X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/2ff143741c68ad7fb8544f3238016b3d9227f3c1..d17c916db7c661aacf65684a5568f8e105e50b3b:/doc/doc-docbook/spec.xfpt?ds=sidebyside diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index f09e0253b..68d9c056f 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -51,6 +51,8 @@ .set ACL "access control lists (ACLs)" .set I "    " +.set drivernamemax "64" + .macro copyyear 2020 .endmacro @@ -161,6 +163,13 @@ .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 . //////////////////////////////////////////////////////////////////////////// @@ -193,6 +202,8 @@ . 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 . at the top level, so we have to put the .chapter directive first. + +. These do not turn up in the HTML output, unfortunately. The PDF does get them. . ///////////////////////////////////////////////////////////////////////////// .chapter "Introduction" "CHID1" @@ -318,6 +329,10 @@ zero, binary binary zero + + headers + header lines + .literal off @@ -2683,10 +2698,8 @@ 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. @@ -3837,9 +3850,11 @@ headers.) .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%&" @@ -3885,7 +3900,9 @@ 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" @@ -3927,12 +3944,31 @@ 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. +.new +.vitem &%-MCL%& +.oindex "&%-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. +.wen + .vitem &%-MCP%& .oindex "&%-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. +.new +.vitem &%-MCp%& +.oindex "&%-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. +.wen + .vitem &%-MCQ%&&~<&'process&~id'&>&~<&'pipe&~fd'&> .oindex "&%-MCQ%&" This option is not intended for use by external callers. It is used internally @@ -4138,8 +4174,9 @@ 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. +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%&" @@ -4782,9 +4819,9 @@ recognized when Exim is run normally. It allows for the setting up of explicit .vitem &%-t%& .oindex "&%-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 @@ -5476,8 +5513,8 @@ 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" @@ -5936,7 +5973,7 @@ 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 @@ -6411,9 +6448,9 @@ 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; @@ -8470,7 +8507,7 @@ will store a result in the &$local_part_data$& variable. .vitem domains .new A &%domains%& router option or &%domains%& ACL condition -will store a result in the &$domain_data$& variable +will store a result in the &$domain_data$& variable. .wen .vitem senders A &%senders%& router option or &%senders%& ACL condition @@ -8775,6 +8812,13 @@ other statements in the same ACL. .cindex "tainted data" "de-tainting" The value will be untainted. +.new +&*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. +.wen + .next Any of the single-key lookup type names may be preceded by @@ -8816,7 +8860,7 @@ 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 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 "=". +Each item starts with a tag and and equals "=" sign. .next .cindex "domain list" "matching literal domain name" @@ -8935,9 +8979,13 @@ 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. @@ -9716,7 +9764,7 @@ 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:'& @@ -10126,7 +10174,7 @@ 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 @@ -10147,7 +10195,7 @@ 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. -.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. @@ -10402,10 +10450,11 @@ 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 @@ -10455,7 +10504,7 @@ 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. @@ -10492,7 +10541,7 @@ ${readsocket{inet:[::1]:1234}{request string}} Only a single host name may be given, but if looking it up yields more than one IP address, they are each tried in turn until a connection is made. For both kinds of socket, Exim makes a connection, writes the request string -unless it is an empty string; and no terminating NUL is ever sent) +(unless it is an empty string; no terminating NUL is ever sent) and reads from the socket until an end-of-file is read. A timeout of 5 seconds is applied. Additional, optional arguments extend what can be done. Firstly, you can vary the timeout. For example: @@ -10958,7 +11007,7 @@ is controlled by the &%print_topbitchars%& option. .vitem &*${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. @@ -11154,6 +11203,10 @@ 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. +.new +&*Note*&: Neither string-expansion of lists referenced by named-list syntax elements, +nor expansion of lookup elements, is done by the &%listnamed%& operator. +.wen .vitem &*${local_part:*&<&'string'&>&*}*& @@ -11421,7 +11474,7 @@ Now deprecated, a synonym for the &%base64%& expansion operator. .cindex "expansion" "string length" .cindex "string" "length in expansion" .cindex "&%strlen%& expansion item" -The item is replace by the length of the expanded string, expressed as a +The item