X-Git-Url: https://vcs.fsf.org/?p=exim.git;a=blobdiff_plain;f=doc%2Fdoc-docbook%2Fspec.xfpt;h=8c7d17b717091e5a64ae4919bdef8a5791db1e6f;hp=44417ca71684a846ab81e3a2da6e94b6ac94effc;hb=a94bdef382a12b5677b6d6f5eb6e686bfc8cf665;hpb=055e2cb463e4e4adf2d9292a50ac274938f9a5ac

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 44417ca71..8c7d17b71 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 "4.87"
 .include ./local_params
 
 .set ACL "access control lists (ACLs)"
 .set I   "    "
 
 .macro copyyear
-2015
+2016
 .endmacro
 
 . /////////////////////////////////////////////////////////////////////////////
@@ -1575,7 +1575,7 @@ If a host is unreachable for a period of time, a number of messages may be
 waiting for it by the time it recovers, and sending them in a single SMTP
 connection is clearly beneficial. Whenever a delivery to a remote host is
 deferred,
-.cindex "hints database"
+.cindex "hints database" "deferred deliveries"
 Exim makes a note in its hints database, and whenever a successful
 SMTP delivery has happened, it looks to see if any other messages are waiting
 for the same host. If any are found, they are sent over the same SMTP
@@ -1860,7 +1860,7 @@ described RFC 2047. This makes it possible to transmit characters that are not
 in the ASCII character set, and to label them as being in a particular
 character set. When Exim is inspecting header lines by means of the &%$h_%&
 mechanism, it decodes them, and translates them into a specified character set
-(default ISO-8859-1). The translation is possible only if the operating system
+(default is set at build time). The translation is possible only if the operating system
 supports the &[iconv()]& function.
 
 However, some of the operating systems that supply &[iconv()]& do not support
@@ -2627,6 +2627,8 @@ 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 +2790,7 @@ 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
@@ -3049,7 +3051,8 @@ 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
@@ -3107,8 +3110,12 @@ users, the output is as in this example:
 .code
 mysql_servers = <value not displayable>
 .endd
-If &%configure_file%& is given as an argument, the name of the run time
-configuration file is output.
+If &%config%& is given as an argument, the config is
+output, as it was parsed, any include file resolved, any comment removed.
+
+If &%config_file%& is given as an argument, the name of the run time
+configuration file is output. (&%configure_file%& works too, for
+backward compatibility.)
 If a list of configuration files was supplied, the value that is output here
 is the name of the file that was actually used.
 
@@ -3147,6 +3154,11 @@ 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
@@ -3548,6 +3560,7 @@ example:
 exim '-D ABC = something' ...
 .endd
 &%-D%& may be repeated up to 10 times on a command line.
+Only macro names up to 22 letters long can be set.
 
 
 .vitem &%-d%&<&'debug&~options'&>
@@ -3814,6 +3827,14 @@ This option is not intended for use by external callers. It is used internally
 by Exim in conjunction with the &%-MC%& option. It signifies that the
 remote host supports the ESMTP &_DSN_& extension.
 
+.new
+.vitem &%-MCG%&
+.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 option.
+.wen
+
 .vitem &%-MCP%&
 .oindex "&%-MCP%&"
 This option is not intended for use by external callers. It is used internally
@@ -4005,7 +4026,8 @@ 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%&"
@@ -4359,7 +4381,10 @@ 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
+.new
+If other commandline options do not specify an action,
+.wen
+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
@@ -4444,8 +4469,29 @@ 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'&>
+.new
+.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 speicify an action, a &'-qG<name>'& option
+will specify a queue to operate on.
+For example:
+.code
+exim -bp -qGquarantine
+mailq -qGquarantime
+exim -qGoffpeak -Rf @special.domain.example
+.endd
+.wen
+
+.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:
@@ -4800,8 +4846,8 @@ help with this. See the comments in &_src/EDITME_& for details.
 Exim's configuration file is divided into a number of different parts. General
 option settings must always appear at the start of the file. The other parts
 are all optional, and may appear in any order. Each part other than the first
-is introduced by the word &"begin"& followed by the name of the part. The
-optional parts are:
+is introduced by the word &"begin"& followed by at least one literal
+space, and the name of the part. The optional parts are:
 
 .ilist
 &'ACL'&: Access control lists for controlling incoming SMTP mail (see chapter
@@ -4987,6 +5033,27 @@ address lists. In Exim 4 these are handled better by named lists &-- see
 section &<<SECTnamedlists>>&.
 
 
+.new
+.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
+&` _DRVR_AUTH_                `&  authehticator drivers
+&` _DRVR_RTR_                 `&  router drivers
+&` _DRVR_TPT_                 `&  transport drivers
+&` _OPT_                      `&  configuration option support
+.endd
+
+Use an &"exim -bP macros"& command to get the list of macros.
+.wen
+
+
 .section "Conditional skips in the configuration file" "SECID46"
 .cindex "configuration file" "conditional skips"
 .cindex "&`.ifdef`&"
@@ -5090,7 +5157,11 @@ 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;
+.new
+if by the letter G, 1024x1024x1024.
+.wen
+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
@@ -5610,7 +5681,7 @@ 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
@@ -5628,6 +5699,44 @@ 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"
@@ -6098,7 +6207,8 @@ 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
@@ -6179,7 +6289,11 @@ 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
+.new
+online Perl manpages, in
+.wen
+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/)).
 
@@ -6560,7 +6674,7 @@ 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
@@ -6617,6 +6731,12 @@ password value. For example:
 &(pgsql)&: The format of the query is an SQL statement that is passed to a
 PostgreSQL database. See section &<<SECTsql>>&.
 
+.next
+.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>>&.
+
 .next
 .cindex "sqlite lookup type"
 .cindex "lookup" "sqlite"
@@ -6993,6 +7113,13 @@ 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%&.
 
+.cindex cacheing "of dns lookup"
+.cindex TTL "of dns lookup"
+.cindex DNS TTL
+Dnsdb lookup results are cached within a single process (and its children).
+The cache entry lifetime is limited to the smallest time-to-live (TTL)
+value of the set of returned DNS records.
+
 
 .section "Pseudo dnsdb record types" "SECID66"
 .cindex "MX record" "in &(dnsdb)& lookup"
@@ -7298,6 +7425,8 @@ The value of the DEREFERENCE parameter must be one of the words &"never"&,
 must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP
 library from trying to follow referrals issued by the LDAP server.
 
+.cindex LDAP timeout
+.cindex timeout "LDAP lookup"
 The name CONNECT is an obsolete name for NETTIME, retained for
 backwards compatibility. This timeout (specified as a number of seconds) is
 enforced from the client end for operations that can be carried out over a
@@ -7312,7 +7441,7 @@ The TIME parameter (also a number of seconds) is passed to the server to
 set a server-side limit on the time taken to complete a search.
 
 The SERVERS parameter allows you to specify an alternate list of ldap servers
-to use for an individual lookup.  The global ldap_servers option provides a
+to use for an individual lookup.  The global &%ldap_default_servers%& option provides a
 default list of ldap servers, and a single lookup can specify a single ldap
 server to use.  But when you need to do a lookup with a list of servers that is
 different than the default list (maybe different order, maybe a completely
@@ -7372,7 +7501,7 @@ SMTP authentication. See the &%ldapauth%& expansion string condition in chapter
 The &(ldapdn)& lookup type returns the Distinguished Name from a single entry
 as a sequence of values, for example
 .code
-cn=manager, o=University of Cambridge, c=UK
+cn=manager,o=University of Cambridge,c=UK
 .endd
 The &(ldap)& lookup type generates an error if more than one entry matches the
 search filter, whereas &(ldapm)& permits this case, and inserts a newline in
@@ -7383,7 +7512,8 @@ directory.
 
