -.new .vitem &*control&~=&~queue/*&<&'options'&>* &&& &*control&~=&~queue_only*& .oindex "&%queue%&" @@ -30964,7 +31823,6 @@ able to send all such messages on a single connection. The control only applies to the current message, not to any subsequent ones that may be received in the same SMTP connection. -.wen .vitem &*control&~=&~submission/*&<&'options'&> .cindex "message" "submission" @@ -31008,7 +31866,7 @@ data is read. that are being submitted at the same time using &%-bs%& or &%-bS%&. .vitem &*control&~=&~utf8_downconvert*& -This control enables conversion of UTF-8 in message addresses +This control enables conversion of UTF-8 in message envelope addresses to a-label form. For details see section &<>&. .endlist vlist @@ -31306,7 +32164,7 @@ different variants of this condition to describe briefly here. See sections .cindex "domain" "ACL checking" .cindex "&ACL;" "testing a recipient domain" .vindex "&$domain_data$&" -This condition is relevant only after a RCPT command. It checks that the domain +This condition is relevant only in a RCPT ACL. It checks that the domain of the recipient address is in the domain list. If percent-hack processing is enabled, it is done before this test is done. If the check succeeds with a lookup, the result of the lookup is placed in &$domain_data$& until the next @@ -31365,7 +32223,7 @@ of the lookup is made available in the &$host_data$& variable. This allows you, for example, to set up a statement like this: .code deny hosts = net-lsearch;/some/file -message = $host_data + message = $host_data .endd which gives a custom error message for each denied host. @@ -31374,7 +32232,7 @@ which gives a custom error message for each denied host. .cindex "local part" "ACL checking" .cindex "&ACL;" "testing a local part" .vindex "&$local_part_data$&" -This condition is relevant only after a RCPT command. It checks that the local +This condition is relevant only in a RCPT ACL. It checks that the local part of the recipient address is in the list. If percent-hack processing is enabled, it is done before this test. If the check succeeds with a lookup, the result of the lookup is placed in &$local_part_data$&, which remains set until @@ -31408,7 +32266,7 @@ messages. Details are given in section &<>&. .cindex "&%recipients%& ACL condition" .cindex "recipient" "ACL checking" .cindex "&ACL;" "testing a recipient" -This condition is relevant only after a RCPT command. It checks the entire +This condition is relevant only in a RCPT ACL. It checks the entire recipient address against a list of recipients. .vitem &*regex&~=&~*&<&'list&~of&~regular&~expressions'&> @@ -31419,6 +32277,12 @@ content-scanning extension, and is available only in the DATA, MIME, and non-SMTP ACLs. It causes the incoming message to be scanned for a match with any of the regular expressions. For details, see chapter &<>&. +.vitem &*seen&~=&~*&<&'parameters'&> +.cindex "&%seen%& ACL condition" +This condition can be used to test if a situation has been previously met, +for example for greylisting. +Details are given in section &<>&. + .vitem &*sender_domains&~=&~*&<&'domain&~list'&> .cindex "&%sender_domains%& ACL condition" .cindex "sender" "ACL checking" @@ -31478,8 +32342,9 @@ send email. Details of how this works are given in section .cindex "header lines" "verifying header names only ASCII" .cindex "verifying" "header names only ASCII" This condition is relevant only in an ACL that is run after a message has been -received, that is, in an ACL specified by &%acl_smtp_data%& or -&%acl_not_smtp%&. It checks all header names (not the content) to make sure +received. +This usually means an ACL specified by &%acl_smtp_data%& or &%acl_not_smtp%&. +It checks all header names (not the content) to make sure there are no non-ASCII characters, also excluding control characters. The allowable characters are decimal ASCII values 33 through 126. @@ -31509,8 +32374,8 @@ section &<>& (callouts are described in section condition to restrict it to bounce messages only: .code deny senders = : - message = A valid sender header is required for bounces !verify = header_sender + message = A valid sender header is required for bounces .endd .vitem &*verify&~=&~header_syntax*& @@ -31634,7 +32499,7 @@ Note that '/' is legal in local-parts; if the address may have such (eg. is generated from the received message) they must be protected from the options parsing by doubling: .code -verify = sender=${sg{${address:$h_sender:}}{/}{//}} +verify = sender=${listquote{/}{${address:$h_sender:}}} .endd .endlist @@ -31676,11 +32541,11 @@ This is usually the required action when &%dnslists%& is used with &%deny%& (which is the most common usage), because it prevents a DNS failure from blocking mail. However, you can change this behaviour by putting one of the following special items in the list: -.display -&`+include_unknown `& behave as if the item is on the list -&`+exclude_unknown `& behave as if the item is not on the list (default) -&`+defer_unknown `& give a temporary error -.endd +.itable none 0 0 2 25* left 75* left +.irow "+include_unknown" "behave as if the item is on the list" +.irow "+exclude_unknown" "behave as if the item is not on the list (default)" +.irow "+defer_unknown " "give a temporary error" +.endtable .cindex "&`+include_unknown`&" .cindex "&`+exclude_unknown`&" .cindex "&`+defer_unknown`&" @@ -31692,8 +32557,8 @@ Testing the list of domains stops as soon as a match is found. If you want to warn for one list and block for another, you can use two different statements: .code deny dnslists = blackholes.mail-abuse.org -warn message = X-Warn: sending host is on dialups list - dnslists = dialups.mail-abuse.org +warn dnslists = dialups.mail-abuse.org + message = X-Warn: sending host is on dialups list .endd .cindex caching "of dns lookup" .cindex DNS TTL @@ -31710,7 +32575,7 @@ or free for small deployments. An overview can be found at -.section "Specifying the IP address for a DNS list lookup" "SECID201" +.subsection "Specifying the IP address for a DNS list lookup" SECID201 .cindex "DNS list" "keyed by explicit IP address" By default, the IP address that is used in a DNS list lookup is the IP address of the calling host. However, you can specify another IP address by listing it @@ -31726,7 +32591,7 @@ MX hosts or nameservers of an email sender address. For an example, see section -.section "DNS lists keyed on domain names" "SECID202" +.subsection "DNS lists keyed on domain names" SECID202 .cindex "DNS list" "keyed by domain name" There are some lists that are keyed on domain names rather than inverted IP addresses (see, e.g., the &'domain based zones'& link at @@ -31734,8 +32599,8 @@ addresses (see, e.g., the &'domain based zones'& link at with these lists. You can change the name that is looked up in a DNS list by listing it after the domain name, introduced by a slash. For example, .code -deny message = Sender's domain is listed at $dnslist_domain - dnslists = dsn.rfc-ignorant.org/$sender_address_domain +deny dnslists = dsn.rfc-ignorant.org/$sender_address_domain + message = Sender's domain is listed at $dnslist_domain .endd This particular example is useful only in ACLs that are obeyed after the RCPT or DATA commands, when a sender address is available. If (for @@ -31756,7 +32621,7 @@ name. The whole condition is true if either of the DNS lookups succeeds. -.section "Multiple explicit keys for a DNS list" "SECTmulkeyfor" +.subsection "Multiple explicit keys for a DNS list" SECTmulkeyfor .cindex "DNS list" "multiple keys for" The syntax described above for looking up explicitly-defined values (either names or IP addresses) in a DNS blacklist is a simplification. After the domain @@ -31799,13 +32664,13 @@ dnslists = black.list.tld/a.domain::b.domain However, when the data for the list is obtained from a lookup, the second form is usually much more convenient. Consider this example: .code -deny message = The mail servers for the domain \ +deny dnslists = sbl.spamhaus.org/<|${lookup dnsdb {>|a=<|\ + ${lookup dnsdb {>|mxh=\ + $sender_address_domain} }} } + message = The mail servers for the domain \ $sender_address_domain \ are listed at $dnslist_domain ($dnslist_value); \ see $dnslist_text. - dnslists = sbl.spamhaus.org/<|${lookup dnsdb {>|a=<|\ - ${lookup dnsdb {>|mxh=\ - $sender_address_domain} }} } .endd Note the use of &`>|`& in the dnsdb lookup to specify the separator for multiple DNS records. The inner dnsdb lookup produces a list of MX hosts @@ -31823,27 +32688,32 @@ The key that was used for a successful DNS list lookup is put into the variable -.section "Data returned by DNS lists" "SECID203" +.subsection "Data returned by DNS lists" SECID203 .cindex "DNS list" "data returned from" DNS lists are constructed using address records in the DNS. The original RBL just used the address 127.0.0.1 on the right hand side of each record, but the RBL+ list and some other lists use a number of values with different meanings. The values used on the RBL+ list are: -.display -127.1.0.1 RBL -127.1.0.2 DUL -127.1.0.3 DUL and RBL -127.1.0.4 RSS -127.1.0.5 RSS and RBL -127.1.0.6 RSS and DUL -127.1.0.7 RSS and DUL and RBL -.endd +.itable none 0 0 2 20* left 80* left +.irow 127.1.0.1 "RBL" +.irow 127.1.0.2 "DUL" +.irow 127.1.0.3 "DUL and RBL" +.irow 127.1.0.4 "RSS" +.irow 127.1.0.5 "RSS and RBL" +.irow 127.1.0.6 "RSS and DUL" +.irow 127.1.0.7 "RSS and DUL and RBL" +.endtable Section &<>& below describes how you can distinguish between different values. Some DNS lists may return more than one address record; see section &<>& for details of how they are checked. +Values returned by a properly running DBSBL should be in the 127.0.0.0/8 +range. If a DNSBL operator loses control of the domain, lookups on it +may start returning other addresses. Because of this, Exim now ignores +returned values outside the 127/8 region. + -.section "Variables set from DNS lists" "SECID204" +.subsection "Variables set from DNS lists" SECID204 .cindex "expansion" "variables, set from DNS list" .cindex "DNS list" "variables set from" .vindex "&$dnslist_domain$&" @@ -31878,7 +32748,7 @@ very meaningful. See section &<>& for a way of obtaining more information. You can use the DNS list variables in &%message%& or &%log_message%& modifiers -&-- although these appear before the condition in the ACL, they are not +&-- even if these appear before the condition in the ACL, they are not expanded until after it has failed. For example: .code deny hosts = !+local_networks @@ -31889,7 +32759,7 @@ deny hosts = !+local_networks -.section "Additional matching conditions for DNS lists" "SECTaddmatcon" +.subsection "Additional matching conditions for DNS lists" SECTaddmatcon .cindex "DNS list" "matching specific returned data" You can add an equals sign and an IP address after a &%dnslists%& domain name in order to restrict its action to DNS records with a matching right hand side. @@ -31935,7 +32805,7 @@ an odd number. -.section "Negated DNS matching conditions" "SECID205" +.subsection "Negated DNS matching conditions" SECID205 You can supply a negative list of IP addresses as part of a &%dnslists%& condition. Whereas .code @@ -31978,10 +32848,18 @@ deny dnslists = relays.ordb.org .endd which is less clear, and harder to maintain. +Negation can also be used with a bitwise-and restriction. +The dnslists condition with only be trus if a result is returned +by the lookup which, anded with the restriction, is all zeroes. +For example: +.code +deny dnslists = zen.spamhaus.org!