is replaced by the length of the expanded string, expressed as a decimal number. &*Note*&: Do not confuse &%strlen%& with &%length%&. All measurement is done in bytes and is not UTF-8 aware. @@ -11719,6 +11772,7 @@ users' filter files may be locked out by the system administrator. .new &*Note:*& Testing a path using this condition is not a sufficient way of de-tainting it. +Consider using a dsearch lookup. .wen .vitem &*first_delivery*& @@ -12324,7 +12378,7 @@ to the relevant file. When, as a result of aliasing or forwarding, a message is directed to a pipe, this variable holds the pipe command when the transport is running. -.vitem "&$auth1$& &-- &$auth3$&" +.vitem "&$auth1$& &-- &$auth4$&" .vindex "&$auth1$&, &$auth2$&, etc" These variables are used in SMTP authenticators (see chapters &<>&&--&<>&). Elsewhere, they are empty. @@ -13703,7 +13757,11 @@ filter file to set values that can be tested in users' filter files. For example, a system filter could set a value indicating how likely it is that a message is junk mail. -.vitem &$spam_$&&'xxx'& +.vitem &$spam_score$& &&& + &$spam_score_int$& &&& + &$spam_bar$& &&& + &$spam_report$& &&& + &$spam_action$& A number of variables whose names start with &$spam$& are available when Exim is compiled with the content-scanning extension. For details, see section &<>&. @@ -14093,6 +14151,10 @@ taint mode of the Perl interpreter. You are encouraged to set this option to a true value. To avoid breaking existing installations, it defaults to false. +.new +&*Note*&: This is entirely separate from Exim's tainted-data tracking. +.wen + .section "Calling Perl subroutines" "SECID86" When the configuration file includes a &%perl_startup%& option you can make use @@ -14527,9 +14589,11 @@ listed in more than one group. .section "Miscellaneous" "SECID96" .table2 +.row &%add_environment%& "environment variables" .row &%bi_command%& "to run for &%-bi%& command line option" .row &%debug_store%& "do extra internal checks" .row &%disable_ipv6%& "do no IPv6 processing" +.row &%keep_environment%& "environment variables" .row &%keep_malformed%& "for broken files &-- should not happen" .row &%localhost_number%& "for unique message ids in clusters" .row &%message_body_newlines%& "retain newlines in &$message_body$&" @@ -16973,7 +17037,7 @@ 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 -.cindex "ESMTP extensions" X_PIPE_CONNECT +.cindex "ESMTP extensions" PIPE_CONNECT If Exim is built with the SUPPORT_PIPE_CONNECT build option this option controls which hosts the facility is advertised to and from which pipeline early-connection (before MAIL) SMTP @@ -16982,7 +17046,9 @@ 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. +.new +The SMTP service extension keyword advertised is &"PIPE_CONNECT"&. +.wen .option prdr_enable main boolean false @@ -17328,7 +17394,7 @@ 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 @@ -17544,7 +17610,7 @@ 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" @@ -17554,6 +17620,11 @@ 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). +.new +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. +.wen .option smtp_accept_max_per_host main string&!! unset @@ -18280,8 +18351,12 @@ 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 +.new +used. +Under Linux this is generated at daemon startup; on other platforms it will be +generated fresh for every connection. +.wen .option tls_crl main string&!! unset .cindex "TLS" "server certificate revocation list" @@ -18729,6 +18804,11 @@ 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%&. +.new +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. +.wen .option address_data routers string&!! unset @@ -18985,7 +19065,7 @@ 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 @@ -18994,7 +19074,7 @@ 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. @@ -19720,6 +19800,10 @@ 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. +.new +This is done immediately after all the preconditions, before the +evaluation of the &%address_data%& option. +.wen The variable is set with the expansion of the value. The variables can be used by the router options (not including any preconditions) @@ -22268,6 +22352,12 @@ and &$original_domain$& is never set. .scindex IIDgenoptra1 "generic options" "transport" .scindex IIDgenoptra2 "options" "generic; for transports" .scindex IIDgenoptra3 "transport" "generic options for" +.new +The name of a transport is limited to be &drivernamemax; ASCII characters long; +prior to Exim 4.95 names would be silently truncated at this length, but now +it is enforced. +.wen + The following generic options apply to all transports: @@ -22567,7 +22657,7 @@ This defaults to the incoming sender address, but can be changed by setting .option return_path_add transports boolean false -.cindex "&'Return-path:'& header line" +.chindex Return-path: If this option is true, a &'Return-path:'& header is added to the message. Although the return path is normally available in the prefix line of BSD mailboxes, this is commonly not displayed