 In the common case where you specify a single attribute in your LDAP query, the
 result is not quoted, and does not contain the attribute name. If the attribute
-has multiple values, they are separated by commas.
+has multiple values, they are separated by commas. Any comma that is
+part of an attribute's value is doubled.
 
 If you specify multiple attributes, the result contains space-separated, quoted
 strings, each preceded by the attribute name and an equals sign. Within the
@@ -7398,7 +7528,9 @@ same as specifying all of an entry's attributes.
 Here are some examples of the output format. The first line of each pair is an
 LDAP query, and the second is the data that is returned. The attribute called
 &%attr1%& has two values, one of them with an embedded comma, whereas
-&%attr2%& has only one value:
+&%attr2%& has only one value. Both attributes are derived from &%attr%&
+(they have SUP &%attr%& in their schema definitions).
+
 .code
 ldap:///o=base?attr1?sub?(uid=fred)
 value1.1,value1,,2
@@ -7406,6 +7538,9 @@ value1.1,value1,,2
 ldap:///o=base?attr2?sub?(uid=fred)
 value two
 
+ldap:///o=base?attr?sub?(uid=fred)
+value1.1,value1,,2,value two
+
 ldap:///o=base?attr1,attr2?sub?(uid=fred)
 attr1="value1.1,value1,,2" attr2="value two"
 
@@ -7465,7 +7600,10 @@ operator is to double any quote characters within the text.
 .cindex "lookup" "Oracle"
 .cindex "InterBase lookup type"
 .cindex "lookup" "InterBase"
-Exim can support lookups in InterBase, MySQL, Oracle, PostgreSQL, and SQLite
+.cindex "Redis lookup type"
+.cindex lookup Redis
+Exim can support lookups in InterBase, MySQL, Oracle, PostgreSQL, Redis,
+and SQLite
 databases. Queries for these databases contain SQL statements, so an example
 might be
 .code
@@ -7492,7 +7630,7 @@ If the result of the query yields more than one row, it is all concatenated,
 with a newline between the data for each row.
 
 
-.section "More about MySQL, PostgreSQL, Oracle, and InterBase" "SECID72"
+.section "More about MySQL, PostgreSQL, Oracle, InterBase, and Redis" "SECID72"
 .cindex "MySQL" "lookup type"
 .cindex "PostgreSQL lookup type"
 .cindex "lookup" "MySQL"
@@ -7501,13 +7639,18 @@ with a newline between the data for each row.
 .cindex "lookup" "Oracle"
 .cindex "InterBase lookup type"
 .cindex "lookup" "InterBase"
-If any MySQL, PostgreSQL, Oracle, or InterBase lookups are used, the
-&%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, or &%ibase_servers%&
+.cindex "Redis lookup type"
+.cindex lookup Redis
+If any MySQL, PostgreSQL, Oracle, InterBase or Redis lookups are used, the
+&%mysql_servers%&, &%pgsql_servers%&, &%oracle_servers%&, &%ibase_servers%&,
+or &%redis_servers%&
 option (as appropriate) must be set to a colon-separated list of server
 information.
-(For MySQL and PostgreSQL only, the global option need not be set if all
+(For MySQL and PostgreSQL, the global option need not be set if all
 queries contain their own server information &-- see section
-&<<SECTspeserque>>&.) Each item in the list is a slash-separated list of four
+&<<SECTspeserque>>&.)
+For all but Redis
+each item in the list is a slash-separated list of four
 items: host name, database name, user name, and password. In the case of
 Oracle, the host name field is used for the &"service name"&, and the database
 name field is not used and should be empty. For example:
@@ -7528,16 +7671,32 @@ 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.
 
+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
+information.
+Each item in the list is a slash-separated list of three items:
+host, database number, and password.
+.olist
+The host is required and may be either an IPv4 address and optional
+port number (separated by a colon, which needs doubling due to the
+higher-level list), or a Unix socket pathname enclosed in parentheses
+.next
+The database number is optional; if present that number is selected in the backend
+.next
+The password is optional; if present it is used to authenticate to the backend
+.endlist
+
 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
-itself are escaped with backslashes. The &%quote_pgsql%& expansion operator, in
-addition, escapes the percent and underscore characters. This cannot be done
-for MySQL because these escapes are not recognized in contexts where these
-characters are not special.
+itself are escaped with backslashes.
+
+The &%quote_redis%& expansion operator
+escapes whitespace and backslash characters with a backslash.
 
 .section "Specifying the server in the query" "SECTspeserque"
-For MySQL and PostgreSQL lookups (but not currently for Oracle and InterBase),
+For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase),
 it is possible to specify a list of servers with an individual query. This is
 done by starting the query with
 .display
@@ -7580,13 +7739,15 @@ ${lookup pgsql{servers=master/db/name/pw; UPDATE ...} }
 .section "Special MySQL features" "SECID73"
 For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
 causes a connection to the server on the local host by means of a Unix domain
-socket. An alternate socket can be specified in parentheses. The full syntax of
-each item in &%mysql_servers%& is:
+socket. An alternate socket can be specified in parentheses.
+An option group name for MySQL option files can be specified in square brackets;
+the default value is &"exim"&.
+The full syntax of each item in &%mysql_servers%& is:
 .display
-<&'hostname'&>::<&'port'&>(<&'socket name'&>)/<&'database'&>/&&&
-  <&'user'&>/<&'password'&>
+<&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&&
+  <&'database'&>/<&'user'&>/<&'password'&>
 .endd
-Any of the three sub-parts of the first field can be omitted. For normal use on
+Any of the four sub-parts of the first field can be omitted. For normal use on
 the local host it can be left blank or set to just &"localhost"&.
 
 No database need be supplied &-- but if it is absent here, it must be given in
@@ -7638,6 +7799,8 @@ domainlist relay_to_domains = sqlite;/some/thing/sqlitedb \
 The only character affected by the &%quote_sqlite%& operator is a single
 quote, which it doubles.
 
+.cindex timeout SQLite
+.cindex sqlite "lookup timeout"
 The SQLite library handles multiple simultaneous accesses to the database
 internally. Multiple readers are permitted, but only one process can
 update at once. Attempts to access the database while it is being updated
@@ -7673,9 +7836,16 @@ 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.
+
+.new
+&'Exception: the router headers_remove option, where list-item
+splitting is done before string-expansion.'&
+.wen
+
+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
@@ -9044,7 +9214,7 @@ 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.
@@ -9064,6 +9234,9 @@ 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'&>&*}}*&"
@@ -9071,8 +9244,8 @@ 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
@@ -9344,6 +9517,17 @@ you can use
 condition = ${if >{$acl_m4}{3}}
 .endd
 
+
+
+.vitem &*${imapfolder{*&<&'foldername'&>&*}}*&
+.cindex expansion "imap folder"
+.cindex "&%imapfolder%& expansion item"
+This item converts a (possibly multilevel, or with non-ASCII characters)
+folder specification to a Maildir name for filesystem use.
+For information on internationalisation support see &<<SECTi18nMDA>>&.
+
+
+
 .vitem &*${length{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&
 .cindex "expansion" "string truncation"
 .cindex "&%length%& expansion item"
@@ -9390,7 +9574,7 @@ yields &"42"&, and
 .code
 ${listextract{-3}{<, x,42,99,& Mailer,,/bin/bash}{result: $value}}
 .endd
-yields &"result: 99"&.
+yields &"result: 42"&.
 
