X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/30c7614399ba7b739f8d0128d23011e46fb39e14..7f6c1f2e14fd20ffe43c86087ab0aca50f240d00:/doc/doc-docbook/spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index cdca6c4b3..c1e451d4d 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -45,14 +45,14 @@
 . Update the Copyright year (only) when changing content.
 . /////////////////////////////////////////////////////////////////////////////
 
-.set previousversion "4.86"
+.set previousversion "4.90"
 .include ./local_params
 
 .set ACL "access control lists (ACLs)"
 .set I   "    "
 
 .macro copyyear
-2015
+2017
 .endmacro
 
 . /////////////////////////////////////////////////////////////////////////////
@@ -436,6 +436,7 @@ directory are:
 .row &_filter.txt_&          "specification of the filter language"
 .row &_Exim3.upgrade_&       "upgrade notes from release 2 to release 3"
 .row &_Exim4.upgrade_&       "upgrade notes from release 3 to release 4"
+.row &_openssl.txt_&         "installing a current OpenSSL release"
 .endtable
 
 The main specification and the specification of the filtering language are also
@@ -463,7 +464,7 @@ which contains what used to be a separate FAQ, as well as various other
 examples, tips, and know-how that have been contributed by Exim users.
 
 .cindex Bugzilla
-An Exim Bugzilla exists at &url(http://bugs.exim.org). You can use
+An Exim Bugzilla exists at &url(https://bugs.exim.org). You can use
 this to report bugs, and also to add items to the wish list. Please search
 first to check that you are not duplicating a previous entry.
 
@@ -492,18 +493,11 @@ via this web page:
 Please ask Debian-specific questions on this list and not on the general Exim
 lists.
 
-.section "Exim training" "SECID4"
-.cindex "training courses"
-Training courses in Cambridge (UK) used to be run annually by the author of
-Exim, before he retired. At the time of writing, there are no plans to run
-further Exim courses in Cambridge. However, if that changes, relevant
-information will be posted at &url(http://www-tus.csx.cam.ac.uk/courses/exim/).
-
 .section "Bug reports" "SECID5"
 .cindex "bug reports"
 .cindex "reporting bugs"
 Reports of obvious bugs can be emailed to &'bugs@exim.org'& or reported
-via the Bugzilla (&url(http://bugs.exim.org)). However, if you are unsure
+via the Bugzilla (&url(https://bugs.exim.org)). However, if you are unsure
 whether some behaviour is a bug or not, the best thing to do is to post a
 message to the &'exim-dev'& mailing list and have it discussed.
 
@@ -514,10 +508,6 @@ message to the &'exim-dev'& mailing list and have it discussed.
 .cindex "distribution" "ftp site"
 The master ftp site for the Exim distribution is
 .display
-&*ftp://ftp.csx.cam.ac.uk/pub/software/email/exim*&
-.endd
-This is mirrored by
-.display
 &*ftp://ftp.exim.org/pub/exim*&
 .endd
 The file references that follow are relative to the &_exim_& directories at
@@ -1677,6 +1667,9 @@ Symbolic links to the sources are installed in this directory, which is where
 the actual building takes place. In most cases, Exim can discover the machine
 architecture and operating system for itself, but the defaults can be
 overridden if necessary.
+.cindex compiler requirements
+.cindex compiler version
+A C99-capable compiler will be required for the build.
 
 
 .section "PCRE library" "SECTpcre"
@@ -2627,6 +2620,8 @@ users to set envelope senders.
 
 .cindex "&'From:'& header line"
 .cindex "&'Sender:'& header line"
+.cindex "header lines" "From:"
+.cindex "header lines" "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.
@@ -2788,7 +2783,7 @@ continuations. As in Exim's run time configuration, white space at the start of
 continuation lines is ignored. Each argument or data line is passed through the
 string expansion mechanism, and the result is output. Variable values from the
 configuration file (for example, &$qualify_domain$&) are available, but no
-message-specific values (such as &$sender_domain$&) are set, because no message
+message-specific values (such as &$message_exim_id$&) are set, because no message
 is being processed (but see &%-bem%& and &%-Mset%&).
 
 &*Note*&: If you use this mechanism to test lookups, and you change the data
@@ -2796,6 +2791,11 @@ files or databases you are using, you must exit and restart Exim before trying
 the same lookup again. Otherwise, because each Exim process caches the results
 of lookups, you will just get the same result as before.
 
+Macro processing is done on lines before string-expansion: new macros can be
+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%&"
 .cindex "testing" "string expansion"
@@ -3049,7 +3049,8 @@ trusted user for the sender of a message to be set in this way.
 .oindex "&%-bmalware%&"
 .cindex "testing", "malware"
 .cindex "malware scan test"
-This debugging option causes Exim to scan the given file,
+This debugging option causes Exim to scan the given file or directory
+(depending on the used scanner interface),
 using the malware scanning framework.  The option of &%av_scanner%& influences
 this option, so if &%av_scanner%&'s value is dependent upon an expansion then
 the expansion should have defaults which apply to this invocation.  ACLs are
@@ -3151,11 +3152,20 @@ using one of the words &%router_list%&, &%transport_list%&, or
 settings can be obtained by using &%routers%&, &%transports%&, or
 &%authenticators%&.
 
+.cindex "environment"
+If &%environment%& is given as an argument, the set of environment
+variables is output, line by line. Using the &%-n%& flag suppresses the value of the
+variables.
+
 .cindex "options" "macro &-- extracting"
 If invoked by an admin user, then &%macro%&, &%macro_list%& and &%macros%&
 are available, similarly to the drivers.  Because macros are sometimes used
 for storing passwords, this option is restricted.
 The output format is one item per line.
+.new
+For the "-bP macro <name>" form, if no such macro is found
+the exit status will be nonzero.
+.wen
 
 .vitem &%-bp%&
 .oindex "&%-bp%&"
@@ -3552,9 +3562,7 @@ example:
 exim '-D ABC = something' ...
 .endd
 &%-D%& may be repeated up to 10 times on a command line.
-.new
 Only macro names up to 22 letters long can be set.
-.wen
 
 
 .vitem &%-d%&<&'debug&~options'&>
@@ -3821,6 +3829,18 @@ 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.
 
+.vitem &%-MCG%&&~<&'queue&~name'&>
+.oindex "&%-MCG%&"
+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%&"
+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
+remote host supports the ESMTP &_CHUNKING_& extension.
+
 .vitem &%-MCP%&
 .oindex "&%-MCP%&"
 This option is not intended for use by external callers. It is used internally
@@ -3849,6 +3869,13 @@ 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%&"
+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%&"
 .cindex "hints database" "not overridden by &%-Mc%&"
@@ -4012,7 +4039,8 @@ for that message.
 .oindex "&%-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 suppresses the name of an option from being output.
+When combined with &%-bP%& it makes the output more terse (suppresses
+option names, environment values and config pretty printing).
 
 .vitem &%-O%&&~<&'data'&>
 .oindex "&%-O%&"
@@ -4256,7 +4284,7 @@ or &%-bs%& is used. For &%-bh%&, the protocol is forced to one of the standard
 SMTP protocol names (see the description of &$received_protocol$& in section
 &<<SECTexpvar>>&). For &%-bs%&, the protocol is always &"local-"& followed by
 one of those same names. For &%-bS%& (batched SMTP) however, the protocol can
-be set by &%-oMr%&.
+be set by &%-oMr%&. Repeated use of this option is not supported.
 
 .vitem &%-oMs%&&~<&'host&~name'&>
 .oindex "&%-oMs%&"
@@ -4356,6 +4384,7 @@ host name and its colon can be omitted when only the protocol is to be set.
 Note the Exim already has two private options, &%-pd%& and &%-ps%&, that refer
 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%&"
@@ -4366,7 +4395,8 @@ relax this restriction (and also the same requirement for the &%-M%&, &%-R%&,
 and &%-S%& options).
 
 .cindex "queue runner" "description of operation"
-The &%-q%& option starts one queue runner process. This scans the queue of
+If other commandline options do not specify an action,
+the &%-q%& option starts one queue runner process. This scans the queue of
 waiting messages, and runs a delivery process for each one in turn. It waits
 for each delivery process to finish before starting the next one. A delivery
 process may not actually do any deliveries if the retry times for the addresses
@@ -4451,8 +4481,27 @@ The &'l'& (the letter &"ell"&) flag specifies that only local deliveries are to
 be done. If a message requires any remote deliveries, it remains on the queue
 for later delivery.
 
-.vitem &%-q%&<&'qflags'&>&~<&'start&~id'&>&~<&'end&~id'&>
+.vitem &%-q[q][i][f[f]][l][G<name>[/<time>]]]%&
+.oindex "&%-qG%&"
+.cindex queue named
+.cindex "named queues"
 .cindex "queue" "delivering specific messages"
+If the &'G'& flag and a name is present, the queue runner operates on the
+queue with the given name rather than the default queue.
+The name should not contain a &'/'& character.
+For a periodic queue run (see below)
+append to the name a slash and a time value.
+
+If other commandline options specify an action, a &'-qG<name>'& option
+will specify a queue to operate on.
+For example:
+.code
+exim -bp -qGquarantine
+mailq -qGquarantine
+exim -qGoffpeak -Rf @special.domain.example
+.endd
+
+.vitem &%-q%&<&'qflags'&>&~<&'start&~id'&>&~<&'end&~id'&>
 When scanning the queue, Exim can be made to skip over messages whose ids are
 lexically less than a given value by following the &%-q%& option with a
 starting message id. For example:
@@ -4887,7 +4936,9 @@ using this syntax:
 .endd
 on a line by itself. Double quotes round the file name are optional. If you use
 the first form, a configuration error occurs if the file does not exist; the
-second form does nothing for non-existent files. In all cases, an absolute file
+second form does nothing for non-existent files.
+The first form allows a relative name. It is resolved relative to
+the directory of the including file. For the second form an absolute file
 name is required.
 
 Includes may be nested to any depth, but remember that Exim reads its
@@ -4994,6 +5045,31 @@ address lists. In Exim 4 these are handled better by named lists &-- see
 section &<<SECTnamedlists>>&.
 
 
+.section "Builtin macros" "SECTbuiltinmacros"
+Exim defines some macros depending on facilities available, which may
+differ due to build-time definitions and from one release to another.
+All of these macros start with an underscore.
+They can be used to conditionally include parts of a configuration
+(see below).
+
+The following classes of macros are defined:
+.display
+&` _HAVE_*                    `&  build-time defines
+&` _DRIVER_ROUTER_*           `&  router drivers
+&` _DRIVER_TRANSPORT_*        `&  transport drivers
+&` _DRIVER_AUTHENTICATOR_*    `&  authenticator drivers
+&` _OPT_MAIN_*                `&  main config options
+&` _OPT_ROUTERS_*             `&  generic router options
+&` _OPT_TRANSPORTS_*          `&  generic transport options
+&` _OPT_AUTHENTICATORS_*      `&  generic authenticator options
+&` _OPT_ROUTER_*_*            `&  private router options
+&` _OPT_TRANSPORT_*_*         `&  private transport options
+&` _OPT_AUTHENTICATOR_*_*     `&  private authenticator options
+.endd
+
+Use an &"exim -bP macros"& command to get the list of macros.
+
+
 .section "Conditional skips in the configuration file" "SECID46"
 .cindex "configuration file" "conditional skips"
 .cindex "&`.ifdef`&"
@@ -5097,7 +5173,9 @@ with the characters &"0x"&, in which case the remainder is interpreted as a
 hexadecimal number.
 
 If an integer value is followed by the letter K, it is multiplied by 1024; if
-it is followed by the letter M, it is multiplied by 1024x1024. When the values
+it is followed by the letter M, it is multiplied by 1024x1024;
+if by the letter G, 1024x1024x1024.
+When the values
 of integer option settings are output, values which are an exact multiple of
 1024 or 1024x1024 are sometimes, but not always, printed using the letters K
 and M. The printing style is independent of the actual input format that was
@@ -5505,19 +5583,27 @@ Another two commented-out option settings follow:
 .cindex "port" "465 and 587"
 .cindex "port" "for message submission"
 .cindex "message" "submission, ports for"
-.cindex "ssmtp protocol"
+.cindex "submissions protocol"
 .cindex "smtps protocol"
+.cindex "ssmtp protocol"
+.cindex "SMTP" "submissions protocol"
 .cindex "SMTP" "ssmtp protocol"
 .cindex "SMTP" "smtps protocol"
 These options provide better support for roaming users who wish to use this
 server for message submission. They are not much use unless you have turned on
 TLS (as described in the previous paragraph) and authentication (about which
-more in section &<<SECTdefconfauth>>&). The usual SMTP port 25 is often blocked
-on end-user networks, so RFC 4409 specifies that message submission should use
-port 587 instead. However some software (notably Microsoft Outlook) cannot be
-configured to use port 587 correctly, so these settings also enable the
-non-standard &"smtps"& (aka &"ssmtp"&) port 465 (see section
-&<<SECTsupobssmt>>&).
+more in section &<<SECTdefconfauth>>&).
+Mail submission from mail clients (MUAs) should be separate from inbound mail
+to your domain (MX delivery) for various good reasons (eg, ability to impose
+much saner TLS protocol and ciphersuite requirements without unintended
+consequences).
+RFC 6409 (previously 4409) specifies use of port 587 for SMTP Submission,
+which uses STARTTLS, so this is the &"submission"& port.
+RFC 8314 specifies use of port 465 as the &"submissions"& protocol,
+which should be used in preference to 587.
+You should also consider deploying SRV records to help clients find
+these ports.
+Older names for &"submissions"& are &"smtps"& and &"ssmtp"&.
 
 Two more commented-out options settings follow:
 .code
@@ -5617,7 +5703,7 @@ It provides a list of domains for which the &"percent hack"& is to operate.
 This is an almost obsolete form of explicit email routing. If you do not know
 anything about it, you can safely ignore this topic.
 
-The last two settings in the main part of the default configuration are
+The next two settings in the main part of the default configuration are
 concerned with messages that have been &"frozen"& on Exim's queue. When a
 message is frozen, Exim no longer continues to try to deliver it. Freezing
 occurs when a bounce message encounters a permanent failure because the sender
@@ -5635,6 +5721,44 @@ message (whether a bounce message or not) is to be timed out (and discarded)
 after a week. In this configuration, the first setting ensures that no failing
 bounce message ever lasts a week.
 
+Exim queues it's messages in a spool directory. If you expect to have
+large queues, you may consider using this option. It splits the spool
+directory into subdirectories to avoid file system degradation from
+many files in a single directory, resulting in better performance.
+Manual manipulation of queued messages becomes more complex (though fortunately
+not often needed).
+.code
+# split_spool_directory = true
+.endd
+
+In an ideal world everybody follows the standards. For non-ASCII
+messages RFC 2047 is a standard, allowing a maximum line length of 76
+characters. Exim adheres that standard and won't process messages which
+violate this standard. (Even ${rfc2047:...} expansions will fail.)
+In particular, the Exim maintainers have had multiple reports of
+problems from Russian administrators of issues until they disable this
+check, because of some popular, yet buggy, mail composition software.
+.code
+# check_rfc2047_length = false
+.endd
+
+If you need to be strictly RFC compliant you may wish to disable the
+8BITMIME advertisement. Use this, if you exchange mails with systems
+that are not 8-bit clean.
+.code
+# accept_8bitmime = false
+.endd
+
+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
+option and by the TIMEZONE_DEFAULT buildtime option.
+.code
+# keep_environment = ^LDAP
+# add_environment = PATH=/usr/bin::/bin
+.endd
 
 
 .section "ACL configuration" "SECID54"
@@ -6105,7 +6229,8 @@ errors:
 This causes any temporarily failing address to be retried every 15 minutes for
 2 hours, then at intervals starting at one hour and increasing by a factor of
 1.5 until 16 hours have passed, then every 6 hours up to 4 days. If an address
-is not delivered after 4 days of temporary failure, it is bounced.
+is not delivered after 4 days of temporary failure, it is bounced. The time is
+measured from first failure, not from the time the message was received.
 
 If the retry section is removed from the configuration, or is empty (that is,
 if no retry rules are defined), Exim will not retry deliveries. This turns
@@ -6186,7 +6311,9 @@ Chapter &<<CHAPplaintext>>& covers both.
 Exim supports the use of regular expressions in many of its options. It
 uses the PCRE regular expression library; this provides regular expression
 matching that is compatible with Perl 5. The syntax and semantics of
-regular expressions is discussed in many Perl reference books, and also in
+regular expressions is discussed in
+online Perl manpages, in
+many Perl reference books, and also in
 Jeffrey Friedl's &'Mastering Regular Expressions'&, which is published by
 O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)).
 
@@ -6567,7 +6694,7 @@ lookup types support only literal keys.
 .endlist ilist
 
 
-.section "Query-style lookup types" "SECID62"
+.section "Query-style lookup types" "SECTquerystylelookups"
 .cindex "lookup" "query-style types"
 .cindex "query-style lookup" "list of types"
 The supported query-style lookup types are listed below. Further details about
@@ -6625,12 +6752,10 @@ password value. For example:
 PostgreSQL database. See section &<<SECTsql>>&.
 
 .next
-.new
 .cindex "Redis lookup type"
 .cindex lookup Redis
-&(redis)&: The format of the query is an SQL statement that is passed to a
-Redis database. See section &<<SECTsql>>&.
-.wen
+&(redis)&: The format of the query is either a simple get or simple set,
+passed to a Redis database. See section &<<SECTsql>>&.
 
 .next
 .cindex "sqlite lookup type"
@@ -7008,14 +7133,12 @@ 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 caching "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"
@@ -7568,7 +7691,6 @@ a query is successfully processed. The result of a query may be that no data is
 found, but that is still a successful query. In other words, the list of
 servers provides a backup facility, not a list of different places to look.
 
-.new
 For Redis the global option need not be specified if all queries contain their
 own server information &-- see section &<<SECTspeserque>>&.
 If specified, the option must be set to a colon-separated list of server
@@ -7584,9 +7706,7 @@ The database number is optional; if present that number is selected in the backe
 .next
 The password is optional; if present it is used to authenticate to the backend
 .endlist
-.wen
 
-.new
 The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators
 convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b
 respectively, and the characters single-quote, double-quote, and backslash
@@ -7594,7 +7714,6 @@ itself are escaped with backslashes.
 
 The &%quote_redis%& expansion operator
 escapes whitespace and backslash characters with a backslash.
-.wen
 
 .section "Specifying the server in the query" "SECTspeserque"
 For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase),
@@ -7641,10 +7760,8 @@ ${lookup pgsql{servers=master/db/name/pw; UPDATE ...} }
 For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
 causes a connection to the server on the local host by means of a Unix domain
 socket. An alternate socket can be specified in parentheses.
-.new
 An option group name for MySQL option files can be specified in square brackets;
 the default value is &"exim"&.
-.wen
 The full syntax of each item in &%mysql_servers%& is:
 .display
 <&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&&
@@ -7711,6 +7828,17 @@ are rejected after a timeout period, during which the SQLite library
 waits for the lock to be released. In Exim, the default timeout is set
 to 5 seconds, but it can be changed by means of the &%sqlite_lock_timeout%&
 option.
+
+.section "More about Redis" "SECTredis"
+.cindex "lookup" "Redis"
+.cindex "redis lookup type"
+Redis is a non-SQL database. Commands are simple get and set.
+Examples:
+.code
+${lookup redis{set keyname ${quote_redis:objvalue plus}}}
+${lookup redis{get keyname}}
+.endd
+
 .ecindex IIDfidalo1
 .ecindex IIDfidalo2
 
@@ -7739,9 +7867,14 @@ domain, host, address and local part lists.
 
 
 
-.section "Expansion of lists" "SECID75"
+.section "Expansion of lists" "SECTlistexpand"
 .cindex "expansion" "of lists"
-Each list is expanded as a single string before it is used. The result of
+Each list is expanded as a single string before it is used.
+
+&'Exception: the router headers_remove option, where list-item
+splitting is done before string-expansion.'&
+
+The result of
 expansion must be a list, possibly containing empty items, which is split up
 into separate items for matching. By default, colon is the separator character,
 but this can be varied if necessary. See sections &<<SECTlistconstruct>>& and
@@ -9004,9 +9137,34 @@ the expansion result is an empty string.
 If the ACL returns defer the result is a forced-fail.  Otherwise the expansion fails.
 
 
+.new
+.vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&"
+.cindex authentication "results header"
+.cindex headers "authentication-results:"
+This item returns a string suitable for insertion as an
+&'Authentication-Results"'&
+header line.
+The given <&'authserv-id'&> is included in the result; typically this
+will ba a domain name identifying the system performing the authentications.
+Methods that may be present in the result include:
+.code
+none
+iprev
+auth
+spf
+dkim
+.endd
+
+Example use (as an ACL modifier):
+.code
+      add_header = :at_start:${authresults {$primary_hostname}}
+.endd
+.wen
+
+
 .vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&&
        {*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&"
-.cindex "expansion" "extracting cerificate fields"
+.cindex "expansion" "extracting certificate fields"
 .cindex "&%certextract%&" "certificate fields"
 .cindex "certificate" "extracting fields"
 The <&'certificate'&> must be a variable of type certificate.
@@ -9110,7 +9268,7 @@ configuration, you must add &%-export-dynamic%& to EXTRALIBS.
 
