X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/fd4d887101c6b4075a477bc275e51c35b94fd4c2..1c5b14999af72b5e2471f708b91631738f07dfb7:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index e34ed8054..690f1ed30 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -1985,10 +1985,9 @@ Two different types of DNS record for handling IPv6 addresses have been defined. AAAA records (analogous to A records for IPv4) are in use, and are currently seen as the mainstream. Another record type called A6 was proposed as better than AAAA because it had more flexibility. However, it was felt to be -over-complex, and its status was reduced to &"experimental"&. It is not known -if anyone is actually using A6 records. Exim has support for A6 records, but -this is included only if you set &`SUPPORT_A6=YES`& in &_Local/Makefile_&. The -support has not been tested for some time. +over-complex, and its status was reduced to &"experimental"&. Exim used to +have a compile option for including A6 record support but this has now been +withdrawn. @@ -6880,8 +6879,8 @@ is used on its own as the result. If the lookup does not succeed, the &<>& for an explanation of what this means. The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, TLSA and TXT, -and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is also -configured). If no type is given, TXT is assumed. When the type is PTR, +and, when Exim is compiled with IPv6 support, AAAA. +If no type is given, TXT is assumed. When the type is PTR, the data can be an IP address, written as normal; inversion and the addition of &%in-addr.arpa%& or &%ip6.arpa%& happens automatically. For example: .code @@ -6890,8 +6889,7 @@ ${lookup dnsdb{ptr=192.168.4.5}{$value}fail} If the data for a PTR record is not a syntactically valid IP address, it is not altered and nothing is added. -For any record type, if multiple records are found (or, for A6 lookups, if a -single record leads to multiple addresses), the data is returned as a +For any record type, if multiple records are found, the data is returned as a concatenation, with newline as the default separator. The order, of course, depends on the DNS resolver. You can specify a different separator character between multiple records by putting a right angle-bracket followed immediately @@ -7013,7 +7011,7 @@ The authorization code can be &"Y"& for yes, &"N"& for no, &"X"& for explicit authorization required but absent, or &"?"& for unknown. .cindex "A+" "in &(dnsdb)& lookup" -The pseudo-type A+ performs an A6 lookup (if configured) followed by an AAAA +The pseudo-type A+ performs an AAAA and then an A lookup. All results are returned; defer processing (see below) is handled separately for each lookup. Example: .code @@ -12451,6 +12449,8 @@ inbound connection when the message was received. It is only useful as the argument of a &%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator, or a &%def%& condition. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. .vitem &$tls_out_ourcert$& .vindex "&$tls_out_ourcert$&" @@ -12465,6 +12465,8 @@ This variable refers to the certificate presented by the peer of an outbound connection. It is only useful as the argument of a &%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator, or a &%def%& condition. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. .vitem &$tls_in_certificate_verified$& .vindex "&$tls_in_certificate_verified$&" @@ -12528,6 +12530,8 @@ When a message is received from a remote host over an encrypted SMTP connection, and Exim is configured to request a certificate from the client, the value of the Distinguished Name of the certificate is made available in the &$tls_in_peerdn$& during subsequent processing. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. The deprecated &$tls_peerdn$& variable refers to the inbound side except when used in the context of an outbound SMTP delivery, when it refers to @@ -12539,6 +12543,8 @@ When a message is being delivered to a remote host over an encrypted SMTP connection, and Exim is configured to request a certificate from the server, the value of the Distinguished Name of the certificate is made available in the &$tls_out_peerdn$& during subsequent processing. +If certificate verification fails it may refer to a failing chain element +which is not the leaf. .vitem &$tls_in_sni$& .vindex "&$tls_in_sni$&" @@ -13282,6 +13288,7 @@ listed in more than one group. .row &%acl_smtp_mail%& "ACL for MAIL" .row &%acl_smtp_mailauth%& "ACL for AUTH on MAIL command" .row &%acl_smtp_mime%& "ACL for MIME parts" +.row &%acl_smtp_notquit%& "ACL for non-QUIT terminations" .row &%acl_smtp_predata%& "ACL for start of data" .row &%acl_smtp_quit%& "ACL for QUIT" .row &%acl_smtp_rcpt%& "ACL for RCPT" @@ -13631,6 +13638,12 @@ This option is available when Exim is built with the content-scanning extension. It defines the ACL that is run for each MIME part in a message. See section &<>& for details. +.option acl_smtp_notquit main string&!! unset +.cindex "not-QUIT, ACL for" +This option defines the ACL that is run when an SMTP session +ends without a QUIT command being received. +See chapter &<>& for further details. + .option acl_smtp_predata main string&!! unset This option defines the ACL that is run when an SMTP DATA command is received, before the message itself is received. See chapter &<>& for @@ -17154,7 +17167,10 @@ and the discussion in chapter &<>&. .option headers_add routers list&!! unset .cindex "header lines" "adding" .cindex "router" "adding header lines" -This option specifies a list of text headers, newline-separated, +This option specifies a list of text headers, +.new +newline-separated (by default, changeable in the usual way), +.wen that is associated with any addresses that are accepted by the router. Each item is separately expanded, at routing time. However, this option has no effect when an address is just being verified. The way in which @@ -17191,7 +17207,10 @@ avoided. The &%repeat_use%& option of the &%redirect%& router may be of help. .option headers_remove routers list&!! unset .cindex "header lines" "removing" .cindex "router" "removing header lines" -This option specifies a list of text headers, colon-separated, +This option specifies a list of text headers, +.new +colon-separated (by default, changeable in the usual way), +.wen that is associated with any addresses that are accepted by the router. Each item is separately expanded, at routing time. However, this option has no effect when an address is just being verified. The way in which @@ -17970,6 +17989,9 @@ There are a few cases where a &(dnslookup)& router will decline to accept an address; if such a router is expected to handle "all remaining non-local domains", then it is important to set &%no_more%&. +The router will defer rather than decline if the domain +is found in the &%fail_defer_domains%& router option. + Reasons for a &(dnslookup)& router to decline currently include: .ilist The domain does not exist in DNS @@ -18055,7 +18077,7 @@ when there is a DNS lookup error. .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_request_domains%& will be done with the dnssec request bit set. -This applies to all of the SRV, MX A6, AAAA, A lookup sequence. +This applies to all of the SRV, MX, AAAA, A lookup sequence. @@ -18067,8 +18089,19 @@ This applies to all of the SRV, MX A6, AAAA, A lookup sequence. DNS lookups for domains matching &%dnssec_request_domains%& will be done with the dnssec request bit set. Any returns not having the Authenticated Data bit (AD bit) set wil be ignored and logged as a host-lookup failure. -This applies to all of the SRV, MX A6, AAAA, A lookup sequence. +This applies to all of the SRV, MX, AAAA, A lookup sequence. + + +.option fail_defer_domains dnslookup "domain list&!!" unset +.cindex "MX record" "not found" +DNS lookups for domains matching &%fail_defer_domains%& +which find no matching record will cause the router to defer +rather than the default behaviour of decline. +This maybe be useful for queueing messages for a newly created +domain while the DNS configuration is not ready. +However, it will result in any message with mistyped domains +also being queued. .option mx_domains dnslookup "domain list&!!" unset @@ -20238,7 +20271,10 @@ value that the router supplies, and also overriding any value associated with .option headers_add transports list&!! unset .cindex "header lines" "adding in transport" .cindex "transport" "header lines; adding" -This option specifies a list of text headers, newline-separated, +This option specifies a list of text headers, +.new +newline-separated (by default, changeable in the usual way), +.wen which are (separately) expanded and added to the header portion of a message as it is transported, as described in section &<>&. Additional header lines can also be specified by @@ -20263,7 +20299,10 @@ checked, since this option does not automatically suppress them. .option headers_remove transports list&!! unset .cindex "header lines" "removing" .cindex "transport" "header lines; removing" -This option specifies a list of header names, colon-separated; +This option specifies a list of header names, +.new +colon-separated (by default, changeable in the usual way); +.wen these headers are omitted from the message as it is transported, as described in section &<>&. Header removal can also be specified by routers. @@ -22988,7 +23027,7 @@ details. .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_request_domains%& will be done with the dnssec request bit set. -This applies to all of the SRV, MX A6, AAAA, A lookup sequence. +This applies to all of the SRV, MX, AAAA, A lookup sequence. @@ -23000,7 +23039,7 @@ This applies to all of the SRV, MX A6, AAAA, A lookup sequence. DNS lookups for domains matching &%dnssec_request_domains%& will be done with the dnssec request bit set. Any returns not having the Authenticated Data bit (AD bit) set wil be ignored and logged as a host-lookup failure. -This applies to all of the SRV, MX A6, AAAA, A lookup sequence. +This applies to all of the SRV, MX, AAAA, A lookup sequence. @@ -24335,6 +24374,13 @@ A server unexpectedly closed the SMTP connection. There may, of course, legitimate reasons for this (host died, network died), but if it repeats a lot for the same host, it indicates something odd. +.vitem &%lookup%& +A DNS lookup for a host failed. +Note that a &%dnslookup%& router will need to have matched +its &%fail_defer_domains%& option for this retry type to be usable. +Also note that a &%manualroute%& router will probably need +its &%host_find_failed%& option set to &%defer&%. + .vitem &%refused_MX%& A connection to a host obtained from an MX record was refused. @@ -27087,8 +27133,8 @@ the feature was not requested by the client. .