X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/8ae9f4a33857f2169441aab0d5a12f09548a2367..fa41615da7020d4d951ed3a0b98464bed66ff58b:/doc/doc-docbook/spec.xfpt?ds=sidebyside

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index af9da690d..f9a8efa98 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -1575,7 +1575,7 @@ If a host is unreachable for a period of time, a number of messages may be
 waiting for it by the time it recovers, and sending them in a single SMTP
 connection is clearly beneficial. Whenever a delivery to a remote host is
 deferred,
-.cindex "hints database"
+.cindex "hints database" "deferred deliveries"
 Exim makes a note in its hints database, and whenever a successful
 SMTP delivery has happened, it looks to see if any other messages are waiting
 for the same host. If any are found, they are sent over the same SMTP
@@ -6060,7 +6060,7 @@ address_pipe:
 .endd
 This transport is used for handling deliveries to pipes that are generated by
 redirection (aliasing or users' &_.forward_& files). The &%return_output%&
-option specifies that any output on stdout or stderr generated by the pipe is to 
+option specifies that any output on stdout or stderr generated by the pipe is to
 be returned to the sender.
 .code
 address_file:
@@ -6993,6 +6993,15 @@ Retries for the dnsdb lookup can be controlled by a retry modifier.
 The form if &"retry_VAL"& where VAL is an integer.
 The default count is set by the main configuration option &%dns_retry%&.
 
+.new
+.cindex cacheing "of dns lookup"
+.cindex TTL "of dns lookup"
+.cindex DNS TTL
+Dnsdb lookup results are cached within a single process (and its children).
+The cache entry lifetime is limited to the smallest time-to-live (TTL)
+value of the set of returned DNS records.
+.wen
+
 
 .section "Pseudo dnsdb record types" "SECID66"
 .cindex "MX record" "in &(dnsdb)& lookup"
@@ -9265,9 +9274,9 @@ Upper case and lower case letters are synonymous in header names. If the
 following character is white space, the terminating colon may be omitted, but
 this is not recommended, because you may then forget it when it is needed. When
 white space terminates the header name, this white space is included in the
-expanded string.  If the message does not contain the given header, the 
-expansion item is replaced by an empty string. (See the &%def%& condition in 
-section &<<SECTexpcond>>& for a means of testing for the existence of a 
+expanded string.  If the message does not contain the given header, the
+expansion item is replaced by an empty string. (See the &%def%& condition in
+section &<<SECTexpcond>>& for a means of testing for the existence of a
 header.)
 
 If there is more than one header with the same name, they are all concatenated
@@ -9390,7 +9399,7 @@ yields &"42"&, and
 .code
 ${listextract{-3}{<, x,42,99,& Mailer,,/bin/bash}{result: $value}}
 .endd
-yields &"result: 99"&.
+yields &"result: 42"&.
 
 If {<&'string3'&>} is omitted, an empty string is used for string3.
 If {<&'string2'&>} is also omitted, the value that was
@@ -11110,7 +11119,8 @@ support for TLS or the content scanning extension.
 When a &%match%& expansion condition succeeds, these variables contain the
 captured substrings identified by the regular expression during subsequent
 processing of the success string of the containing &%if%& expansion item.
-However, they do not retain their values afterwards; in fact, their previous
+In the expansion condition case
+they do not retain their values afterwards; in fact, their previous
 values are restored at the end of processing an &%if%& item. The numerical
 variables may also be set externally by some other matching process which
 precedes the expansion of the string. For example, the commands available in
@@ -11318,9 +11328,10 @@ not the same as the user id of the originator of a message (see
 &$originator_uid$&). If Exim re-execs itself, this variable in the new
 incarnation normally contains the Exim uid.
 
-.vitem &$compile_date$&
-.vindex "&$compile_date$&"
-The date on which the Exim binary was compiled.
+.vitem &$callout_address$&
+.vindex "&$callout_address$&"
+After a callout for verification, spamd or malware daemon service, the
+address that was connected to.
 
 .vitem &$compile_number$&
 .vindex "&$compile_number$&"
@@ -12157,6 +12168,12 @@ increases for each accepted recipient. It can be referenced in an ACL.
 This variable is set to contain the matching regular expression after a
 &%regex%& ACL condition has matched (see section &<<SECTscanregex>>&).
 
+.vitem "&$regex1$&, &$regex2$&, etc"
+.cindex "regex submatch variables (&$1regex$& &$2regex$& etc)"
+When a &%regex%& or &%mime_regex%& ACL condition succeeds,
+these variables contain the
+captured substrings identified by the regular expression.
+
 
 .vitem &$reply_address$&
 .vindex "&$reply_address$&"
@@ -14460,7 +14477,7 @@ routing, but which are not used for listening by the daemon. See section
 . Allow this long option name to split; give it unsplit as a fifth argument
 . for the automatic .oindex that is generated by .option.
 
-.option "extract_addresses_remove_ &~&~arguments" main boolean true &&&
+.option "extract_addresses_remove_arguments" main boolean true &&&
          extract_addresses_remove_arguments
 .oindex "&%-t%&"
 .cindex "command line" "addresses with &%-t%&"
@@ -20522,6 +20539,32 @@ transport, the &[initgroups()]& function is called when running the transport
 to ensure that any additional groups associated with the uid are set up.
 