 .vitem "&*${env{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&"
 .cindex "expansion" "extracting value from environment"
-.cindex "environment" "value from"
+.cindex "environment" "values from"
 The key is first expanded separately, and leading and trailing white space
 removed.
 This is then searched for as a name in the environment.
@@ -9130,6 +9288,9 @@ search failure.
 If {<&'string1'&>} is omitted the search result is substituted on
 search success.
 
+The environment is adjusted by the &%keep_environment%& and
+&%add_environment%& main section options.
+
 
 .vitem "&*${extract{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&&
        {*&<&'string3'&>&*}}*&"
@@ -9137,8 +9298,8 @@ search success.
 .cindex "&%extract%&" "substrings by key"
 The key and <&'string1'&> are first expanded separately. Leading and trailing
 white space is removed from the key (but not from any of the strings). The key
-must not consist entirely of digits. The expanded <&'string1'&> must be of the
-form:
+must not be empty and must not consist entirely of digits.
+The expanded <&'string1'&> must be of the form:
 .display
 <&'key1'&> = <&'value1'&>  <&'key2'&> = <&'value2'&> ...
 .endd
@@ -9213,7 +9374,7 @@ item in a new list; if the condition is false, the item is discarded. The
 separator used for the output list is the same as the one used for the
 input, but a separator setting is not included in the output. For example:
 .code
-${filter{a:b:c}{!eq{$item}{b}}
+${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.
@@ -9320,12 +9481,15 @@ message, and any that are added by an ACL statement or by a system
 filter. Header lines that are added to a particular copy of a message by a
 router or transport are not accessible.
 
-For incoming SMTP messages, no header lines are visible in ACLs that are obeyed
-before the DATA ACL, because the header structure is not set up until the
-message is received. Header lines that are added in a RCPT ACL (for example)
+For incoming SMTP messages, no header lines are visible in
+ACLs that are obeyed before the data phase completes,
+because the header structure is not set up until the message is received.
+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 a DATA ACL is running, however, header lines added
-by earlier ACLs are visible.
+point they are added.
+When any of the above ACLs ar
+running, however, header lines added by earlier ACLs are visible.
 
 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
@@ -9412,14 +9576,12 @@ condition = ${if >{$acl_m4}{3}}
 
 
 
-.new
 .vitem &*${imapfolder{*&<&'foldername'&>&*}}*&
 .cindex expansion "imap folder"
 .cindex "&%imapfolder%& expansion item"
 This item converts a (possibly multilevel, or with non-ASCII characters)
 folder specification to a Maildir name for filesystem use.
 For information on internationalisation support see &<<SECTi18nMDA>>&.
-.wen
 
 
 
@@ -9654,7 +9816,7 @@ locks out the use of this expansion item in filter files.
 
 
 .vitem "&*${readsocket{*&<&'name'&>&*}{*&<&'request'&>&*}&&&
-        {*&<&'timeout'&>&*}{*&<&'eol&~string'&>&*}{*&<&'fail&~string'&>&*}}*&"
+        {*&<&'options'&>&*}{*&<&'eol&~string'&>&*}{*&<&'fail&~string'&>&*}}*&"
 .cindex "expansion" "inserting from a socket"
 .cindex "socket, use of in expansion"
 .cindex "&%readsocket%& expansion item"
@@ -9684,6 +9846,15 @@ extend what can be done. Firstly, you can vary the timeout. For example:
 .code
 ${readsocket{/socket/name}{request string}{3s}}
 .endd
+The third argument is a list of options, of which the first element is the timeout
+and must be present if the argument is given.
+Further elements are options of form &'name=value'&.
+One option type is currently recognised, defining whether (the default)
+or not a shutdown is done on the connection after sending the request.
+Example, to not do so (preferred, eg. by some webservers):
+.code
+${readsocket{/socket/name}{request string}{3s:shutdown=no}}
+.endd
 A fourth argument allows you to change any newlines that are in the data
 that is read, in the same way as for &%readfile%& (see above). This example
 turns them into spaces:
@@ -9836,7 +10007,7 @@ a regular expression, and a substitution string. For example:
 ${sg{abcdefabcdef}{abc}{xyz}}
 .endd
 yields &"xyzdefxyzdef"&. Because all three arguments are expanded before use,
-if any $ or \ characters are required in the regular expression or in the
+if any $, } or \ characters are required in the regular expression or in the
 substitution string, they have to be escaped. For example:
 .code
 ${sg{abcdef}{^(...)(...)\$}{\$2\$1}}
@@ -9987,7 +10158,15 @@ character. For example:
 .code
 ${addresses:>& Chief <ceo@up.stairs>, sec@base.ment (dogsbody)}
 .endd
-expands to &`ceo@up.stairs&&sec@base.ment`&. Compare the &*address*& (singular)
+expands to &`ceo@up.stairs&&sec@base.ment`&. The string is expanded
+first, so if the expanded string starts with >, it may change the output
+separator unintentionally. This can be avoided by setting the output
+separator explicitly:
+.code
+${addresses:>:$h_from:}
+.endd
+
+Compare the &*address*& (singular)
 expansion item, which extracts the working address from a single RFC2822
 address. See the &*filter*&, &*map*&, and &*reduce*& items for ways of
 processing lists.
@@ -10016,6 +10195,19 @@ Last:user@example.com
 user@example.com
 .endd
 
+.vitem &*${base32:*&<&'digits'&>&*}*&
+.cindex "&%base32%& expansion item"
+.cindex "expansion" "conversion to base 32"
+The string must consist entirely of decimal digits. The number is converted to
+base 32 and output as a (empty, for zero) string of characters.
+Only lowercase letters are used.
+
+.vitem &*${base32d:*&<&'base-32&~digits'&>&*}*&
+.cindex "&%base32d%& expansion item"
+.cindex "expansion" "conversion to base 32"
+The string must consist entirely of base-32 digits.
+The number is converted to decimal and output as a string.
+
 .vitem &*${base62:*&<&'digits'&>&*}*&
 .cindex "&%base62%& expansion item"
 .cindex "expansion" "conversion to base 62"
@@ -10034,7 +10226,6 @@ environments where Exim uses base 36 instead of base 62 for its message
 identifiers, base-36 digits. The number is converted to decimal and output as a
 string.
 
-.new
 .vitem &*${base64:*&<&'string'&>&*}*&
 .cindex "expansion" "base64 encoding"
 .cindex "base64 encoding" "in string expansion"
@@ -10051,7 +10242,6 @@ returns the base64 encoding of the DER form of the certificate.
 .cindex "base64 decoding" "in string expansion"
 .cindex "&%base64d%& expansion item"
 This operator converts a base64-encoded string into the un-coded form.
-.wen
 
 
 .vitem &*${domain:*&<&'string'&>&*}*&
@@ -10069,6 +10259,13 @@ escape sequences starting with a backslash. Whether characters with the most
 significant bit set (so-called &"8-bit characters"&) count as printing or not
 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,
+they are converted to escape sequences starting with a backslash.
+Backslashes and DEL characters are also converted.
+
 
 .vitem &*${eval:*&<&'string'&>&*}*&&~and&~&*${eval10:*&<&'string'&>&*}*&
 .cindex "expansion" "expression evaluation"
@@ -10198,7 +10395,6 @@ as is, and other byte values are converted to &`\xNN`&, for example a
 byte value 127 is converted to &`\x7f`&.
 
 
-.new
 .vitem &*${ipv6denorm:*&<&'string'&>&*}*&
 .cindex "&%ipv6denorm%& expansion item"
 .cindex "IP address" normalisation
@@ -10216,7 +10412,6 @@ Leading zeroes of groups are omitted, and the longest
 set of zero-valued groups is replaced with a double colon.
 A trailing ipv4-style dotted-decimal set is converted to hex.
 Pure IPv4 addresses are converted to IPv4-mapped IPv6.
-.wen
 
 
 .vitem &*${lc:*&<&'string'&>&*}*&
@@ -10444,7 +10639,7 @@ variables or headers inside regular expressions.
 .cindex "SHA-1 hash"
 .cindex "expansion" "SHA-1 hashing"
 .cindex certificate fingerprint
-.cindex "&%sha2%& expansion item"
+.cindex "&%sha1%& expansion item"
 The &%sha1%& operator computes the SHA-1 hash value of the string, and returns
 it as a 40-digit hexadecimal number, in which any letters are in upper case.
 
@@ -10452,16 +10647,38 @@ If the string is a single variable of type certificate,
 returns the SHA-1 hash fingerprint of the certificate.
 
 
-.vitem &*${sha256:*&<&'certificate'&>&*}*&
+.vitem &*${sha256:*&<&'string'&>&*}*&
 .cindex "SHA-256 hash"
 .cindex certificate fingerprint
 .cindex "expansion" "SHA-256 hashing"
 .cindex "&%sha256%& expansion item"
-The &%sha256%& operator computes the SHA-256 hash fingerprint of the
-certificate,
+The &%sha256%& operator computes the SHA-256 hash value of the string
+and returns
+it as a 64-digit hexadecimal number, in which any letters are in upper case.
+
+If the string is a single variable of type certificate,
+returns the SHA-256 hash fingerprint of the certificate.
+
+
+.vitem &*${sha3:*&<&'string'&>&*}*& &&&
+       &*${sha3_<n>:*&<&'string'&>&*}*&
+.cindex "SHA3 hash"
+.cindex "expansion" "SHA3 hashing"
+.cindex "&%sha3%& expansion item"
+The &%sha3%& operator computes the SHA3-256 hash value of the string
 and returns
 it as a 64-digit hexadecimal number, in which any letters are in upper case.
-Only arguments which are a single variable of certificate type are supported.
+
+If a number is appended, separated by an underbar, it specifies
+the output length.  Values of 224, 256, 384 and 512 are accepted;
+with 256 being the default.
+
+The &%sha3%& expansion item is only supported if Exim has been
+compiled with GnuTLS 3.5.0 or later,
+.new
+or OpenSSL 1.1.1 or later.
+The macro "_CRYPTO_HASH_SHA3" will be defined if it is supported.
+.wen
 
 
 .vitem &*${stat:*&<&'string'&>&*}*&
@@ -10484,9 +10701,7 @@ systems for files larger than 2GB.
 
 .vitem &*${str2b64:*&<&'string'&>&*}*&
 .cindex "&%str2b64%& expansion item"
-.new
 Now deprecated, a synonym for the &%base64%& expansion operator.
-.wen
 
 
 
@@ -10541,7 +10756,6 @@ This forces the letters in the string into upper-case.
 .cindex "&%utf8clean%& expansion item"
 This replaces any invalid utf-8 sequence in the string by the character &`?`&.
 
-.new
 .vitem "&*${utf8_domain_to_alabel:*&<&'string'&>&*}*&" &&&
        "&*${utf8_domain_from_alabel:*&<&'string'&>&*}*&" &&&
        "&*${utf8_localpart_to_alabel:*&<&'string'&>&*}*&" &&&
@@ -10556,7 +10770,6 @@ This replaces any invalid utf-8 sequence in the string by the character &`?`&.
 .cindex "&%utf8_localpart_from_alabel%& expansion item"
 These convert EAI mail name components between UTF-8 and a-label forms.
 For information on internationalisation support see &<<SECTi18nMTA>>&.
-.wen
 .endlist
 
 
@@ -10874,9 +11087,12 @@ colon-separated components are permitted, each containing from one to four
 hexadecimal digits. There may be fewer than eight components if an empty
 component (adjacent colons) is present. Only one empty component is permitted.
 
-&*Note*&: The checks are just on the form of the address; actual numerical
-values are not considered. Thus, for example, 999.999.999.999 passes the IPv4
-check. The main use of these tests is to distinguish between IP addresses and
+&*Note*&: The checks used to be just on the form of the address; actual numerical
+values were not considered. Thus, for example, 999.999.999.999 passed the IPv4
+check.
+This is no longer the case.
+
+The main use of these tests is to distinguish between IP addresses and
 host names, or between IPv4 and IPv6 addresses. For example, you could use
 .code
 ${if isip4{$sender_host_address}...
@@ -11033,8 +11249,8 @@ example is:
 ${if match_domain{a.b.c}{x.y.z:a.b.c:p.q.r}{yes}{no}}
 .endd
 In each case, the second argument may contain any of the allowable items for a
-list of the appropriate type. Also, because the second argument (after
-expansion) is a standard form of list, it is possible to refer to a named list.
+list of the appropriate type. Also, because the second argument
+is a standard form of list, it is possible to refer to a named list.
 Thus, you can use conditions like this:
 .code
 ${if match_domain{$domain}{+local_domains}{...
@@ -11484,20 +11700,11 @@ 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 &$demime_errorlevel$&
-.vindex "&$demime_errorlevel$&"
-This variable is available when Exim is compiled with
-the content-scanning extension and the obsolete &%demime%& condition. For
-details, see section &<<SECTdemimecond>>&.
-
-.vitem &$demime_reason$&
-.vindex "&$demime_reason$&"
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete &%demime%& condition. For details,
-see section &<<SECTdemimecond>>&.
+.vitem &$dkim_verify_status$&
+Results of DKIM verification.
+For details see section &<<SECDKIMVFY>>&.
 
 .vitem &$dkim_cur_signer$& &&&
-       &$dkim_verify_status$& &&&
        &$dkim_verify_reason$& &&&
        &$dkim_domain$& &&&
        &$dkim_identity$& &&&
@@ -11517,13 +11724,13 @@ see section &<<SECTdemimecond>>&.
        &$dkim_key_notes$& &&&
        &$dkim_key_length$&
 These variables are only available within the DKIM ACL.
-For details see chapter &<<CHAPdkim>>&.
+For details see section &<<SECDKIMVFY>>&.
 
 .vitem &$dkim_signers$&
 .vindex &$dkim_signers$&
 When a message has been received this variable contains
 a colon-separated list of signer domains and identities for the message.
-For details see chapter &<<CHAPdkim>>&.
+For details see section &<<SECDKIMVFY>>&.
 
 .vitem &$dnslist_domain$& &&&
        &$dnslist_matched$& &&&
@@ -11627,12 +11834,6 @@ The first character is a major version number, currently 4.
 Then after a dot, the next group of digits is a minor version number.
 There may be other characters following the minor version.
 
-.vitem &$found_extension$&
-.vindex "&$found_extension$&"
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete &%demime%& condition. For details,
-see section &<<SECTdemimecond>>&.
-
 .vitem &$header_$&<&'name'&>
 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
@@ -11654,7 +11855,8 @@ explicitly set a home directory for use by a transport; this can be overridden
 by a setting on the transport itself.
 
 When running a filter test via the &%-bf%& option, &$home$& is set to the value
-of the environment variable HOME.
+of the environment variable HOME, which is subject to the
+&%keep_environment%& and &%add_environment%& main config options.
 
 .vitem &$host$&
 .vindex "&$host$&"
@@ -11730,6 +11932,12 @@ See &$host_lookup_deferred$&.
 This variable is set to the remote host's TCP port whenever &$host$& is set
 for an outbound connection.
 
+.vitem &$initial_cwd$&
+.vindex "&$initial_cwd$&
+This variable contains the full path name of the initial working
+directory of the current Exim process. This may differ from the current
+working directory, as Exim changes this to "/" during early startup, and
+to &$spool_directory$& later.
 
 .vitem &$inode$&
 .vindex "&$inode$&"
@@ -11916,6 +12124,7 @@ when the ACL &%malware%& condition is true (see section &<<SECTscanvirus>>&).
 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.
 
 .vitem &$message_age$&
 .cindex "message" "age of"
@@ -11958,6 +12167,10 @@ in bytes. The count starts from the character after the blank line that
 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)
+the CRLF line-terminators are included in the count.
+
 .vitem &$message_exim_id$&
 .vindex "&$message_exim_id$&"
 When a message is being received or delivered, this variable contains the
@@ -12008,6 +12221,8 @@ deny message   = Too many lines in message header
 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.
+
 .vitem &$message_size$&
 .cindex "size" "of message"
 .cindex "message" "size"
@@ -12084,7 +12299,7 @@ normally the gid of the Exim user.
 .cindex "uid (user id)" "of originating user"
 .cindex "sender" "uid"
 .vindex "&$caller_uid$&"
-.vindex "&$originaltor_uid$&"
+.vindex "&$originator_uid$&"
 The value of &$caller_uid$& that was set when the message was received. For
 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
@@ -12125,23 +12340,19 @@ a single-component name, Exim calls &[gethostbyname()]& (or
 qualified host name. See also &$smtp_active_hostname$&.
 
 
-.new
-.vitem &$proxy_host_address$& &&&
-       &$proxy_host_port$& &&&
-       &$proxy_target_address$& &&&
-       &$proxy_target_port$& &&&
+.vitem &$proxy_external_address$& &&&
+       &$proxy_external_port$& &&&
+       &$proxy_local_address$& &&&
+       &$proxy_local_port$& &&&
        &$proxy_session$&
 These variables are only available when built with Proxy Protocol
-or Socks5 support
+or SOCKS5 support.
 For details see chapter &<<SECTproxyInbound>>&.
-.wen
 
-.new
 .vitem &$prdr_requested$&
 .cindex "PRDR" "variable for"
 This variable is set to &"yes"& if PRDR was requested by the client for the
 current message, otherwise &"no"&.
-.wen
 
 .vitem &$prvscheck_address$&
 This variable is used in conjunction with the &%prvscheck%& expansion item,
@@ -12167,6 +12378,12 @@ The value set for the &%qualify_domain%& option in the configuration file.
 The value set for the &%qualify_recipient%& option in the configuration file,
 or if not set, the value of &$qualify_domain$&.
 
+.vitem &$queue_name$&
+.vindex &$queue_name$&
+.cindex "named queues"
+.cindex queues named
+The name of the spool queue in use; empty for the default queue.
+
 .vitem &$rcpt_count$&
 .vindex "&$rcpt_count$&"
 When a message is being received by SMTP, this variable contains the number of
@@ -12479,6 +12696,11 @@ validating resolver (e.g. unbound, or bind with suitable configuration).
 If you have changed &%host_lookup_order%& so that &`bydns`& is not the first
 mechanism in the list, then this variable will be false.
 
+This requires that your system resolver library support EDNS0 (and that
+DNSSEC flags exist in the system headers).  If the resolver silently drops
+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 "&$sender_host_name$&"
@@ -12621,6 +12843,13 @@ argument, that is, the text that follows the command name, with leading white
 space removed. Following the introduction of &$smtp_command$&, this variable is
 somewhat redundant, but is retained for backwards compatibility.
 
+.vitem &$smtp_command_history$&
+.cindex SMTP "command history"
+.vindex "&$smtp_command_history$&"
+A comma-separated list (with no whitespace) of the most-recent SMTP commands
+received, in time-order left to right.  Only a limited number of commands
+are remembered.
+
 .vitem &$smtp_count_at_connection_start$&
 .vindex "&$smtp_count_at_connection_start$&"
 This variable is set greater than zero only in processes spawned by the Exim
@@ -12645,6 +12874,14 @@ A number of variables whose names start with &$spam$& are available when Exim
 is compiled with the content-scanning extension. For details, see section
 &<<SECTscanspamass>>&.
 
+.new
+.vitem &$spf_header_comment$& &&&
+       &$spf_received$& &&&
+       &$spf_result$& &&&
+       &$spf_smtp_comment$&
+These variables are only available if Exim is built with SPF support.
+For details see section &<<SECSPF>>&.
+.wen
 
 .vitem &$spool_directory$&
 .vindex "&$spool_directory$&"
@@ -12700,13 +12937,16 @@ If TLS has not been negotiated, the value will be 0.
 
 .vitem &$tls_in_ourcert$&
 .vindex "&$tls_in_ourcert$&"
-.cindex certificate veriables
+.cindex certificate variables
 This variable refers to the certificate presented to the peer of an
 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.
 
+&*Note*&: Under current versions of OpenSSL, when a list of more than one
+file is used for &%tls_certificate%&, this variable is not reliable.
+
 .vitem &$tls_in_peercert$&
 .vindex "&$tls_in_peercert$&"
 This variable refers to the certificate presented by the peer of an
@@ -12755,7 +12995,7 @@ When a message is received from a remote host over an encrypted SMTP
 connection, this variable is set to the cipher suite that was negotiated, for
 example DES-CBC3-SHA. In other circumstances, in particular, for message
 received over unencrypted connections, the variable is empty. Testing
-&$tls_cipher$& for emptiness is one way of distinguishing between encrypted and
+&$tls_in_cipher$& for emptiness is one way of distinguishing between encrypted and
 non-encrypted connections during ACL processing.
 
 The deprecated &$tls_cipher$& variable is the same as &$tls_in_cipher$& during message reception,
@@ -12770,6 +13010,10 @@ and then set to the outgoing cipher suite if one is negotiated. See chapter
 &<<CHAPTLS>>& for details of TLS support and chapter &<<CHAPsmtptrans>>& for
 details of the &(smtp)& transport.
 
+.vitem &$tls_out_dane$&
+.vindex &$tls_out_dane$&
+DANE active status.  See section &<<SECDANE>>&.
+
 .vitem &$tls_in_ocsp$&
 .vindex "&$tls_in_ocsp$&"
 When a message is received from a remote client connection
@@ -12835,6 +13079,10 @@ During outbound
 SMTP deliveries, this variable reflects the value of the &%tls_sni%& option on
 the transport.
 