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 -does not in fact control any access. For this reason, the only verbs that are -permitted are &%accept%& and &%warn%&. +does not in fact control any access. For this reason, it may only accept +or warn as its final result. This ACL can be used for tasks such as custom logging at the end of an SMTP session. For example, you can use ACL variables in other ACLs to count @@ -30458,17 +30504,39 @@ av_scanner = aveserver:/var/run/aveserver This daemon-type scanner is GPL and free. You can get it at &url(http://www.clamav.net/). Some older versions of clamd do not seem to unpack MIME containers, so it used to be recommended to unpack MIME attachments -in the MIME ACL. This no longer believed to be necessary. One option is -required: either the path and name of a UNIX socket file, or a hostname or IP -number, and a port, separated by space, as in the second of these examples: +in the MIME ACL. This is no longer believed to be necessary. + +The options are a list of server specifiers, which may be +a UNIX socket specification, +a TCP socket specification, +or a (global) option. + +A socket specification consists of a space-separated list. +For a Unix socket the first element is a full path for the socket, +for a TCP socket the first element is the IP address +and the second a port number, +Any further elements are per-server (non-global) options. +These per-server options are supported: +.code +retry= Retry on connect fail +.endd + +The &`retry`& option specifies a time after which a single retry for +a failed connect is made. The default is to not retry. + +If a Unix socket file is specified, only one server is supported. + +Examples: .code av_scanner = clamd:/opt/clamd/socket av_scanner = clamd:192.0.2.3 1234 av_scanner = clamd:192.0.2.3 1234:local +av_scanner = clamd:192.0.2.3 1234 retry=10s av_scanner = clamd:192.0.2.3 1234 : 192.0.2.4 1234 .endd -If the value of av_scanner points to a UNIX socket file or contains the local -keyword, then the ClamAV interface will pass a filename containing the data +If the value of av_scanner points to a UNIX socket file or contains the +&`local`& +option, then the ClamAV interface will pass a filename containing the data to be scanned, which will should normally result in less I/O happening and be more efficient. Normally in the TCP case, the data is streamed to ClamAV as Exim does not assume that there is a common filesystem with the remote host. @@ -30719,8 +30787,7 @@ deny message = This message contains malware ($malware_name) The &%spam%& ACL condition calls SpamAssassin's &%spamd%& daemon to get a spam score and a report for the message. .new -Support is also provided for Rspamd (which can speak SpamAssassin's protocol but -provides reduced functionality when used in this mode). +Support is also provided for Rspamd. For more information about installation and configuration of SpamAssassin or Rspamd refer to their respective websites at @@ -30778,21 +30845,47 @@ condition defers. Unix and TCP socket specifications may be mixed in any order. Each element of the list is a list itself, space-separated by default and changeable in the usual way. + +For TCP socket specifications a host name or IP (v4 or v6, but +subject to list-separator quoting rules) address can be used, +and the port can be one or a dash-separated pair. +In the latter case, the range is tried in strict order. + Elements after the first for Unix sockets, or second for TCP socket, are options. The supported option are: .code -variant=rspamd Use Rspamd rather than SpamAssassin protocol -time=- Use only between these times of day +pri= Selection priority weight= Selection bias -backup Use only if all non-backup servers fail +time=- Use only between these times of day +retry= Retry on connect fail +tmo= Connection time limit +variant=rspamd Use Rspamd rather than SpamAssassin protocol .endd +The &`pri`& option specifies a priority for the server within the list, +higher values being tried first. +The deafult priority is 1. + +The &`weight`& option specifies a selection bias. +Within a priority set +servers are queried in a random fashion, weighted by this value. +The default value for selection bias is 1. + Time specifications for the &`time`& option are .. in the local time zone; each element being one or more digits. +Either the seconds or both minutes and seconds, plus the leading &`.`& +characters, may be omitted and will be taken as zero. -Servers are queried in a random fashion, weighted by the selection bias. -The default value for selection bias is 1. +Timeout specifications for the &`retry`& and &`tmo`& options +are the usual Exim time interval standard, eg. &`20s`& or &`1m`&. + +The &`tmo`& option specifies an overall timeout for communication. +The default value is two minutes. + +The &`retry`& option specifies a time after which a single retry for +a failed connect is made. +The default is to not retry. .wen The &%spamd_address%& variable is expanded before use if it starts with @@ -30821,6 +30914,12 @@ have multiple recipients, not necessarily all in the same domain. Because the &%spam%& condition has to be called from a DATA ACL in order to be able to read the contents of the message, the variables &$local_part$& and &$domain$& are not set. +Careful enforcement of single-recipient messages +(eg. by responding with defer in the recipient ACL for all recipients +after the first), +or the use of PRDR, +.cindex "PRDR" "use for per-user SpamAssassin profiles" +are needed to use this feature. The right-hand side of the &%spam%& condition is expanded before being used, so you can put lookups or conditions there. When the right-hand side evaluates to