 
+.new
+.option max_parallel transports integer&!! unset
+.cindex limit "transport parallelism"
+.cindex transport "parallel processes"
+.cindex transport "concurrency limit"
+.cindex "delivery" "parallelism for transport"
+If this option is set and expands to an integer greater than zero
+it limits the number of concurrent runs of the transport.
+The control does not apply to shadow transports.
+
+.cindex "hints database" "transport concurrency control"
+Exim implements this control by means of a hints database in which a record is
+incremented whenever a transport process is beaing created. The record
+is decremented and possibly removed when the process terminates.
+Obviously there is scope for
+records to get left lying around if there is a system or program crash. To
+guard against this, Exim ignores any records that are more than six hours old.
+
+If you use this option, you should also arrange to delete the
+relevant hints database whenever your system reboots. The names of the files
+start with &_misc_& and they are kept in the &_spool/db_& directory. There
+may be one or two files, depending on the type of DBM in use. The same files
+are used for ETRN and smtp transport serialization.
+.wen
+
+
 .option message_size_limit transports string&!! 0
 .cindex "limit" "message size per transport"
 .cindex "size" "of message, limit"
@@ -22419,6 +22462,10 @@ If two messages arrive at almost the same time, and both are routed to a pipe
 delivery, the two pipe transports may be run concurrently. You must ensure that
 any pipe commands you set up are robust against this happening. If the commands
 write to a file, the &%exim_lock%& utility might be of use.
+.new
+Alternatively the &%max_parallel%& option could be used with a value
+of "1" to enforce serialization.
+.wen
 
 
 
@@ -22699,7 +22746,7 @@ See the &%timeout_defer%& option for how timeouts are handled.
 .cindex "&(pipe)& transport" "logging output"
 If this option is set, and the status returned by the command is
 one of the codes listed in &%temp_errors%& (that is, delivery was deferred),
-and any output was produced on stdout or stderr, the first line of it is 
+and any output was produced on stdout or stderr, the first line of it is
 written to the main log.
 
 
@@ -23601,6 +23648,10 @@ start with &_misc_& and they are kept in the &_spool/db_& directory. There
 may be one or two files, depending on the type of DBM in use. The same files
 are used for ETRN serialization.
 
+.new
+See also the &%max_parallel%& generic transport option.
+.wen
+
 
 .option size_addition smtp integer 1024
 .cindex "SMTP" "SIZE"
@@ -29037,7 +29088,8 @@ 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 the syntax of all header lines that can contain
 lists of addresses (&'Sender:'&, &'From:'&, &'Reply-To:'&, &'To:'&, &'Cc:'&,
-and &'Bcc:'&). Unqualified addresses (local parts without domains) are
+and &'Bcc:'&), returning true if there are no problems.
+Unqualified addresses (local parts without domains) are
 permitted only in locally generated messages and from hosts that match
 &%sender_unqualified_hosts%& or &%recipient_unqualified_hosts%&, as
 appropriate.
@@ -29199,9 +29251,15 @@ deny  dnslists = blackholes.mail-abuse.org
 warn  message  = X-Warn: sending host is on dialups list
       dnslists = dialups.mail-abuse.org
 .endd
-DNS list lookups are cached by Exim for the duration of the SMTP session,
+.cindex cacheing "of dns lookup"
+.cindex DNS TTL
+DNS list lookups are cached by Exim for the duration of the SMTP session
+.new
+(but limited by the DNS return TTL value),
+.wen
 so a lookup based on the IP address is done at most once for any incoming
-connection. Exim does not share information between multiple incoming
+connection (assuming long-enough TTL).
+Exim does not share information between multiple incoming
 connections (but your local name server cache should be active).
 
 
@@ -30954,6 +31012,10 @@ malware = * / defer_ok / tmo=10s
 .endd
 A timeout causes the ACL to defer.
 
+.vindex "&$callout_address$&"
+When a connection is made to the scanner the expansion variable &$callout_address$&
+is set to record the actual address used.
+
 .vindex "&$malware_name$&"
 When a virus is found, the condition sets up an expansion variable called
 &$malware_name$& that contains the name of the virus. You can use it in a
@@ -31104,6 +31166,10 @@ a dollar sign. In this case, the expansion may return a string that is
 used as the list so that multiple spamd servers can be the result of an
 expansion.
 
+.vindex "&$callout_address$&"
+When a connection is made to the server the expansion variable &$callout_address$&
+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
@@ -31462,6 +31528,8 @@ deny message = contains blacklisted regex ($regex_match_string)
 The conditions returns true if any one of the regular expressions matches. The
 &$regex_match_string$& expansion variable is then set up and contains the
 matching regular expression.
+The expansion variables &$regex1$& &$regex2$& etc
+are set to any substrings captured by the regular expression.
 
 &*Warning*&: With large messages, these conditions can be fairly
 CPU-intensive.
@@ -36231,6 +36299,9 @@ Serializing ETRN runs (when &%smtp_etrn_serialize%& is set)
 .next
 Serializing delivery to a specific host (when &%serialize_hosts%& is set in an
 &(smtp)& transport)
+.next
+Limiting the concurrency of specific transports (when &%max_parallel%& is set
+in a transport)
 .endlist