+.vitem &$tls_out_tlsa_usage$&
+.vindex &$tls_out_tlsa_usage$&
+Bitfield of TLSA record types found.  See section &<<SECDANE>>&.
+
 .vitem &$tod_bsdinbox$&
 .vindex "&$tod_bsdinbox$&"
 The time of day and the date, in the format required for BSD-style mailbox
@@ -12890,8 +13138,7 @@ or external command, as described above. It is also used during a
 
 .vitem &$verify_mode$&
 .vindex "&$verify_mode$&"
-While a router or transport is being run in verify mode
-or for cutthrough delivery,
+While a router or transport is being run in verify mode or for cutthrough delivery,
 contains "S" for sender-verification or "R" for recipient-verification.
 Otherwise, empty.
 
@@ -12967,6 +13214,15 @@ overriding the setting of &%perl_at_start%&.
 There is also a command line option &%-pd%& (for delay) which suppresses the
 initial startup, even if &%perl_at_start%& is set.
 
+.ilist
+.oindex "&%perl_taintmode%&"
+.cindex "Perl" "taintmode"
+To provide more security executing Perl code via the embedded Perl
+interpreter, the &%perl_taintmode%& option can be set. This enables the
+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.
+
 
 .section "Calling Perl subroutines" "SECID86"
 When the configuration file includes a &%perl_startup%& option you can make use
@@ -13201,23 +13457,32 @@ value of &%daemon_smtp_ports%& is no longer relevant in this example.)
 
 
 
-.section "Support for the obsolete SSMTP (or SMTPS) protocol" "SECTsupobssmt"
+.section "Support for the submissions (aka SSMTP or SMTPS) protocol" "SECTsupobssmt"
+.cindex "submissions protocol"
 .cindex "ssmtp protocol"
 .cindex "smtps protocol"
 .cindex "SMTP" "ssmtp protocol"
 .cindex "SMTP" "smtps protocol"
-Exim supports the obsolete SSMTP protocol (also known as SMTPS) that was used
-before the STARTTLS command was standardized for SMTP. Some legacy clients
-still use this protocol. If the &%tls_on_connect_ports%& option is set to a
-list of port numbers or service names,
-connections to those ports must use SSMTP. The most
-common use of this option is expected to be
+Exim supports the use of TLS-on-connect, used by mail clients in the
+&"submissions"& protocol, historically also known as SMTPS or SSMTP.
+For some years, IETF Standards Track documents only blessed the
+STARTTLS-based Submission service (port 587) while common practice was to support
+the same feature set on port 465, but using TLS-on-connect.
+If your installation needs to provide service to mail clients
+(Mail User Agents, MUAs) then you should provide service on both the 587 and
+the 465 TCP ports.
+
+If the &%tls_on_connect_ports%& option is set to a list of port numbers or
+service names, connections to those ports must first establish TLS, before
+proceeding to the application layer use of the SMTP protocol.
+
+The common use of this option is expected to be
 .code
 tls_on_connect_ports = 465
 .endd
-because 465 is the usual port number used by the legacy clients. There is also
-a command line option &%-tls-on-connect%&, which forces all ports to behave in
-this way when a daemon is started.
+per RFC 8314.
+There is also a command line option &%-tls-on-connect%&, which forces all ports
+to behave in this way when a daemon is started.
 
 &*Warning*&: Setting &%tls_on_connect_ports%& does not of itself cause the
 daemon to listen on those ports. You must still specify them in
@@ -13392,6 +13657,7 @@ listed in more than one group.
 .section "Miscellaneous" "SECID96"
 .table2
 .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_malformed%&              "for broken files &-- should not happen"
 .row &%localhost_number%&            "for unique message ids in clusters"
@@ -13399,6 +13665,7 @@ listed in more than one group.
 .row &%message_body_visible%&        "how much to show in &$message_body$&"
 .row &%mua_wrapper%&                 "run in &""MUA wrapper""& mode"
 .row &%print_topbitchars%&           "top-bit characters are printing"
+.row &%spool_wireformat%&            "use wire-format spool data files when possible"
 .row &%timezone%&                    "force time zone"
 .endtable
 
@@ -13418,6 +13685,7 @@ listed in more than one group.
 .section "Privilege controls" "SECID98"
 .table2
 .row &%admin_groups%&                "groups that are Exim admin users"
+.row &%commandline_checks_require_admin%& "require admin for various checks"
 .row &%deliver_drop_privilege%&      "drop root for delivery processes"
 .row &%local_from_check%&            "insert &'Sender:'& if necessary"
 .row &%local_from_prefix%&           "for testing &'From:'& for local sender"
@@ -13445,6 +13713,7 @@ listed in more than one group.
 .row &%slow_lookup_log%&             "control logging of slow DNS lookups"
 .row &%syslog_duplication%&          "controls duplicate log lines on syslog"
 .row &%syslog_facility%&             "set syslog &""facility""& field"
+.row &%syslog_pid%&                  "pid in syslog lines"
 .row &%syslog_processname%&          "set syslog &""ident""& field"
 .row &%syslog_timestamp%&            "timestamp syslog lines"
 .row &%write_rejectlog%&             "control use of message log"
@@ -13495,6 +13764,7 @@ listed in more than one group.
 .table2
 .row &%perl_at_start%&               "always start the interpreter"
 .row &%perl_startup%&                "code to obey when starting Perl"
+.row &%perl_taintmode%&		     "enable taint mode in Perl"
 .endtable
 
 
@@ -13706,6 +13976,7 @@ See also the &'Policy controls'& section above.
 .table2
 .row &%accept_8bitmime%&             "advertise 8BITMIME"
 .row &%auth_advertise_hosts%&        "advertise AUTH to these hosts"
+.row &%chunking_advertise_hosts%&    "advertise CHUNKING to these hosts"
 .row &%dsn_advertise_hosts%&         "advertise DSN extensions to these hosts"
 .row &%ignore_fromline_hosts%&       "allow &""From ""& from these hosts"
 .row &%ignore_fromline_local%&       "allow &""From ""& from local SMTP"
@@ -13879,8 +14150,9 @@ acknowledgment is sent. See chapter &<<CHAPACL>>& for further details.
 .option acl_smtp_dkim main string&!! unset
 .cindex DKIM "ACL for"
 This option defines the ACL that is run for each DKIM signature
+(by default, or as specified in the dkim_verify_signers option)
 of a received message.
-See chapter &<<CHAPdkim>>& for further details.
+See section &<<SECDKIMVFY>>& for further details.
 
 .option acl_smtp_etrn main string&!! unset
 .cindex "ETRN" "ACL for"
@@ -13947,6 +14219,12 @@ received. See chapter &<<CHAPACL>>& for further details.
 This option defines the ACL that is run when an SMTP VRFY command is
 received. See chapter &<<CHAPACL>>& for further details.
 
+.option add_environment main "string list" empty
+.cindex "environment" "set values"
+This option allows to set individual environment variables that the
+currently linked libraries and programs in child processes use.
+See &<<SECTpipeenv>>& for the environment of &(pipe)& transports.
+
 .option admin_groups main "string list&!!" unset
 .cindex "admin user"
 This option is expanded just once, at the start of Exim's processing. If the
@@ -14108,7 +14386,7 @@ If the message being returned has lines longer than this value it is
 treated as if the &%bounce_return_size_limit%& (below) restriction was exceeded.
 
 The option also applies to bounces returned when an error is detected
-during reception of a messsage.
+during reception of a message.
 In this case lines from the original are truncated.
 
 The option does not apply to messages generated by an &(autoreply)& transport.
@@ -14189,11 +14467,11 @@ $primary_hostname-$tod_epoch-testing
 See section &<<CALLaddparcall>>& for details of how this value is used.
 
 
-.option check_log_inodes main integer 0
+.option check_log_inodes main integer 100
 See &%check_spool_space%& below.
 
 
-.option check_log_space main integer 0
+.option check_log_space main integer 10M
 See &%check_spool_space%& below.
 
 .oindex "&%check_rfc2047_length%&"
@@ -14208,11 +14486,11 @@ of the RFC, generates overlong encoded words. If &%check_rfc2047_length%& is
 set false, Exim recognizes encoded words of any length.
 
 
-.option check_spool_inodes main integer 0
+.option check_spool_inodes main integer 100
 See &%check_spool_space%& below.
 
 
-.option check_spool_space main integer 0
+.option check_spool_space main integer 10M
 .cindex "checking disk space"
 .cindex "disk space, checking"
 .cindex "spool directory" "checking space"
@@ -14223,7 +14501,7 @@ message is accepted.
 .vindex "&$log_space$&"
 .vindex "&$spool_inodes$&"
 .vindex "&$spool_space$&"
-When any of these options are set, they apply to all incoming messages. If you
+When any of these options are nonzero, they apply to all incoming messages. If you
 want to apply different checks to different kinds of message, you can do so by
 testing the variables &$log_inodes$&, &$log_space$&, &$spool_inodes$&, and
 &$spool_space$& in an ACL with appropriate additional conditions.
@@ -14232,7 +14510,7 @@ testing the variables &$log_inodes$&, &$log_space$&, &$spool_inodes$&, and
 &%check_spool_space%& and &%check_spool_inodes%& check the spool partition if
 either value is greater than zero, for example:
 .code
-check_spool_space = 10M
+check_spool_space = 100M
 check_spool_inodes = 100
 .endd
 The spool partition is the one that contains the directory defined by
@@ -14251,12 +14529,38 @@ SIZE parameter on the MAIL command, its value is added to the
 &%check_spool_space%& is zero, unless &%no_smtp_check_spool_space%& is set.
 
 The values for &%check_spool_space%& and &%check_log_space%& are held as a
-number of kilobytes. If a non-multiple of 1024 is specified, it is rounded up.
+number of kilobytes (though specified in bytes).
+If a non-multiple of 1024 is specified, it is rounded up.
 
 For non-SMTP input and for batched SMTP input, the test is done at start-up; on
 failure a message is written to stderr and Exim exits with a non-zero code, as
 it obviously cannot send an error message of any kind.
 
+There is a slight performance penalty for these checks.
+Versions of Exim preceding 4.88 had these disabled by default;
+high-rate installations confident they will never run out of resources
+may wish to deliberately disable them.
+
+.option chunking_advertise_hosts main "host list&!!" *
+.cindex CHUNKING advertisement
+.cindex "RFC 3030" "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.
+
+.option commandline_checks_require_admin main boolean &`false`&
+.cindex "restricting access to features"
+This option restricts various basic checking features to require an
+administrative user.
+This affects most of the &%-b*%& options, such as &%-be%&.
+
+.option debug_store main boolean &`false`&
+.cindex debugging "memory corruption"
+.cindex memory debugging
+This option, when true, enables extra checking in Exim's internal memory
+management.  For use when a memory corruption issue is being investigated,
+it should normally be left as default.
+
 .option daemon_smtp_ports main string &`smtp`&
 .cindex "port" "for daemon"
 .cindex "TCP/IP" "setting listening ports"
@@ -14278,6 +14582,7 @@ See &%daemon_startup_retries%&.
 .option delay_warning main "time list" 24h
 .cindex "warning of delay"
 .cindex "delay warning, specifying"
+.cindex "queue" "delay warning"
 When a message is delayed, Exim sends a warning message to the sender at
 intervals specified by this option. The data is a colon-separated list of times
 after which to send warning messages. If the value of the option is an empty
@@ -14380,7 +14685,7 @@ to handle IPv6 literal addresses.
 This option gives a list of DKIM domains for which the DKIM ACL is run.
 It is expanded after the message is received; by default it runs
 the ACL once for each signature in the message.
-See chapter &<<CHAPdkim>>&.
+See section &<<SECDKIMVFY>>&.
 
 
 .option dns_again_means_nonexist main "domain list&!!" unset
@@ -14446,6 +14751,7 @@ If the resolver library does not support DNSSEC then this option has no effect.
 .option dns_ipv4_lookup main "domain list&!!" unset
 .cindex "IPv6" "DNS lookup for AAAA records"
 .cindex "DNS" "IPv6 lookup for AAAA records"
+.cindex DNS "IPv6 disabling"
 When Exim is compiled with IPv6 support and &%disable_ipv6%& is not set, it
 looks for IPv6 address records (AAAA records) as well as IPv4 address records
 (A records) when trying to find IP addresses for hosts, unless the host's
@@ -14505,6 +14811,7 @@ record in the authoritative section is used instead.
 .option dns_use_edns0 main integer -1
 .cindex "DNS" "resolver options"
 .cindex "DNS" "EDNS0"
+.cindex "DNS" "OpenBSD
 If this option is set to a non-negative number then Exim will initialise the
 DNS resolver library to either use or not use EDNS0 extensions, overriding
 the system default. A value of 0 coerces EDNS0 off, a value of 1 coerces EDNS0
@@ -14512,6 +14819,10 @@ on.
 
 If the resolver library does not support EDNS0 then this option has no effect.
 
+OpenBSD's asr resolver routines are known to ignore the EDNS0 option; this
+means that DNSSEC will not work with Exim on that platform either, unless Exim
+is linked against an alternative DNS client library.
+
 
 .option drop_cr main boolean false
 This is an obsolete option that is now a no-op. It used to affect the way Exim
@@ -14607,12 +14918,10 @@ own &'Reply-To:'& header line, the value of the &%errors_reply_to%& option is
 not used.
 
 
-.new
 .option event_action main string&!! unset
 .cindex events
 This option declares a string to be expanded for Exim's events mechanism.
-For details see &<<CHAPevents>>&.
-.wen
+For details see chapter &<<CHAPevents>>&.
 
 
 .option exim_group main string "compile-time configured"
@@ -14960,12 +15269,10 @@ If the &%smtp_connection%& log selector is not set, this option has no effect.
 
 
 
-.new
 .option hosts_proxy main "host list&!!" unset
 .cindex proxy "proxy protocol"
 This option enables use of Proxy Protocol proxies for incoming
-connections.  For details see &<<SECTproxyInbound>>&.
-.wen
+connections.  For details see section &<<SECTproxyInbound>>&.
 
 
 .option hosts_treat_as_local main "domain list&!!" unset
@@ -15034,6 +15341,34 @@ process rather than a remote host, and is using &%-bs%& to inject the messages,
 .option ignore_fromline_local main boolean false
 See &%ignore_fromline_hosts%& above.
 
+.option keep_environment main "string list" unset
+.cindex "environment" "values from"
+This option contains a string list of environment variables to keep.
+You have to trust these variables or you have to be sure that
+these variables do not impose any security risk. Keep in mind that
+during the startup phase Exim is running with an effective UID 0 in most
+installations. As the default value is an empty list, the default
+environment for using libraries, running embedded Perl code, or running
+external binaries is empty, and does not not even contain PATH or HOME.
+
+Actually the list is interpreted as a list of patterns
+(&<<SECTlistexpand>>&), except that it is not expanded first.
+
+WARNING: Macro substitution is still done first, so having a macro
+FOO and having FOO_HOME in your &%keep_environment%& option may have
+unexpected results. You may work around this using a regular expression
+that does not match the macro name: ^[F]OO_HOME$.
+
+Current versions of Exim issue a warning during startup if you do not mention
+&%keep_environment%& in your runtime configuration file and if your
+current environment is not empty. Future versions may not issue that warning
+anymore.
+
+See the &%add_environment%& main config option for a way to set
+environment variables to a fixed value.  The environment for &(pipe)&
+transports is handled separately, see section &<<SECTpipeenv>>& for
+details.
+
 
 .option keep_malformed main time 4d
 This option specifies the length of time to keep messages whose spool files
@@ -15111,6 +15446,7 @@ connecting on a regular LDAP port.  This is the LDAP equivalent of SMTP's
 of SSL-on-connect.
 In the event of failure to negotiate TLS, the action taken is controlled
 by &%ldap_require_cert%&.
+This option is ignored for &`ldapi`& connections.
 
 
 .option ldap_version main integer unset
@@ -15451,7 +15787,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)&
 transport driver.
 
 
-.option openssl_options main "string list" "+no_sslv2 +single_dh_use"
+.option openssl_options main "string list" "+no_sslv2 +single_dh_use +no_ticket"
 .cindex "OpenSSL "compatibility options"
 This option allows an administrator to adjust the SSL options applied
 by OpenSSL to connections.  It is given as a space-separated list of items,
@@ -15582,14 +15918,20 @@ local parts. Exim's default configuration does this.
 
 
 .option perl_at_start main boolean false
+.cindex "Perl"
 This option is available only when Exim is built with an embedded Perl
 interpreter. See chapter &<<CHAPperl>>& for details of its use.
 
 
 .option perl_startup main string unset
+.cindex "Perl"
 This option is available only when Exim is built with an embedded Perl
 interpreter. See chapter &<<CHAPperl>>& for details of its use.
 
+.option perl_startup main boolean false
+.cindex "Perl"
+This Option enables the taint mode of the embedded Perl interpreter.
+
 
 .option pgsql_servers main "string list" unset
 .cindex "PostgreSQL lookup type" "server list"
@@ -15694,12 +16036,13 @@ different spool directories.
 
 
 .option prod_requires_admin main boolean true
+.cindex "restricting access to features"
 .oindex "&%-M%&"
 .oindex "&%-R%&"
 .oindex "&%-q%&"
 The &%-M%&, &%-R%&, and &%-q%& command-line options require the caller to be an
 admin user unless &%prod_requires_admin%& is set false. See also
-&%queue_list_requires_admin%&.
+&%queue_list_requires_admin%& and &%commandline_checks_require_admin%&.
 
 
 .option qualify_domain main string "see below"
@@ -15738,10 +16081,12 @@ next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&.
 
 
 .option queue_list_requires_admin main boolean true
+.cindex "restricting access to features"
 .oindex "&%-bp%&"
 The &%-bp%& command-line option, which lists the messages that are on the
 queue, requires the caller to be an admin user unless
-&%queue_list_requires_admin%& is set false. See also &%prod_requires_admin%&.
+&%queue_list_requires_admin%& is set false.
+See also &%prod_requires_admin%& and &%commandline_checks_require_admin%&.
 
 
 .option queue_only main boolean false
@@ -15829,7 +16174,7 @@ large list. In most situations, &%queue_run_in_order%& should not be set.
 
 
 
-.option queue_run_max main integer 5
+.option queue_run_max main integer&!! 5
 .cindex "queue runner" "maximum number of"
 This controls the maximum number of queue runner processes that an Exim daemon
 can run simultaneously. This does not mean that it starts them all at once,
@@ -15844,6 +16189,11 @@ the limit, allowing any number of simultaneous queue runner processes to be
 run. If you do not want queue runs to occur, omit the &%-q%&&'xx'& setting on
 the daemon's command line.
 
+.cindex queues named
+.cindex "named queues"
+To set limits for different named queues use
+an expansion depending on the &$queue_name$& variable.
+
 .option queue_smtp_domains main "domain list&!!" unset
 .cindex "queueing incoming messages"
 .cindex "message" "queueing remote deliveries"
@@ -16072,6 +16422,12 @@ it qualifies them only if the message came from a host that matches
 &%sender_unqualified_hosts%&, or if the message was submitted locally (not
 using TCP/IP), and the &%-bnq%& option was not set.
 
+.option set_environment main "string list" empty
+.cindex "environment"
+This option allows to set individual environment variables that the
+currently linked libraries and programs in child processes use. The
+default list is empty,
+
 
 .option slow_lookup_log main integer 0
 .cindex "logging" "slow lookups"
@@ -16507,27 +16863,29 @@ example, instead of &"Administrative prohibition"&, it might give:
 .endd
 
 
-.new
 .option smtputf8_advertise_hosts main "host list&!!" *
 .cindex "SMTPUTF8" "advertising"
 When Exim is built with support for internationalised mail names,
-the availability therof is advertised in
+the availability thereof is advertised in
 response to EHLO only to those client hosts that match this option. See
 chapter &<<CHAPi18n>>& for details of Exim's support for internationalisation.
-.wen
 
 
-.option spamd_address main string "see below"
+.option spamd_address main string "127.0.0.1 783"
 This option is available when Exim is compiled with the content-scanning
 extension. It specifies how Exim connects to SpamAssassin's &%spamd%& daemon.
-The default value is
-.code
-127.0.0.1 783
-.endd
 See section &<<SECTscanspamass>>& for more details.
 
 
 
+.new
+.option spf_guess main string "v=spf1 a/24 mx/24 ptr ?all"
+This option is available when Exim is compiled with SPF support.
+See section &<<SECSPF>>& for more details.
+.wen
+
+
+
 .option split_spool_directory main boolean false
 .cindex "multiple spool directories"
 .cindex "spool directory" "split"
@@ -16578,6 +16936,30 @@ as failures in the configuration file.
 By using this option to override the compiled-in path, it is possible to run
 tests of Exim without using the standard spool.
 
+.option spool_wireformat main boolean false
+.cindex "spool directory" "file formats"
+If this option is set, Exim may for some messages use an alternate format
+for data-files in the spool which matches the wire format.
+Doing this permits more efficient message reception and transmission.
+Currently it is only done for messages received using the EMSTP CHUNKING
+option.
+
+The following variables will not have useful values:
+.code
+$max_received_linelength
+$body_linecount
+$body_zerocount
+.endd
+
+Users of the local_scan() API (see &<<CHAPlocalscan>>&),
+and any external programs which are passed a reference to a message data file
+(except via the &"regex"&, &"malware"& or &"spam"&) ACL conditions)
+will need to be aware of the potential different format.
+
+Using any of the ACL conditions noted will negate the reception benefit
+(as a Unix-mbox-format file is constructed for them).
+The transmission benefit is maintained.
+
 .option sqlite_lock_timeout main time 5s
 .cindex "sqlite lookup type" "lock timeout"
 This option controls the timeout that the &(sqlite)& lookup uses when trying to
@@ -16633,6 +17015,15 @@ If this option is unset, &"mail"& is used. See chapter &<<CHAPlog>>& for
 details of Exim's logging.
 