&0.255.255.0 +.endd -.section "Handling multiple DNS records from a DNS list" "SECThanmuldnsrec" + +.subsection "Handling multiple DNS records from a DNS list" SECThanmuldnsrec A DNS lookup for a &%dnslists%& condition may return more than one DNS record, thereby providing more than one IP address. When an item in a &%dnslists%& list is followed by &`=`& or &`&&`& and a list of IP addresses, in order to restrict @@ -32045,7 +32923,7 @@ between &`=`& and &`==`& and between &`&&`& and &`=&&`&. -.section "Detailed information from merged DNS lists" "SECTmordetinf" +.subsection "Detailed information from merged DNS lists" SECTmordetinf .cindex "DNS list" "information from merged" When the facility for restricting the matching IP values in a DNS list is used, the text from the TXT record that is set in &$dnslist_text$& may not reflect @@ -32064,12 +32942,12 @@ restrictions, to get the TXT record. As a byproduct of this, there is also a check that the IP being tested is indeed on the first list. The first domain is the one that is put in &$dnslist_domain$&. For example: .code -deny message = \ - rejected because $sender_host_address is blacklisted \ - at $dnslist_domain\n$dnslist_text - dnslists = \ +deny dnslists = \ sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \ dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10 + message = \ + rejected because $sender_host_address is blacklisted \ + at $dnslist_domain\n$dnslist_text .endd For the first blacklist item, this starts by doing a lookup in &'sbl-xbl.spamhaus.org'& and testing for a 127.0.0.2 return. If there is a @@ -32094,7 +32972,7 @@ done. Only if there is a match is one of the more specific lists consulted. -.section "DNS lists and IPv6" "SECTmorednslistslast" +.subsection "DNS lists and IPv6" SECTmorednslistslast .cindex "IPv6" "DNS black lists" .cindex "DNS list" "IPv6 usage" If Exim is asked to do a dnslist lookup for an IPv6 address, it inverts it @@ -32127,6 +33005,61 @@ address you should specify alternate list separators for both the outer dnslists = <; dnsbl.example.com/<|$acl_m_addrslist .endd + +.section "Previously seen user and hosts" "SECTseen" +.cindex "&%seen%& ACL condition" +.cindex greylisting +The &%seen%& ACL condition can be used to test whether a +situation has been previously met. +It uses a hints database to record a timestamp against a key. +The syntax of the condition is: +.display +&`seen =`& <&'optional flag'&><&'time interval'&> &`/`& <&'options'&> +.endd + +For example, +.code +defer seen = -5m / key=${sender_host_address}_$local_part@$domain +.endd +in a RCPT ACL will implement simple greylisting. + +The parameters for the condition are +a possible minus sign, +then an interval, +then, slash-separated, a list of options. +The interval is taken as an offset before the current time, +and used for the test. +If the interval is preceded by a minus sign then the condition returns +whether a record is found which is before the test time. +Otherwise, the condition returns whether one is found which is since the +test time. + +Options are read in order with later ones overriding earlier ones. + +The default key is &$sender_host_address$&. +An explicit key can be set using a &%key=value%& option. + +If a &%readonly%& option is given then +no record create or update is done. +If a &%write%& option is given then +a record create or update is always done. +An update is done if the test is for &"since"&. +If none of those hold and there was no existing record, +a record is created. + +Creates and updates are marked with the current time. + +Finally, a &"before"& test which succeeds, and for which the record +is old enough, will be refreshed with a timestamp of the test time. +This can prevent tidying of the database from removing the entry. +The interval for this is, by default, 10 days. +An explicit interval can be set using a +&%refresh=value%& option. + +Note that &"seen"& should be added to the list of hints databases +for maintenance if this ACL condition is used. + + .section "Rate limiting incoming messages" "SECTratelimiting" .cindex "rate limiting" "client sending" .cindex "limiting client sending rates" @@ -32195,18 +33128,25 @@ behaviour. The lookup key is not affected by changes to the update mode and the &%count=%& option. -.section "Ratelimit options for what is being measured" "ratoptmea" +.subsection "Ratelimit options for what is being measured" ratoptmea .cindex "rate limiting" "per_* options" -The &%per_conn%& option limits the client's connection rate. It is not +.vlist +.vitem per_conn +.cindex "rate limiting" per_conn +This option limits the client's connection rate. It is not normally used in the &%acl_not_smtp%&, &%acl_not_smtp_mime%&, or &%acl_not_smtp_start%& ACLs. -The &%per_mail%& option limits the client's rate of sending messages. This is +.vitem per_mail +.cindex "rate limiting" per_conn +This option limits the client's rate of sending messages. This is the default if none of the &%per_*%& options is specified. It can be used in &%acl_smtp_mail%&, &%acl_smtp_rcpt%&, &%acl_smtp_predata%&, &%acl_smtp_mime%&, &%acl_smtp_data%&, or &%acl_not_smtp%&. -The &%per_byte%& option limits the sender's email bandwidth. It can be used in +.vitem per_byte +.cindex "rate limiting" per_conn +This option limits the sender's email bandwidth. It can be used in the same ACLs as the &%per_mail%& option, though it is best to use this option in the &%acl_smtp_mime%&, &%acl_smtp_data%& or &%acl_not_smtp%& ACLs; if it is used in an earlier ACL, Exim relies on the SIZE parameter given by the client @@ -32214,35 +33154,50 @@ 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 +.vitem per_rcpt +.cindex "rate limiting" per_rcpt +This option causes Exim to limit the rate at which recipients are accepted. It can be used in the &%acl_smtp_rcpt%&, &%acl_smtp_predata%&, -&%acl_smtp_mime%&, &%acl_smtp_data%&, or &%acl_smtp_rcpt%& ACLs. In +&%acl_smtp_mime%&, or &%acl_smtp_data%& ACLs. In &%acl_smtp_rcpt%& the rate is updated one recipient at a time; in the other ACLs the rate is updated with the total (accepted) recipient count in one go. Note that in either case the rate limiting engine will see a message with many recipients as a large high-speed burst. -The &%per_addr%& option is like the &%per_rcpt%& option, except it counts the +.vitem per_addr +.cindex "rate limiting" per_addr +This option is like the &%per_rcpt%& option, except it counts the number of different recipients that the client has sent messages to in the last time period. That is, if the client repeatedly sends messages to the same recipient, its measured rate is not increased. This option can only be used in &%acl_smtp_rcpt%&. -The &%per_cmd%& option causes Exim to recompute the rate every time the +.vitem per_cmd +.cindex "rate limiting" per_cmd +This option causes Exim to recompute the rate every time the condition is processed. This can be used to limit the rate of any SMTP command. If it is used in multiple ACLs it can limit the aggregate rate of multiple different commands. -The &%count=%& option can be used to alter how much Exim adds to the client's -measured rate. For example, the &%per_byte%& option is equivalent to -&`per_mail/count=$message_size`&. If there is no &%count=%& option, Exim +.vitem count +.cindex "rate limiting" count +This option can be used to alter how much Exim adds to the client's +measured rate. +A value is required, after an equals sign. +For example, the &%per_byte%& option is equivalent to +&`per_mail/count=$message_size`&. +If there is no &%count=%& option, Exim increases the measured rate by one (except for the &%per_rcpt%& option in ACLs -other than &%acl_smtp_rcpt%&). The count does not have to be an integer. +other than &%acl_smtp_rcpt%&). +The count does not have to be an integer. -The &%unique=%& option is described in section &<>& below. +.vitem unique +.cindex "rate limiting" unique +This option is described in section &<>& below. +.endlist -.section "Ratelimit update modes" "ratoptupd" +.subsection "Ratelimit update modes" ratoptupd .cindex "rate limiting" "reading data without updating" You can specify one of three options with the &%ratelimit%& condition to control when its database is updated. This section describes the &%readonly%& @@ -32259,12 +33214,12 @@ new rate. .code acl_check_connect: deny ratelimit = 100 / 5m / readonly - log_message = RATE CHECK: $sender_rate/$sender_rate_period \ + log_message = RATE CHECK: $sender_rate/$sender_rate_period \ (max $sender_rate_limit) # ... acl_check_mail: warn ratelimit = 100 / 5m / strict - log_message = RATE UPDATE: $sender_rate/$sender_rate_period \ + log_message = RATE UPDATE: $sender_rate/$sender_rate_period \ (max $sender_rate_limit) .endd @@ -32283,7 +33238,7 @@ update mode defaults to &%readonly%& and you cannot specify the &%strict%& or next section) so you must specify the &%readonly%& option explicitly. -.section "Ratelimit options for handling fast clients" "ratoptfast" +.subsection "Ratelimit options for handling fast clients" ratoptfast .cindex "rate limiting" "strict and leaky modes" If a client's average rate is greater than the maximum, the rate limiting engine can react in two possible ways, depending on the presence of the @@ -32314,7 +33269,7 @@ attempt to send mail can be calculated with this formula: .endd -.section "Limiting the rate of different events" "ratoptuniq" +.subsection "Limiting the rate of different events" ratoptuniq .cindex "rate limiting" "counting unique events" The &%ratelimit%& &%unique=%& option controls a mechanism for counting the rate of different events. For example, the &%per_addr%& option uses this @@ -32352,7 +33307,7 @@ are logged incorrectly; any countermeasures you configure will be as effective as intended. -.section "Using rate limiting" "useratlim" +.subsection "Using rate limiting" useratlim Exim's other ACL facilities are used to define what counter-measures are taken when the rate limit is exceeded. This might be anything from logging a warning (for example, while measuring existing sending rates in order to define @@ -32374,16 +33329,16 @@ deny authenticated = * ratelimit = 100 / 1d / strict / $authenticated_id # System-wide rate limit -defer message = Sorry, too busy. Try again later. - ratelimit = 10 / 1s / $primary_hostname +defer ratelimit = 10 / 1s / $primary_hostname + message = Sorry, too busy. Try again later. # Restrict incoming rate from each host, with a default # set using a macro and special cases looked up in a table. -defer message = Sender rate exceeds $sender_rate_limit \ - messages per $sender_rate_period - ratelimit = ${lookup {$sender_host_address} \ +defer ratelimit = ${lookup {$sender_host_address} \ cdb {DB/ratelimits.cdb} \ {$value} {RATELIMIT} } + message = Sender rate exceeds $sender_rate_limit \ + messages per $sender_rate_period .endd &*Warning*&: If you have a busy server with a lot of &%ratelimit%& tests, especially with the &%per_rcpt%& option, you may suffer from a performance @@ -32432,6 +33387,13 @@ The &%success_on_redirect%& option causes verification always to succeed immediately after a successful redirection. By default, if a redirection generates just one address, that address is also verified. See further discussion in section &<>&. +.next +If the &%quota%& option is specified for recipient verify, +successful routing to an appendfile transport is followed by a call into +the transport to evaluate the quota status for the recipient. +No actual delivery is done, but verification will succeed if the quota +is sufficient for the message (if the sender gave a message size) or +not already exceeded (otherwise). .endlist .cindex "verifying address" "differentiating failures" @@ -32448,6 +33410,7 @@ warn !verify = sender If you are writing your own custom rejection message or log message when denying access, you can use this variable to include information about the verification failure. +This variable is cleared at the end of processing the ACL verb. In addition, &$sender_verify_failure$& or &$recipient_verify_failure$& (as appropriate) contains one of the following words: @@ -32465,6 +33428,8 @@ connection, HELO, or MAIL). &%recipient%&: The RCPT command in a callout was rejected. .next &%postmaster%&: The postmaster check in a callout was rejected. +.next +&%quota%&: The quota check for a local recipient did non pass. .endlist The main use of these variables is expected to be to distinguish between @@ -32559,10 +33524,17 @@ output before performing a callout in an ACL, to avoid unexpected timeouts in clients when the SMTP PIPELINING extension is in use. The flushing can be disabled by using a &%control%& modifier to set &%no_callout_flush%&. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using recipient verify" +A recipient callout which gets a 2&'xx'& code +will assign untainted values to the +&$domain_data$& and &$local_part_data$& variables, +corresponding to the domain and local parts of the recipient address. + -.section "Additional parameters for callouts" "CALLaddparcall" +.subsection "Additional parameters for callouts" CALLaddparcall .cindex "callout" "additional parameters for" The &%callout%& option can be followed by an equals sign and a number of optional parameters, separated by commas. For example: @@ -32750,7 +33722,7 @@ actual callouts are performed than when an empty sender or postmaster is used. -.section "Callout caching" "SECTcallvercache" +.subsection "Callout caching" SECTcallvercache .cindex "hints database" "callout cache" .cindex "callout" "cache, description of" .cindex "caching" "callout" @@ -32762,7 +33734,7 @@ a specific address, and the other records information that applies to the entire domain (for example, that it accepts the local part &'postmaster'&). When an original callout fails, a detailed SMTP error message is given about -the failure. However, for subsequent failures use the cache data, this message +the failure. However, for subsequent failures that use the cache data, this message is not available. The expiry times for negative and positive address cache records are @@ -32794,6 +33766,36 @@ behaviour will be the same. +.section "Quota caching" "SECTquotacache" +.cindex "hints database" "quota cache" +.cindex "quota" "cache, description of" +.cindex "caching" "quota" +Exim caches the results of quota verification +in order to reduce the amount of resources used. +The &"callout"& hints database is used. + +The default cache periods are five minutes for a positive (good) result +and one hour for a negative result. +To change the periods the &%quota%& option can be followed by an equals sign +and a number of optional paramemters, separated by commas. +For example: +.code +verify = recipient/quota=cachepos=1h,cacheneg=1d +.endd +Possible parameters are: +.vlist +.vitem &*cachepos&~=&~*&<&'time&~interval'&> +.cindex "quota cache" "positive entry expiry, specifying" +Set the lifetime for a positive cache entry. +A value of zero seconds is legitimate. + +.vitem &*cacheneg&~=&~*&<&'time&~interval'&> +.cindex "quota cache" "negative entry expiry, specifying" +As above, for a negative entry. + +.vitem &*no_cache*& +Set both positive and negative lifetimes to zero. + .section "Sender address verification reporting" "SECTsenaddver" .cindex "verifying" "suppressing error details" See section &<>& for a general discussion of @@ -32972,16 +33974,16 @@ list called &%batv_senders%&. Then, in the ACL for RCPT commands, you could use this: .code # Bounces: drop unsigned addresses for BATV senders -deny message = This address does not send an unsigned reverse path - senders = : +deny senders = : recipients = +batv_senders + message = This address does not send an unsigned reverse path # Bounces: In case of prvs-signed address, check signature. -deny message = Invalid reverse path signature. - senders = : +deny senders = : condition = ${prvscheck {$local_part@$domain}\ {PRVSCHECK_SQL}{1}} !condition = $prvscheck_result + message = Invalid reverse path signature. .endd The first statement rejects recipients for bounce messages that are addressed to plain BATV sender addresses, because it is known that BATV senders do not @@ -33518,13 +34520,13 @@ imposed by your anti-virus scanner. Here is a very simple scanning example: .code -deny message = This message contains malware ($malware_name) - malware = * +deny malware = * + message = This message contains malware ($malware_name) .endd The next example accepts messages when there is a problem with the scanner: .code -deny message = This message contains malware ($malware_name) - malware = */defer_ok +deny malware = */defer_ok + message = This message contains malware ($malware_name) .endd The next example shows how to use an ACL variable to scan with both sophie and aveserver. It assumes you have set: @@ -33533,13 +34535,13 @@ av_scanner = $acl_m0 .endd in the main Exim configuration. .code -deny message = This message contains malware ($malware_name) - set acl_m0 = sophie +deny set acl_m0 = sophie malware = * + message = This message contains malware ($malware_name) -deny message = This message contains malware ($malware_name) - set acl_m0 = aveserver +deny set acl_m0 = aveserver malware = * + message = This message contains malware ($malware_name) .endd @@ -33668,8 +34670,8 @@ is set to record the actual address used. .section "Calling SpamAssassin from an Exim ACL" "SECID206" Here is a simple example of the use of the &%spam%& condition in a DATA ACL: .code -deny message = This message was classified as SPAM - spam = joe +deny spam = joe + message = This message was classified as SPAM .endd The right-hand side of the &%spam%& condition specifies a name. This is relevant if you have set up multiple SpamAssassin profiles. If you do not want @@ -33701,9 +34703,9 @@ large ones may cause significant performance degradation. As most spam messages are quite small, it is recommended that you do not scan the big ones. For example: .code -deny message = This message was classified as SPAM - condition = ${if < {$message_size}{10K}} +deny condition = ${if < {$message_size}{10K}} spam = nobody + message = This message was classified as SPAM .endd The &%spam%& condition returns true if the threshold specified in the user's @@ -33761,8 +34763,8 @@ 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 +deny spam = joe/defer_ok + message = This message was classified as SPAM .endd This causes messages to be accepted even if there is a problem with &%spamd%&. @@ -33780,9 +34782,9 @@ warn spam = nobody add_header = Subject: *SPAM* $h_Subject: # reject spam at high scores (> 12) -deny message = This message scored $spam_score spam points. - spam = nobody:true +deny spam = nobody:true condition = ${if >{$spam_score_int}{120}{1}{0}} + message = This message scored $spam_score spam points. .endd @@ -33986,10 +34988,10 @@ As an example, the following will ban &"HTML mail"& (including that sent with alternative plain text), while allowing HTML files to be attached. HTML coverletter mail attached to non-HTML coverletter mail will also be allowed: .code -deny message = HTML mail is not accepted here -!condition = $mime_is_rfc822 -condition = $mime_is_coverletter -condition = ${if eq{$mime_content_type}{text/html}{1}{0}} +deny !condition = $mime_is_rfc822 + condition = $mime_is_coverletter + condition = ${if eq{$mime_content_type}{text/html}{1}{0}} + message = HTML mail is not accepted here .endd .vitem &$mime_is_multipart$& @@ -34042,8 +35044,8 @@ expanded before being used, you must also escape dollar signs and backslashes with more backslashes, or use the &`\N`& facility to disable expansion. Here is a simple example that contains two regular expressions: .code -deny message = contains blacklisted regex ($regex_match_string) - regex = [Mm]ortgage : URGENT BUSINESS PROPOSAL +deny regex = [Mm]ortgage : URGENT BUSINESS PROPOSAL + message = contains blacklisted regex ($regex_match_string) .endd The conditions returns true if any one of the regular expressions matches. The &$regex_match_string$& expansion variable is then set up and contains the @@ -34111,10 +35113,8 @@ HAVE_LOCAL_SCAN=yes LOCAL_SCAN_SOURCE=Local/local_scan.c .endd for example. The function must be called &[local_scan()]&; -.new the source file(s) for it should first #define LOCAL_SCAN and then #include "local_scan.h". -.wen It is called by Exim after it has received a message, when the success return code is about to be sent. This is after all the ACLs have been run. The return code from your @@ -34318,11 +35318,11 @@ C variables are as follows: .vlist .vitem &*int&~body_linecount*& This variable contains the number of lines in the message's body. -It is not valid if the &%spool_files_wireformat%& option is used. +It is not valid if the &%spool_wireformat%& option is used. .vitem &*int&~body_zerocount*& This variable contains the number of binary zero bytes in the message's body. -It is not valid if the &%spool_files_wireformat%& option is used. +It is not valid if the &%spool_wireformat%& option is used. .vitem &*unsigned&~int&~debug_selector*& This variable is set to zero when no debugging is taking place. Otherwise, it @@ -34357,7 +35357,7 @@ discussed below. .vitem &*header_line&~*header_last*& A pointer to the last of the header lines. -.vitem &*uschar&~*headers_charset*& +.vitem &*const&~uschar&~*headers_charset*& The value of the &%headers_charset%& configuration option. .vitem &*BOOL&~host_checking*& @@ -34642,11 +35642,11 @@ added zero byte is not included in the returned count. .vitem &*int&~lss_match_domain(uschar&~*domain,&~uschar&~*list)*& This function checks for a match in a domain list. Domains are always matched caselessly. The return value is one of the following: -.display -&`OK `& match succeeded -&`FAIL `& match failed -&`DEFER `& match deferred -.endd +.itable none 0 0 2 15* left 85* left +.irow &`OK`& "match succeeded" +.irow &`FAIL`& "match failed" +.irow &`DEFER`& "match deferred" +.endtable DEFER is usually caused by some kind of lookup defer, such as the inability to contact a database. @@ -34795,7 +35795,6 @@ dropping of a TCP/IP connection), you can call &'smtp_fflush()'&, which has no arguments. It flushes the output stream, and returns a non-zero value if there is an error. -.new .vitem &*void&~*store_get(int,BOOL)*& This function accesses Exim's internal store (memory) manager. It gets a new chunk of memory whose size is given by the first argument. @@ -34804,7 +35803,6 @@ data possibly coming from an attacker (eg. the message content), FALSE if it is locally-sourced. Exim bombs out if it ever runs out of memory. See the next section for a discussion of memory handling. -.wen .vitem &*void&~*store_get_perm(int,BOOL)*& This function is like &'store_get()'&, but it always gets memory from the @@ -34883,6 +35881,7 @@ The system filter is run at the start of a delivery attempt, before any routing is done. If a message fails to be completely delivered at the first attempt, the system filter is run again at the start of every retry. If you want your filter to do something only once per message, you can make use +.cindex retry condition of the &%first_delivery%& condition in an &%if%& command in the filter to prevent it happening on retries. @@ -35125,20 +36124,20 @@ address if its delivery failed. .section "Per-address filtering" "SECTperaddfil" -.vindex "&$domain$&" -.vindex "&$local_part$&" +.vindex "&$domain_data$&" +.vindex "&$local_part_data$&" In contrast to the system filter, which is run just once per message for each delivery attempt, it is also possible to set up a system-wide filtering operation that runs once for each recipient address. In this case, variables -such as &$local_part$& and &$domain$& can be used, and indeed, the choice of -filter file could be made dependent on them. This is an example of a router -which implements such a filter: +such as &$local_part_data$& and &$domain_data$& can be used, +and indeed, the choice of filter file could be made dependent on them. +This is an example of a router which implements such a filter: .code central_filter: check_local_user driver = redirect domains = +local_domains - file = /central/filters/$local_part + file = /central/filters/$local_part_data no_verify allow_filter allow_freeze @@ -35379,9 +36378,9 @@ incoming SMTP message from a source that is not permitted to send them. -.section "Resent- header lines" "SECID220" -.cindex "&%Resent-%& header lines" -.cindex "header lines" "Resent-" +.section "Header lines" +.subsection "Resent- header lines" SECID220 +.chindex Resent- RFC 2822 makes provision for sets of header lines starting with the string &`Resent-`& to be added to a message when it is resent by the original recipient to somebody else. These headers are &'Resent-Date:'&, @@ -35421,14 +36420,14 @@ The logic for adding &'Sender:'& is duplicated for &'Resent-Sender:'& when any -.section "The Auto-Submitted: header line" "SECID221" +.subsection Auto-Submitted: SECID221 Whenever Exim generates an autoreply, a bounce, or a delay warning message, it includes the header line: .code Auto-Submitted: auto-replied .endd -.section "The Bcc: header line" "SECID222" +.subsection Bcc: SECID222 .cindex "&'Bcc:'& header line" If Exim is called with the &%-t%& option, to take recipient addresses from a message's header, it removes any &'Bcc:'& header line that may exist (after @@ -35436,14 +36435,13 @@ extracting its addresses). If &%-t%& is not present on the command line, any existing &'Bcc:'& is not removed. -.section "The Date: header line" "SECID223" -.cindex "&'Date:'& header line" -.cindex "header lines" "Date:" +.subsection Date: SECID223 +.cindex Date: If a locally-generated or submission-mode message has no &'Date:'& header line, Exim adds one, using the current date and time, unless the &%suppress_local_fixups%& control has been specified. -.section "The Delivery-date: header line" "SECID224" +.subsection Delivery-date: SECID224 .cindex "&'Delivery-date:'& header line" .oindex "&%delivery_date_remove%&" &'Delivery-date:'& header lines are not part of the standard RFC 2822 header @@ -35454,9 +36452,8 @@ set (the default), Exim removes &'Delivery-date:'& header lines from incoming messages. -.section "The Envelope-to: header line" "SECID225" -.cindex "&'Envelope-to:'& header line" -.cindex "header lines" "Envelope-to:" +.subsection Envelope-to: SECID225 +.chindex Envelope-to: .oindex "&%envelope_to_remove%&" &'Envelope-to:'& header lines are not part of the standard RFC 2822 header set. Exim can be configured to add them to the final delivery of messages. (See the @@ -35466,9 +36463,8 @@ messages in transit. If the &%envelope_to_remove%& configuration option is set messages. -.section "The From: header line" "SECTthefrohea" -.cindex "&'From:'& header line" -.cindex "header lines" "From:" +.subsection From: SECTthefrohea +.chindex From: .cindex "Sendmail compatibility" "&""From""& line" .cindex "message" "submission" .cindex "submission mode" @@ -35510,9 +36506,8 @@ user, this is replaced by an address containing the user's login name and full name as described in section &<>&. -.section "The Message-ID: header line" "SECID226" -.cindex "&'Message-ID:'& header line" -.cindex "header lines" "Message-ID:" +.subsection Message-ID: SECID226 +.chindex Message-ID: .cindex "message" "submission" .oindex "&%message_id_header_text%&" If a locally-generated or submission-mode incoming message does not contain a @@ -35526,9 +36521,8 @@ in this header line by setting the &%message_id_header_text%& and/or &%message_id_header_domain%& options. -.section "The Received: header line" "SECID227" -.cindex "&'Received:'& header line" -.cindex "header lines" "Received:" +.subsection Received: SECID227 +.chindex Received: A &'Received:'& header line is added at the start of every message. The contents are defined by the &%received_header_text%& configuration option, and Exim automatically adds a semicolon and a timestamp to the configured string. @@ -35543,9 +36537,8 @@ changed to the time of acceptance, which is (apart from a small delay while the -H spool file is written) the earliest time at which delivery could start. -.section "The References: header line" "SECID228" -.cindex "&'References:'& header line" -.cindex "header lines" "References:" +.subsection References: SECID228 +.chindex References: Messages created by the &(autoreply)& transport include a &'References:'& header line. This is constructed according to the rules that are described in section 3.64 of RFC 2822 (which states that replies should contain such a @@ -35558,9 +36551,8 @@ incoming message. If there are more than 12, the first one and then the final -.section "The Return-path: header line" "SECID229" -.cindex "&'Return-path:'& header line" -.cindex "header lines" "Return-path:" +.subsection Return-path: SECID229 +.chindex Return-path: .oindex "&%return_path_remove%&" &'Return-path:'& header lines are defined as something an MTA may insert when it does the final delivery of messages. (See the generic &%return_path_add%& @@ -35570,10 +36562,10 @@ default), Exim removes &'Return-path:'& header lines from incoming messages. -.section "The Sender: header line" "SECTthesenhea" +.subsection Sender: SECTthesenhea .cindex "&'Sender:'& header line" .cindex "message" "submission" -.cindex "header lines" "Sender:" +.chindex Sender: For a locally-originated message from an untrusted user, Exim may remove an existing &'Sender:'& header line, and it may add a new one. You can modify these actions by setting the &%local_sender_retain%& option true, the @@ -35896,13 +36888,14 @@ used to contain the envelope information. .cindex "outgoing LMTP over TCP/IP" .cindex "EHLO" .cindex "HELO" -.cindex "SIZE option on MAIL command" +.cindex "SIZE" "option on MAIL command" Outgoing SMTP and LMTP over TCP/IP is implemented by the &(smtp)& transport. The &%protocol%& option selects which protocol is to be used, but the actual processing is the same in both cases. +.cindex "ESMTP extensions" SIZE If, in response to its EHLO command, Exim is told that the SIZE -parameter is supported, it adds SIZE=<&'n'&> to each subsequent MAIL +extension is supported, it adds SIZE=<&'n'&> to each subsequent MAIL command. The value of <&'n'&> is the message size plus the value of the &%size_addition%& option (default 1024) to allow for additions to the message such as per-transport header lines, or changes made in a @@ -35974,7 +36967,7 @@ square bracket of the IP address. -.section "Errors in outgoing SMTP" "SECToutSMTPerr" +.subsection "Errors in outgoing SMTP" SECToutSMTPerr .cindex "error" "in outgoing SMTP" .cindex "SMTP" "errors in outgoing" .cindex "host" "error" @@ -36209,7 +37202,7 @@ however, available with &'inetd'&. Exim can be configured to verify addresses in incoming SMTP commands as they are received. See chapter &<>& for details. It can also be configured to rewrite addresses at this time &-- before any syntax checking is done. See -section &<>&. +section &<>&. Exim can also be configured to limit the rate at which a client host submits MAIL and RCPT commands in a single SMTP session. See the @@ -36217,7 +37210,7 @@ MAIL and RCPT commands in a single SMTP session. See the -.section "Unrecognized SMTP commands" "SECID234" +.subsection "Unrecognized SMTP commands" SECID234 .cindex "SMTP" "unrecognized commands" If Exim receives more than &%smtp_max_unknown_commands%& unrecognized SMTP commands during a single SMTP connection, it drops the connection after sending @@ -36227,7 +37220,7 @@ abuse that subvert web servers into making connections to SMTP ports; in these circumstances, a number of non-SMTP lines are sent first. -.section "Syntax and protocol errors in SMTP commands" "SECID235" +.subsection "Syntax and protocol errors in SMTP commands" SECID235 .cindex "SMTP" "syntax errors" .cindex "SMTP" "protocol errors" A syntax error is detected if an SMTP command is recognized, but there is @@ -36241,7 +37234,7 @@ broken clients that loop sending bad commands (yes, it has been seen). -.section "Use of non-mail SMTP commands" "SECID236" +.subsection "Use of non-mail SMTP commands" SECID236 .cindex "SMTP" "non-mail commands" The &"non-mail"& SMTP commands are those other than MAIL, RCPT, and DATA. Exim counts such commands, and drops the connection if there are too @@ -36270,7 +37263,7 @@ specific badly-behaved hosts that you have to live with. -.section "The VRFY and EXPN commands" "SECID237" +.subsection "The VRFY and EXPN commands" SECID237 When Exim receives a VRFY or EXPN command on a TCP/IP connection, it runs the ACL specified by &%acl_smtp_vrfy%& or &%acl_smtp_expn%& (as appropriate) in order to decide whether the command should be accepted or not. @@ -36291,14 +37284,15 @@ EXPN is treated as an &"address test"& (similar to the &%-bt%& option) rather than a verification (the &%-bv%& option). If an unqualified local part is given as the argument to EXPN, it is qualified with &%qualify_domain%&. Rejections of VRFY and EXPN commands are logged on the main and reject logs, and -VRFY verification failures are logged on the main log for consistency with +VRFY verification failures are logged in the main log for consistency with RCPT failures. -.section "The ETRN command" "SECTETRN" +.subsection "The ETRN command" SECTETRN .cindex "ETRN" "processing" -RFC 1985 describes an SMTP command called ETRN that is designed to +.cindex "ESMTP extensions" ETRN +RFC 1985 describes an ESMTP command called ETRN that is designed to overcome the security problems of the TURN command (which has fallen into disuse). When Exim receives an ETRN command on a TCP/IP connection, it runs the ACL specified by &%acl_smtp_etrn%& in order to decide whether the command @@ -36653,10 +37647,10 @@ lists in a separate domain from normal mail. For example: lists: driver = redirect domains = lists.example - file = /usr/lists/$local_part + file = ${lookup {$local_part} dsearch,ret=full {/usr/lists}} forbid_pipe forbid_file - errors_to = $local_part-request@lists.example + errors_to = ${quote_local_part:$local_part-request}@lists.example no_more .endd This router is skipped for domains other than &'lists.example'&. For addresses @@ -36744,18 +37738,19 @@ lists_request: driver = redirect domains = lists.example local_part_suffix = -request - file = /usr/lists/$local_part$local_part_suffix + local_parts = ${lookup {$local_part} dsearch,filter=file {/usr/lists}} + file = /usr/lists/${local_part_data}-request no_more lists_post: driver = redirect domains = lists.example - senders = ${if exists {/usr/lists/$local_part}\ - {lsearch;/usr/lists/$local_part}{*}} - file = /usr/lists/$local_part + local_parts = ${lookup {$local_part} dsearch,filter=file,ret=full {/usr/lists}} + senders = ${if exists {$local_part_data} {lsearch;$local_part_data}{*}} + file = ${lookup {$local_part} dsearch,ret=full {/usr/lists}} forbid_pipe forbid_file - errors_to = $local_part-request@lists.example + errors_to = ${quote_local_part:$local_part-request}@lists.example no_more lists_closed: @@ -36813,7 +37808,7 @@ verp_smtp: max_rcpt = 1 return_path = \ ${if match {$return_path}{^(.