 If {<&'string3'&>} is omitted, an empty string is used for string3.
 If {<&'string2'&>} is also omitted, the value that was
@@ -9598,7 +9782,8 @@ ${readsocket{inet:[::1]:1234}{request string}}
 Only a single host name may be given, but if looking it up yields more than
 one IP address, they are each tried in turn until a connection is made. For
 both kinds of socket, Exim makes a connection, writes the request string
-(unless it is an empty string) and reads from the socket until an end-of-file
+unless it is an empty string; and no terminating NUL is ever sent)
+and reads from the socket until an end-of-file
 is read. A timeout of 5 seconds is applied. Additional, optional arguments
 extend what can be done. Firstly, you can vary the timeout. For example:
 .code
@@ -9936,6 +10121,21 @@ Last:user@example.com
 user@example.com
 .endd
 
+.new
+.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.
+.wen
+
 .vitem &*${base62:*&<&'digits'&>&*}*&
 .cindex "&%base62%& expansion item"
 .cindex "expansion" "conversion to base 62"
@@ -9954,6 +10154,23 @@ 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.
 
+.vitem &*${base64:*&<&'string'&>&*}*&
+.cindex "expansion" "base64 encoding"
+.cindex "base64 encoding" "in string expansion"
+.cindex "&%base64%& expansion item"
+.cindex certificate "base64 of DER"
+This operator converts a string into one that is base64 encoded.
+
+If the string is a single variable of type certificate,
+returns the base64 encoding of the DER form of the certificate.
+
+
+.vitem &*${base64d:*&<&'string'&>&*}*&
+.cindex "expansion" "base64 decoding"
+.cindex "base64 decoding" "in string expansion"
+.cindex "&%base64d%& expansion item"
+This operator converts a base64-encoded string into the un-coded form.
+
 
 .vitem &*${domain:*&<&'string'&>&*}*&
 .cindex "domain" "extraction"
@@ -9970,6 +10187,15 @@ 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.
 
+.new
+.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.
+.wen
+
 
 .vitem &*${eval:*&<&'string'&>&*}*&&~and&~&*${eval10:*&<&'string'&>&*}*&
 .cindex "expansion" "expression evaluation"
@@ -10099,6 +10325,25 @@ as is, and other byte values are converted to &`\xNN`&, for example a
 byte value 127 is converted to &`\x7f`&.
 
 
+.vitem &*${ipv6denorm:*&<&'string'&>&*}*&
+.cindex "&%ipv6denorm%& expansion item"
+.cindex "IP address" normalisation
+This expands an IPv6 address to a full eight-element colon-separated set
+of hex digits including leading zeroes.
+A trailing ipv4-style dotted-decimal set is converted to hex.
+Pure IPv4 addresses are converted to IPv4-mapped IPv6.
+
+.vitem &*${ipv6norm:*&<&'string'&>&*}*&
+.cindex "&%ipv6norm%& expansion item"
+.cindex "IP address" normalisation
+.cindex "IP address" "canonical form"
+This converts an IPv6 address to canonical form.
+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.
+
+
 .vitem &*${lc:*&<&'string'&>&*}*&
 .cindex "case forcing in strings"
 .cindex "string" "case forcing"
@@ -10182,11 +10427,14 @@ Letters in IPv6 addresses are always output in lower case.
 .vitem &*${md5:*&<&'string'&>&*}*&
 .cindex "MD5 hash"
 .cindex "expansion" "MD5 hash"
-.cindex "certificate fingerprint"
+.cindex certificate fingerprint
 .cindex "&%md5%& expansion item"
 The &%md5%& operator computes the MD5 hash value of the string, and returns it
 as a 32-digit hexadecimal number, in which any letters are in lower case.
 
+If the string is a single variable of type certificate,
+returns the MD5 hash fingerprint of the certificate.
+
 
 .vitem &*${nhash_*&<&'n'&>&*_*&<&'m'&>&*:*&<&'string'&>&*}*&
 .cindex "expansion" "numeric hash"
@@ -10282,7 +10530,7 @@ f.7.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
 This operator encodes text according to the rules of RFC 2047. This is an
 encoding that is used in header lines to encode non-ASCII characters. It is
 assumed that the input string is in the encoding specified by the
-&%headers_charset%& option, which defaults to ISO-8859-1. If the string
+&%headers_charset%& option, which gets its default at build time. If the string
 contains only characters in the range 33&--126, and no instances of the
 characters
 .code
@@ -10320,22 +10568,47 @@ variables or headers inside regular expressions.
 .vitem &*${sha1:*&<&'string'&>&*}*&
 .cindex "SHA-1 hash"
 .cindex "expansion" "SHA-1 hashing"
-.cindex "certificate fingerprint"
-.cindex "&%sha2%& expansion item"
+.cindex certificate fingerprint
+.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.
 
+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 certificate fingerprint
 .cindex "expansion" "SHA-256 hashing"
 .cindex "&%sha256%& expansion item"
-The &%sha256%& operator computes the SHA-256 hash fingerprint of the
-certificate,
+.new
+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.
+.wen
+
+If the string is a single variable of type certificate,
+returns the SHA-256 hash fingerprint of the certificate.
+
+
+.new
+.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.
+.wen
 
 
 .vitem &*${stat:*&<&'string'&>&*}*&
@@ -10357,10 +10630,8 @@ the system administrator. &*Warning*&: The file size may be incorrect on 32-bit
 systems for files larger than 2GB.
 
 .vitem &*${str2b64:*&<&'string'&>&*}*&
-.cindex "expansion" "base64 encoding"
-.cindex "base64 encoding" "in string expansion"
 .cindex "&%str2b64%& expansion item"
-This operator converts a string into one that is base64 encoded.
+Now deprecated, a synonym for the &%base64%& expansion operator.
 
 
 
@@ -10414,6 +10685,21 @@ This forces the letters in the string into upper-case.
 .cindex "expansion" "utf-8 forcing"
 .cindex "&%utf8clean%& expansion item"
 This replaces any invalid utf-8 sequence in the string by the character &`?`&.
+
+.vitem "&*${utf8_domain_to_alabel:*&<&'string'&>&*}*&" &&&
+       "&*${utf8_domain_from_alabel:*&<&'string'&>&*}*&" &&&
+       "&*${utf8_localpart_to_alabel:*&<&'string'&>&*}*&" &&&
+       "&*${utf8_localpart_from_alabel:*&<&'string'&>&*}*&"
+.cindex expansion UTF-8
+.cindex UTF-8 expansion
+.cindex EAI
+.cindex internationalisation
+.cindex "&%utf8_domain_to_alabel%& expansion item"
+.cindex "&%utf8_domain_from_alabel%& expansion item"
+.cindex "&%utf8_localpart_to_alabel%& expansion item"
+.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>>&.
 .endlist
 
 
@@ -11210,7 +11496,7 @@ this variable holds the pipe command when the transport is running.
 .vitem "&$auth1$& &-- &$auth3$&"
 .vindex "&$auth1$&, &$auth2$&, etc"
 These variables are used in SMTP authenticators (see chapters
-&<<CHAPplaintext>>&&--&<<CHAPspa>>&). Elsewhere, they are empty.
+&<<CHAPplaintext>>&&--&<<CHAPtlsauth>>&). Elsewhere, they are empty.
 
 .vitem &$authenticated_id$&
 .cindex "authentication" "id"
@@ -11319,7 +11605,6 @@ not the same as the user id of the originator of a message (see
 &$originator_uid$&). If Exim re-execs itself, this variable in the new
 incarnation normally contains the Exim uid.
 
-.vitem &$callout_address$&
 .vitem &$callout_address$&
 .vindex "&$callout_address$&"
 After a callout for verification, spamd or malware daemon service, the
@@ -11342,18 +11627,6 @@ contain the trailing slash. If &$config_file$& does not contain a slash,
 .vindex "&$config_file$&"
 The name of the main configuration file Exim is using.
 
-.vitem &$demime_errorlevel$&
-.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 &$dkim_cur_signer$& &&&
        &$dkim_verify_status$& &&&
        &$dkim_verify_reason$& &&&
@@ -11372,7 +11645,8 @@ see section &<<SECTdemimecond>>&.
        &$dkim_key_nosubdomains$& &&&
        &$dkim_key_srvtype$& &&&
        &$dkim_key_granularity$& &&&
-       &$dkim_key_notes$&
+       &$dkim_key_notes$& &&&
+       &$dkim_key_length$&
 These variables are only available within the DKIM ACL.
 For details see chapter &<<CHAPdkim>>&.
 