 
+.option syslog_pid main boolean true
+.cindex "syslog" "pid"
+If &%syslog_pid%& is set false, the PID on Exim's log lines are
+omitted when these lines are sent to syslog. (Syslog normally prefixes
+the log lines with the PID of the logging process automatically.) You need
+to enable the &`+pid`& log selector item, if you want Exim to write it's PID
+into the logs.) See chapter &<<CHAPlog>>& for details of Exim's logging.
+
+
 
 .option syslog_processname main string &`exim`&
 .cindex "syslog" "process name; setting"
@@ -16660,6 +17051,7 @@ generates any deliveries to files or pipes, or any new mail messages, the
 appropriate &%system_filter_..._transport%& option(s) must be set, to define
 which transports are to be used. Details of this facility are given in chapter
 &<<CHAPsystemfilter>>&.
+A forced expansion failure results in no filter operation.
 
 
 .option system_filter_directory_transport main string&!! unset
@@ -16745,6 +17137,7 @@ messages that are released by &%ignore_bounce_errors_after%&).
 
 .option timezone main string unset
 .cindex "timezone, setting"
+.cindex "environment" "values from"
 The value of &%timezone%& is used to set the environment variable TZ while
 running Exim (if it is different on entry). This ensures that all timestamps
 created by Exim are in the required timezone. If you want all your timestamps
@@ -16760,9 +17153,7 @@ runs. This is appropriate behaviour for obtaining wall-clock time on some, but
 unfortunately not all, operating systems.
 
 
-.new
 .option tls_advertise_hosts main "host list&!!" *
-.wen
 .cindex "TLS" "advertising"
 .cindex "encryption" "on SMTP connection"
 .cindex "SMTP" "encrypted connection"
@@ -16770,18 +17161,18 @@ 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
 chapter &<<CHAPTLS>>& for details of Exim's support for TLS.
-.new
 Note that the default value requires that a certificate be supplied
-using the &%tls_certificate%& option.  If no certificate is available then
-the &%tls_advertise_hosts%& option should be set empty.
-.wen
+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&!! unset
+.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 the absolute path to a
-file which contains the server's certificates. The server's private key is also
+The value of this option is expanded, and must then be a list of absolute paths to
+files which contains the server's certificates.  Commonly only one file is
+needed.
+The server's private key is also
 assumed to be in this file if &%tls_privatekey%& is unset. See chapter
 &<<CHAPTLS>>& for further details.
 
@@ -16790,16 +17181,36 @@ receiving incoming messages as a server. If you want to supply certificates for
 use when sending messages as a client, you must set the &%tls_certificate%&
 option in the relevant &(smtp)& transport.
 
+&*Note*&: If you use filenames based on IP addresses, change the list
+separator in the usual way to avoid confusion under IPv6.
+
+&*Note*&: Under current versions of OpenSSL, when a list of more than one
+file is used, the &$tls_in_ourcert$& variable is unreliable.
+
+&*Note*&: OCSP stapling is not usable under OpenSSL
+when a list of more than one file is used.
+
 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
 &<<SECTtlssni>>& will be re-expanded.
 
+If this option is unset or empty a fresh self-signed certificate will be
+generated for every connection.
+
 .option tls_crl main string&!! unset
 .cindex "TLS" "server certificate revocation list"
 .cindex "certificate" "revocation list for server"
 This option specifies a certificate revocation list. The expanded value must
-be the name of a file that contains a CRL in PEM format.
+be the name of a file that contains CRLs in PEM format.
+
+.new
+Under OpenSSL the option can specify a directory with CRL files.
+
+&*Note:*& Under OpenSSL the option must, if given, supply a CRL
+for each signing element of the certificate chain (i.e. all but the leaf).
+For the file variant this can be multiple PEM blocks in the one file.
+.wen
 
 See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
 
@@ -16830,7 +17241,13 @@ larger prime than requested.
 The value of this option is expanded and indicates the source of DH parameters
 to be used by Exim.
 
-If it is a filename starting with a &`/`&, then it names a file from which DH
+&*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.
+
+If &%tls_dhparam%& is a filename starting with a &`/`&,
+then it names a file from which DH
 parameters should be loaded.  If the file exists, it should hold a PEM-encoded
 PKCS#3 representation of the DH prime.  If the file does not exist, for
 OpenSSL it is an error.  For GnuTLS, Exim will attempt to create the file and
@@ -16847,22 +17264,36 @@ does not exist, Exim will attempt to create it.
 See section &<<SECTgnutlsparam>>& for further details.
 
 If Exim is using OpenSSL and this option is empty or unset, then Exim will load
-a default DH prime; the default is the 2048 bit prime described in section
+a default DH prime; the default is Exim-specific but lacks verifiable provenance.
+
+In older versions of Exim the default was the 2048 bit prime described in section
 2.2 of RFC 5114, "2048-bit MODP Group with 224-bit Prime Order Subgroup", which
 in IKE is assigned number 23.
 
 Otherwise, the option must expand to the name used by Exim for any of a number
-of DH primes specified in RFC 2409, RFC 3526 and RFC 5114.  As names, Exim uses
-"ike" followed by the number used by IKE, of "default" which corresponds to
-"ike23".
+of DH primes specified in RFC 2409, RFC 3526, RFC 5114, RFC 7919, or from other
+sources.  As names, Exim uses a standard specified name, else "ike" followed by
+the number used by IKE, or "default" which corresponds to
+&`exim.dev.20160529.3`&.
 
-The available primes are:
+The available standard primes are:
+&`ffdhe2048`&, &`ffdhe3072`&, &`ffdhe4096`&, &`ffdhe6144`&, &`ffdhe8192`&,
 &`ike1`&, &`ike2`&, &`ike5`&,
 &`ike14`&, &`ike15`&, &`ike16`&, &`ike17`&, &`ike18`&,
-&`ike22`&, &`ike23`& (aka &`default`&) and &`ike24`&.
+&`ike22`&, &`ike23`& and &`ike24`&.
+
+The available additional primes are:
+&`exim.dev.20160529.1`&, &`exim.dev.20160529.2`& and &`exim.dev.20160529.3`&.
 
 Some of these will be too small to be accepted by clients.
 Some may be too large to be accepted by clients.
+The open cryptographic community has suspicions about the integrity of some
+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
+candidates for removal the next time we have backwards-incompatible changes.
 
 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,
@@ -16880,17 +17311,20 @@ prior to the 4.80 release, as Debian used to patch Exim to raise the minimum
 acceptable bound from 1024 to 2048.
 
 
-.option tls_eccurve main string&!! prime256v1
+.option tls_eccurve main string&!! &`auto`&
 .cindex TLS "EC cryptography"
-If built with a recent-enough version of OpenSSL,
-this option selects a EC curve for use by Exim.
+This option selects a EC curve for use by Exim when used with OpenSSL.
+It has no effect when Exim is used with GnuTLS.
+
+After expansion it must contain a valid EC curve parameter, such as
+&`prime256v1`&, &`secp384r1`&, or &`P-512`&. Consult your OpenSSL manual
+for valid selections.
 
-Curve names of the form &'prime256v1'& are accepted.
-For even more-recent library versions, names of the form &'P-512'&
-are also accepted, plus the special value &'auto'&
-which tell the library to choose.
+For OpenSSL versions before (and not including) 1.0.2, the string
+&`auto`& selects &`prime256v1`&. For more recent OpenSSL versions
+&`auto`& tells the library to choose.
 
-If the option is set to an empty string, no EC curves will be enabled.
+If the option expands to an empty string, no EC curves will be enabled.
 
 
 .option tls_ocsp_file main string&!! unset
@@ -16901,8 +17335,12 @@ must if set expand to the absolute path to a file which contains a current
 status proof for the server's certificate, as obtained from the
 Certificate Authority.
 
-.new
 Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later).
+
+.new
+For GnuTLS 3.5.6 or later the expanded value of this option can be a list
+of files, to match a list given for the &%tls_certificate%& option.
+The ordering of the two lists must match.
 .wen
 
 
@@ -16916,10 +17354,11 @@ further details, see section &<<SECTsupobssmt>>&.
 
 
 
-.option tls_privatekey main string&!! 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 the absolute path to a
-file which contains the server's private key. If this option is unset, or if
+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.
+If this option is unset, or if
 the expansion is forced to fail, or the result is an empty string, the private
 key is assumed to be in the same file as the server's certificates. See chapter
 &<<CHAPTLS>>& for further details.
@@ -17430,7 +17869,7 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence.
 .cindex "DNSSEC" "MX lookup"
 .cindex "security" "MX lookup"
 .cindex "DNS" "DNSSEC"
-DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+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
 (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.
@@ -18365,7 +18804,9 @@ records.
 MX records of equal priority are sorted by Exim into a random order. Exim then
 looks for address records for the host names obtained from MX or SRV records.
 When a host has more than one IP address, they are sorted into a random order,
-except that IPv6 addresses are always sorted before IPv4 addresses. If all the
+.new
+except that IPv6 addresses are sorted before IPv4 addresses. If all the
+.wen
 IP addresses found are discarded by a setting of the &%ignore_target_hosts%&
 generic option, the router declines.
 
@@ -18498,6 +18939,24 @@ However, it will result in any message with mistyped domains
 also being queued.
 
 
+.new
+.option ipv4_only "string&!!" unset
+.cindex IPv6 disabling
+.cindex DNS "IPv6 disabling"
+The string is expanded, and if the result is anything but a forced failure,
+or an empty string, or one of the strings “0” or “no” or “false”
+(checked without regard to the case of the letters),
+only A records are used.
+
+.option ipv4_prefer "string&!!" unset
+.cindex IPv4 preference
+.cindex DNS "IPv4 preference"
+The string is expanded, and if the result is anything but a forced failure,
+or an empty string, or one of the strings “0” or “no” or “false”
+(checked without regard to the case of the letters),
+A records are sorted before AAAA records (inverting the default).
+.wen
+
 .option mx_domains dnslookup "domain list&!!" unset
 .cindex "MX record" "required to exist"
 .cindex "SRV record" "required to exist"
@@ -19102,8 +19561,8 @@ whether obtained from an MX lookup or not.
 
 
 .section "How the options are used" "SECThowoptused"
-The options are a sequence of words; in practice no more than three are ever
-present. One of the words can be the name of a transport; this overrides the
+The options are a sequence of words, space-separated.
+One of the words can be the name of a transport; this overrides the
 &%transport%& option on the router for this particular routing rule only. The
 other words (if present) control randomization of the list of hosts on a
 per-rule basis, and how the IP addresses of the hosts are to be found when
@@ -19123,6 +19582,12 @@ also look in &_/etc/hosts_& or other sources of information.
 &%bydns%&: look up address records for the hosts directly in the DNS; fail if
 no address records are found. If there is a temporary DNS error (such as a
 timeout), delivery is deferred.
+.new
+.next
+&%ipv4_only%&: in direct DNS lookups, look up only A records.
+.next
+&%ipv4_prefer%&: in direct DNS lookups, sort A records before AAAA records.
+.wen
 .endlist
 
 For example:
@@ -19142,6 +19607,10 @@ instead of TRY_AGAIN. That is why the default action is to try a DNS
 lookup first. Only if that gives a definite &"no such host"& is the local
 function called.
 
+&*Compatibility*&: From Exim 4.85 until fixed for 4.90, there was an
+inadvertent constraint that a transport name as an option had to be the last
+option specified.
+
 
 
 If no IP address for a host can be found, what happens is controlled by the
@@ -19731,12 +20200,17 @@ list1:   :include:/opt/lists/list1
 .endd
 .next
 .cindex "address redirection" "to black hole"
-Sometimes you want to throw away mail to a particular local part. Making the
-&%data%& option expand to an empty string does not work, because that causes
-the router to decline. Instead, the alias item
+.cindex "delivery" "discard"
+.cindex "delivery" "blackhole"
 .cindex "black hole"
 .cindex "abandoning mail"
-&':blackhole:'& can be used. It does what its name implies. No delivery is
+Sometimes you want to throw away mail to a particular local part.  Making the
+&%data%& option expand to an empty string does not work, because that causes
+the router to decline. Instead, the alias item
+.code
+:blackhole:
+.endd
+can be used. It does what its name implies. No delivery is
 done, and no error message is generated. This has the same effect as specifying
 &_/dev/null_& as a destination, but it can be independently disabled.
 
@@ -20014,11 +20488,15 @@ relative path is then passed to the transport unmodified.
 
 
 .option forbid_blackhole redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, the &':blackhole:'& item may not appear in a
 redirection list.
 
 
 .option forbid_exim_filter redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is set true, only Sieve filters are permitted when
 &%allow_filter%& is true.
 
@@ -20026,7 +20504,9 @@ If this option is set true, only Sieve filters are permitted when
 
 
 .option forbid_file redirect boolean false
+.cindex "restricting access to features"
 .cindex "delivery" "to file; forbidding"
+.cindex "filter" "locking out certain features"
 .cindex "Sieve filter" "forbidding delivery to a file"
 .cindex "Sieve filter" "&""keep""& facility; disabling"
 If this option is true, this router may not generate a new address that
@@ -20037,17 +20517,22 @@ locks out the Sieve's &"keep"& facility.
 
 
 .option forbid_filter_dlfunc redirect boolean false
+.cindex "restricting access to features"
 .cindex "filter" "locking out certain features"
 If this option is true, string expansions in Exim filters are not allowed to
 make use of the &%dlfunc%& expansion facility to run dynamically loaded
 functions.
 
 .option forbid_filter_existstest redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 .cindex "expansion" "statting a file"
 If this option is true, string expansions in Exim filters are not allowed to
 make use of the &%exists%& condition or the &%stat%& expansion item.
 
 .option forbid_filter_logwrite redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, use of the logging facility in Exim filters is not
 permitted. Logging is in any case available only if the filter is being run
 under some unprivileged uid (which is normally the case for ordinary users'
@@ -20055,27 +20540,37 @@ under some unprivileged uid (which is normally the case for ordinary users'
 
 
 .option forbid_filter_lookup redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, string expansions in Exim filter files are not allowed
 to make use of &%lookup%& items.
 
 
 .option forbid_filter_perl redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 This option has an effect only if Exim is built with embedded Perl support. If
 it is true, string expansions in Exim filter files are not allowed to make use
 of the embedded Perl support.
 
 
 .option forbid_filter_readfile redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, string expansions in Exim filter files are not allowed
 to make use of &%readfile%& items.
 
 
 .option forbid_filter_readsocket redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, string expansions in Exim filter files are not allowed
 to make use of &%readsocket%& items.
 
 
 .option forbid_filter_reply redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, this router may not generate an automatic reply
 message. Automatic replies can be generated only from Exim or Sieve filter
 files, not from traditional forward files. This option is forced to be true if
@@ -20083,11 +20578,15 @@ files, not from traditional forward files. This option is forced to be true if
 
 
 .option forbid_filter_run redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, string expansions in Exim filter files are not allowed
 to make use of &%run%& items.
 
 
 .option forbid_include redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is true, items of the form
 .code
 :include:<path name>
@@ -20096,6 +20595,8 @@ are not permitted in non-filter redirection lists.
 
 
 .option forbid_pipe redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 .cindex "delivery" "to pipe; forbidding"
 If this option is true, this router may not generate a new address which
 specifies delivery to a pipe, either from an Exim filter or from a conventional
@@ -20103,6 +20604,8 @@ forward file. This option is forced to be true if &%one_time%& is set.
 
 
 .option forbid_sieve_filter redirect boolean false
+.cindex "restricting access to features"
+.cindex "filter" "locking out certain features"
 If this option is set true, only Exim filters are permitted when
 &%allow_filter%& is true.
 
@@ -20391,7 +20894,7 @@ See &%skip_syntax_errors%& above.
 .chapter "Environment for running local transports" "CHAPenvironment" &&&
          "Environment for local transports"
 .scindex IIDenvlotra1 "local transports" "environment for"
-.scindex IIDenvlotra2 "environment for local transports"
+.scindex IIDenvlotra2 "environment" "local transports"
 .scindex IIDenvlotra3 "transport" "local; environment for"
 Local transports handle deliveries to files and pipes. (The &(autoreply)&
 transport can be thought of as similar to a pipe.) Exim always runs transports
@@ -20656,8 +21159,7 @@ resent to other recipients.
 .option event_action transports string&!! unset
 .cindex events
 This option declares a string to be expanded for Exim's events mechanism.
-For details see &<<CHAPevents>>&.
-.wen
+For details see chapter &<<CHAPevents>>&.
 
 
 .option group transports string&!! "Exim group"
@@ -20707,7 +21209,7 @@ is forced to fail, no action is taken. Other expansion failures are treated as
 errors and cause the delivery to be deferred.
 
 Unlike most options, &%headers_remove%& can be specified multiple times
-for a router; all listed headers are removed.
+for a transport; all listed headers are removed.
 
 &*Warning*&: Because of the separate expansion of the list items,
 items that contain a list separator must have it doubled.
@@ -20761,7 +21263,6 @@ 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"
@@ -20773,7 +21274,7 @@ 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
+incremented whenever a transport process is being 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
@@ -20784,7 +21285,6 @@ 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
@@ -20933,9 +21433,7 @@ headers that some sites insist on.
 This option sets up a filtering (in the Unix shell sense) process for messages
 at transport time. It should not be confused with mail filtering as set up by
 individual users or via a system filter.
-.new
 If unset, or expanding to an empty string, no filtering is done.
-.wen
 
 When the message is about to be written out, the command specified by
 &%transport_filter%& is started up in a separate, parallel process, and
@@ -21772,10 +22270,14 @@ the obvious value which users understand most easily.
 
 The value of the option is expanded, and must then be a numerical value
 (decimal point allowed), optionally followed by one of the letters K, M, or G,
-for kilobytes, megabytes, or gigabytes. If Exim is running on a system with
+for kilobytes, megabytes, or gigabytes, optionally followed by a slash
+and further option modifiers. If Exim is running on a system with
 large file support (Linux and FreeBSD have this), mailboxes larger than 2G can
 be handled.
 
+The option modifier &%no_check%& can be used to force delivery even if the over
+quota condition is met. The quota gets updated as usual.
+
 &*Note*&: A value of zero is interpreted as &"no quota"&.
 
 The expansion happens while Exim is running as root, before it changes uid for
@@ -21810,6 +22312,8 @@ can only be used if &%quota%& is also set. The value is expanded; an expansion
 failure causes delivery to be deferred. A value of zero is interpreted as
 &"no quota"&.
 
+The option modifier &%no_check%& can be used to force delivery even if the over
+quota condition is met. The quota gets updated as usual.
 
 .option quota_is_inclusive appendfile boolean true
 See &%quota%& above.
@@ -22687,10 +23191,8 @@ 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
 
 
 
@@ -22810,11 +23312,12 @@ with &%use_shell%&, and the whole mechanism is inherently less secure.
 
 .section "Environment variables" "SECTpipeenv"
 .cindex "&(pipe)& transport" "environment for command"
-.cindex "environment for pipe transport"
+.cindex "environment" "&(pipe)& transport"
 The environment variables listed below are set up when the command is invoked.
 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.
+environment. The environment for the &(pipe)& transport is not subject
+to the &%add_environment%& and &%keep_environment%& main config options.
 .display
 &`DOMAIN            `&   the domain of the address
 &`HOME              `&   the home directory, if set
@@ -22909,7 +23412,7 @@ Exim, and each argument is separately expanded, as described in section
 
 .option environment pipe string&!! unset
 .cindex "&(pipe)& transport" "environment for command"
-.cindex "environment for &(pipe)& transport"
+.cindex "environment" "&(pipe)& transport"
 This option is used to add additional variables to the environment in which the
 command runs (see section &<<SECTpipeenv>>& for the default list). Its value is
 a string which is expanded, and then interpreted as a colon-separated list of
@@ -23034,12 +23537,10 @@ message_suffix =
 &`\n`& to &`\r\n`& in &%message_suffix%&.
 
 
-.option path pipe string "see below"
-This option specifies the string that is set up in the PATH environment
-variable of the subprocess. The default is:
-.code
-/bin:/usr/bin
-.endd
+.option path pipe string&!! "/bin:/usr/bin"
+This option is expanded and
+specifies the string that is set up in the PATH environment
+variable of the subprocess.
 If the &%command%& option does not yield an absolute path name, the command is
 sought in the PATH directories, in the usual way. &*Warning*&: This does not
 apply to a command specified as a transport filter.
@@ -23418,13 +23919,15 @@ 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%&.
 
 
-.option dkim_domain smtp string&!! unset
+.option dkim_domain smtp string list&!! unset
 .option dkim_selector smtp string&!! unset
 .option dkim_private_key smtp string&!! unset
 .option dkim_canon smtp string&!! unset
 .option dkim_strict smtp string&!! unset
-.option dkim_sign_headers smtp string&!! unset
-DKIM signing options.  For details see &<<SECDKIMSIGN>>&.
+.option dkim_sign_headers smtp string&!! "per RFC"
+.option dkim_hash smtp string&!! sha256
+.option dkim_identity smtp string&!! unset
+DKIM signing options.  For details see section &<<SECDKIMSIGN>>&.
 