by MUAs, and so the user does not @@ -22943,6 +23033,11 @@ If &%file%& or &%directory%& is set for a delivery from a redirection, it is used to determine the file or directory name for the delivery. Normally, the contents of &$address_file$& are used in some way in the string expansion. .endlist +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. @@ -23090,14 +23185,34 @@ directories defined by the &%directory%& option. In the case of maildir delivery, it applies to the top level directory, not the maildir directories beneath. +.new 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. +.wen + +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%&. +.new +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" +If "belowhome" checking is used, the file or directory path +becomes de-tainted. +.wen + .option directory appendfile string&!! unset This option is mutually exclusive with the &%file%& option, but one of &%file%& @@ -23110,6 +23225,11 @@ 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. +.new +The result of expansion must not be tainted, unless the &%create_file%& option +specifies a path. +.wen + .option directory_file appendfile string&!! "see below" .cindex "base62" @@ -23142,6 +23262,11 @@ 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%&. +.new +The result of expansion must not be tainted, unless the &%create_file%& option +specifies a path. +.wen + .cindex "NFS" "lock file" .cindex "locking files" .cindex "lock files" @@ -25209,7 +25334,7 @@ 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. @@ -25221,7 +25346,7 @@ 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. @@ -25502,9 +25627,9 @@ TLS session for any host that matches this list. .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 @@ -25524,9 +25649,12 @@ 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 +.new +and &%hosts_require_auth%& permits, +.wen +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" @@ -25540,11 +25668,14 @@ 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. +.new +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. +.wen +See the &%dnssec_request_domains%& router and transport options. See section &<>&. .option hosts_try_fastopen smtp "host list&!!" * @@ -25629,7 +25760,7 @@ 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. .new @@ -25702,7 +25833,7 @@ 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). @@ -27063,6 +27194,12 @@ 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. +.new +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. +.wen + .cindex "AUTH" "description of" .cindex "ESMTP extensions" AUTH Very briefly, the way SMTP authentication works is as follows: @@ -27355,7 +27492,7 @@ 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 @@ -27463,7 +27600,7 @@ encode '\0user@domain.com\0pas$$word' .endd gives an incorrect answer because of the unescaped &"@"& and &"$"& characters. -If you have the &%mimencode%& command installed, another way to do produce +If you have the &%mimencode%& command installed, another way to produce base64-encoded strings is to run the command .code echo -e -n `\0user\0password' | mimencode @@ -27805,7 +27942,14 @@ fixed_plain: client_send = ^username^mysecret .endd The lack of colons means that the entire text is sent with the AUTH -command, with the circumflex characters converted to NULs. A similar example +command, with the circumflex characters converted to NULs. +.new +Note that due to the ambiguity of parsing three consectutive circumflex characters +there is no way to provide a password having a leading circumflex. +.wen + + +A similar example that uses the LOGIN mechanism is: .code fixed_login: @@ -28079,7 +28223,7 @@ connection, a client certificate has been verified, the &"valid-client-cert"& option is passed. When authentication succeeds, the identity of the user who authenticated is placed in &$auth1$&. -The Dovecot configuration to match the above wil look +The Dovecot configuration to match the above will look something like: .code conf.d/10-master.conf :- @@ -28129,6 +28273,12 @@ realease for the SCRAM-SHA-256 method. The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined when this happens. +.new +To see the list of mechanisms supported by the library run Exim with "auth" debug +enabled and look for a line containing "GNU SASL supports". +Note however that some may not have been tested from Exim. +.wen + .option client_authz gsasl string&!! unset This option can be used to supply an &'authorization id'& @@ -28148,21 +28298,44 @@ the password to be used, in clear. This option is exapanded before use, and should result in the account name to be used. + .option client_spassword gsasl string&!! unset +.new +This option is only supported for library versions 1.9.1 and greater. +The macro _HAVE_AUTH_GSASL_SCRAM_S_KEY will be defined when this is so. +.wen + If a SCRAM mechanism is being used and this option is set +and correctly sized it is used in preference to &%client_password%&. The value after expansion should be a 40 (for SHA-1) or 64 (for