@@ -11484,12 +11758,6 @@ 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
@@ -11511,7 +11779,8 @@ 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 "&$host$&"
@@ -11587,6 +11856,12 @@ 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 "&$inode$&"
@@ -11982,6 +12257,22 @@ a single-component name, Exim calls &[gethostbyname()]& (or
 qualified host name. See also &$smtp_active_hostname$&.
 
 
+.new
+.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
+For details see chapter &<<SECTproxyInbound>>&.
+.wen
+
+.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"&.
+
 .vitem &$prvscheck_address$&
 This variable is used in conjunction with the &%prvscheck%& expansion item,
 which is described in sections &<<SECTexpansionitems>>& and
@@ -12006,6 +12297,14 @@ 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 &$qualify_domain$&.
 
+.new
+.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.
+.wen
+
 .vitem &$rcpt_count$&
 .vindex "&$rcpt_count$&"
 When a message is being received by SMTP, this variable contains the number of
@@ -12539,6 +12838,7 @@ If TLS has not been negotiated, the value will be 0.
 
 .vitem &$tls_in_ourcert$&
 .vindex "&$tls_in_ourcert$&"
+.cindex certificate veriables
 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
@@ -12593,7 +12893,7 @@ 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,
@@ -12629,6 +12929,7 @@ See &$tls_in_ocsp$& for values.
 .vitem &$tls_in_peerdn$&
 .vindex "&$tls_in_peerdn$&"
 .vindex "&$tls_peerdn$&"
+.cindex certificate "extracting fields"
 When a message is received from a remote host over an encrypted SMTP
 connection, and Exim is configured to request a certificate from the client,
 the value of the Distinguished Name of the certificate is made available in the
@@ -12727,8 +13028,7 @@ 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.
 
@@ -12804,6 +13104,17 @@ 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.
 
+.new
+.ilist
+.oindex "&%perl_taintmode%&"
+.cindex "Perl" "taintmode"
+To provide more security executing Perl code via the embedded Perl
+interpeter, 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.
+.wen
+
 
 .section "Calling Perl subroutines" "SECID86"
 When the configuration file includes a &%perl_startup%& option you can make use
@@ -13271,6 +13582,7 @@ listed in more than one group.
 
 .section "Logging" "SECID99"
 .table2
+.row &%event_action%&                "custom logging"
 .row &%hosts_connection_nolog%&      "exemption from connect logging"
 .row &%log_file_path%&               "override compiled-in value"
 .row &%log_selector%&                "set/unset optional logging"
@@ -13281,6 +13593,7 @@ 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"
@@ -13331,6 +13644,7 @@ 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
 
 
@@ -13412,6 +13726,7 @@ listed in more than one group.
 .row &%helo_verify_hosts%&           "HELO hard-checked for these hosts"
 .row &%host_lookup%&                 "host name looked up for these hosts"
 .row &%host_lookup_order%&           "order of DNS and local name lookups"
+.row &%hosts_proxy%&                 "use proxy protocol for these hosts"
 .row &%host_reject_connection%&      "reject connection from these hosts"
 .row &%hosts_treat_as_local%&        "useful in some cluster configurations"
 .row &%local_scan_timeout%&          "timeout for &[local_scan()]&"
@@ -13541,11 +13856,13 @@ 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"
 .row &%pipelining_advertise_hosts%&  "advertise pipelining to these hosts"
 .row &%prdr_enable%&                 "advertise PRDR to all hosts"
+.row &%smtputf8_advertise_hosts%&    "advertise SMTPUTF8 to these hosts"
 .row &%tls_advertise_hosts%&         "advertise TLS to these hosts"
 .endtable
 
@@ -13621,6 +13938,7 @@ See also the &'Policy controls'& section above.
 .row &%bounce_message_file%&         "content of bounce"
 .row &%bounce_message_text%&         "content of bounce"
 .row &%bounce_return_body%&          "include body if returning message"
+.row &%bounce_return_linesize_limit%& "limit on returned message line length"
 .row &%bounce_return_message%&       "include original message in bounce"
 .row &%bounce_return_size_limit%&    "limit on returned message"
 .row &%bounce_sender_authentication%& "send authenticated sender with bounce"
@@ -13780,6 +14098,12 @@ 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
@@ -13929,6 +14253,24 @@ error that is detected during reception, only those header lines preceding the
 point at which the error was detected are returned.
 .cindex "bounce message" "including original"
 
+.option bounce_return_linesize_limit main integer 998
+.cindex "size" "of bounce lines, limit"
+.cindex "bounce message" "line length limit"
+.cindex "limit" "bounce message line length"
+This option sets a limit in bytes on the line length of messages
+that are returned to senders due to delivery problems,
+when &%bounce_return_message%& is true.
+The default value corresponds to RFC limits.
+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 message.
+In this case lines from the original are truncated.
+
+The option does not apply to messages generated by an &(autoreply)& transport.
+
+
 .option bounce_return_message main boolean true
 If this option is set false, none of the original message is included in
 bounce messages generated by Exim. See also &%bounce_return_size_limit%& and
@@ -14004,11 +14346,15 @@ $primary_hostname-$tod_epoch-testing
 See section &<<CALLaddparcall>>& for details of how this value is used.
 
 
-.option check_log_inodes main integer 0
+.new
+.option check_log_inodes main integer 100
+.wen
 See &%check_spool_space%& below.
 
 
-.option check_log_space main integer 0
+.new
+.option check_log_space main integer 10M
+.wen
 See &%check_spool_space%& below.
 
 .oindex "&%check_rfc2047_length%&"
@@ -14023,11 +14369,15 @@ 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
+.new
+.option check_spool_inodes main integer 100
+.wen
 See &%check_spool_space%& below.
 
 
-.option check_spool_space main integer 0
+.new
+.option check_spool_space main integer 10M
+.wen
 .cindex "checking disk space"
 .cindex "disk space, checking"
 .cindex "spool directory" "checking space"
@@ -14038,7 +14388,7 @@ 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.
@@ -14047,7 +14397,7 @@ 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
@@ -14066,12 +14416,29 @@ 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.
 
+.new
+There is a slight performance penalty for these checks.
+Versions of Exim preceding 4.88 had these disabled by default;
+high-rate intallations confident they will never run out of resources
+may wish to deliberately disable them.
+.wen
+
+.new
+.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.
+.wen
+
 .option daemon_smtp_ports main string &`smtp`&
 .cindex "port" "for daemon"
 .cindex "TCP/IP" "setting listening ports"
@@ -14093,6 +14460,7 @@ 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
@@ -14422,6 +14790,12 @@ own &'Reply-To:'& header line, the value of the &%errors_reply_to%& option is
 not used.
 
 
+.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>>&.
+
+
 .option exim_group main string "compile-time configured"
 .cindex "gid (group id)" "Exim's own"
 .cindex "Exim group"
@@ -14767,6 +15141,12 @@ If the &%smtp_connection%& log selector is not set, this option has no effect.
 
 
 
+.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>>&.
+
+
 .option hosts_treat_as_local main "domain list&!!" unset
 .cindex "local host" "domains treated as"
 .cindex "host" "treated as local"
@@ -14833,6 +15213,34 @@ 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
@@ -14843,6 +15251,7 @@ logged.
 
 .option ldap_ca_cert_dir main string unset
 .cindex "LDAP", "TLS CA certificate directory"
+.cindex certificate "directory for LDAP"
 This option indicates which directory contains CA certificates for verifying
 a TLS certificate presented by an LDAP server.
 While Exim does not provide a default value, your SSL library may.
@@ -14852,6 +15261,7 @@ and constrained to be a directory.
 