 
 .option delay_after_cutoff smtp boolean true
@@ -23480,7 +23983,7 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence.
 .cindex "DNSSEC" "MX lookup"
 .cindex "security" "MX lookup"
 .cindex "DNS" "DNSSEC"
-DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+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
 (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.
@@ -23667,6 +24170,23 @@ been started will not be passed to a new delivery process for sending another
 message on the same connection. See section &<<SECTmulmessam>>& for an
 explanation of when this might be needed.
 
+.option hosts_noproxy_tls smtp "host list&!!" *
+.cindex "TLS" "passing connection"
+.cindex "multiple SMTP deliveries"
+.cindex "TLS" "multiple message deliveries"
+For any host that matches this list, a TLS session which has
+been started will not be passed to a new delivery process for sending another
+message on the same session.
+
+The traditional implementation closes down TLS and re-starts it in the new
+process, on the same open TCP connection, for each successive message
+sent.  If permitted by this option a pipe to to the new process is set up
+instead, and the original process maintains the TLS connection and proxies
+the SMTP connection from and to the new process and any subsequents.
+The new process has no access to TLS information, so cannot include it in
+logging.
+
+
 
 .option hosts_override smtp boolean false
 If this option is set and the &%hosts%& option is also set, any hosts that are
@@ -23714,6 +24234,17 @@ 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
+.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.
+There will be no fallback to in-clear communication.
+See section &<<SECDANE>>&.
+.wen
+
 .option hosts_require_ocsp smtp "host list&!!" unset
 .cindex "TLS" "requiring for certain servers"
 Exim will request, and check for a valid Certificate Status being given, on a
@@ -23735,6 +24266,46 @@ connects. If authentication fails, Exim will try to transfer the message
 unauthenticated. See also &%hosts_require_auth%&, and chapter
 &<<CHAPSMTPAUTH>>& for details of authentication.
 
+.option hosts_try_chunking smtp "host list&!!" *
+.cindex CHUNKING "enabling, in client"
+.cindex BDAT "SMTP command"
+.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.
+BDAT will not be used in conjunction with a transport filter.
+
+.new
+.option hosts_try_dane smtp "host list&!!" unset
+.cindex DANE "transport options"
+.cindex DANE "attempting for certain servers"
+If built with DANE support, Exim  will lookup a
+TLSA record for any host matching the list.
+If found and verified by DNSSEC,
+a DANE-verified TLS connection is made to that host;
+there will be no fallback to in-clear communication.
+See section &<<SECDANE>>&.
+.wen
+
+.option hosts_try_fastopen smtp "host list&!!" unset
+.cindex "fast open, TCP" "enabling, in client"
+.cindex "TCP Fast Open" "enabling, in client"
+.cindex "RFC 7413" "TCP Fast Open"
+This option provides a list of servers to which, provided
+the facility is supported by this system, Exim will attempt to
+perform a TCP Fast Open.
+No data is sent on the SYN segment but, if the remote server also
+supports the facility, it can send its SMTP banner immediately after
+the SYN,ACK segment.  This can save up to one round-trip time.
+
+The facility is only active for previously-contacted servers,
+as the initiator must present a cookie in the SYN segment.
+
+On (at least some) current Linux distributions the facility must be enabled
+in the kernel by the sysadmin before the support is usable.
+There is no option for control of the server side; if the system supports
+it it is always enabled.  Note that lengthy operations in the connect ACL,
+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"
 This option provides a list of servers to which, provided they announce
@@ -23882,9 +24453,7 @@ 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
@@ -23904,12 +24473,10 @@ Alternatively, if the value of &%size_addition%& is set negative, it disables
 the use of the SIZE option altogether.
 
 
-.new
 .option socks_proxy smtp string&!! unset
 .cindex proxy SOCKS
 This option enables use of SOCKS proxies for connections made by the
-transport.  For details see &<<SECTproxySOCKS>>&.
-.wen
+transport.  For details see section &<<SECTproxySOCKS>>&.
 
 
 .option tls_certificate smtp string&!! unset
@@ -24069,7 +24636,7 @@ and certificate verification fails the TLS connection is closed.
 .option tls_verify_hosts smtp "host list&!!" unset
 .cindex "TLS" "server certificate verification"
 .cindex "certificate" "verification of server"
-This option gives a list of hosts for which. on encrypted connections,
+This option gives a list of hosts for which, on encrypted connections,
 certificate verification must succeed.
 The &%tls_verify_certificates%& option must also be set.
 If both this option and &%tls_try_verify_hosts%& are unset
@@ -25614,6 +26181,17 @@ turned into a permanent error if you wish. In the second case, Exim tries to
 deliver the message unauthenticated.
 .endlist
 
+Note that the hostlist test for whether to do authentication can be
+confused if name-IP lookups change between the time the peer is decided
+on and the transport running.  For example, with a manualroute
+router given a host name, and DNS "round-robin" use by that name: if
+the local resolver cache times out between the router and the transport
+running, the transport may get an IP for the name for its authentication
+check which does not match the connection peer IP.
+No authentication will then be done, despite the names being identical.
+
+For such cases use a separate transport which always authenticates.
+
 .cindex "AUTH" "on MAIL command"
 When Exim has authenticated itself to a remote server, it adds the AUTH
 parameter to the MAIL commands it sends, if it has an authenticated sender for
@@ -26523,7 +27101,7 @@ tls:
 .endd
 This accepts a client certificate that is verifiable against any
 of your configured trust-anchors
-which usually means the full set of public CAs)
+(which usually means the full set of public CAs)
 and which has a SAN with a good account name.
 Note that the client cert is on the wire in-clear, including the SAN,
 whereas a plaintext SMTP AUTH done inside TLS is not.
@@ -26535,7 +27113,7 @@ whereas a plaintext SMTP AUTH done inside TLS is not.
 . to require one of a set of specific certs that define a given account
 . (the verification is still required, but mostly irrelevant).
 . This would help for per-device use.
-. 
+.
 . However, for the future we really need support for checking a
 . user cert in LDAP - which probably wants a base-64 DER.
 
@@ -26587,22 +27165,36 @@ in order to get TLS to work.
 
 
 
-.section "Support for the legacy &""ssmtp""& (aka &""smtps""&) protocol" &&&
+.section "Support for the &""submissions""& (aka &""ssmtp""& and &""smtps""&) protocol" &&&
          "SECID284"
+.cindex "submissions protocol"
 .cindex "ssmtp protocol"
 .cindex "smtps protocol"
+.cindex "SMTP" "submissions protocol"
 .cindex "SMTP" "ssmtp protocol"
 .cindex "SMTP" "smtps protocol"
-Early implementations of encrypted SMTP used a different TCP port from normal
-SMTP, and expected an encryption negotiation to start immediately, instead of
-waiting for a STARTTLS command from the client using the standard SMTP
-port. The protocol was called &"ssmtp"& or &"smtps"&, and port 465 was
-allocated for this purpose.
-
-This approach was abandoned when encrypted SMTP was standardized, but there are
-still some legacy clients that use it. Exim supports these clients by means of
-the &%tls_on_connect_ports%& global option. Its value must be a list of port
-numbers; the most common use is expected to be:
+The history of port numbers for TLS in SMTP is a little messy and has been
+contentious.  As of RFC 8314, the common practice of using the historically
+allocated port 465 for "email submission but with TLS immediately upon connect
+instead of using STARTTLS" is officially blessed by the IETF, and recommended
+in preference to STARTTLS.
+
+The name originally assigned to the port was &"ssmtp"& or &"smtps"&, but as
+clarity emerged over the dual roles of SMTP, for MX delivery and Email
+Submission, nomenclature has shifted.  The modern name is now &"submissions"&.
+
+This approach was, for a while, officially abandoned when encrypted SMTP was
+standardized, but many clients kept using it, even as the TCP port number was
+reassigned for other use.
+Thus you may encounter guidance claiming that you shouldn't enable use of
+this port.
+In practice, a number of mail-clients have only supported submissions, not
+submission with STARTTLS upgrade.
+Ideally, offer both submission (587) and submissions (465) service.
+
+Exim supports TLS-on-connect by means of the &%tls_on_connect_ports%&
+global option. Its value must be a list of port numbers;
+the most common use is expected to be:
 .code
 tls_on_connect_ports = 465
 .endd
@@ -26614,7 +27206,7 @@ an extra port &-- rather, it specifies different behaviour on a port that is
 defined elsewhere.
 
 There is also a &%-tls-on-connect%& command line option. This overrides
-&%tls_on_connect_ports%&; it forces the legacy behaviour for all ports.
+&%tls_on_connect_ports%&; it forces the TLS-only behaviour for all ports.
 
 
 
@@ -26669,6 +27261,9 @@ When using OpenSSL, this option is ignored.
 (If an API is found to let OpenSSL be configured in this way,
 let the Exim Maintainers know and we'll likely use it).
 .next
+With GnuTLS, if an explicit list is used for the &%tls_privatekey%& main option
+main option, it must be ordered to match the &%tls_certificate%& list.
+.next
 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
@@ -26824,6 +27419,10 @@ tls_require_ciphers = ${if =={$received_port}{25}\
                            {HIGH:!MD5:!SHA1}}
 .endd
 
+This example will prefer ECDSA-authenticated ciphers over RSA ones:
+.code
+tls_require_ciphers = ECDSA:RSA:!COMPLEMENTOFDEFAULT
+.endd
 
 
 .section "Requiring specific ciphers or other parameters in GnuTLS" &&&
@@ -26854,7 +27453,8 @@ Documentation of the strings accepted may be found in the GnuTLS manual, under
 &url(http://www.gnutls.org/manual/html_node/Priority-Strings.html),
 but beware that this relates to GnuTLS 3, which may be newer than the version
 installed on your system.  If you are using GnuTLS 3,
-&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string, then the example code)
+then the example code
+&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string)
 on that site can be used to test a given string.
 
 For example:
@@ -26884,10 +27484,12 @@ tls_require_ciphers = ${if =={$received_port}{25}\
 .cindex "TLS" "configuring an Exim server"
 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 unset, which means
-that STARTTLS is not advertised at all. This default is chosen because you
-need to set some other options in order to make TLS available, and also it is
-sensible for systems that want to use TLS only as a client.
+but not to any others. The default value of this option is *, which means
+that STARTTLS is always advertised.  Set it to blank to never advertise;
+this is reasonable for systems that want to use TLS only as a client.
+
+If STARTTLS is to be used you
+need to set some other options in order to make TLS available.
 
 If a client issues a STARTTLS command and there is some configuration
 problem in the server, the command is rejected with a 454 error. If the client
@@ -26899,13 +27501,17 @@ with the error
 If a STARTTLS command is issued within an existing TLS session, it is
 rejected with a 554 error code.
 
-To enable TLS operations on a server, you must set &%tls_advertise_hosts%& to
-match some hosts. You can, of course, set it to * to match all hosts.
-However, this is not all you need to do. TLS sessions to a server won't work
-without some further configuration at the server end.
+To enable TLS operations on a server, the &%tls_advertise_hosts%& option
+must be set to match some hosts. The default is * which matches all hosts.
 
-It is rumoured that all existing clients that support TLS/SSL use RSA
-encryption. To make this work you need to set, in the server,
+If this is all you do, TLS encryption will be enabled but not authentication -
+meaning that the peer has no assurance it is actually you he is talking to.
+You gain protection from a passive sniffer listening on the wire but not
+from someone able to intercept the communication.
+
+Further protection requires some further configuration at the server end.
+
+To make TLS work you need to set, in the server,
 .code
 tls_certificate = /some/file/name
 tls_privatekey = /some/file/name
@@ -26924,6 +27530,13 @@ is assumed to be the case. The certificate file may also contain intermediate
 certificates that need to be sent to the client to enable it to authenticate
 the server's certificate.
 
+For dual-stack (eg. RSA and ECDSA) configurations, these options can be
+colon-separated lists of file paths.  Ciphers using given authentication
+algorithms require the presence of a suitable certificate to supply the
+public-key.  The server selects among the certificates to present to the
+client depending on the selected cipher, hence the priority ordering for
+ciphers will affect which certificate is used.
+
 If you do not understand about certificates and keys, please try to find a
 source of this background information, which is not Exim-specific. (There are a
 few comments below in section &<<SECTcerandall>>&.)
@@ -27070,9 +27683,7 @@ 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,
-.new
 or with GnuTLS earlier than version 3.3.16 / 3.4.8
-.wen
 support for OCSP stapling is included.
 
 There is a global option called &%tls_ocsp_file%&.
@@ -27159,11 +27770,10 @@ if it requests it. If the server is Exim, it will request a certificate only if
 
 If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it
 specifies a collection of expected server certificates.
-These may be the system default set (depending on library version),
-a file or,
-depending on library version, a directory,
-must name a file or,
-for OpenSSL only (not GnuTLS), a directory.
+These may be
+the system default set (depending on library version),
+a file,
+or (depending on library version) a directory.
 The client verifies the server's certificate
 against this collection, taking into account any revoked certificates that are
 in the list defined by &%tls_crl%&.
@@ -27261,26 +27871,24 @@ option (prior to expansion) then the following options will be re-expanded
 during TLS session handshake, to permit alternative values to be chosen:
 
 .ilist
-.vindex "&%tls_certificate%&"
 &%tls_certificate%&
 .next
-.vindex "&%tls_crl%&"
 &%tls_crl%&
 .next
-.vindex "&%tls_privatekey%&"
 &%tls_privatekey%&
 .next
-.vindex "&%tls_verify_certificates%&"
 &%tls_verify_certificates%&
 .next
-.vindex "&%tls_ocsp_file%&"
 &%tls_ocsp_file%&
 .endlist
 
 Great care should be taken to deal with matters of case, various injection
 attacks in the string (&`../`& or SQL), and ensuring that a valid filename
-can always be referenced; it is important to remember that &$tls_sni$& is
+can always be referenced; it is important to remember that &$tls_in_sni$& is
 arbitrary unverified data provided prior to authentication.
+Further, the initial certificate is loaded before SNI is arrived, so
+an expansion for &%tls_certificate%& must have a default which is used
+when &$tls_in_sni$& is empty.
 
 The Exim developers are proceeding cautiously and so far no other TLS options
 are re-expanded.
@@ -27305,8 +27913,15 @@ an entirely new delivery process for each message, passing the socket from
 one process to the next. This implementation does not fit well with the use
 of TLS, because there is quite a lot of state information associated with a TLS
 connection, not just a socket identification. Passing all the state information
-to a new process is not feasible. Consequently, Exim shuts down an existing TLS
-session before passing the socket to a new process. The new process may then
+to a new process is not feasible. Consequently, for sending using TLS Exim
+starts an additional proxy process for handling the encryption, piping the
+unencrypted data stream from and to the delivery processes.
+
+An older mode of operation can be enabled on a per-host basis by the
+&%hosts_noproxy_tls%& option on the &(smtp)& transport.  If the host matches
+this list the proxy process described above is not used; instead Exim
+shuts down an existing TLS session being run by the delivery process
+before passing the socket to a new process. The new process may then
 try to start a new TLS session, and if successful, may try to re-authenticate
 if AUTH is in use, before sending the next message.
 
@@ -27427,6 +28042,124 @@ Open-source PKI book, available online at
 
 
 
+.new
+.section DANE "SECDANE"
+.cindex DANE
+DNS-based Authentication of Named Entities, as applied to SMTP over TLS, provides assurance to a client that
+it is actually talking to the server it wants to rather than some attacker operating a Man In The Middle (MITM)
+operation.  The latter can terminate the TLS connection you make, and make another one to the server (so both
+you and the server still think you have an encrypted connection) and, if one of the "well known" set of
+Certificate Authorities has been suborned - something which *has* been seen already (2014), a verifiable
+certificate (if you're using normal root CAs, eg. the Mozilla set, as your trust anchors).
+
+What DANE does is replace the CAs with the DNS as the trust anchor.  The assurance is limited to a) the possibility
+that the DNS has been suborned, b) mistakes made by the admins of the target server.   The attack surface presented
+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
+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
+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 traceable to the one
+defined by (one of?) the TSLA records
+
+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.
+
+The TLSA record for the server may have "certificate usage" of DANE-TA(2) or DANE-EE(3).  The latter specifies
+the End Entity directly, i.e. the certificate involved is that of the server (and should be the sole one transmitted
+during the TLS handshake); this is appropriate for a single system, using a self-signed certificate.
+DANE-TA usage is effectively declaring a specific CA to be used; this might be a private CA or a public,
+well-known one.  A private CA at simplest is just a self-signed certificate which is used to sign
+cerver certificates, but running one securely does require careful arrangement.  If a private CA is used
+then either all clients must be primed with it, or (probably simpler) the server TLS handshake must transmit
+the entire certificate chain from CA to server-certificate.  If a public CA is used then all clients must be primed with it
+(losing one advantage of DANE) - but the attack surface is reduced from all public CAs to that single CA.
+DANE-TA is commonly used for several services and/or servers, each having a TLSA query-domain CNAME record,
+all of which point to a single TLSA record.
+
+The TLSA record should have a Selector field of SPKI(1) and a Matching Type field of SHA2-512(2).
+
+At the time of writing, &url(https://www.huque.com/bin/gen_tlsa)
+is useful for quickly generating TLSA records; and commands like
+
+.code
+  openssl x509 -in -pubkey -noout <certificate.pem \
+  | openssl rsa -outform der -pubin 2>/dev/null \
+  | openssl sha512 \
+  | awk '{print $2}'
+.endd
+
+are workable for 4th-field hashes.
+
+For use with the DANE-TA model, server certificates must have a correct name (SubjectName or SubjectAltName).
+
+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:
+
+.code
+  hosts_request_ocsp = ${if or { {= {0}{$tls_out_tlsa_usage}} \
+				 {= {4}{$tls_out_tlsa_usage}} } \
+                         {*}{}}
+.endd
+
+The (new) variable &$tls_out_tlsa_usage$& is a bitfield with numbered bits set for TLSA record usage codes.
+The zero above means DANE was not in use, the four means that only DANE-TA usage TLSA records were
+found. If the definition of &%hosts_request_ocsp%& includes the
+string "tls_out_tlsa_usage", they are re-expanded in time to
+control the OCSP request.
+
+This modification of hosts_request_ocsp is only done if it has the default value of "*".  Admins who change it, and
+those who use &%hosts_require_ocsp%&, should consider the interaction with DANE in their OCSP settings.
+
+
+For client-side DANE there are two new smtp transport options, &%hosts_try_dane%& and &%hosts_require_dane%&.
+The latter variant will result in failure if the target host is not DNSSEC-secured.
+
+DANE will only be usable if the target host has DNSSEC-secured MX, A and TLSA records.
+
+A TLSA lookup will be done if either of the above options match and the host-lookup succeeded using dnssec.
+If a TLSA lookup is done and succeeds, a DANE-verified TLS connection
+will be required for the host.  If it does not, the host will not
+be used; there is no fallback to non-DANE or non-TLS.
+
+If DANE is requested and useable (see above) the following transport options are ignored:
+.code
+  hosts_require_tls
+  tls_verify_hosts
+  tls_try_verify_hosts
+  tls_verify_certificates
+  tls_crl
+  tls_verify_cert_hostnames
+.endd
+
+If DANE is not usable, whether requested or not, and CA-anchored
+verification evaluation is wanted, the above variables should be set appropriately.
+
+Currently the &%dnssec_request_domains%& must be active and &%dnssec_require_domains%& is ignored.
+
+If verification was successful using DANE then the "CV" item in the delivery log line will show as "CV=dane".
+
+There is a new variable &$tls_out_dane$& which will have "yes" if
+verification succeeded using DANE and "no" otherwise (only useful
+in combination with EXPERIMENTAL_EVENT), and a new variable &$tls_out_tlsa_usage$& (detailed above).
+
+Under GnuTLS, DANE is only supported from version 3.0.0 onwards.
+.wen
+
+
+
 . ////////////////////////////////////////////////////////////////////////////
 . ////////////////////////////////////////////////////////////////////////////
 
@@ -27460,9 +28193,6 @@ a realistic ACL for checking RCPT commands. This is discussed in chapter
 .section "Testing ACLs" "SECID188"
 The &%-bh%& command line option provides a way of testing your ACL
 configuration locally by running a fake SMTP session with which you interact.
-The host &'relay-test.mail-abuse.org'& provides a service for checking your
-relaying configuration (see section &<<SECTcheralcon>>& for more details).
-
 
 
 .section "Specifying when ACLs are used" "SECID189"
@@ -27577,11 +28307,9 @@ Note that a client may issue more than one EHLO or HELO command in an SMTP
 session, and indeed is required to issue a new EHLO or HELO after successfully
 setting up encryption following a STARTTLS command.
 
-.new
 Note also that a deny neither forces the client to go away nor means that
 mail will be refused on the connection.  Consider checking for
 &$sender_helo_name$& being defined in a MAIL or RCPT ACL to do that.
-.wen
 
 If the command is accepted by an &%accept%& verb that has a &%message%&
 modifier, the message may not contain more than one line (it will be truncated
@@ -27608,6 +28336,15 @@ received, before the final response to the DATA command is sent. This is
 the ACL specified by &%acl_smtp_data%&, which is the second ACL that is
 associated with the DATA command.
 