SHA-256) character string with the PBKDF2-prepared password, hex-encoded. + Note that this value will depend on the salt and iteration-count supplied by the server. - +The option is expanded before use. +.new +During the expansion &$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. +.wen .option server_channelbinding gsasl boolean false -Do not set this true and rely on the properties -without consulting a cryptographic engineer. - 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 @@ -28182,9 +28355,16 @@ 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). + +.new +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. +.wen .option server_hostname gsasl string&!! "see below" @@ -28504,7 +28684,7 @@ 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 @@ -29723,7 +29903,7 @@ Ivan is the author of the popular TLS testing tools at .section "Certificate chains" "SECID186" -The file named by &%tls_certificate%& may contain more than one +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. @@ -30031,7 +30211,7 @@ 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. @@ -32422,6 +32602,13 @@ 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. +.new +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. +.wen + .section "Variables set from DNS lists" "SECID204" .cindex "expansion" "variables, set from DNS list" @@ -32558,6 +32745,14 @@ 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 + @@ -36000,8 +36195,7 @@ 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-" +.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:'&, @@ -36057,8 +36251,7 @@ existing &'Bcc:'& is not removed. .section "The Date: header line" "SECID223" -.cindex "&'Date:'& header line" -.cindex "header lines" "Date:" +.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. @@ -36075,8 +36268,7 @@ messages. .section "The Envelope-to: header line" "SECID225" -.cindex "&'Envelope-to:'& header line" -.cindex "header lines" "Envelope-to:" +.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 @@ -36087,8 +36279,7 @@ messages. .section "The From: header line" "SECTthefrohea" -.cindex "&'From:'& header line" -.cindex "header lines" "From:" +.chindex From: .cindex "Sendmail compatibility" "&""From""& line" .cindex "message" "submission" .cindex "submission mode" @@ -36131,8 +36322,7 @@ name as described in section &<>&. .section "The Message-ID: header line" "SECID226" -.cindex "&'Message-ID:'& header line" -.cindex "header lines" "Message-ID:" +.chindex Message-ID: .cindex "message" "submission" .oindex "&%message_id_header_text%&" If a locally-generated or submission-mode incoming message does not contain a @@ -36147,8 +36337,7 @@ in this header line by setting the &%message_id_header_text%& and/or .section "The Received: header line" "SECID227" -.cindex "&'Received:'& header line" -.cindex "header lines" "Received:" +.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. @@ -36164,8 +36353,7 @@ changed to the time of acceptance, which is (apart from a small delay while the .section "The References: header line" "SECID228" -.cindex "&'References:'& header line" -.cindex "header lines" "References:" +.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 @@ -36179,8 +36367,7 @@ 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:" +.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%& @@ -36193,7 +36380,7 @@ default), Exim removes &'Return-path:'& header lines from incoming messages. .section "The Sender: header line" "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 @@ -37981,7 +38168,7 @@ 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: .code @@ -38293,8 +38480,11 @@ 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 +.new +remote IP address (and port if enabled) +.wen +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. @@ -38523,6 +38713,7 @@ selection marked by asterisks: &` outgoing_port `& add remote port to => lines &`*queue_run `& start and end queue runs &` queue_time `& time on queue for one recipient +&`*queue_time_exclusive `& exclude recieve time from QT times &` queue_time_overall `& time on queue for whole message &` pid `& Exim process id &` pipelining `& PIPELINING use, on <= and => lines @@ -38661,6 +38852,7 @@ 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" @@ -38669,7 +38861,10 @@ 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 +.new +&"=>"&, &"->"&, &"=="& and &"**"& lines. +.wen The latter can be disabled by turning off the &%outgoing_interface%& option. .next .cindex log "incoming proxy address" @@ -38760,18 +38955,13 @@ 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 @@ -38830,10 +39020,12 @@ 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" @@ -38936,7 +39128,7 @@ 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" @@ -41016,6 +41208,15 @@ 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. +.new +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/$dkim_selector +.endd +.wen + .option dkim_private_key smtp string&!! unset This sets the private key to use. You can use the &%$dkim_domain%& and