 .option ldap_ca_cert_file main string unset
 .cindex "LDAP", "TLS CA certificate file"
+.cindex certificate "file for LDAP"
 This option indicates which file contains CA certificates for verifying
 a TLS certificate presented by an LDAP server.
 While Exim does not provide a default value, your SSL library may.
@@ -14861,6 +15271,7 @@ and constrained to be a file.
 
 .option ldap_cert_file main string unset
 .cindex "LDAP" "TLS client certificate file"
+.cindex certificate "file for LDAP"
 This option indicates which file contains an TLS client certificate which
 Exim should present to the LDAP server during TLS negotiation.
 Should be used together with &%ldap_cert_key%&.
@@ -14868,6 +15279,7 @@ Should be used together with &%ldap_cert_key%&.
 
 .option ldap_cert_key main string unset
 .cindex "LDAP" "TLS client key file"
+.cindex certificate "key for LDAP"
 This option indicates which file contains the secret/private key to use
 to prove identity to the LDAP server during TLS negotiation.
 Should be used together with &%ldap_cert_file%&, which contains the
@@ -15246,7 +15658,7 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)&
 transport driver.
 
 
-.option openssl_options main "string list" "+no_sslv2"
+.option openssl_options main "string list" "+no_sslv2 +single_dh_use"
 .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,
@@ -15377,14 +15789,20 @@ 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"
@@ -15624,7 +16042,7 @@ 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,
@@ -15639,6 +16057,13 @@ 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.
 
+.new
+.cindex queues named
+.cindex "named queues"
+To set limits for different named queues use
+an expansion depending on the &$queue_name$& variable.
+.wen
+
 .option queue_smtp_domains main "domain list&!!" unset
 .cindex "queueing incoming messages"
 .cindex "message" "queueing remote deliveries"
@@ -15867,6 +16292,12 @@ 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"
@@ -16301,6 +16732,15 @@ example, instead of &"Administrative prohibition"&, it might give:
 550 failing address in "From" header is: <user@dom.ain
 .endd
 
+
+.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
+response to EHLO only to those client hosts that match this option. See
+chapter &<<CHAPi18n>>& for details of Exim's support for internationalisation.
+
+
 .option spamd_address main string "see below"
 This option is available when Exim is compiled with the content-scanning
 extension. It specifies how Exim connects to SpamAssassin's &%spamd%& daemon.
@@ -16417,6 +16857,15 @@ 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"
@@ -16529,6 +16978,7 @@ 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
@@ -16544,7 +16994,7 @@ runs. This is appropriate behaviour for obtaining wall-clock time on some, but
 unfortunately not all, operating systems.
 
 
-.option tls_advertise_hosts main "host list&!!" unset
+.option tls_advertise_hosts main "host list&!!" *
 .cindex "TLS" "advertising"
 .cindex "encryption" "on SMTP connection"
 .cindex "SMTP" "encrypted connection"
@@ -16552,6 +17002,9 @@ 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.
+Note that the default value requires that a certificate be supplied
+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
@@ -16572,6 +17025,11 @@ 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.
 
+.new
+If this option is unset or empty a fresh self-signed certificate will be
+generated for every connection.
+.wen
+
 .option tls_crl main string&!! unset
 .cindex "TLS" "server certificate revocation list"
 .cindex "certificate" "revocation list for server"
@@ -16607,7 +17065,15 @@ 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
+.new
+&*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.
+.wen
+
+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
@@ -16623,23 +17089,39 @@ Exim will attempt to load a file from inside the spool directory.  If the file
 does not exist, Exim will attempt to create it.
 See section &<<SECTgnutlsparam>>& for further details.
 
+.new
 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.
+.wen
 
 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,
@@ -16665,7 +17147,7 @@ this option selects a EC curve for use by Exim.
 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.
+which tells the library to choose.
 
 If the option is set to an empty string, no EC curves will be enabled.
 
@@ -16678,9 +17160,7 @@ 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).
-.wen
 
 
 .option tls_on_connect_ports main "string list" unset
@@ -17207,7 +17687,7 @@ 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.
@@ -19508,12 +19988,17 @@ 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.
 
@@ -20168,7 +20653,7 @@ 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
@@ -20430,6 +20915,12 @@ its removal from incoming messages, so that delivered messages can safely be
 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>>&.
+
+
 .option group transports string&!! "Exim group"
 .cindex "transport" "group; specifying"
 This option specifies a gid for running the transport process, overriding any
@@ -20477,7 +20968,7 @@ 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.
@@ -20531,6 +21022,30 @@ transport, the &[initgroups()]& function is called when running the transport
 to ensure that any additional groups associated with the uid are set up.
 
 
+.option max_parallel transports integer&!! unset
+.cindex limit "transport parallelism"
+.cindex transport "parallel processes"
+.cindex transport "concurrency limit"
+.cindex "delivery" "parallelism for transport"
+If this option is set and expands to an integer greater than zero
+it limits the number of concurrent runs of the transport.
+The control does not apply to shadow transports.
+
+.cindex "hints database" "transport concurrency control"
+Exim implements this control by means of a hints database in which a record is
+incremented whenever a transport process is beaing created. The record
+is decremented and possibly removed when the process terminates.
+Obviously there is scope for
+records to get left lying around if there is a system or program crash. To
+guard against this, Exim ignores any records that are more than six hours old.
+
+If you use this option, you should also arrange to delete the
+relevant hints database whenever your system reboots. The names of the files
+start with &_misc_& and they are kept in the &_spool/db_& directory. There
+may be one or two files, depending on the type of DBM in use. The same files
+are used for ETRN and smtp transport serialization.
+
+
 .option message_size_limit transports string&!! 0
 .cindex "limit" "message size per transport"
 .cindex "size" "of message, limit"
@@ -20677,6 +21192,7 @@ 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.
+If unset, or expanding to an empty string, no filtering is done.
 
 When the message is about to be written out, the command specified by
 &%transport_filter%& is started up in a separate, parallel process, and
@@ -22428,6 +22944,8 @@ 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.
+Alternatively the &%max_parallel%& option could be used with a value
+of "1" to enforce serialization.
 
 
 
@@ -22547,11 +23065,12 @@ 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
@@ -22646,7 +23165,7 @@ 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
@@ -22771,12 +23290,12 @@ 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"
+.new
+This option is expanded and
+.wen
+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.
@@ -23155,6 +23674,15 @@ 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_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 delay_after_cutoff smtp boolean true
 This option controls what happens when all remote IP addresses for a given
 domain have been inaccessible for so long that they have passed their retry
@@ -23208,7 +23736,7 @@ 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.
@@ -23463,6 +23991,35 @@ connects. If authentication fails, Exim will try to transfer the message
 unauthenticated. See also &%hosts_require_auth%&, and chapter
 &<<CHAPSMTPAUTH>>& for details of authentication.
 
+.new
+.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 conjuction with a transport filter.
+.wen
+
+.new
+.option hosts_try_fastopen smtp "host list!!" unset
+.option "fast open, TCP" "enabling, in client"
+.option "TCP Fast Open" "enabling, in client"
+.option "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.
+.wen
+
 .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
@@ -23610,6 +24167,8 @@ 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.
 
+See also the &%max_parallel%& generic transport option.
+
 
 .option size_addition smtp integer 1024
 .cindex "SMTP" "SIZE"
@@ -23628,6 +24187,12 @@ Alternatively, if the value of &%size_addition%& is set negative, it disables
 the use of the SIZE option altogether.
 
 
+.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>>&.
+
+
 .option tls_certificate smtp string&!! unset
 .cindex "TLS" "client certificate, location of"
 .cindex "certificate" "client, location of"
@@ -23785,7 +24350,7 @@ 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
@@ -24261,7 +24826,7 @@ replaced, not just the working part. The replacement must be a complete RFC
 2822 address, including the angle brackets if necessary. If text outside angle
 brackets contains a character whose value is greater than 126 or less than 32
 (except for tab), the text is encoded according to RFC 2047. The character set
-is taken from &%headers_charset%&, which defaults to ISO-8859-1.
+is taken from &%headers_charset%&, which gets its default at build time.
 