+.cindex CHUNKING "BDAT command"
+.cindex BDAT "SMTP command"
+.cindex "RFC 3030" CHUNKING
+If CHUNKING was advertised and a BDAT command sequence is received,
+the &%acl_smtp_predata%& ACL is not run.
+. XXX why not?  It should be possible, for the first BDAT.
+The &%acl_smtp_data%& is run after the last BDAT command and all of
+the data specified is received.
+
 For both of these ACLs, it is not possible to reject individual recipients. An
 error response rejects the entire message. Unfortunately, it is known that some
 MTAs do not treat hard (5&'xx'&) responses to the DATA command (either
@@ -27630,7 +28367,7 @@ otherwise specified, the default action is to accept.
 
 This ACL is evaluated before &%acl_smtp_mime%& and &%acl_smtp_data%&.
 
-For details on the operation of DKIM, see chapter &<<CHAPdkim>>&.
+For details on the operation of DKIM, see section &<<SECDKIM>>&.
 
 
 .section "The SMTP MIME ACL" "SECID194"
@@ -27660,11 +28397,9 @@ for some or all recipients.
 PRDR may be used to support per-user content filtering.  Without it
 one must defer any recipient after the first that has a different
 content-filter configuration.  With PRDR, the RCPT-time check
-.new
 .cindex "PRDR" "variable for"
 for this can be disabled when the variable &$prdr_requested$&
 is &"yes"&.
-.wen
 Any required difference in behaviour of the main DATA-time
 ACL should however depend on the PRDR-time ACL having run, as Exim
 will avoid doing so in some situations (e.g.  single-recipient mails).
@@ -27749,8 +28484,8 @@ acl_smtp_rcpt = ${if ={25}{$interface_port} \
                      {acl_check_rcpt} {acl_check_rcpt_submit} }
 .endd
 In the default configuration file there are some example settings for
-providing an RFC 4409 message submission service on port 587 and a
-non-standard &"smtps"& service on port 465. You can use a string
+providing an RFC 4409 message &"submission"& service on port 587 and
+an RFC 8314 &"submissions"& service on port 465. You can use a string
 expansion like this to choose an ACL for MUAs on these ports which is
 more appropriate for this purpose than the default ACL on port 25.
 
@@ -27820,6 +28555,9 @@ run. A &"discard"& return from the DATA or the non-SMTP ACL discards all the
 remaining recipients. The &"discard"& return is not permitted for the
 &%acl_smtp_predata%& ACL.
 
+If the ACL for VRFY returns &"accept"&, a recipient verify (without callout)
+is done on the address and the result determines the SMTP response.
+
 
 .cindex "&[local_scan()]& function" "when all recipients discarded"
 The &[local_scan()]& function is always run, even if there are no remaining
@@ -27931,7 +28669,7 @@ provides a means of specifying an &"and"& conjunction between conditions. For
 example:
 .code
 deny  dnslists = list1.example
-dnslists = list2.example
+      dnslists = list2.example
 .endd
 If there are no conditions, the verb is always obeyed. Exim stops evaluating
 the conditions and modifiers when it reaches a condition that fails. What
@@ -27953,8 +28691,8 @@ after &%endpass%&, the ACL returns &"deny"&. Consider this statement, used to
 check a RCPT command:
 .code
 accept domains = +local_domains
-endpass
-verify = recipient
+       endpass
+       verify = recipient
 .endd
 If the recipient domain does not match the &%domains%& condition, control
 passes to the next statement. If it does match, the recipient is verified, and
@@ -28506,6 +29244,19 @@ all the conditions are true, wherever it appears in an ACL command, whereas
 effect.
 
 
+.vitem &*queue*&&~=&~<&'text'&>
+.cindex "&%queue%& ACL modifier"
+.cindex "named queues" "selecting in ACL"
+This modifier specifies the use of a named queue for spool files
+for the message.
+It can only be used before the message is received (i.e. not in
+the DATA ACL).
+This could be used, for example, for known high-volume burst sources
+of traffic, or for quarantine of messages.
+Separate queue-runner processes will be needed for named queues.
+If the text after expansion is empty, the default queue is used.
+
+
 .vitem &*remove_header*&&~=&~<&'text'&>
 This modifier specifies one or more header names in a colon-separated list
  that are to be removed from an incoming message, assuming, of course, that
@@ -28519,6 +29270,7 @@ This modifier puts a value into one of the ACL variables (see section
 
 
 .vitem &*udpsend*&&~=&~<&'parameters'&>
+.cindex "UDP communications"
 This modifier sends a UDP packet, for purposes such as statistics
 collection or behaviour monitoring. The parameters are expanded, and
 the result of the expansion must be a colon-separated list consisting
@@ -28592,7 +29344,7 @@ Notice that we put back the lower cased version afterwards, assuming that
 is what is wanted for subsequent tests.
 
 
-.vitem &*control&~=&~cutthrough_delivery*&
+.vitem &*control&~=&~cutthrough_delivery/*&<&'options'&>
 .cindex "&ACL;" "cutthrough routing"
 .cindex "cutthrough" "requesting"
 This option requests delivery be attempted while the item is being received.
@@ -28606,7 +29358,9 @@ and data is copied from one to the other.
 
 An attempt to set this option for any recipient but the first
 for a mail will be quietly ignored.
-If a recipient-verify callout connection is subsequently
+If a recipient-verify callout
+(with use_sender)
+connection is subsequently
 requested in the same ACL it is held open and used for
 any subsequent recipients and the data,
 otherwise one is made after the initial RCPT ACL completes.
@@ -28616,19 +29370,37 @@ and cannot depend on content of received headers.
 Note also that headers cannot be
 modified by any of the post-data ACLs (DATA, MIME and DKIM).
 Headers may be modified by routers (subject to the above) and transports.
+The Received-By: header is generated as soon as the body reception starts,
+rather than the traditional time after the full message is received;
+this will affect the timestamp.
+
+All the usual ACLs are called; if one results in the message being
+rejected, all effort spent in delivery (including the costs on
+the ultimate destination) will be wasted.
+Note that in the case of data-time ACLs this includes the entire
+message body.
 
 Cutthrough delivery is not supported via transport-filters or when DKIM signing
 of outgoing messages is done, because it sends data to the ultimate destination
 before the entire message has been received from the source.
-It is not supported for messages received with the SMTP PRDR option in use.
+It is not supported for messages received with the SMTP PRDR
+or CHUNKING
+options in use.
 
 Should the ultimate destination system positively accept or reject the mail,
 a corresponding indication is given to the source system and nothing is queued.
-If there is a temporary error the item is queued for later delivery in the
-usual fashion. If the item is successfully delivered in cutthrough mode
+If the item is successfully delivered in cutthrough mode
 the delivery log lines are tagged with ">>" rather than "=>" and appear
 before the acceptance "<=" line.
 
+If there is a temporary error the item is queued for later delivery in the
+usual fashion.
+This behaviour can be adjusted by appending the option &*defer=*&<&'value'&>
+to the control; the default value is &"spool"& and the alternate value
+&"pass"& copies an SMTP defer response from the target back to the initiator
+and does not queue the message.
+Note that this is independent of any recipient verify conditions in the ACL.
+
 Delivery in this mode avoids the generation of a bounce mail to a
 (possibly faked)
 sender when the destination system is doing content-scan based rejection.
@@ -28638,17 +29410,22 @@ sender when the destination system is doing content-scan based rejection.
 .cindex "&ACL;" "enabling debug logging"
 .cindex "debugging" "enabling from an ACL"
 This control turns on debug logging, almost as though Exim had been invoked
-with &`-d`&, with the output going to a new logfile, by default called
-&'debuglog'&.  The filename can be adjusted with the &'tag'& option, which
+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.  Some examples (which depend on variables that don't exist in all
+option.
+Logging started this way may be stopped, and the file removed,
+with the &'kill'& option.
+Some examples (which depend on variables that don't exist in all
 contexts):
 .code
       control = debug
       control = debug/tag=.$sender_host_address
       control = debug/opts=+expand+acl
       control = debug/tag=.$message_exim_id/opts=+expand
+      control = debug/kill
 .endd
 
 
@@ -28656,7 +29433,7 @@ contexts):
 .cindex "disable DKIM verify"
 .cindex "DKIM" "disable verify"
 This control turns off DKIM verification processing entirely.  For details on
-the operation and configuration of DKIM, see chapter &<<CHAPdkim>>&.
+the operation and configuration of DKIM, see section &<<SECDKIM>>&.
 
 
 .vitem &*control&~=&~dscp/*&<&'value'&>
@@ -28845,12 +29622,10 @@ data is read.
 &*Note:*& This control applies only to the current message, not to any others
 that are being submitted at the same time using &%-bs%& or &%-bS%&.
 
-.new
 .vitem &*control&~=&~utf8_downconvert*&
 This control enables conversion of UTF-8 in message addresses
 to a-label form.
-For details see &<<SECTi18nMTA>>&.
-.wen
+For details see section &<<SECTi18nMTA>>&.
 .endlist vlist
 
 
@@ -28889,7 +29664,7 @@ any ACL verb, including &%deny%& (though this is potentially useful only in a
 RCPT ACL).
 
 Headers will not be added to the message if the modifier is used in
-DATA, MIME or DKIM ACLs for messages delivered by cutthrough routing.
+DATA, MIME or DKIM ACLs for a message delivered by cutthrough routing.
 
 Leading and trailing newlines are removed from
 the data for the &%add_header%& modifier; if it then
@@ -28990,8 +29765,8 @@ receiving a message). The message must ultimately be accepted for
 with any ACL verb, including &%deny%&, though this is really not useful for
 any verb that doesn't result in a delivered message.
 
-Headers will not be removed to the message if the modifier is used in
-DATA, MIME or DKIM ACLs for messages delivered by cutthrough routing.
+Headers will not be removed from the message if the modifier is used in
+DATA, MIME or DKIM ACLs for a message delivered by cutthrough routing.
 
 More than one header can be removed at the same time by using a colon separated
 list of header names. The header matching is case insensitive. Wildcards are
@@ -29129,12 +29904,6 @@ If all goes well, the condition is true. It is false only if there are
 problems such as a syntax error or a memory shortage. For more details, see
 chapter &<<CHAPexiscan>>&.
 
-.vitem &*demime&~=&~*&<&'extension&~list'&>
-.cindex "&%demime%& ACL condition"
-This condition is available only when Exim is compiled with the
-content-scanning extension. Its use is described in section
-&<<SECTdemimecond>>&.
-
 .vitem &*dnslists&~=&~*&<&'list&~of&~domain&~names&~and&~other&~data'&>
 .cindex "&%dnslists%& ACL condition"
 .cindex "DNS list" "in ACL"
@@ -29469,6 +30238,13 @@ to avoid doing it more than once per message.
 .cindex "&%verify%& ACL condition"
 This is a variation of the previous option, in which a modified address is
 verified as a sender.
+
+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:}}{/}{//}}
+.endd
 .endlist
 
 
@@ -29528,12 +30304,10 @@ deny  dnslists = blackholes.mail-abuse.org
 warn  message  = X-Warn: sending host is on dialups list
       dnslists = dialups.mail-abuse.org
 .endd
-.cindex cacheing "of dns lookup"
+.cindex caching "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 (assuming long-enough TTL).
 Exim does not share information between multiple incoming
@@ -29643,7 +30417,7 @@ multiple DNS records. The inner dnsdb lookup produces a list of MX hosts
 and the outer dnsdb lookup finds the IP addresses for these hosts. The result
 of expanding the condition might be something like this:
 .code
-dnslists = sbl.spahmaus.org/<|192.168.2.3|192.168.5.6|...
+dnslists = sbl.spamhaus.org/<|192.168.2.3|192.168.5.6|...
 .endd
 Thus, this example checks whether or not the IP addresses of the sender
 domain's mail servers are on the Spamhaus black list.
@@ -30533,6 +31307,21 @@ command when performing the callout, instead of an empty address. There is no
 need to use this option unless you know that the called hosts make use of the
 sender when checking recipients. If used indiscriminately, it reduces the
 usefulness of callout caching.
+
+.vitem &*hold*&
+This option applies to recipient callouts only. For example:
+.code
+require  verify = recipient/callout=use_sender,hold
+.endd
+It causes the connection to be held open and used for any further recipients
+and for eventual delivery (should that be done quickly).
+Doing this saves on TCP and SMTP startup costs, and TLS costs also
+when that is used for the connections.
+The advantage is only gained if there are no callout cache hits
+(which could be enforced by the no_cache option),
+if the use_sender option is used,
+if neither the random nor the use_postmaster option is used,
+and if no other callouts intervene.
 .endlist
 
 If you use any of the parameters that set a non-empty sender for the MAIL
@@ -30766,6 +31555,7 @@ address and some time-based randomizing information. The &%prvs%& expansion
 item creates a signed address, and the &%prvscheck%& expansion item checks one.
 The syntax of these expansion items is described in section
 &<<SECTexpansionitems>>&.
+The validity period on signed addresses is seven days.
 
 As an example, suppose the secret per-address keys are stored in an MySQL
 database. A query to look up the key for an address could be defined as a macro
@@ -30905,14 +31695,6 @@ in chapter &<<CHAPdefconfil>>&.
 You can check the relay characteristics of your configuration in the same way
 that you can test any ACL behaviour for an incoming SMTP connection, by using
 the &%-bh%& option to run a fake SMTP session with which you interact.
-
-For specifically testing for unwanted relaying, the host
-&'relay-test.mail-abuse.org'& provides a useful service. If you telnet to this
-host from the host on which Exim is running, using the normal telnet port, you
-will see a normal telnet connection message and then quite a long delay. Be
-patient. The remote host is making an SMTP connection back to your host, and
-trying a number of common probes to test for open relay vulnerability. The
-results of the tests will eventually appear on your terminal.
 .ecindex IIDacl
 
 
@@ -30955,10 +31737,6 @@ conditions.
 Two new main configuration options: &%av_scanner%& and &%spamd_address%&.
 .endlist
 
-There is another content-scanning configuration option for &_Local/Makefile_&,
-called WITH_OLD_DEMIME. If this is set, the old, deprecated &%demime%& ACL
-condition is compiled, in addition to all the other content-scanning features.
-
 Content-scanning is continually evolving, and new features are still being
 added. While such features are still unstable and liable to incompatible
 changes, they are made available in Exim by setting options whose names begin
@@ -31010,7 +31788,10 @@ av_scanner = sophie:/var/run/sophie
 If the value of &%av_scanner%& starts with a dollar character, it is expanded
 before use.
 The usual list-parsing of the content (see &<<SECTlistconstruct>>&) applies.
-The following scanner types are supported in this release:
+The following scanner types are supported in this release,
+.new
+though individual ones can be included or not at build time:
+.wen
 
 .vlist
 .vitem &%avast%&
@@ -31098,8 +31879,6 @@ 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.
-There is an option WITH_OLD_CLAMAV_STREAM in &_src/EDITME_& available, should
-you be running a version of ClamAV prior to 0.95.
 
 The final example shows that multiple TCP targets can be specified.  Exim will
 randomly use one for each incoming email (i.e. it load balances them).  Note
@@ -31181,6 +31960,16 @@ av_scanner = f-protd:localhost 10200-10204
 .endd
 If you omit the argument, the default values show above are used.
 
+.vitem &%f-prot6d%&
+.cindex "virus scanners" "f-prot6d"
+The f-prot6d scanner is accessed using the FPSCAND protocol over TCP.
+One argument is taken, being a space-separated hostname and port number.
+For example:
+.code
+av_scanner = f-prot6d:localhost 10200
+.endd
+If you omit the argument, the default values show above are used.
+
 .vitem &%fsecure%&
 .cindex "virus scanners" "F-Secure"
 The F-Secure daemon scanner (&url(http://www.f-secure.com)) takes one
@@ -31208,7 +31997,7 @@ This is a daemon type scanner that is aimed mainly at Polish users, though some
 parts of documentation are now available in English. You can get it at
 &url(http://linux.mks.com.pl/). The only option for this scanner type is
 the maximum number of processes used simultaneously to scan the attachments,
-provided that the demime facility is employed and also provided that mksd has
+provided that mksd has
 been run with at least the same number of child processes. For example:
 .code
 av_scanner = mksd:2
@@ -31224,14 +32013,16 @@ an address (which may be an IP address and port, or the path of a Unix socket),
 a commandline to send (may include a single %s which will be replaced with
 the path to the mail file to be scanned),
 an RE to trigger on from the returned data,
-an RE to extract malware_name from the returned data.
+and an RE to extract malware_name from the returned data.
 For example:
 .code
-av_scanner = sock:127.0.0.1 6001:%s:(SPAM|VIRUS):(.*)\$
+av_scanner = sock:127.0.0.1 6001:%s:(SPAM|VIRUS):(.*)$
 .endd
-Default for the socket specifier is &_/tmp/malware.sock_&.
-Default for the commandline is &_%s\n_&.
-Both regular-expressions are required.
+Note that surrounding whitespace is stripped from each option, meaning
+there is no way to specify a trailing newline.
+The socket specifier and both regular-expressions are required.
+Default for the commandline is &_%s\n_& (note this does have a trailing newline);
+specify an empty element to get this.
 
 .vitem &%sophie%&
 .cindex "virus scanners" "Sophos and Sophie"
@@ -31299,23 +32090,17 @@ When a virus is found, the condition sets up an expansion variable called
 &%message%& modifier that specifies the error returned to the sender, and/or in
 logging data.
 
-If your virus scanner cannot unpack MIME and TNEF containers itself, you should
-use the &%demime%& condition (see section &<<SECTdemimecond>>&) before the
-&%malware%& condition.
-
 Beware the interaction of Exim's &%message_size_limit%& with any size limits
 imposed by your anti-virus scanner.
 
 Here is a very simple scanning example:
 .code
 deny message = This message contains malware ($malware_name)
-     demime = *
      malware = *
 .endd
 The next example accepts messages when there is a problem with the scanner:
 .code
 deny message = This message contains malware ($malware_name)
-     demime = *
      malware = */defer_ok
 .endd
 The next example shows how to use an ACL variable to scan with both sophie and
@@ -31365,6 +32150,15 @@ configuration as follows (example):
 .code
 spamd_address = 192.168.99.45 387
 .endd
+The SpamAssassin protocol relies on a TCP half-close from the client.
+If your SpamAssassin client side is running a Linux system with an
+iptables firewall, consider setting
+&%net.netfilter.nf_conntrack_tcp_timeout_close_wait%& to at least the
+timeout, Exim uses when waiting for a response from the SpamAssassin
+server (currently defaulting to 120s).  With a lower value the Linux
+connection tracking may consider your half-closed connection as dead too
+soon.
+
 
 To use Rspamd (which by default listens on all local addresses
 on TCP port 11333)
@@ -31395,7 +32189,7 @@ 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.
+and changeable in the usual way; take care to not double the separator.
 
 For TCP socket specifications a host name or IP (v4 or v6, but
 subject to list-separator quoting rules) address can be used,
@@ -31522,6 +32316,9 @@ spam bar is 50 characters.
 A multiline text table, containing the full SpamAssassin report for the
 message. Useful for inclusion in headers or reject messages.
 This variable is only usable in a DATA-time ACL.
+Beware that SpamAssassin may return non-ASCII characters, especially
+when running in country-specific locales, which are not legal
+unencoded in headers.
 
 .vitem &$spam_action$&
 For SpamAssassin either 'reject' or 'no action' depending on the
@@ -31745,7 +32542,7 @@ All parts contained within an attachment multipart are attachments.
 
 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-HMTL coverletter mail will also be allowed:
+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
@@ -31811,90 +32608,6 @@ are set to any substrings captured by the regular expression.
 &*Warning*&: With large messages, these conditions can be fairly
 CPU-intensive.
 
-
-
-
-.section "The demime condition" "SECTdemimecond"
-.cindex "content scanning" "MIME checking"
-.cindex "MIME content scanning"
-The &%demime%& ACL condition provides MIME unpacking, sanity checking and file
-extension blocking. It is usable only in the DATA and non-SMTP ACLs. The
-&%demime%& condition uses a simpler interface to MIME decoding than the MIME
-ACL functionality, but provides no additional facilities. Please note that this
-condition is deprecated and kept only for backward compatibility. You must set
-the WITH_OLD_DEMIME option in &_Local/Makefile_& at build time to be able to
-use the &%demime%& condition.
-
-The &%demime%& condition unpacks MIME containers in the message. It detects
-errors in MIME containers and can match file extensions found in the message
-against a list. Using this facility produces files containing the unpacked MIME
-parts of the message in the temporary scan directory. If you do antivirus
-scanning, it is recommended that you use the &%demime%& condition before the
-antivirus (&%malware%&) condition.
-
-On the right-hand side of the &%demime%& condition you can pass a
-colon-separated list of file extensions that it should match against. For
-example:
-.code
-deny message = Found blacklisted file attachment
-     demime  = vbs:com:bat:pif:prf:lnk
-.endd
-If one of the file extensions is found, the condition is true, otherwise it is
-false. If there is a temporary error while demimeing (for example, &"disk
-full"&), the condition defers, and the message is temporarily rejected (unless
-the condition is on a &%warn%& verb).
-
-The right-hand side is expanded before being treated as a list, so you can have
-conditions and lookups there. If it expands to an empty string, &"false"&, or
-zero (&"0"&), no demimeing is done and the condition is false.
-
-The &%demime%& condition set the following variables:
-
-.vlist
-.vitem &$demime_errorlevel$&
-.vindex "&$demime_errorlevel$&"
-When an error is detected in a MIME container, this variable contains the
-severity of the error, as an integer number. The higher the value, the more
-severe the error (the current maximum value is 3). If this variable is unset or
-zero, no error occurred.
-
-.vitem &$demime_reason$&
-.vindex "&$demime_reason$&"
-When &$demime_errorlevel$& is greater than zero, this variable contains a
-human-readable text string describing the MIME error that occurred.
-.endlist
-
-.vlist
-.vitem &$found_extension$&
-.vindex "&$found_extension$&"
-When the &%demime%& condition is true, this variable contains the file
-extension it found.
-.endlist
-
-Both &$demime_errorlevel$& and &$demime_reason$& are set by the first call of
-the &%demime%& condition, and are not changed on subsequent calls.
-
-If you do not want to check for file extensions, but rather use the &%demime%&
-condition for unpacking or error checking purposes, pass &"*"& as the
-right-hand side value. Here is a more elaborate example of how to use this
-facility:
-.code
-# Reject messages with serious MIME container errors
-deny  message = Found MIME error ($demime_reason).
-      demime = *
-      condition = ${if >{$demime_errorlevel}{2}{1}{0}}
-
-# Reject known virus spreading file extensions.
-# Accepting these is pretty much braindead.
-deny  message = contains $found_extension file (blacklisted).
-      demime  = com:vbs:bat:pif:scr
-
-# Freeze .exe and .doc files. Postmaster can
-# examine them and eventually thaw them.
-deny  log_message = Another $found_extension file.
-      demime = exe:doc
-      control = freeze
-.endd
 .ecindex IIDcosca
 
 
@@ -32149,9 +32862,11 @@ 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.
 