+?)-request@your.dom.example\$}\ - {$1-request+$local_part=$domain@your.dom.example}fail} + {${quote_local_part:$1-request+$local_part=$domain}@your.dom.example}fail} .endd This has the effect of rewriting the return path (envelope sender) on outgoing SMTP messages, if the local part of the original return path ends in @@ -36864,7 +37859,7 @@ verp_dnslookup: transport = remote_smtp errors_to = \ ${if match {$return_path}{^(.+?)-request@your.dom.example\$}} - {$1-request+$local_part=$domain@your.dom.example}fail} + {${quote_local_part:$1-request+$local_part=$domain}@your.dom.example}fail} no_more .endd Before you start sending out messages with VERPed return paths, you must also @@ -36915,13 +37910,11 @@ virtual: data = ${lookup{$local_part}lsearch{/etc/mail/virtual/$domain_data}} no_more .endd -.new The &%domains%& option specifies that the router is to be skipped, unless there is a file in the &_/etc/mail/virtual_& directory whose name is the same as the domain that is being processed. The &(dsearch)& lookup used results in an untainted version of &$domain$& being placed into the &$domain_data$& variable. -.wen When the router runs, it looks up the local part in the file to find a new address (or list of addresses). The &%no_more%& @@ -36952,7 +37945,7 @@ follows: .code my_mailboxes: driver = appendfile - file = /var/mail/$domain/$local_part + file = /var/mail/$domain_data/$local_part_data user = mail .endd This uses a directory of mailboxes for each domain. The &%user%& setting is @@ -36992,7 +37985,7 @@ It runs a user's &_.forward_& file for all local parts of the form cases by testing the variable &$local_part_suffix$&. For example: .code if $local_part_suffix contains -special then -save /home/$local_part/Mail/special +save /home/$local_part_data/Mail/special endif .endd If the filter file does not exist, or does not deal with such addresses, they @@ -37007,9 +38000,9 @@ another MTA: userforward: driver = redirect check_local_user - file = $home/.forward$local_part_suffix local_part_suffix = -* local_part_suffix_optional + file = ${lookup {.forward$local_part_suffix} dsearch,ret=full {$home} {$value}fail} allow_filter .endd If there is no suffix, &_.forward_& is used; if the suffix is &'-special'&, for @@ -37360,9 +38353,9 @@ implying the use of a default path. When Exim encounters an empty item in the list, it searches the list defined by LOG_FILE_PATH, and uses the first item it finds that is neither empty nor &"syslog"&. This means that an empty item in &%log_file_path%& can be used to -mean &"use the path specified at build time"&. It no such item exists, log +mean &"use the path specified at build time"&. If no such item exists, log files are written in the &_log_& subdirectory of the spool directory. This is -equivalent to the setting: +equivalent to the configuration file setting: .code log_file_path = $spool_directory/log/%slog .endd @@ -37373,7 +38366,7 @@ that is where the logs are written. A log file path may also contain &`%D`& or &`%M`& if datestamped log filenames are in use &-- see section &<>& below. -Here are some examples of possible settings: +Here are some examples of possible Makefile settings: .display &`LOG_FILE_PATH=syslog `& syslog only &`LOG_FILE_PATH=:syslog `& syslog and default path @@ -37548,16 +38541,16 @@ One line is written to the main log for each message received, and for each successful, unsuccessful, and delayed delivery. These lines can readily be picked out by the distinctive two-character flags that immediately follow the timestamp. The flags are: -.display -&`<=`& message arrival -&`(=`& message fakereject -&`=>`& normal message delivery -&`->`& additional address in same delivery -&`>>`& cutthrough message delivery -&`*>`& delivery suppressed by &%-N%& -&`**`& delivery failed; address bounced -&`==`& delivery deferred; temporary problem -.endd +.itable none 0 0 2 10* left 90* left +.irow &%<=%& "message arrival" +.irow &%(=%& "message fakereject" +.irow &%=>%& "normal message delivery" +.irow &%->%& "additional address in same delivery" +.irow &%>>%& "cutthrough message delivery" +.irow &%*>%& "delivery suppressed by &%-N%&" +.irow &%**%& "delivery failed; address bounced" +.irow &%==%& "delivery deferred; temporary problem" +.endtable .section "Logging message reception" "SECID251" @@ -37657,7 +38650,8 @@ fields record the router and transport that were used to process the address. If SMTP AUTH was used for the delivery there is an additional item A= followed by the name of the authenticator that was used. If an authenticated identification was set up by the authenticator's &%client_set_id%& -option, this is logged too, separated by a colon from the authenticator name. +option, this is logged too, as a second colon-separated list item. +Optionally (see the &%smtp_mailauth%& &%log_selector%&) there may be a third list item. If a shadow transport was run after a successful local delivery, the log line for the successful delivery has an item added on the end, of the form @@ -37671,8 +38665,9 @@ parentheses afterwards. When more than one address is included in a single delivery (for example, two SMTP RCPT commands in one transaction) the second and subsequent addresses are flagged with &`->`& instead of &`=>`&. When two or more messages are delivered -down a single SMTP connection, an asterisk follows the IP address in the log -lines for the second and subsequent messages. +down a single SMTP connection, an asterisk follows the +remote IP address (and port if enabled) +in the log lines for the second and subsequent messages. When two or more messages are delivered down a single TLS connection, the DNS and some TLS-related information logged for the first message delivered will not be present in the log lines for the second and subsequent messages. @@ -37874,63 +38869,64 @@ log_selector = +arguments -retry_defer .endd The list of optional log items is in the following table, with the default selection marked by asterisks: -.display -&` 8bitmime `& received 8BITMIME status -&`*acl_warn_skipped `& skipped &%warn%& statement in ACL -&` address_rewrite `& address rewriting -&` all_parents `& all parents in => lines -&` arguments `& command line arguments -&`*connection_reject `& connection rejections -&`*delay_delivery `& immediate delivery delayed -&` deliver_time `& time taken to attempt delivery -&` delivery_size `& add &`S=`&&'nnn'& to => lines -&`*dkim `& DKIM verified domain on <= lines -&` dkim_verbose `& separate full DKIM verification result line, per signature -&`*dnslist_defer `& defers of DNS list (aka RBL) lookups -&` dnssec `& DNSSEC secured lookups -&`*etrn `& ETRN commands -&`*host_lookup_failed `& as it says -&` ident_timeout `& timeout for ident connection -&` incoming_interface `& local interface on <= and => lines -&` incoming_port `& remote port on <= lines -&`*lost_incoming_connection `& as it says (includes timeouts) -&` millisec `& millisecond timestamps and RT,QT,DT,D times -&`*msg_id `& on <= lines, Message-ID: header value -&` msg_id_created `& on <= lines, Message-ID: header value when one had to be added -&` outgoing_interface `& local interface on => lines -&` outgoing_port `& add remote port to => lines -&`*queue_run `& start and end queue runs -&` queue_time `& time on queue for one recipient -&` queue_time_overall `& time on queue for whole message -&` pid `& Exim process id -&` pipelining `& PIPELINING use, on <= and => lines -&` proxy `& proxy address on <= and => lines -&` receive_time `& time taken to receive message -&` received_recipients `& recipients on <= lines -&` received_sender `& sender on <= lines -&`*rejected_header `& header contents on reject log -&`*retry_defer `& &"retry time not reached"& -&` return_path_on_delivery `& put return path on => and ** lines -&` sender_on_delivery `& add sender to => lines -&`*sender_verify_fail `& sender verification failures -&`*size_reject `& rejection because too big -&`*skip_delivery `& delivery skipped in a queue run -&`*smtp_confirmation `& SMTP confirmation on => lines -&` smtp_connection `& incoming SMTP connections -&` smtp_incomplete_transaction`& incomplete SMTP transactions -&` smtp_mailauth `& AUTH argument to MAIL commands -&` smtp_no_mail `& session with no MAIL commands -&` smtp_protocol_error `& SMTP protocol errors -&` smtp_syntax_error `& SMTP syntax errors -&` subject `& contents of &'Subject:'& on <= lines -&`*tls_certificate_verified `& certificate verification status -&`*tls_cipher `& TLS cipher suite on <= and => lines -&` tls_peerdn `& TLS peer DN on <= and => lines -&` tls_sni `& TLS SNI on <= lines -&` unknown_in_list `& DNS lookup failed in list match - -&` all `& all of the above -.endd +.itable none 0 0 3 2.8in left 10pt center 3in left +.irow &`8bitmime`&   "received 8BITMIME status" +.irow &`acl_warn_skipped`& * "skipped &%warn%& statement in ACL" +.irow &`address_rewrite`&   "address rewriting" +.irow &`all_parents`&   "all parents in => lines" +.irow &`arguments`&   "command line arguments" +.irow &`connection_reject`& * "connection rejections" +.irow &`delay_delivery`& * "immediate delivery delayed" +.irow &`deliver_time`&   "time taken to attempt delivery" +.irow &`delivery_size`&   "add &`S=`&&'nnn'& to => lines" +.irow &`dkim`& * "DKIM verified domain on <= lines" +.irow &`dkim_verbose`&   "separate full DKIM verification result line, per signature" +.irow &`dnslist_defer`& * "defers of DNS list (aka RBL) lookups" +.irow &`dnssec`&   "DNSSEC secured lookups" +.irow &`etrn`& * "ETRN commands" +.irow &`host_lookup_failed`& * "as it says" +.irow &`ident_timeout`&   "timeout for ident connection" +.irow &`incoming_interface`&   "local interface on <= and => lines" +.irow &`incoming_port`&   "remote port on <= lines" +.irow &`lost_incoming_connection`& * "as it says (includes timeouts)" +.irow &`millisec`&   "millisecond timestamps and RT,QT,DT,D times" +.irow &`msg_id`& * "on <= lines, Message-ID: header value" +.irow &`msg_id_created`&   "on <= lines, Message-ID: header value when one had to be added" +.irow &`outgoing_interface`&   "local interface on => lines" +.irow &`outgoing_port`&   "add remote port to => lines" +.irow &`queue_run`& * "start and end queue runs" +.irow &`queue_time`&   "time on queue for one recipient" +.irow &`queue_time_exclusive`&   "exclude recieve time from QT times" +.irow &`queue_time_overall`&   "time on queue for whole message" +.irow &`pid`&   "Exim process id" +.irow &`pipelining`&   "PIPELINING use, on <= and => lines" +.irow &`proxy`&   "proxy address on <= and => lines" +.irow &`receive_time`&   "time taken to receive message" +.irow &`received_recipients`&   "recipients on <= lines" +.irow &`received_sender`&   "sender on <= lines" +.irow &`rejected_header`& * "header contents on reject log" +.irow &`retry_defer`& * "&&retry time not reached&&" +.irow &`return_path_on_delivery`&   "put return path on => and ** lines" +.irow &`sender_on_delivery`&   "add sender to => lines" +.irow &`sender_verify_fail`& * "sender verification failures" +.irow &`size_reject`& * "rejection because too big" +.irow &`skip_delivery`& * "delivery skipped in a queue run" +.irow &`smtp_confirmation`& * "SMTP confirmation on => lines" +.irow &`smtp_connection`&   "incoming SMTP connections" +.irow &`smtp_incomplete_transaction`&   "incomplete SMTP transactions" +.irow &`smtp_mailauth`&   "AUTH argument to MAIL commands" +.irow &`smtp_no_mail`&   "session with no MAIL commands" +.irow &`smtp_protocol_error`&   "SMTP protocol errors" +.irow &`smtp_syntax_error`&   "SMTP syntax errors" +.irow &`subject`&   "contents of &'Subject:'& on <= lines" +.irow &`tls_certificate_verified`& * "certificate verification status" +.irow &`tls_cipher`& * "TLS cipher suite on <= and => lines" +.irow &`tls_peerdn`&   "TLS peer DN on <= and => lines" +.irow &`tls_resumption`&   "append * to cipher field" +.irow &`tls_sni`&   "TLS SNI on <= lines" +.irow &`unknown_in_list`&   "DNS lookup failed in list match" +.irow &`all`&   "&*all of the above*&" +.endtable See also the &%slow_lookup_log%& main configuration option, section &<>& @@ -38038,6 +39034,7 @@ routing email addresses, but it does apply to &"byname"& lookups. client's ident port times out. .next .cindex "log" "incoming interface" +.cindex "log" "outgoing interface" .cindex "log" "local interface" .cindex "log" "local address and port" .cindex "TCP/IP" "logging local address and port" @@ -38046,7 +39043,8 @@ client's ident port times out. to the &"<="& line as an IP address in square brackets, tagged by I= and followed by a colon and the port number. The local interface and port are also added to other SMTP log lines, for example, &"SMTP connection from"&, to -rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines. +rejection lines, and (despite the name) to outgoing +&"=>"&, &"->"&, &"=="& and &"**"& lines. The latter can be disabled by turning off the &%outgoing_interface%& option. .next .cindex log "incoming proxy address" @@ -38124,7 +39122,7 @@ On accept lines, where PIPELINING was offered but not used by the client, the field has a minus appended. .cindex "pipelining" "early connection" -If Exim is built with the SUPPORT_PIPE_CONNECT build option +If Exim is built without the DISABLE_PIPE_CONNECT build option accept "L" fields have a period appended if the feature was offered but not used, or an asterisk appended if used. Delivery "L" fields have an asterisk appended if used. @@ -38137,18 +39135,13 @@ Delivery "L" fields have an asterisk appended if used. .cindex "log" "queue time" &%queue_time%&: The amount of time the message has been in the queue on the local host is logged as QT=<&'time'&> on delivery (&`=>`&) lines, for example, -&`QT=3m45s`&. The clock starts when Exim starts to receive the message, so it -includes reception time as well as the delivery time for the current address. -This means that it may be longer than the difference between the arrival and -delivery log line times, because the arrival log line is not written until the -message has been successfully received. +&`QT=3m45s`&. If millisecond logging is enabled, short times will be shown with greater precision, eg. &`QT=1.578s`&. .next &%queue_time_overall%&: The amount of time the message has been in the queue on the local host is logged as QT=<&'time'&> on &"Completed"& lines, for -example, &`QT=3m45s`&. The clock starts when Exim starts to receive the -message, so it includes reception time as well as the total delivery time. +example, &`QT=3m45s`&. .next .cindex "log" "receive duration" &%receive_time%&: For each message, the amount of real time it has taken to @@ -38207,10 +39200,12 @@ it is too big. .cindex "log" "frozen messages; skipped" .cindex "frozen messages" "logging skipping" &%skip_delivery%&: A log line is written whenever a message is skipped during a -queue run because it is frozen or because another process is already delivering -it. +queue run because it another process is already delivering it or because +it is frozen. .cindex "&""spool file is locked""&" -The message that is written is &"spool file is locked"&. +.cindex "&""message is frozen""&" +The message that is written is either &"spool file is locked"& or +&"message is frozen"&. .next .cindex "log" "smtp confirmation" .cindex "SMTP" "logging confirmation" @@ -38313,7 +39308,7 @@ unchanged, or whether they should be rendered as escape sequences. when TLS is in use. The item is &`CV=yes`& if the peer's certificate was verified using a CA trust anchor, -&`CA=dane`& if using a DNS trust anchor, +&`CV=dane`& if using a DNS trust anchor, and &`CV=no`& if not. .next .cindex "log" "TLS cipher" @@ -38327,8 +39322,15 @@ connection, the cipher suite used is added to the log line, preceded by X=. connection, and a certificate is supplied by the remote host, the peer DN is added to the log line, preceded by DN=. .next +.cindex "log" "TLS resumption" +.cindex "TLS" "logging session resumption" +&%tls_resumption%&: When a message is sent or received over an encrypted +connection and the TLS session resumed one used on a previous TCP connection, +an asterisk is appended to the X= cipher field in the log line. +.next .cindex "log" "TLS SNI" .cindex "TLS" "logging SNI" +.cindex SNI logging &%tls_sni%&: When a message is received over an encrypted connection, and the remote host provided the Server Name Indication extension, the SNI is added to the log line, preceded by SNI=. @@ -38385,9 +39387,9 @@ the next chapter. The utilities described here are: "check address acceptance from given IP" .irow &<>& &'exim_dbmbuild'& "build a DBM file" .irow &<>& &'exinext'& "extract retry information" -.irow &<>& &'exim_dumpdb'& "dump a hints database" -.irow &<>& &'exim_tidydb'& "clean up a hints database" -.irow &<>& &'exim_fixdb'& "patch a hints database" +.irow &<>& &'exim_dumpdb'& "dump a hints database" +.irow &<>& &'exim_tidydb'& "clean up a hints database" +.irow &<>& &'exim_fixdb'& "patch a hints database" .irow &<>& &'exim_lock'& "lock a mailbox file" .endtable @@ -38422,12 +39424,12 @@ but the format of the output is different. For this reason, there are some system configuration options that configure exactly how &'exiwhat'& works. If it doesn't seem to be working for you, check the following compile-time options: -.display -&`EXIWHAT_PS_CMD `& the command for running &'ps'& -&`EXIWHAT_PS_ARG `& the argument for &'ps'& -&`EXIWHAT_EGREP_ARG `& the argument for &'egrep'& to select from &'ps'& output -&`EXIWHAT_KILL_ARG `& the argument for the &'kill'& command -.endd +.itable none 0 0 2 30* left 70* left +.irow &`EXIWHAT_PS_CMD`& "the command for running &'ps'&" +.irow &`EXIWHAT_PS_ARG`& "the argument for &'ps'&" +.irow &`EXIWHAT_EGREP_ARG`& "the argument for &'egrep'& to select from &'ps'& output" +.irow &`EXIWHAT_KILL_ARG`& "the argument for the &'kill'& command" +.endtable An example of typical output from &'exiwhat'& is .code 164 daemon: -q1h, listening on port 25 @@ -38453,9 +39455,6 @@ or (in case &*-a*& switch is specified) .code exim -bp .endd -The &*-C*& option is used to specify an alternate &_exim.conf_& which might -contain alternate exim configuration the queue management might be using. - to obtain a queue listing, and then greps the output to select messages that match given criteria. The following selection options are available: @@ -38512,7 +39511,20 @@ Display messages in reverse order. Include delivered recipients in queue listing. .endlist +The following options give alternates for configuration: + +.vlist +.vitem &*-C*&&~<&'config&~file'&> +is used to specify an alternate &_exim.conf_& which might +contain alternate exim configuration the queue management might be using. + +.vitem &*-E*&&~<&'path'&> +can be used to specify a path for the exim binary, +overriding the built-in one. +.endlist + There is one more option, &%-h%&, which outputs a list of options. +At least one selection option, or either the &*-c*& or &*-h*& option, must be given. @@ -38872,6 +39884,8 @@ for remote hosts .next &'ratelimit'&: the data for implementing the ratelimit ACL condition .next +&'tls'&: TLS session resumption data +.next &'misc'&: other hints data .endlist @@ -38889,15 +39903,20 @@ in a transport) -.section "exim_dumpdb" "SECID261" +.section "exim_dumpdb" "SECTdumpdb" .cindex "&'exim_dumpdb'&" The entire contents of a database are written to the standard output by the -&'exim_dumpdb'& program, which has no options or arguments other than the -spool and database names. For example, to dump the retry database: +&'exim_dumpdb'& program, +taking as arguments the spool and database names. +An option &'-z'& may be given to request times in UTC; +otherwise times are in the local timezone. +An option &'-k'& may be given to dump only the record keys. +For example, to dump the retry database: .code exim_dumpdb /var/spool/exim retry .endd -Two lines of output are produced for each entry: +For the retry database +two lines of output are produced for each entry: .code T:mail.ref.example:192.168.242.242 146 77 Connection refused 31-Oct-1995 12:00:12 02-Nov-1995 12:21:39 02-Nov-1995 20:21:39 * @@ -38926,7 +39945,7 @@ cross-references. -.section "exim_tidydb" "SECID262" +.section "exim_tidydb" "SECTtidydb" .cindex "&'exim_tidydb'&" The &'exim_tidydb'& utility program is used to tidy up the contents of a hints database. If run with no options, it removes all records that are more than 30 @@ -38975,11 +39994,11 @@ databases is likely to keep on increasing. -.section "exim_fixdb" "SECID263" +.section "exim_fixdb" "SECTfixdb" .cindex "&'exim_fixdb'&" The &'exim_fixdb'& program is a utility for interactively modifying databases. Its main use is for testing Exim, but it might also be occasionally useful for -getting round problems in a live system. It has no options, and its interface +getting round problems in a live system. Its interface is somewhat crude. On entry, it prompts for input with a right angle-bracket. A key of a database record can then be entered, and the data for that record is displayed. @@ -38996,6 +40015,10 @@ resets the time of the next delivery attempt. Time values are given as a sequence of digit pairs for year, month, day, hour, and minute. Colons can be used as optional separators. +Both displayed and input times are in the local timezone by default. +If an option &'-z'& is used on the command line, displayed times +are in UTC. + @@ -39766,7 +40789,7 @@ Consider the use of the &%inlisti%& expansion condition instead. .cindex "security" "data sources" .cindex "security" "regular expressions" .cindex "regular expressions" "security" -.cindex "PCRE" "security" +.cindex "PCRE2" "security" If configuration data for Exim can come from untrustworthy sources, there are some issues to be aware of: @@ -39776,7 +40799,7 @@ Use of &%${expand...}%& may provide a path for shell injection attacks. Letting untrusted data provide a regular expression is unwise. .next Using &%${match...}%& to apply a fixed regular expression against untrusted -data may result in pathological behaviour within PCRE. Be aware of what +data may result in pathological behaviour within PCRE2. Be aware of what "backtracking" means and consider options for being more strict with a regular expression. Avenues to explore include limiting what can match (avoiding &`.`& when &`[a-z0-9]`& or other character class will do), use of atomic grouping and @@ -40017,8 +41040,16 @@ was received, in the conventional Unix form &-- the number of seconds since the start of the epoch. The second number is a count of the number of messages warning of delayed delivery that have been sent to the sender. -There follow a number of lines starting with a hyphen. These can appear in any -order, and are omitted when not relevant: +There follow a number of lines starting with a hyphen. +These contain variables, can appear in any +order, and are omitted when not relevant. + +If there is a second hyphen after the first, +the corresponding data is tainted. +If there is a value in parentheses, the data is quoted for a lookup. + +The following word specifies a variable, +and the remainder of the item depends on the variable. .vlist .vitem "&%-acl%&&~<&'number'&>&~<&'length'&>" @@ -40174,9 +41205,6 @@ was received from the client, this records the Distinguished Name from that certificate. .endlist -Any of the above may have an extra hyphen prepended, to indicate the the -corresponding data is untrusted. - Following the options there is a list of those addresses to which the message is not to be delivered. This set of addresses is initialized from the command line when the &%-t%& option is used and &%extract_addresses_remove_arguments%& @@ -40285,8 +41313,8 @@ There is no dot-stuffing (and no dot-termination). . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.chapter "DKIM, SPF and DMARC" "CHAPdkim" &&& - "DKIM, SPF and DMARC Support" +.chapter "DKIM, SPF, SRS and DMARC" "CHAPdkim" &&& + "DKIM, SPF, SRS and DMARC Support" .section "DKIM (DomainKeys Identified Mail)" SECDKIM .cindex "DKIM" @@ -40340,8 +41368,8 @@ where you accept mail from relay sources (internal hosts or authenticated senders). -.section "Signing outgoing messages" "SECDKIMSIGN" -.cindex "DKIM" "signing" +.subsection "Signing outgoing messages" SECDKIMSIGN +.cindex DKIM signing For signing to be usable you must have published a DKIM record in DNS. Note that RFC 8301 (which does not cover EC keys) says: @@ -40361,25 +41389,34 @@ but for EC keys it is the base64 of the pure key; no ASN.1 wrapping. Signing is enabled by setting private options on the SMTP transport. These options take (expandable) strings as arguments. -.option dkim_domain smtp string list&!! unset +.option dkim_domain smtp "string list&!!" unset The domain(s) you want to sign with. After expansion, this can be a list. Each element in turn, lowercased, +.vindex "&$dkim_domain$&" is put into the &%$dkim_domain%& expansion variable while expanding the remaining signing options. If it is empty after expansion, DKIM signing is not done, and no error will result even if &%dkim_strict%& is set. -.option dkim_selector smtp string list&!! unset +.option dkim_selector smtp "string list&!!" unset This sets the key selector string. After expansion, which can use &$dkim_domain$&, this can be a list. Each element in turn is put in the expansion +.vindex "&$dkim_selector$&" variable &%$dkim_selector%& which may be used in the &%dkim_private_key%& option along with &%$dkim_domain%&. If the option is empty after expansion, DKIM signing is not done for this domain, and no error will result even if &%dkim_strict%& is set. +To do, for example, dual-signing with RSA and EC keys +this could be be used: +.code +dkim_selector = ec_sel : rsa_sel +dkim_private_key = KEYS_DIR/$dkim_selector +.endd + .option dkim_private_key smtp string&!! unset This sets the private key to use. You can use the &%$dkim_domain%& and @@ -40491,9 +41528,7 @@ When unspecified, the header names listed in RFC4871 will be used, whether or not each header is present in the message. The default list is available for the expansion in the macro &"_DKIM_SIGN_HEADERS"& -.new and an oversigning variant is in &"_DKIM_OVERSIGN_HEADERS"&. -.wen If a name is repeated, multiple headers by that name (or the absence thereof) will be signed. The textually later headers in the headers part of the @@ -40517,8 +41552,8 @@ both creation (t=) and expiry (x=) tags will be included. RFC 6376 lists these tags as RECOMMENDED. -.section "Verifying DKIM signatures in incoming mail" "SECDKIMVFY" -.cindex "DKIM" "verification" +.subsection "Verifying DKIM signatures in incoming mail" SECDKIMVFY +.cindex DKIM verification Verification of DKIM signatures in SMTP incoming email is done for all messages for which an ACL control &%dkim_disable_verify%& has not been set. @@ -40744,10 +41779,8 @@ Notes from the key record (tag n=). .vitem &%$dkim_key_length%& Number of bits in the key. -.new Valid only once the key is loaded, which is at the time the header signature is verified, which is after the body hash is. -.wen Note that RFC 8301 says: .code @@ -40771,10 +41804,10 @@ verb to a group of domains or identities. For example: .code # Warn when Mail purportedly from GMail has no gmail signature -warn log_message = GMail sender without gmail.com DKIM signature - sender_domains = gmail.com +warn sender_domains = gmail.com dkim_signers = gmail.com dkim_status = none + log_message = GMail sender without gmail.com DKIM signature .endd Note that the above does not check for a total lack of DKIM signing; @@ -40786,10 +41819,10 @@ results against the actual result of verification. This is typically used to restrict an ACL verb to a list of verification outcomes, for example: .code -deny message = Mail from Paypal with invalid/missing signature - sender_domains = paypal.com:paypal.de +deny sender_domains = paypal.com:paypal.de dkim_signers = paypal.com:paypal.de dkim_status = none:invalid:fail + message = Mail from Paypal with invalid/missing signature .endd The possible status keywords are: 'none','invalid','fail' and 'pass'. Please @@ -40860,6 +41893,9 @@ You may deny messages when this occurs. .vitem &%temperror%& This indicates a temporary error during all processing, including Exim's SPF processing. You may defer messages when this occurs. + +.vitem &%invalid%& +There was an error during processing of the SPF lookup .endlist You can prefix each string with an exclamation mark to invert @@ -40873,13 +41909,16 @@ deny spf = fail message = $sender_host_address is not allowed to send mail from \ ${if def:sender_address_domain \ {$sender_address_domain}{$sender_helo_name}}. \ - Please see http://www.open-spf.org/Why?scope=\ - ${if def:sender_address_domain {mfrom}{helo}};\ + Please see http://www.open-spf.org/Why;\ identity=${if def:sender_address_domain \ {$sender_address}{$sender_helo_name}};\ ip=$sender_host_address .endd +Note: The above mentioned URL may not be as helpful as expected. You are +encouraged to replace the link with a link to a site with more +explanations. + When the spf condition has run, it sets up several expansion variables: @@ -40893,10 +41932,14 @@ variables: .vitem &$spf_received$& .vindex &$spf_received$& - This contains a complete Received-SPF: header that can be - added to the message. Please note that according to the SPF - draft, this header must be added at the top of the header - list. Please see section 10 on how you can do this. + This contains a complete Received-SPF: header (name and + content) that can be added to the message. Please note that + according to the SPF draft, this header must be added at the + top of the header list, i.e. with +.code +add_header = :at_start:$spf_received +.endd + See section &<>& for further details. Note: in case of "Best-guess" (see below), the convention is to put this string in a header called X-SPF-Guess: instead. @@ -40904,8 +41947,8 @@ variables: .vitem &$spf_result$& .vindex &$spf_result$& This contains the outcome of the SPF check in string form, - one of pass, fail, softfail, none, neutral, permerror or - temperror. + currently one of pass, fail, softfail, none, neutral, permerror, + temperror, or &"(invalid)"&. .vitem &$spf_result_guessed$& .vindex &$spf_result_guessed$& @@ -40914,8 +41957,11 @@ variables: .vitem &$spf_smtp_comment$& .vindex &$spf_smtp_comment$& +.vindex &%spf_smtp_comment_template%& This contains a string that can be used in a SMTP response to the calling party. Useful for "fail". + The string is generated by the SPF library from the template configured in the main config + option &%spf_smtp_comment_template%&. .endlist @@ -40976,6 +42022,107 @@ The lookup will return the same result strings as can appear in +.subsection "SRS (Sender Rewriting Scheme)" SECTSRS +.cindex SRS "sender rewriting scheme" + +SRS can be used to modify sender addresses when forwarding so that +SPF verification does not object to them. +It operates by encoding the original envelope sender in a new +sender local part and using a domain run by the forwarding site +as the new domain for the sender. Any DSN message should be returned +to this new sender at the forwarding site, which can extract the +original sender from the coded local part and forward the DSN to +the originator. + +This is a way of avoiding the breakage that SPF does to forwarding. +The constructed local-part will be longer than the original, +leading to possible problems with very long addresses. +The changing of the sender address also hinders the tracing of mail +problems. + +Exim can be built to include native SRS support. To do this +SUPPORT_SRS=yes must be defined in &_Local/Makefile_&. +If this has been done, the macros _HAVE_SRS and _HAVE_NATIVE_SRS +will be defined. +The support is limited to SRS0-encoding; SRS1 is not supported. + +.cindex SRS excoding +To encode an address use this expansion item: +.vlist +.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*& +.cindex "&%srs_encode%& expansion item" +.cindex SRS "expansion item" +The first argument should be a secret known and used by all systems +handling the recipient domain for the original message. +There is no need to periodically change this key; a timestamp is also +encoded. +The second argument should be given as the envelope sender address before this +encoding operation. +If this value is empty the the expansion result will be empty. +The third argument should be the recipient domain of the message when +it arrived at this system. +.endlist + +.cindex SRS decoding +To decode an address use this expansion condition: +.vlist +.vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*& +The first argument should be the recipient local prt as is was received. +The second argument is the site secret. + +If the messages is not for an SRS-encoded recipient the condition will +return false. If it is, the condition will return true and the variable +&$srs_recipient$& will be set to the decoded (original) value. +.endlist + +Example usage: +.code + #macro + SRS_SECRET = + + #routers + + outbound: + driver = dnslookup + # if outbound, and forwarding has been done, use an alternate transport + domains = ! +my_domains + transport = ${if eq {$local_part@$domain} \ + {$original_local_part@$original_domain} \ + {remote_smtp} {remote_forwarded_smtp}} + + inbound_srs: + driver = redirect + senders = : + domains = +my_domains + # detect inbound bounces which are SRS'd, and decode them + condition = ${if inbound_srs {$local_part} {SRS_SECRET}} + data = $srs_recipient + + inbound_srs_failure: + driver = redirect + senders = : + domains = +my_domains + # detect inbound bounces which look SRS'd but are invalid + condition = ${if inbound_srs {$local_part} {}} + allow_fail + data = :fail: Invalid SRS recipient address + + #... further routers here + + + # transport; should look like the non-forward outbound + # one, plus the max_rcpt and return_path options + remote_forwarded_smtp: + driver = smtp + # modify the envelope from, for mails that we forward + max_rcpt = 1 + return_path = ${srs_encode {SRS_SECRET} {$return_path} {$original_domain}} +.endd + + + + + .section DMARC SECDMARC .cindex DMARC verification @@ -40997,7 +42144,8 @@ This description assumes that headers will be in /usr/local/include, and that the libraries are in /usr/local/lib. -. subsection +.subsection Configuration SSECDMARCCONFIG +.cindex DMARC configuration There are three main-configuration options: .cindex DMARC "configuration options" @@ -41010,10 +42158,8 @@ during domain parsing. Maintained by Mozilla, the most current version can be downloaded from a link at &url(https://publicsuffix.org/list/public_suffix_list.dat). See also the util/renew-opendmarc-tlds.sh script. -.new The default for the option is unset. If not set, DMARC processing is disabled. -.wen The &%dmarc_history_file%& option, if set @@ -41040,9 +42186,9 @@ If not set (the default), the From: header is expanded from the dsn_from option, and <> is used for the envelope from. -. I wish we had subsections... - +.subsection Controls SSECDMARCCONTROLS .cindex DMARC controls + By default, the DMARC processing will run for any remote, non-authenticated user. It makes sense to only verify DMARC status of messages coming from remote, untrusted sources. You can @@ -41073,7 +42219,8 @@ send them.) There are no options to either control. Both must appear before the DATA acl. -. subsection +.subsection ACL SSECDMARCACL +.cindex DMARC "ACL condition" DMARC checks cam be run on incoming SMTP messages by using the &"dmarc_status"& ACL condition in the DATA ACL. You are required to @@ -41087,16 +42234,16 @@ The &"dmarc_status"& condition takes a list of strings on its right-hand side. These strings describe recommended action based on the DMARC check. To understand what the policy recommendations mean, refer to the DMARC website above. Valid strings are: -.display -&'accept '& The DMARC check passed and the library recommends accepting the email. -&'reject '& The DMARC check failed and the library recommends rejecting the email. -&'quarantine '& The DMARC check failed and the library recommends keeping it for further inspection. -&'none '& The DMARC check passed and the library recommends no specific action, neutral. -&'norecord '& No policy section in the DMARC record for this sender domain. -&'nofrom '& Unable to determine the domain of the sender. -&'temperror '& Library error or dns error. -&'off '& The DMARC check was disabled for this email. -.endd +.itable none 0 0 2 20* left 80* left +.irow &'accept'& "The DMARC check passed and the library recommends accepting the email" +.irow &'reject'& "The DMARC check failed and the library recommends rejecting the email" +.irow &'quarantine'& "The DMARC check failed and the library recommends keeping it for further inspection" +.irow &'none'& "The DMARC check passed and the library recommends no specific action, neutral" +.irow &'norecord'& "No policy section in the DMARC record for this RFC5322.From field" +.irow &'nofrom'& "Unable to determine the domain of the sender" +.irow &'temperror'& "Library error or dns error" +.irow &'off'& "The DMARC check was disabled for this email" +.endtable You can prefix each string with an exclamation mark to invert its meaning, for example "!accept" will match all results but "accept". The string list is evaluated left-to-right in a @@ -41141,7 +42288,8 @@ are "none", "reject" and "quarantine". It is blank when there is any error, including no DMARC record. .endlist -. subsection +.subsection Logging SSECDMARCLOGGING +.cindex DMARC logging By default, Exim's DMARC configuration is intended to be non-intrusive and conservative. To facilitate this, Exim will not @@ -41168,7 +42316,8 @@ Configure, somewhere before the DATA ACL, the control option to enable sending DMARC forensic reports .endlist -. subsection +.subsection Example SSECDMARCEXAMPLE +.cindex DMARC example Example usage: .code @@ -41256,18 +42405,19 @@ automatically determines which version is in use. The Proxy Protocol header is the first data received on a TCP connection and is inserted before any TLS-on-connect handshake from the client; Exim negotiates TLS between Exim-as-server and the remote client, not between -Exim and the proxy server. +Exim and the proxy server. The Proxy Protocol header must be received +within &%proxy_protocol_timeout%&, which defaults to 3s. The following expansion variables are usable (&"internal"& and &"external"& here refer to the interfaces of the proxy): -.display -&'proxy_external_address '& IP of host being proxied or IP of remote interface of proxy -&'proxy_external_port '& Port of host being proxied or Port on remote interface of proxy -&'proxy_local_address '& IP of proxy server inbound or IP of local interface of proxy -&'proxy_local_port '& Port of proxy server inbound or Port on local interface of proxy -&'proxy_session '& boolean: SMTP connection via proxy -.endd +.itable none 0 0 2 30* left 70* left +.irow $proxy_external_address "IP of host being proxied or IP of remote interface of proxy" +.irow $proxy_external_port "Port of host being proxied or Port on remote interface of proxy" +.irow $proxy_local_address "IP of proxy server inbound or IP of local interface of proxy" +.irow $proxy_local_port "Port of proxy server inbound or Port on local interface of proxy" +.irow $proxy_session "boolean: SMTP connection via proxy" +.endtable If &$proxy_session$& is set but &$proxy_external_address$& is empty there was a protocol error. The variables &$sender_host_address$& and &$sender_host_port$& @@ -41288,8 +42438,8 @@ A possible solution is: # Or do some kind of IP lookup in a flat file or database # LIMIT = ${lookup{$sender_host_address}iplsearch{/etc/exim/proxy_limits}} - defer message = Too many connections from this IP right now - ratelimit = LIMIT / 5s / per_conn / strict + defer ratelimit = LIMIT / 5s / per_conn / strict + message = Too many connections from this IP right now .endd @@ -41314,15 +42464,15 @@ is an IP address and any subsequent elements are options. Options are a string =. The list of options is in the following table: -.display -&'auth '& authentication method -&'name '& authentication username -&'pass '& authentication password -&'port '& tcp port -&'tmo '& connection timeout -&'pri '& priority -&'weight '& selection bias -.endd +.itable none 0 0 2 10* left 90* left +.irow &'auth'& "authentication method" +.irow &'name'& "authentication username" +.irow &'pass'& "authentication password" +.irow &'port'& "tcp port" +.irow &'tmo'& "connection timeout" +.irow &'pri'& "priority" +.irow &'weight'& "selection bias" +.endtable More details on each of these options follows: @@ -41385,6 +42535,7 @@ requirement, upon libidn2. .section "MTA operations" SECTi18nMTA .cindex SMTPUTF8 "ESMTP option" +.cindex "ESMTP extensions" SMTPUTF8 The main configuration option &%smtputf8_advertise_hosts%& specifies a host list. If this matches the sending host and accept_8bitmime is true (the default) then the ESMTP option @@ -41431,22 +42582,27 @@ may use the following modifier: control = utf8_downconvert control = utf8_downconvert/ .endd -This sets a flag requiring that addresses are converted to -a-label form before smtp delivery, for use in a -Message Submission Agent context. +This sets a flag requiring that envelope addresses are converted to +a-label form before smtp delivery. +This is usually for use in a Message Submission Agent context, +but could be used for any message. + If a value is appended it may be: -.display -&`1 `& (default) mandatory downconversion -&`0 `& no downconversion -&`-1 `& if SMTPUTF8 not supported by destination host -.endd +.itable none 0 0 2 5* right 95* left +.irow &`1`& "mandatory downconversion" +.irow &`0`& "no downconversion" +.irow &`-1`& "if SMTPUTF8 not supported by destination host" +.endtable +If no value is given, 1 is used. If mua_wrapper is set, the utf8_downconvert control is initially set to -1. The smtp transport has an option &%utf8_downconvert%&. If set it must expand to one of the three values described above, -and it overrides any previously set value. +or an empty string. +If non-empty it overrides value previously set +(due to mua_wrapper or by an ACL control). There is no explicit support for VRFY and EXPN. @@ -41536,25 +42692,25 @@ Events have names which correspond to the point in process at which they fire. The name is placed in the variable &$event_name$& and the event action expansion must check this, as it will be called for every possible event type. -.new The current list of events is: -.wen -.display -&`dane:fail after transport `& per connection -&`msg:complete after main `& per message -&`msg:defer after transport `& per message per delivery try -&`msg:delivery after transport `& per recipient -&`msg:rcpt:host:defer after transport `& per recipient per host -&`msg:rcpt:defer after transport `& per recipient -&`msg:host:defer after transport `& per host per delivery try; host errors -&`msg:fail:delivery after transport `& per recipient -&`msg:fail:internal after main `& per recipient -&`tcp:connect before transport `& per connection -&`tcp:close after transport `& per connection -&`tls:cert before both `& per certificate in verification chain -&`smtp:connect after transport `& per connection -&`smtp:ehlo after transport `& per connection -.endd +.itable all 0 0 4 25* left 10* center 15* center 50* left +.row auth:fail after both "per driver per authentication attempt" +.row dane:fail after transport "per connection" +.row msg:complete after main "per message" +.row msg:defer after transport "per message per delivery try" +.row msg:delivery after transport "per recipient" +.row msg:rcpt:host:defer after transport "per recipient per host" +.row msg:rcpt:defer after transport "per recipient" +.row msg:host:defer after transport "per host per delivery try; host errors" +.row msg:fail:delivery after transport "per recipient" +.row msg:fail:internal after main "per recipient" +.row tcp:connect before transport "per connection" +.row tcp:close after transport "per connection" +.row tls:cert before both "per certificate in verification chain" +.row tls:fail:connect after main "per connection" +.row smtp:connect after transport "per connection" +.row smtp:ehlo after transport "per connection" +.endtable New event types may be added in future. The event name is a colon-separated list, defining the type of @@ -41570,23 +42726,25 @@ should define the event action. An additional variable, &$event_data$&, is filled with information varying with the event type: -.display -&`dane:fail `& failure reason -&`msg:defer `& error string -&`msg:delivery `& smtp confirmation message -&`msg:fail:internal `& failure reason -&`msg:fail:delivery `& smtp error message -&`msg:host:defer `& error string -&`msg:rcpt:host:defer `& error string -&`msg:rcpt:defer `& error string -&`tls:cert `& verification chain depth -&`smtp:connect `& smtp banner -&`smtp:ehlo `& smtp ehlo response -.endd +.itable all 0 0 2 20* left 80* left +.row auth:fail "smtp response" +.row dane:fail "failure reason" +.row msg:defer "error string" +.row msg:delivery "smtp confirmation message" +.row msg:fail:internal "failure reason" +.row msg:fail:delivery "smtp error message" +.row msg:host:defer "error string" +.row msg:rcpt:host:defer "error string" +.row msg:rcpt:defer "error string" +.row tls:cert "verification chain depth" +.row tls:fail:connect "error string" +.row smtp:connect "smtp banner" +.row smtp:ehlo "smtp ehlo response" +.endtable The :defer events populate one extra variable: &$event_defer_errno$&. -For complex operations an ACL expansion can be used in &%event_action%& +For complex operations an ACL expansion can be used in &%event_action%&, however due to the multiple contexts that Exim operates in during the course of its processing: .ilist @@ -41602,11 +42760,12 @@ a useful way of writing to the main log. The expansion of the event_action option should normally return an empty string. Should it return anything else the following will be forced: -.display -&`tcp:connect `& do not connect -&`tls:cert `& refuse verification -&`smtp:connect `& close connection -.endd +.itable all 0 0 2 20* left 80* left +.row auth:fail "log information to write" +.row tcp:connect "do not connect" +.row tls:cert "refuse verification" +.row smtp:connect "close connection" +.endtable All other message types ignore the result string, and no other use is made of it.