 When the &"w"& flag is set on a rule that causes an envelope address to be
 rewritten, all but the working part of the replacement address is discarded.
@@ -26237,6 +26802,24 @@ tls:
                        }    }   } }
   server_set_id =     ${if = {1}{${listcount:$auth1}} {$auth1}{}}
 .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)
+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.
+
+. An alternative might use
+. .code
+.   server_param1 = ${sha256:$tls_in_peercert}
+. .endd
+. 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.
+
 .ecindex IIDtlsauth1
 .ecindex IIDtlsauth2
 
@@ -26552,7 +27135,8 @@ 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:
@@ -26597,10 +27181,17 @@ 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.
+
+.new
+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.
+.wen
+
+Further protection requires some further configuration at the server end.
 
 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,
@@ -26768,9 +27359,7 @@ 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%&.
@@ -26977,8 +27566,13 @@ during TLS session handshake, to permit alternative values to be chosen:
 
 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.
+.new
+Further, the initial cerificate 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.
+.wen
 
 The Exim developers are proceeding cautiously and so far no other TLS options
 are re-expanded.
@@ -27158,9 +27752,6 @@ 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"
@@ -27275,6 +27866,10 @@ 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.
 
+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.
+
 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
 at the first newline and a panic logged if it does). Such a message cannot
@@ -27300,6 +27895,17 @@ 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.
 
+.new
+.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.
+.wen
+
 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
@@ -27352,8 +27958,10 @@ 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
-for this can be disabled when the MAIL-time $smtp_command included
-"PRDR".  Any required difference in behaviour of the main DATA-time
+.cindex "PRDR" "variable for"
+for this can be disabled when the variable &$prdr_requested$&
+is &"yes"&.
+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).
 
@@ -27619,7 +28227,7 @@ 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
@@ -27641,8 +28249,8 @@ 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
@@ -28194,6 +28802,19 @@ all the conditions are true, wherever it appears in an ACL command, whereas
 effect.
 
 
+.new
+.vitem &*queue*&&~=&~<&'text'&>
+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.
+.wen
+
+
 .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
@@ -28280,7 +28901,7 @@ 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.
@@ -28294,7 +28915,9 @@ 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.
@@ -28305,6 +28928,12 @@ 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.
 
+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.
@@ -28312,11 +28941,20 @@ It is not supported for messages received with the SMTP PRDR option 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.
 
+.new
+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 receipient verify conditions in the ACL.
+.wen
+
 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.
@@ -28330,13 +28968,18 @@ with &`-d`&, with the output going to a new logfile, 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.
+.new
+Logging may be stopped, and the file removed, with the &'kill'& option.
+.wen
+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
 
 
@@ -28532,6 +29175,11 @@ 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%&.
+
+.vitem &*control&~=&~utf8_downconvert*&
+This control enables conversion of UTF-8 in message addresses
+to a-label form.
+For details see &<<SECTi18nMTA>>&.
 .endlist vlist
 
 
@@ -28570,7 +29218,7 @@ 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
@@ -28671,8 +29319,8 @@ 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
@@ -28810,12 +29458,6 @@ 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"
@@ -29209,9 +29851,13 @@ deny  dnslists = blackholes.mail-abuse.org
 warn  message  = X-Warn: sending host is on dialups list
       dnslists = dialups.mail-abuse.org
 .endd
-DNS list lookups are cached by Exim for the duration of the SMTP session,
+.cindex cacheing "of dns lookup"
+.cindex DNS TTL
+DNS list lookups are cached by Exim for the duration of the SMTP session
+(but limited by the DNS return TTL value),
 so a lookup based on the IP address is done at most once for any incoming
-connection. Exim does not share information between multiple incoming
+connection (assuming long-enough TTL).
+Exim does not share information between multiple incoming
 connections (but your local name server cache should be active).
 
 
@@ -30580,14 +31226,6 @@ 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
 
 
@@ -30630,10 +31268,6 @@ 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
@@ -30883,7 +31517,7 @@ 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
@@ -30974,23 +31608,17 @@ 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
@@ -31070,7 +31698,7 @@ 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,
@@ -31079,7 +31707,7 @@ In the latter case, the range is tried in strict order.
 
 Elements after the first for Unix sockets, or second for TCP socket,
 are options.
-The supported option are:
+The supported options are:
 .code
 pri=<priority>      Selection priority
 weight=<value>      Selection bias
@@ -31197,6 +31825,11 @@ 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.
+.new
+Beware that SpamAssassin may return non-ASCII characters, especially
+when running in country-specific locales, which are not legal
+unencoded in headers.
+.wen
 
 .vitem &$spam_action$&
 For SpamAssassin either 'reject' or 'no action' depending on the
@@ -31486,90 +32119,6 @@ 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
 
 
@@ -32866,6 +33415,7 @@ 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:'&,
@@ -32922,6 +33472,7 @@ 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.
@@ -32939,6 +33490,7 @@ 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
@@ -32950,6 +33502,7 @@ 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"
@@ -32993,6 +33546,7 @@ 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
@@ -33008,6 +33562,7 @@ 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.
@@ -33024,6 +33579,7 @@ 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
@@ -33038,6 +33594,7 @@ 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%&
@@ -33050,6 +33607,7 @@ 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
@@ -33750,13 +34308,18 @@ specific badly-behaved hosts that you have to live with.
 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.
-If no ACL is defined, the command is rejected.
 
 .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.
 When VRFY is accepted, it runs exactly the same code as when Exim is
-called with the &%-bv%& option.
+called with the &%-bv%& option, and returns 250/451/550
+SMTP response codes.
 
 .cindex "EXPN" "processing"
+If no ACL for EXPN is defined, the command is rejected.
 When EXPN is accepted, a single-level expansion of the address is done.
 EXPN is treated as an &"address test"& (similar to the &%-bt%& option) rather
 than a verification (the &%-bv%& option). If an unqualified local part is given
@@ -35013,6 +35576,7 @@ 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
@@ -35076,6 +35640,7 @@ extensions (ESMTP), encryption, or authentication were used. If the SMTP
 session was encrypted, there is an additional X field that records the cipher
 suite that was used.
 
+.cindex log protocol
 The protocol is set to &"esmtpsa"& or &"esmtpa"& for messages received from
 hosts that have authenticated themselves using the SMTP AUTH command. The first
 value is used when the SMTP connection was encrypted (&"secure"&). In this case
@@ -35100,7 +35665,7 @@ data when a message is received. See section &<<SECTlogselector>>& below.
 .cindex "log" "delivery line"
 The format of the single-line entry in the main log that is written for every
 delivery is shown in one of the examples below, for local and remote
-deliveries, respectively. Each example has been split into two lines in order
+deliveries, respectively. Each example has been split into multiple lines in order
 to fit it on the page:
 .code
 2002-10-31 08:59:13 16ZCW1-0005MB-00 => marv
@@ -35239,18 +35804,23 @@ the following table:
 &`CV  `&        certificate verification status
 &`D   `&        duration of &"no mail in SMTP session"&
 &`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
 &`P   `&        on &`<=`& lines: protocol used
 &`    `&        on &`=>`& and &`**`& lines: return path
+&`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
+&`S   `&        size of message in bytes
 &`SNI `&        server name indication from TLS client hello
 &`ST  `&        shadow transport name
 &`T   `&        on &`<=`& lines: message subject (topic)
@@ -35328,20 +35898,20 @@ selection marked by asterisks:
 &` deliver_time               `&  time taken to perform delivery
 &` delivery_size              `&  add &`S=`&&'nnn'& to => lines
 &`*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
 &` 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
+&` proxy                      `&  proxy address on <= and => lines
 &` received_recipients        `&  recipients on <= lines
 &` received_sender            `&  sender on <= lines
 &`*rejected_header            `&  header contents on reject log
@@ -35436,6 +36006,14 @@ the &"=>"& line, tagged with S=.
 &%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
@@ -35464,9 +36042,16 @@ 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
+.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..
+See &<<SECTproxyInbound>>& for more information.
 .next
 .cindex "log" "incoming remote port"
 .cindex "port" "logging remote"
@@ -35489,22 +36074,18 @@ connection is unexpectedly dropped.
 .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"
 &%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.
@@ -36251,6 +36832,9 @@ Serializing ETRN runs (when &%smtp_etrn_serialize%& is set)
 .next
 Serializing delivery to a specific host (when &%serialize_hosts%& is set in an
 &(smtp)& transport)
+.next
+Limiting the concurrency of specific transports (when &%max_parallel%& is set
+in a transport)
 .endlist
 
 
@@ -37626,17 +38210,17 @@ 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.
 