 .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.
 
 .vitem &*unsigned&~int&~debug_selector*&
 This variable is set to zero when no debugging is taking place. Otherwise, it
@@ -33191,6 +33906,7 @@ 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-"
 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:'&,
@@ -33247,6 +33963,7 @@ existing &'Bcc:'& is not removed.
 
 .section "The Date: header line" "SECID223"
 .cindex "&'Date:'& header line"
+.cindex "header lines" "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.
@@ -33264,6 +33981,7 @@ messages.
 
 .section "The Envelope-to: header line" "SECID225"
 .cindex "&'Envelope-to:'& header line"
+.cindex "header lines" "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
@@ -33275,6 +33993,7 @@ messages.
 
 .section "The From: header line" "SECTthefrohea"
 .cindex "&'From:'& header line"
+.cindex "header lines" "From:"
 .cindex "Sendmail compatibility" "&""From""& line"
 .cindex "message" "submission"
 .cindex "submission mode"
@@ -33318,6 +34037,7 @@ name as described in section &<<SECTconstr>>&.
 
 .section "The Message-ID: header line" "SECID226"
 .cindex "&'Message-ID:'& header line"
+.cindex "header lines" "Message-ID:"
 .cindex "message" "submission"
 .oindex "&%message_id_header_text%&"
 If a locally-generated or submission-mode incoming message does not contain a
@@ -33333,6 +34053,7 @@ 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:"
 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.
@@ -33349,6 +34070,7 @@ 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:"
 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
@@ -33363,6 +34085,7 @@ 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:"
 .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%&
@@ -33375,6 +34098,7 @@ 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:"
 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
@@ -34076,13 +34800,11 @@ 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.
 
-.new
 .cindex "VRFY" "processing"
 When no ACL is defined for VRFY, or if it rejects without
 setting an explicit response code, the command is accepted
 (with a 252 SMTP response code)
 in order to support awkward clients that do a VRFY before every RCPT.
-.wen
 When VRFY is accepted, it runs exactly the same code as when Exim is
 called with the &%-bv%& option, and returns 250/451/550
 SMTP response codes.
@@ -35345,6 +36067,7 @@ 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
@@ -35467,6 +36190,10 @@ 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.
+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.
+TLS cipher information is still available.
 
 .cindex "delivery" "cutthrough; logging"
 .cindex "cutthrough" "logging"
@@ -35571,23 +36298,31 @@ the following table:
 &`    `&        command list for &"no mail in SMTP session"&
 &`CV  `&        certificate verification status
 &`D   `&        duration of &"no mail in SMTP session"&
+&`DKIM`&        domain verified in incoming message
 &`DN  `&        distinguished name from peer certificate
+&`DS  `&        DNSSEC secured lookups
 &`DT  `&        on &`=>`& lines: time taken for a delivery
 &`F   `&        sender address (on delivery lines)
 &`H   `&        host name and IP address
 &`I   `&        local interface used
+&`K   `&        CHUNKING extension used
 &`id  `&        message id for incoming message
+&`M8S `&        8BITMIME status for incoming message
 &`P   `&        on &`<=`& lines: protocol used
 &`    `&        on &`=>`& and &`**`& lines: return path
-&`PRX `&        on &'<='& and&`=>`& lines: proxy address
+&`PRDR`&        PRDR extension used
+&`PRX `&        on &`<=`& and &`=>`& lines: proxy address
+&`Q   `&        alternate queue name
 &`QT  `&        on &`=>`& lines: time spent on queue so far
 &`    `&        on &"Completed"& lines: time spent on queue
 &`R   `&        on &`<=`& lines: reference for local bounce
-&`    `&        on &`=>`&  &`**`& and &`==`& lines: router name
-&`S   `&        size of message
+&`    `&        on &`=>`&  &`>>`& &`**`& and &`==`& lines: router name
+&`RT  `&        on &`<=`& lines: time taken for reception
+&`S   `&        size of message in bytes
 &`SNI `&        server name indication from TLS client hello
 &`ST  `&        shadow transport name
 &`T   `&        on &`<=`& lines: message subject (topic)
+&`TFO `&        connection took advantage of TCP Fast Open
 &`    `&        on &`=>`& &`**`& and &`==`& lines: transport name
 &`U   `&        local user or RFC 1413 identity
 &`X   `&        TLS cipher suite
@@ -35634,6 +36369,12 @@ A delivery set up by a router configured with
 .endd
 failed. The delivery was discarded.
 .endlist olist
+.next
+.new
+.cindex DKIM "log line"
+&'DKIM: d='&&~&~Verbose results of a DKIM verification attempt, if enabled for
+logging and the message has a DKIM signature header.
+.wen
 .endlist ilist
 
 
@@ -35661,24 +36402,24 @@ selection marked by asterisks:
 &`*delay_delivery             `&  immediate delivery delayed
 &` deliver_time               `&  time taken to perform 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)
-.new
+&` millisec                   `&  millisecond timestamps and RT,QT,DT,D times
 &` outgoing_interface         `&  local interface on => lines
-.wen
 &` 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
-.new
 &` proxy                      `&  proxy address on <= and => lines
-.wen
 &` received_recipients        `&  recipients on <= lines
 &` received_sender            `&  sender on <= lines
 &`*rejected_header            `&  header contents on reject log
@@ -35761,18 +36502,39 @@ process is started because &%queue_only%& is set or &%-odq%& was used.
 .cindex "log" "delivery duration"
 &%deliver_time%&: For each delivery, the amount of real time it has taken to
 perform the actual delivery is logged as DT=<&'time'&>, for example, &`DT=1s`&.
+If millisecond logging is enabled, short times will be shown with greater
+precision, eg. &`DT=0.304s`&.
 .next
 .cindex "log" "message size on delivery"
 .cindex "size" "of message"
 &%delivery_size%&: For each delivery, the size of message delivered is added to
 the &"=>"& line, tagged with S=.
 .next
+.new
+.cindex log "DKIM verification"
+.cindex DKIM "verification logging"
+&%dkim%&: For message acceptance log lines, when an DKIM signature in the header
+verifies successfully a tag of DKIM is added, with one of the verified domains.
+.next
+.cindex log "DKIM verification"
+.cindex DKIM "verification logging"
+&%dkim_verbose%&: A log entry is written for each attempted DKIM verification.
+.wen
+.next
 .cindex "log" "dnslist defer"
 .cindex "DNS list" "logging defer"
 .cindex "black list (DNS)"
 &%dnslist_defer%&: A log entry is written if an attempt to look up a host in a
 DNS black list suffers a temporary error.
 .next
+.cindex log dnssec
+.cindex dnssec logging
+&%dnssec%&: For message acceptance and (attempted) delivery log lines, when
+dns lookups gave secure results a tag of DS is added.
+For acceptance this covers the reverse and forward lookups for host name verification.
+It does not cover helo-name verification.
+For delivery this covers the SRV, MX, A and/or AAAA lookups.
+.next
 .cindex "log" "ETRN commands"
 .cindex "ETRN" "logging"
 &%etrn%&: Every valid ETRN command that is received is logged, before the ACL
@@ -35801,20 +36563,16 @@ 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.
-.new
 The latter can be disabled by turning off the &%outgoing_interface%& option.
-.wen
 .next
-.new
 .cindex log "incoming proxy address"
 .cindex proxy "logging proxy address"
 .cindex "TCP/IP" "logging proxy address"
 &%proxy%&: The internal (closest to the system running Exim) IP address
 of the proxy, tagged by PRX=, on the &"<="& line for a message accepted
 on a proxied connection
-or the &"=>"& line for a message delivered on a proxied connection..
+or the &"=>"& line for a message delivered on a proxied connection.
 See &<<SECTproxyInbound>>& for more information.
-.wen
 .next
 .cindex "log" "incoming remote port"
 .cindex "port" "logging remote"
@@ -35832,27 +36590,29 @@ important with the widening use of NAT (see RFC 2505).
 &%lost_incoming_connection%&: A log line is written when an incoming SMTP
 connection is unexpectedly dropped.
 .next
+.cindex "log" "millisecond timestamps"
+.cindex millisecond logging
+.cindex timestamps "millisecond, in logs"
+&%millisec%&: Timestamps have a period and three decimal places of finer granularity
+appended to the seconds value.
+.next
 .cindex "log" "outgoing interface"
 .cindex "log" "local interface"
 .cindex "log" "local address and port"
 .cindex "TCP/IP" "logging local address and port"
 .cindex "interface" "logging"
-.new
 &%outgoing_interface%&: If &%incoming_interface%& is turned on, then the
 interface on which a message was sent is added to delivery lines as an I= tag
 followed by IP address in square brackets. You can disable this by turning
 off the &%outgoing_interface%& option.
-.wen
 .next
 .cindex "log" "outgoing remote port"
-.cindex "port" "logging outgoint remote"
-.cindex "TCP/IP" "logging ougtoing remote port"
+.cindex "port" "logging outgoing remote"
+.cindex "TCP/IP" "logging outgoing remote port"
 &%outgoing_port%&: The remote port number is added to delivery log lines (those
 containing => tags) following the IP address.
-.new
 The local port is also added if &%incoming_interface%& and
 &%outgoing_interface%& are both enabled.
-.wen
 This option is not included in the default setting, because for most ordinary
 configurations, the remote port number is always 25 (the SMTP port), and the
 local port is a random ephemeral port.
@@ -35874,11 +36634,21 @@ 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.
+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.
+.new
+.next
+.cindex "log" "receive duration"
+&%receive_time%&: For each message, the amount of real time it has taken to
+perform the reception is logged as RT=<&'time'&>, for example, &`RT=1s`&.
+If millisecond logging is enabled, short times will be shown with greater
+precision, eg. &`RT=0.204s`&.
+.wen
 .next
 .cindex "log" "recipients"
 &%received_recipients%&: The recipients of a message are listed in the main log
@@ -36031,9 +36801,16 @@ specifies whether characters with values greater than 127 should be logged
 unchanged, or whether they should be rendered as escape sequences.
 .next
 .cindex "log" "certificate verification"
+.cindex log DANE
+.cindex DANE logging
 &%tls_certificate_verified%&: An extra item is added to <= and => log lines
 when TLS is in use. The item is &`CV=yes`& if the peer's certificate was
-verified, and &`CV=no`& if not.
+verified
+.new
+using a CA trust anchor,
+&`CA=dane`& if using a DNS trust anchor,
+.wen
+and &`CV=no`& if not.
 .next
 .cindex "log" "TLS cipher"
 .cindex "TLS" "logging cipher"
@@ -36326,8 +37103,7 @@ autodetection of some well known compression extensions.
 .cindex "&'exipick'&"
 John Jetmore's &'exipick'& utility is included in the Exim distribution. It
 lists messages from the queue according to a variety of criteria. For details
-of &'exipick'&'s facilities, visit the web page at
-&url(http://www.exim.org/eximwiki/ToolExipickManPage) or run &'exipick'& with
+of &'exipick'&'s facilities, run &'exipick'& with
 the &%--help%& option.
 
 
@@ -37577,6 +38353,11 @@ the contents of files on the spool via the Exim monitor (which runs
 unprivileged), Exim must be built to allow group read access to its spool
 files.
 
+By default, regular users are trusted to perform basic testing and
+introspection commands, as themselves.  This setting can be tightened by
+setting the &%commandline_checks_require_admin%& option.
+This affects most of the checking options,
+such as &%-be%& and anything else &%-b*%&.
 
 
 .section "Spool files" "SECID275"
@@ -37677,9 +38458,8 @@ lock will be lost at the instant of rename.
 .next
 .vindex "&$body_linecount$&"
 If you change the number of lines in the file, the value of
-&$body_linecount$&, which is stored in the -H file, will be incorrect. At
-present, this value is not used by Exim, but there is no guarantee that this
-will always be the case.
+&$body_linecount$&, which is stored in the -H file, will be incorrect and can
+cause incomplete transmission of messages or undeliverable messages.
 .next
 If the message is in MIME format, you must take care not to break it.
 .next
@@ -37698,6 +38478,11 @@ file remains in existence. When Exim next processes the message, it notices the
 -J file and uses it to update the -H file before starting the next delivery
 attempt.
 
+Files whose names end with -K or .eml may also be seen in the spool.
+These are temporaries used for DKIM or malware processing, when that is used.
+They should be tidied up by normal operations; any old ones are probably
+relics of crashes and can be removed.
+
 .section "Format of the -H file" "SECID282"
 .cindex "uid (user id)" "in spool file"
 .cindex "gid (group id)" "in spool file"
@@ -37775,8 +38560,8 @@ The address of an authenticated sender &-- the value of the
 &$authenticated_sender$& variable.
 
 .vitem "&%-body_linecount%&&~<&'number'&>"
-This records the number of lines in the body of the message, and is always
-present.
+This records the number of lines in the body of the message, and is
+present unless &%-spool_file_wireformat%& is.
 
 .vitem "&%-body_zerocount%&&~<&'number'&>"
 This records the number of binary zero bytes in the body of the message, and is
@@ -37858,6 +38643,12 @@ to ensure that the caller is displayed in queue listings).
 If a message was scanned by SpamAssassin, this is present. It records the value
 of &$spam_score_int$&.
 
+.vitem &%-spool_file_wireformat%&
+The -D file for this message is in wire-format (for ESMTP CHUNKING)
+rather than Unix-format.
+The line-ending is CRLF rather than newline.
+There is still, however, no leading-dot-stuffing.
+
 .vitem &%-tls_certificate_verified%&
 A TLS certificate was received from the client that sent this message, and the
 certificate was verified by the server.
@@ -37965,31 +38756,49 @@ unqualified domain &'foundation'&.
 .ecindex IIDforspo2
 .ecindex IIDforspo3
 
+.section "Format of the -D file" "SECID282a"
+The data file is traditionally in Unix-standard format: lines are ended with
+an ASCII newline character.
+However, when the &%spool_wireformat%& main option is used some -D files
+can have an alternate format.
+This is flagged by a &%-spool_file_wireformat%& line in the corresponding -H file.
+The -D file lines (not including the first name-component line) are
+suitable for direct copying to the wire when transmitting using the
+ESMTP CHUNKING option, meaning lower processing overhead.
+Lines are terminated with an ASCII CRLF pair.
+There is no dot-stuffing (and no dot-termination).
+
 . ////////////////////////////////////////////////////////////////////////////
 . ////////////////////////////////////////////////////////////////////////////
 
-.chapter "Support for DKIM (DomainKeys Identified Mail)" "CHAPdkim" &&&
-         "DKIM Support"
+.chapter "DKIM and SPF" "CHAPdkim" &&&
+         "DKIM and SPF Support"
 .cindex "DKIM"
 
+.section "DKIM (DomainKeys Identified Mail)" SECDKIM
+
 DKIM is a mechanism by which messages sent by some entity can be provably
 linked to a domain which that entity controls.  It permits reputation to
 be tracked on a per-domain basis, rather than merely upon source IP address.
-DKIM is documented in RFC 4871.
+DKIM is documented in RFC 6376.
 
 .new
-DKIM support is compiled into Exim by default if TLS support is present.
+As DKIM relies on the message being unchanged in transit, messages handled
+by a mailing-list (which traditionally adds to the message) will not match
+any original DKIM signature.
 .wen
+
+DKIM support is compiled into Exim by default if TLS support is present.
 It can be disabled by setting DISABLE_DKIM=yes in &_Local/Makefile_&.
 
-Exim's DKIM implementation allows to
+Exim's DKIM implementation allows for
 .olist
-Sign outgoing messages: This function is implemented in the SMTP transport.
+Signing outgoing messages: This function is implemented in the SMTP transport.
 It can co-exist with all other Exim features
 (including transport filters)
 except cutthrough delivery.
 .next
-Verify signatures in incoming messages: This is implemented by an additional
+Verifying signatures in incoming messages: This is implemented by an additional
 ACL (acl_smtp_dkim), which can be called several times per message, with
 different signature contexts.
 .endlist
@@ -37998,8 +38807,12 @@ In typical Exim style, the verification implementation does not include any
 default "policy". Instead it enables you to build your own policy using
 Exim's standard controls.
 
+.new
 Please note that verification of DKIM signatures in incoming mail is turned
-on by default for logging purposes. For each signature in incoming email,
+on by default for logging (in the <= line) purposes.
+
+Additional log detail can be enabled using the &%dkim_verbose%& log_selector.
+When set, for each signature in incoming email,
 exim will log a line displaying the most important signature details, and the
 signature status. Here is an example (with line-breaks added for clarity):
 .code
@@ -38008,6 +38821,8 @@ signature status. Here is an example (with line-breaks added for clarity):
     c=relaxed/relaxed a=rsa-sha1
     i=@facebookmail.com t=1252484542 [verification succeeded]
 .endd
+.wen
+
 You might want to turn off DKIM verification processing entirely for internal
 or relay mail sources. To do that, set the &%dkim_disable_verify%& ACL
 control modifier. This should typically be done in the RCPT ACL, at points
@@ -38018,69 +38833,142 @@ senders).
 .section "Signing outgoing messages" "SECDKIMSIGN"
 .cindex "DKIM" "signing"
 
-Signing is implemented by setting private options on the SMTP transport.
-These options take (expandable) strings as arguments.
+.new
+For signing to be usable you must have published a DKIM record in DNS.
+Note that RFC 8301 says:
+.code
+rsa-sha1 MUST NOT be used for signing or verifying.
 
-.option dkim_domain smtp string&!! unset
-MANDATORY:
-The domain you want to sign with. The result of this expanded
-option is put into the &%$dkim_domain%& expansion variable.
+Signers MUST use RSA keys of at least 1024 bits for all keys.
+Signers SHOULD use RSA keys of at least 2048 bits.
+.endd
 
-.option dkim_selector smtp string&!! unset
-MANDATORY:
-This sets the key selector string. You can use the &%$dkim_domain%& expansion
-variable to look up a matching selector. The result is put in the expansion
+Note also that the key content (the 'p=' field)
+in the DNS record is different between RSA and EC keys;
+for the former it is the base64 of the ASN.1 for the RSA public key
+(equivalent to the private-key .pem with the header/trailer stripped)
+but for EC keys it is the base64 of the pure key; no ASN.1 wrapping.
+.wen
+
+Signing is enabled by setting private options on the SMTP transport.
+These options take (expandable) strings as arguments.
+
+.option dkim_domain smtp string list&!! unset
+The domain(s) you want to sign with.
+After expansion, this can be a list.
+Each element in turn is put into the &%$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
+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
 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.
 
 .option dkim_private_key smtp string&!! unset
-MANDATORY:
-This sets the private key to use. You can use the &%$dkim_domain%& and
+This sets the private key to use.
+You can use the &%$dkim_domain%& and
 &%$dkim_selector%& expansion variables to determine the private key to use.
 The result can either
 .ilist
-be a valid RSA private key in ASCII armor, including line breaks.
+be a valid RSA private key in ASCII armor (.pem file), including line breaks
+.new
+.next
+with GnuTLS 3.6.0 or later, be a valid Ed25519 private key (same format as above)
+.wen
 .next
 start with a slash, in which case it is treated as a file that contains
-the private key.
+the private key
 .next
 be "0", "false" or the empty string, in which case the message will not
 be signed. This case will not result in an error, even if &%dkim_strict%&
 is set.
 .endlist
 
+.new
+Note that RFC 8301 says:
+.code
+Signers MUST use RSA keys of at least 1024 bits for all keys.
+Signers SHOULD use RSA keys of at least 2048 bits.
+.endd
+
+Support for EC keys is being developed under
+&url(https://datatracker.ietf.org/doc/draft-ietf-dcrup-dkim-crypto/).
+They are considerably smaller than RSA keys for equivalent protection.
+As they are a recent development, users should consider dual-signing
+(by setting a list of selectors, and an expansion for this option)
+for some transition period.
+The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
+for EC keys.
+.wen
+
+.option dkim_hash smtp string&!! sha256
+Can be set alternatively to &"sha1"& to use an alternate hash
+method.
+
+.new
+Note that RFC 8301 says:
+.code
+rsa-sha1 MUST NOT be used for signing or verifying.
+.endd
+.wen
+
+.option dkim_identity smtp string&!! unset
+If set after expansion, the value is used to set an "i=" tag in
+the signing header.  The DKIM standards restrict the permissible
+syntax of this optional tag to a mail address, with possibly-empty
+local part, an @, and a domain identical to or subdomain of the "d="
+tag value.  Note that Exim does not check the value.
+
 .option dkim_canon smtp string&!! unset
-OPTIONAL:
 This option sets the canonicalization method used when signing a message.
 The DKIM RFC currently supports two methods: "simple" and "relaxed".
 The option defaults to "relaxed" when unset. Note: the current implementation
 only supports using the same canonicalization method for both headers and body.
 
 .option dkim_strict smtp string&!! unset
-OPTIONAL:
 This  option  defines  how  Exim  behaves  when  signing a message that
 should be signed fails for some reason.  When the expansion evaluates to
 either "1" or "true", Exim will defer. Otherwise Exim will send the message
 unsigned. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion
 variables here.
 
-.option dkim_sign_headers smtp string&!! unset
-OPTIONAL:
-When set, this option must expand to (or be specified as) a colon-separated
-list of header names. Headers with these names will be included in the message
-signature. When unspecified, the header names recommended in RFC4871 will be
-used.
-
-
-.section "Verifying DKIM signatures in incoming mail" "SECID514"
+.option dkim_sign_headers smtp string&!! "see below"
+If set, this option must expand to a colon-separated
+list of header names.
+Headers with these names, or the absence or such a header, will be included
+in the message signature.
+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".
+
+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
+message are signed first, if there are multiples.
+
+A name can be prefixed with either an '=' or a '+' character.
+If an '=' prefix is used, all headers that are present with this name
+will be signed.
+If a '+' prefix if used, all headers that are present with this name
+will be signed, and one signature added for a missing header with the
+name will be appended.
+
+
+.section "Verifying DKIM signatures in incoming mail" "SECDKIMVFY"
 .cindex "DKIM" "verification"
 
-Verification of DKIM signatures in incoming email is implemented via the
+Verification of DKIM signatures in SMTP incoming email is implemented via the
 &%acl_smtp_dkim%& ACL. By default, this ACL is called once for each
 syntactically(!) correct signature in the incoming message.
 A missing ACL definition defaults to accept.
 If any ACL call does not accept, the message is not accepted.
-If a cutthrough delivery was in progress for the message it is
+If a cutthrough delivery was in progress for the message, that is
 summarily dropped (having wasted the transmission effort).
 
 To evaluate the signature in the ACL a large number of expansion variables
@@ -38118,6 +39006,9 @@ dkim_verify_signers = $sender_address_domain:$dkim_signers
 If a domain or identity is listed several times in the (expanded) value of
 &%dkim_verify_signers%&, the ACL is only called once for that domain or identity.
 
+If multiple signatures match a domain (or identity), the ACL is called once
+for each matching signature.
+
 
 Inside the &%acl_smtp_dkim%&, the following expansion variables are
 available (from most to least important):
@@ -38128,8 +39019,10 @@ available (from most to least important):
 The signer that is being evaluated in this ACL run. This can be a domain or
 an identity. This is one of the list items from the expanded main option
 &%dkim_verify_signers%& (see above).
+
 .vitem &%$dkim_verify_status%&
-A string describing the general status of the signature. One of
+Within the DKIM ACL,
+a string describing the general status of the signature. One of
 .ilist
 &%none%&: There is no signature in the message for the current domain or
 identity (as reflected by &%$dkim_cur_signer%&).
@@ -38142,6 +39035,21 @@ available in &%$dkim_verify_reason%&.
 .next
 &%pass%&: The signature passed verification. It is valid.
 .endlist
+
+This variable can be overwritten using an ACL 'set' modifier.
+This might, for instance, be done to enforce a policy restriction on
+hash-method or key-size:
+.code
+  warn	condition =	${if eq {$dkim_algo}{rsa-sha1}}
+	condition =	${if eq {$dkim_verify_status}{pass}}
+	logwrite =	NOTE: forcing dkim verify fail (was pass)
+	set dkim_verify_status = fail
+	set dkim_verify_reason = hash too weak
+.endd
+
+After all the DKIM ACL runs have completed, the value becomes a
+colon-separated list of the values after each run.
+
 .vitem &%$dkim_verify_reason%&
 A string giving a little bit more detail when &%$dkim_verify_status%& is either
 "fail" or "invalid". One of
@@ -38161,53 +39069,105 @@ could not be verified. This may mean that headers were modified,
 re-written or otherwise changed in a way which is incompatible with
 DKIM verification. It may of course also mean that the signature is forged.
 .endlist
+
+This variable can be overwritten, with any value, using an ACL 'set' modifier.
+
 .vitem &%$dkim_domain%&
 The signing domain. IMPORTANT: This variable is only populated if there is
 an actual signature in the message for the current domain or identity (as
 reflected by &%$dkim_cur_signer%&).
+
 .vitem &%$dkim_identity%&
 The signing identity, if present. IMPORTANT: This variable is only populated
 if there is an actual signature in the message for the current domain or
 identity (as reflected by &%$dkim_cur_signer%&).
+
 .vitem &%$dkim_selector%&
 The key record selector string.
+
 .vitem &%$dkim_algo%&
 The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'.
+.new
+If running under GnuTLS 3.6.0 or later, may also be 'ed25519-sha256'.
+The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
+for EC keys.
+.wen
+
+.new
+Note that RFC 8301 says:
+.code
+rsa-sha1 MUST NOT be used for signing or verifying.
+
+DKIM signatures identified as having been signed with historic
+algorithms (currently, rsa-sha1) have permanently failed evaluation
+.endd
+
+To enforce this you must have a DKIM ACL which checks this variable
+and overwrites the &$dkim_verify_status$& variable as discussed above.
+.wen
+
 .vitem &%$dkim_canon_body%&
 The body canonicalization method. One of 'relaxed' or 'simple'.
-.vitem &%dkim_canon_headers%&
+
+.vitem &%$dkim_canon_headers%&
 The header canonicalization method. One of 'relaxed' or 'simple'.
+
 .vitem &%$dkim_copiedheaders%&
 A transcript of headers and their values which are included in the signature
 (copied from the 'z=' tag of the signature).
+Note that RFC6376 requires that verification fail if the From: header is
+not included in the signature.  Exim does not enforce this; sites wishing
+strict enforcement should code the check explicitly.
+
 .vitem &%$dkim_bodylength%&
 The number of signed body bytes. If zero ("0"), the body is unsigned. If no
 limit was set by the signer, "9999999999999" is returned. This makes sure
 that this variable always expands to an integer value.
+
 .vitem &%$dkim_created%&
 UNIX timestamp reflecting the date and time when the signature was created.
 When this was not specified by the signer, "0" is returned.
+
 .vitem &%$dkim_expires%&
 UNIX timestamp reflecting the date and time when the signer wants the
 signature to be treated as "expired". When this was not specified by the
 signer, "9999999999999" is returned. This makes it possible to do useful
 integer size comparisons against this value.
+
 .vitem &%$dkim_headernames%&
 A colon-separated list of names of headers included in the signature.
+
 .vitem &%$dkim_key_testing%&
 "1" if the key record has the "testing" flag set, "0" if not.
+
 .vitem &%$dkim_key_nosubdomains%&
 "1" if the key record forbids subdomaining, "0" otherwise.
+
 .vitem &%$dkim_key_srvtype%&
 Service type (tag s=) from the key record. Defaults to "*" if not specified
 in the key record.
+
 .vitem &%$dkim_key_granularity%&
 Key granularity (tag g=) from the key record. Defaults to "*" if not specified
 in the key record.
+
 .vitem &%$dkim_key_notes%&
 Notes from the key record (tag n=).
+
 .vitem &%$dkim_key_length%&
 Number of bits in the key.
+
+.new
+Note that RFC 8301 says:
+.code
+Verifiers MUST NOT consider signatures using RSA keys of
+less than 1024 bits as valid signatures.
+.endd
+
+To enforce this you must have a DKIM ACL which checks this variable
+and overwrites the &$dkim_verify_status$& variable as discussed above.
+.wen
+
 .endlist
 
 In addition, two ACL conditions are provided:
@@ -38220,13 +39180,16 @@ for a match against the domain or identity that the ACL is currently verifying
 verb to a group of domains or identities. For example:
 
 .code
-# Warn when Mail purportedly from GMail has no signature at all
-warn log_message = GMail sender without DKIM signature
+# Warn when Mail purportedly from GMail has no gmail signature
+warn log_message = GMail sender without gmail.com DKIM signature
      sender_domains = gmail.com
      dkim_signers = gmail.com
      dkim_status = none
 .endd
 
+Note that the above does not check for a total lack of DKIM signing;
+for that check for empty &$h_DKIM-Signature:$& in the data ACL.
+
 .vitem &%dkim_status%&
 ACL condition that checks a colon-separated list of possible DKIM verification
 results against the actual result of verification. This is typically used
@@ -38244,6 +39207,178 @@ see the documentation of the &%$dkim_verify_status%& expansion variable above
 for more information of what they mean.
 .endlist
 
+
+
+
+.new
+.section "SPF (Sender Policy Framework)" SECSPF
+.cindex SPF verification
+
+SPF is a mechanism whereby a domain may assert which IP addresses may transmit
+messages with its domain in the envelope from, documented by RFC 7208.
+For more information on SPF see &url(http://www.openspf.org).
+
+Messages sent by a system not authorised will fail checking of such assertions.
+This includes retransmissions done by traditional forwarders.
+
+SPF verification support is built into Exim if SUPPORT_SPF=yes is set in
+&_Local/Makefile_&.  The support uses the &_libspf2_& library
+&url(http://www.libspf2.org/).
+There is no Exim involvement on the trasmission of messages; publishing certain
+DNS records is all that is required.
+
+For verification, an ACL condition and an expansion lookup are provided.
+
+.cindex SPF "ACL condition"
+.cindex ACL "spf condition"
+The ACL condition "spf" can be used at or after the MAIL ACL.
+It takes as an argument a list of strings giving the outcome of the SPF check,
+and will succeed for any matching outcome.
+Valid strings are:
+.vlist
+.vitem &%pass%&
+The SPF check passed, the sending host is positively verified by SPF.
+
+.vitem &%fail%&
+The SPF check failed, the sending host is NOT allowed to send mail for the
+domain in the envelope-from address.
+
+.vitem &%softfail%&
+The SPF check failed, but the queried domain can't absolutely confirm that this
+is a forgery.
+
+.vitem &%none%&
+The queried domain does not publish SPF records.
+
+.vitem &%neutral%&
+The SPF check returned a "neutral" state.  This means the queried domain has
+published a SPF record, but wants to allow outside servers to send mail under
+its domain as well.  This should be treated like "none".
+
+.vitem &%permerror%&
+This indicates a syntax error in the SPF record of the queried domain.
+You may deny messages when this occurs. (Changed in 4.83)
+
+.vitem &%temperror%&
+This indicates a temporary error during all processing, including Exim's
+SPF processing.  You may defer messages when this occurs.
+(Changed in 4.83)
+
+.vitem &%err_temp%&
+Same as permerror, deprecated in 4.83, will be removed in a future release.
+
+.vitem &%err_perm%&
+Same as temperror, deprecated in 4.83, will be removed in a future release.
+.endlist
+
+You can prefix each string with an exclamation mark to  invert
+its meaning,  for example  "!fail" will  match all  results but
+"fail".  The  string  list is  evaluated  left-to-right,  in a
+short-circuit fashion.
+
+Example:
+.code
+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.openspf.org/Why?scope=\
+               ${if def:sender_address_domain {mfrom}{helo}};\
+               identity=${if def:sender_address_domain \
+                             {$sender_address}{$sender_helo_name}};\
+               ip=$sender_host_address
+.endd
+
+When the spf condition has run, it sets up several expansion
+variables:
+
+.cindex SPF "verification variables"
+.vlist
+.vitem &$spf_header_comment$&
+.vindex &$spf_header_comment$&
+  This contains a human-readable string describing the outcome
+  of the SPF check. You can add it to a custom header or use
+  it for logging purposes.
+
+.vitem &$spf_received$&
+.vindex &$spf_received$&
+  This contains a complete Received-SPF: header that can be
+  added to the message. Please note that according to the SPF
+  draft, this header must be added at the top of the header
+  list. Please see section 10 on how you can do this.
+
+  Note: in case of "Best-guess" (see below), the convention is
+  to put this string in a header called X-SPF-Guess: instead.
+
+.vitem &$spf_result$&
+.vindex &$spf_result$&
+  This contains the outcome of the SPF check in string form,
+  one of pass, fail, softfail, none, neutral, permerror or
+  temperror.
+
+.vitem &$spf_smtp_comment$&
+.vindex &$spf_smtp_comment$&
+  This contains a string that can be used in a SMTP response
+  to the calling party. Useful for "fail".
+.endlist
+
+
+.cindex SPF "ACL condition"
+.cindex ACL "spf_guess condition"
+.cindex SPF "best guess"
+In addition to SPF, you can also perform checks for so-called
+"Best-guess".  Strictly speaking, "Best-guess" is not standard
+SPF, but it is supported by the same framework that enables SPF
+capability.
+Refer to &url(http://www.openspf.org/FAQ/Best_guess_record)
+for a description of what it means.
+
+To access this feature, simply use the spf_guess condition in place
+of the spf one.  For example:
+
+.code
+deny spf_guess = fail
+     message = $sender_host_address doesn't look trustworthy to me
+.endd
+
+In case you decide to reject messages based on this check, you
+should note that although it uses the same framework, "Best-guess"
+is not SPF, and therefore you should not mention SPF at all in your
+reject message.
+
+When the spf_guess condition has run, it sets up the same expansion
+variables as when spf condition is run, described above.
+
+Additionally, since Best-guess is not standardized, you may redefine
+what "Best-guess" means to you by redefining the main configuration
+&%spf_guess%& option.
+For example, the following:
+
+.code
+spf_guess = v=spf1 a/16 mx/16 ptr ?all
+.endd
+
+would relax host matching rules to a broader network range.
+
+
+.cindex SPF "lookup expansion"
+.cindex lookup spf
+A lookup expansion is also available. It takes an email
+address as the key and an IP address as the database:
+
+.code
+  ${lookup {username@domain} spf {ip.ip.ip.ip}}
+.endd
+
+The lookup will return the same result strings as they can appear in
+&$spf_result$& (pass,fail,softfail,neutral,none,err_perm,err_temp).
+Currently, only IPv4 addresses are supported.
+
+
+. wen-for SPF section
+.wen
+
+
 . ////////////////////////////////////////////////////////////////////////////
 . ////////////////////////////////////////////////////////////////////////////
 
@@ -38252,7 +39387,6 @@ for more information of what they mean.
 .cindex "proxy support"
 .cindex "proxy" "access via"
 
-.new
 A proxy is an intermediate system through which communication is passed.
 Proxies may provide a security, availability or load-distribution function.
 
@@ -38269,9 +39403,9 @@ To include this support, include &"SUPPORT_PROXY=yes"&
 in Local/Makefile.
 
 It was built on specifications from:
-http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt
+(&url(http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt)).
 That URL was revised in May 2014 to version 2 spec:
-http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e
+(&url(http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e)).
 
 The purpose of this facility is so that an application load balancer,
 such as HAProxy, can sit in front of several Exim servers
@@ -38285,18 +39419,25 @@ recorded in an ACL (example is below).
 Use of a proxy is enabled by setting the &%hosts_proxy%&
 main configuration option to a hostlist; connections from these
 hosts will use Proxy Protocol.
+Exim supports both version 1 and version 2 of the Proxy Protocol and
+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.
 
 The following expansion variables are usable
 (&"internal"& and &"external"& here refer to the interfaces
 of the proxy):
 .display
-&'proxy_host_address   '& internal IP address of the proxy
-&'proxy_host_port      '& internal TCP port of the proxy
-&'proxy_target_address '& external IP address of the proxy
-&'proxy_target_port    '& external TCP port of the proxy
-&'proxy_session        '& boolean: SMTP connection via proxy
+&'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
-If &$proxy_session$& is set but &$proxy_host_address$& is empty
+If &$proxy_session$& is set but &$proxy_external_address$& is empty
 there was a protocol error.
 
 Since the real connections are all coming from the proxy, and the
@@ -38338,7 +39479,7 @@ Each proxy specifier is a list
 (space-separated by default) where the initial element
 is an IP address and any subsequent elements are options.
 
-Options are a string <name>=<value>. 
+Options are a string <name>=<value>.
 The list of options is in the following table:
 .display
 &'auth   '& authentication method
@@ -38390,7 +39531,6 @@ overall connection applies to the set of proxied attempts.
 To log the (local) IP of a proxy in the incoming or delivery logline,
 add &"+proxy"& to the &%log_selector%& option.
 This will add a component tagged with &"PRX="& to the line.
-.wen
 
 . ////////////////////////////////////////////////////////////////////////////
 . ////////////////////////////////////////////////////////////////////////////
@@ -38400,13 +39540,16 @@ This will add a component tagged with &"PRX="& to the line.
 .cindex internationalisation "email address"
 .cindex EAI
 .cindex i18n
-.cindex UTF-8 "mail name handling"
+.cindex utf8 "mail name handling"
 
-.new
 Exim has support for Internationalised mail names.
 To include this it must be built with SUPPORT_I18N and the libidn library.
 Standards supported are RFCs 2060, 5890, 6530 and 6533.
 
+If Exim is built with SUPPORT_I18N_2008 (in addition to SUPPORT_I18N, not
+instead of it) then IDNA2008 is supported; this adds an extra library
+requirement, upon libidn2.
+
 .section "MTA operations" SECTi18nMTA
 .cindex SMTPUTF8 "ESMTP option"
 The main configuration option &%smtputf8_advertise_hosts%& specifies
@@ -38435,10 +39578,11 @@ form of the name.
 
 .cindex log protocol
 .cindex SMTPUTF8 logging
+.cindex i18n logging
 Log lines and Received-by: header lines will acquire a "utf8"
 prefix on the protocol element, eg. utf8esmtp.
 
-The following expansion operator can be used:
+The following expansion operators can be used:
 .code
 ${utf8_domain_to_alabel:str}
 ${utf8_domain_from_alabel:str}
@@ -38446,7 +39590,12 @@ ${utf8_localpart_to_alabel:str}
 ${utf8_localpart_from_alabel:str}
 .endd
 
-ACLs may use the following modifier:
+.cindex utf8 "address downconversion"
+.cindex i18n "utf8 address downconversion"
+.new
+The RCPT ACL
+.wen
+may use the following modifier:
 .display
 control = utf8_downconvert
 control = utf8_downconvert/<value>
@@ -38490,7 +39639,7 @@ the "headers charset" command (in a filter file)
 or &%headers_charset%& main configuration option (otherwise),
 to the
 modified UTF-7 encoding specified by RFC 2060,
-with the following exception: All occurences of <sep>
+with the following exception: All occurrences of <sep>
 (which has to be a single character)
 are replaced with periods ("."), and all periods and slashes that are not
 <sep> and are not in the <specials> string are BASE64 encoded.
@@ -38511,7 +39660,6 @@ Examples:
 Note that the source charset setting is vital, and also that characters
 must be representable in UTF-16.
 
-.wen
 
 . ////////////////////////////////////////////////////////////////////////////
 . ////////////////////////////////////////////////////////////////////////////
@@ -38520,9 +39668,8 @@ must be representable in UTF-16.
          "Events"
 .cindex events
 
-.new
 The events mechanism in Exim can be used to intercept processing at a number
-of points.  It was originally invented to giave a way to do customised logging
+of points.  It was originally invented to give a way to do customised logging
 actions (for example, to a database) but can also be used to modify some
 processing actions.
 
@@ -38561,7 +39708,7 @@ The current list of events is:
 &`msg:rcpt:host:defer    after    transport  `& per recipient per host
 &`msg:rcpt:defer         after    transport  `& per recipient
 &`msg:host:defer         after    transport  `& per attempt
-&`msg:fail:delivery      after    main       `& per recipient
+&`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
@@ -38578,10 +39725,13 @@ The second column in the table above describes whether the event fires
 before or after the action is associates with.  Those which fire before
 can be used to affect that action (more on this below).
 
+The third column in the table above says what section of the configuration
+should define the event action.
+
 An additional variable, &$event_data$&, is filled with information varying
 with the event type:
 .display
-&`msg:delivery         `& smtp confirmation mssage
+&`msg:delivery         `& smtp confirmation message
 &`msg:rcpt:host:defer  `& error string
 &`msg:rcpt:defer       `& error string
 &`msg:host:defer       `& error string
@@ -38592,7 +39742,7 @@ with the event type:
 The :defer events populate one extra variable: &$event_defer_errno$&.
 
 For complex operations an ACL expansion can be used in &%event_action%&
-however due to the multiple contextx that Exim operates in during
+however due to the multiple contexts that Exim operates in during
 the course of its processing:
 .ilist
 variables set in transport events will not be visible outside that
@@ -38626,7 +39776,6 @@ For tls:cert events, if GnuTLS is in use this will trigger only per
 chain element received on the connection.
 For OpenSSL it will trigger for every chain element including those
 loaded locally.
-.wen
 
 . ////////////////////////////////////////////////////////////////////////////
 . ////////////////////////////////////////////////////////////////////////////