-Since version 4.70, DKIM support is compiled into Exim by default. It can be
-disabled by setting DISABLE_DKIM=yes in Local/Makefile.
+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
@@ -37662,10 +38246,10 @@ where you accept mail from relay sources (internal hosts or authenticated
 senders).
 
 
-.section "Signing outgoing messages" "SECID513"
+.section "Signing outgoing messages" "SECDKIMSIGN"
 .cindex "DKIM" "signing"
 
-Signing is implemented by setting private options on the SMTP transport.
+Signing is enabled by setting private options on the SMTP transport.
 These options take (expandable) strings as arguments.
 
 .option dkim_domain smtp string&!! unset
@@ -37677,7 +38261,7 @@ option is put into the &%$dkim_domain%& expansion variable.
 MANDATORY:
 This sets the key selector string. You can use the &%$dkim_domain%& expansion
 variable to look up a matching selector. The result is put in the expansion
-variable &%$dkim_selector%& which should be used in the &%dkim_private_key%&
+variable &%$dkim_selector%& which may be used in the &%dkim_private_key%&
 option along with &%$dkim_domain%&.
 
 .option dkim_private_key smtp string&!! unset
@@ -37722,7 +38306,7 @@ used.
 .section "Verifying DKIM signatures in incoming mail" "SECID514"
 .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.
@@ -37775,6 +38359,7 @@ 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 &%$dkim_verify_status%&
 A string describing the general status of the signature. One of
 .ilist
@@ -37789,6 +38374,7 @@ available in &%$dkim_verify_reason%&.
 .next
 &%pass%&: The signature passed verification. It is valid.
 .endlist
+
 .vitem &%$dkim_verify_reason%&
 A string giving a little bit more detail when &%$dkim_verify_status%& is either
 "fail" or "invalid". One of
@@ -37808,51 +38394,75 @@ 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
+
 .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'.
+
 .vitem &%$dkim_canon_body%&
 The body canonicalization method. One of 'relaxed' or 'simple'.
+
 .vitem &%dkim_canon_headers%&
 The header canonicalization method. One of 'relaxed' or 'simple'.
+
 .vitem &%$dkim_copiedheaders%&
 A transcript of headers and their values which are included in the signature
 (copied from the 'z=' tag of the signature).
+.new
+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.
+.wen
+
 .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.
 .endlist
 
 In addition, two ACL conditions are provided:
@@ -37865,13 +38475,18 @@ 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
 
+.new
+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.
+.wen
+
 .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
@@ -37892,6 +38507,386 @@ for more information of what they mean.
 . ////////////////////////////////////////////////////////////////////////////
 . ////////////////////////////////////////////////////////////////////////////
 
+.chapter "Proxies" "CHAPproxies" &&&
+         "Proxy support"
+.cindex "proxy support"
+.cindex "proxy" "access via"
+
+A proxy is an intermediate system through which communication is passed.
+Proxies may provide a security, availability or load-distribution function.
+
+
+.section "Inbound proxies" SECTproxyInbound
+.cindex proxy inbound
+.cindex proxy "server side"
+.cindex proxy "Proxy protocol"
+.cindex "Proxy protocol" proxy
+
+Exim has support for receiving inbound SMTP connections via a proxy
+that uses &"Proxy Protocol"& to speak to it.
+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
+That URL was revised in May 2014 to version 2 spec:
+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
+to distribute load.
+Exim uses the local protocol communication with the proxy to obtain
+the remote SMTP system IP address and port information.
+There is no logging if a host passes or
+fails Proxy Protocol negotiation, but it can easily be determined and
+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.
+
+.new
+The following expansion variables are usable
+(&"internal"& and &"external"& here refer to the interfaces
+of the proxy):
+.display
+&'proxy_external_address   '& IP of host being proxied or IP of remote interface of proxy
+&'proxy_external_port      '& Port of host being proxied or Port on remote interface of proxy
+&'proxy_local_address '& IP of proxy server inbound or IP of local interface of proxy
+&'proxy_local_port    '& Port of proxy server inbound or Port on local interface of proxy
+&'proxy_session        '& boolean: SMTP connection via proxy
+.endd
+If &$proxy_session$& is set but &$proxy_external_address$& is empty
+there was a protocol error.
+.wen
+
+Since the real connections are all coming from the proxy, and the
+per host connection tracking is done before Proxy Protocol is
+evaluated, &%smtp_accept_max_per_host%& must be set high enough to
+handle all of the parallel volume you expect per inbound proxy.
+With the option set so high, you lose the ability
+to protect your server from many connections from one IP.
+In order to prevent your server from overload, you
+need to add a per connection ratelimit to your connect ACL.
+A possible solution is:
+.display
+  # Set max number of connections per host
+  LIMIT   = 5
+  # Or do some kind of IP lookup in a flat file or database
+  # LIMIT = ${lookup{$sender_host_address}iplsearch{/etc/exim/proxy_limits}}
+
+  defer   message        = Too many connections from this IP right now
+          ratelimit      = LIMIT / 5s / per_conn / strict
+.endd
+
+
+
+.section "Outbound proxies" SECTproxySOCKS
+.cindex proxy outbound
+.cindex proxy "client side"
+.cindex proxy SOCKS
+.cindex SOCKS proxy
+Exim has support for sending outbound SMTP via a proxy
+using a protocol called SOCKS5 (defined by RFC1928).
+The support can be optionally included by defining SUPPORT_SOCKS=yes in
+Local/Makefile.
+
+Use of a proxy is enabled by setting the &%socks_proxy%& option
+on an smtp transport.
+The option value is expanded and should then be a list
+(colon-separated by default) of proxy specifiers.
+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>.
+The list of options is in the following table:
+.display
+&'auth   '& authentication method
+&'name   '& authentication username
+&'pass   '& authentication password
+&'port   '& tcp port
+&'tmo    '& connection timeout
+&'pri    '& priority
+&'weight '& selection bias
+.endd
+
+More details on each of these options follows:
+
+.ilist
+.cindex authentication "to proxy"
+.cindex proxy authentication
+&%auth%&: Either &"none"& (default) or &"name"&.
+Using &"name"& selects username/password authentication per RFC 1929
+for access to the proxy.
+Default is &"none"&.
+.next
+&%name%&: sets the username for the &"name"& authentication method.
+Default is empty.
+.next
+&%pass%&: sets the password for the &"name"& authentication method.
+Default is empty.
+.next
+&%port%&: the TCP port number to use for the connection to the proxy.
+Default is 1080.
+.next
+&%tmo%&: sets a connection timeout in seconds for this proxy.
+Default is 5.
+.next
+&%pri%&: specifies a priority for the proxy within the list,
+higher values being tried first.
+The default priority is 1.
+.next
+&%weight%&: specifies a selection bias.
+Within a priority set servers are queried in a random fashion,
+weighted by this value.
+The default value for selection bias is 1.
+.endlist
+
+Proxies from the list are tried according to their priority
+and weight settings until one responds.  The timeout for the
+overall connection applies to the set of proxied attempts.
+
+.section Logging SECTproxyLog
+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.
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
+.chapter "Internationalisation" "CHAPi18n" &&&
+         "Internationalisation""
+.cindex internationalisation "email address"
+.cindex EAI
+.cindex i18n
+.cindex UTF-8 "mail name handling"
+
+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.
+
+.section "MTA operations" SECTi18nMTA
+.cindex SMTPUTF8 "ESMTP option"
+The main configuration option &%smtputf8_advertise_hosts%& specifies
+a host list.  If this matches the sending host and
+accept_8bitmime is true (the default) then the ESMTP option
+SMTPUTF8 will be advertised.
+
+If the sender specifies the SMTPUTF8 option on a MAIL command
+international handling for the message is enabled and
+the expansion variable &$message_smtputf8$& will have value TRUE.
+
+The option &%allow_utf8_domains%& is set to true for this
+message. All DNS lookups are converted to a-label form
+whatever the setting of &%allow_utf8_domains%&
+when Exim is built with SUPPORT_I18N.
+
+Both localparts and domain are maintained as the original
+UTF-8 form internally; any comparison or regular-expression use will
+require appropriate care.  Filenames created, eg. by
+the appendfile transport, will have UTF-8 names.
+
+HELO names sent by the smtp transport will have any UTF-8
+components expanded to a-label form,
+and any certificate name checks will be done using the a-label
+form of the name.
+
+.cindex log protocol
+.cindex SMTPUTF8 logging
+Log lines and Received-by: header lines will acquire a "utf8"
+prefix on the protocol element, eg. utf8esmtp.
+
+The following expansion operators can be used:
+.code
+${utf8_domain_to_alabel:str}
+${utf8_domain_from_alabel:str}
+${utf8_localpart_to_alabel:str}
+${utf8_localpart_from_alabel:str}
+.endd
+
+ACLs may use the following modifier:
+.display
+control = utf8_downconvert
+control = utf8_downconvert/<value>
+.endd
+This sets a flag requiring that addresses are converted to
+a-label form before smtp delivery, for use in a
+Message Submission Agent context.
+If a value is appended it may be:
+.display
+&`1  `& (default) mandatory downconversion
+&`0  `& no downconversion
+&`-1 `& if SMTPUTF8 not supported by destination host
+.endd
+
+If mua_wrapper is set, the utf8_downconvert control
+is initially set to -1.
+
+
+There is no explicit support for VRFY and EXPN.
+Configurations supporting these should inspect
+&$smtp_command_argument$& for an SMTPUTF8 argument.
+
+There is no support for LMTP on Unix sockets.
+Using the "lmtp" protocol option on an smtp transport,
+for LMTP over TCP, should work as expected.
+
+There is no support for DSN unitext handling,
+and no provision for converting logging from or to UTF-8.
+
+
+
+.section "MDA operations" SECTi18nMDA
+To aid in constructing names suitable for IMAP folders
+the following expansion operator can be used:
+.code
+${imapfolder {<string>} {<sep>} {<specials>}}
+.endd
+
+The string is converted from the charset specified by
+the "headers charset" command (in a filter file)
+or &%headers_charset%& main configuration option (otherwise),
+to the
+modified UTF-7 encoding specified by RFC 2060,
+with the following exception: All occurences of <sep>
+(which has to be a single character)
+are replaced with periods ("."), and all periods and slashes that are not
+<sep> and are not in the <specials> string are BASE64 encoded.
+
+The third argument can be omitted, defaulting to an empty string.
+The second argument can be omitted, defaulting to "/".
+
+This is the encoding used by Courier for Maildir names on disk, and followed
+by many other IMAP servers.
+
+Examples:
+.display
+&`${imapfolder {Foo/Bar}}       `& yields &`Foo.Bar`&
+&`${imapfolder {Foo/Bar}{.}{/}} `& yields &`Foo&&AC8-Bar`&
+&`${imapfolder {Räksmörgås}}    `& yields &`R&&AOQ-ksm&&APY-rg&&AOU-s`&
+.endd
+
+Note that the source charset setting is vital, and also that characters
+must be representable in UTF-16.
+
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
+.chapter "Events" "CHAPevents" &&&
+         "Events"
+.cindex events
+
+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
+actions (for example, to a database) but can also be used to modify some
+processing actions.
+
+Most installations will never need to use Events.
+The support can be left out of a build by defining DISABLE_EVENT=yes
+in &_Local/Makefile_&.
+
+There are two major classes of events: main and transport.
+The main configuration option &%event_action%& controls reception events;
+a transport option &%event_action%& controls delivery events.
+
+Both options are a string which is expanded when the event fires.
+An example might look like:
+.cindex logging custom
+.code
+event_action = ${if eq {msg:delivery}{$event_name} \
+{${lookup pgsql {SELECT * FROM record_Delivery( \
+    '${quote_pgsql:$sender_address_domain}',\
+    '${quote_pgsql:${lc:$sender_address_local_part}}', \
+    '${quote_pgsql:$domain}', \
+    '${quote_pgsql:${lc:$local_part}}', \
+    '${quote_pgsql:$host_address}', \
+    '${quote_pgsql:${lc:$host}}', \
+    '${quote_pgsql:$message_exim_id}')}} \
+} {}}
+.endd
+
+Events have names which correspond to the point in process at which they fire.
+The name is placed in the variable &$event_name$& and the event action
+expansion must check this, as it will be called for every possible event type.
+
+The current list of events is:
+.display
+&`msg:complete           after    main       `& per message
+&`msg:delivery           after    transport  `& per recipient
+&`msg:rcpt:host:defer    after    transport  `& per recipient per host
+&`msg:rcpt:defer         after    transport  `& per recipient
+&`msg:host:defer         after    transport  `& per attempt
+&`msg:fail:delivery      after    main       `& per recipient
+&`msg:fail:internal      after    main       `& per recipient
+&`tcp:connect            before   transport  `& per connection
+&`tcp:close              after    transport  `& per connection
+&`tls:cert               before   both       `& per certificate in verification chain
+&`smtp:connect           after    transport  `& per connection
+.endd
+New event types may be added in future.
+
+The event name is a colon-separated list, defining the type of
+event in a tree of possibilities.  It may be used as a list
+or just matched on as a whole.  There will be no spaces in the name.
+
+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).
+
+An additional variable, &$event_data$&, is filled with information varying
+with the event type:
+.display
+&`msg:delivery         `& smtp confirmation mssage
+&`msg:rcpt:host:defer  `& error string
+&`msg:rcpt:defer       `& error string
+&`msg:host:defer       `& error string
+&`tls:cert             `& verification chain depth
+&`smtp:connect         `& smtp banner
+.endd
+
+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
+the course of its processing:
+.ilist
+variables set in transport events will not be visible outside that
+transport call
+.next
+acl_m variables in a server context are lost on a new connection,
+and after smtp helo/ehlo/mail/starttls/rset commands
+.endlist
+Using an ACL expansion with the logwrite modifier can be
+a useful way of writing to the main log.
+
+The expansion of the event_action option should normally
+return an empty string.  Should it return anything else the
+following will be forced:
+.display
+&`msg:delivery     `&  (ignored)
+&`msg:host:defer   `&  (ignored)
+&`msg:fail:delivery`&  (ignored)
+&`tcp:connect      `&  do not connect
+&`tcp:close        `&  (ignored)
+&`tls:cert         `&  refuse verification
+&`smtp:connect     `&  close connection
+.endd
+No other use is made of the result string.
+
+For a tcp:connect event, if the connection is being made to a proxy
+then the address and port variables will be that of the proxy and not
+the target system.
+
+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.
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
 .chapter "Adding new drivers or lookup types" "CHID13" &&&
          "Adding drivers or lookups"
 .cindex "adding drivers"