Fix ${domain:} for a bare local-part input. Bug 2375

[users/jgh/exim.git] / doc / doc-docbook / spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index bfacdef81e69f5e311acdc2249bc12d05c3aba0d..63db8ef707902698dd85819f785ca7639e290690 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -2528,6 +2528,8 @@ use of Exim's filtering capabilities, you should make the document entitled
 If you are already running Exim on your host, building and installing a new
 version automatically makes it available to MUAs, or any other programs that
 call the MTA directly. However, if you are running an Exim daemon, you do need
 If you are already running Exim on your host, building and installing a new
 version automatically makes it available to MUAs, or any other programs that
 call the MTA directly. However, if you are running an Exim daemon, you do need

+.cindex restart "on HUP signal"
+.cindex signal "HUP, to restart"

 to send it a HUP signal, to make it re-execute itself, and thereby pick up the
 new binary. You do not need to stop processing mail in order to install a new
 version of Exim. The install script does not modify an existing runtime
 to send it a HUP signal, to make it re-execute itself, and thereby pick up the
 new binary. You do not need to stop processing mail in order to install a new
 version of Exim. The install script does not modify an existing runtime


@@ -2626,6 +2628,7 @@ supplementary group is one of those listed in the &%trusted_groups%&
 configuration option. Note that the Exim group is not automatically trusted.
 
 .cindex '&"From"& line'
 configuration option. Note that the Exim group is not automatically trusted.
 
 .cindex '&"From"& line'

+.cindex "envelope from"

 .cindex "envelope sender"
 Trusted users are always permitted to use the &%-f%& option or a leading
 &"From&~"& line to specify the envelope sender of a message that is passed to
 .cindex "envelope sender"
 Trusted users are always permitted to use the &%-f%& option or a leading
 &"From&~"& line to specify the envelope sender of a message that is passed to


@@ -2765,9 +2768,12 @@ used to specify a path on the command line if a pid file is required.
 
 The SIGHUP signal
 .cindex "SIGHUP"
 
 The SIGHUP signal
 .cindex "SIGHUP"

+.cindex restart "on HUP signal"
+.cindex signal "HUP, to restart"

 .cindex "daemon" "restarting"
 .cindex signal "to reload configuration"
 .cindex daemon "reload configuration"
 .cindex "daemon" "restarting"
 .cindex signal "to reload configuration"
 .cindex daemon "reload configuration"

+.cindex reload configuration

 can be used to cause the daemon to re-execute itself. This should be done
 whenever Exim's configuration file, or any file that is incorporated into it by
 means of the &%.include%& facility, is changed, and also whenever a new version
 can be used to cause the daemon to re-execute itself. This should be done
 whenever Exim's configuration file, or any file that is incorporated into it by
 means of the &%.include%& facility, is changed, and also whenever a new version


@@ -2877,6 +2883,7 @@ separate document entitled &'Exim's interfaces to mail filtering'&.
 
 When testing a filter file,
 .cindex "&""From""& line"
 
 When testing a filter file,
 .cindex "&""From""& line"

+.cindex "envelope from"

 .cindex "envelope sender"
 .oindex "&%-f%&" "for filter testing"
 the envelope sender can be set by the &%-f%& option,
 .cindex "envelope sender"
 .oindex "&%-f%&" "for filter testing"
 the envelope sender can be set by the &%-f%& option,


@@ -3717,6 +3724,7 @@ between &%-F%& and the <&'string'&> is optional.
 .cindex "sender" "address"
 .cindex "address" "sender"
 .cindex "trusted users"
 .cindex "sender" "address"
 .cindex "address" "sender"
 .cindex "trusted users"

+.cindex "envelope from"

 .cindex "envelope sender"
 .cindex "user" "trusted"
 This option sets the address of the envelope sender of a locally-generated
 .cindex "envelope sender"
 .cindex "user" "trusted"
 This option sets the address of the envelope sender of a locally-generated


@@ -9211,7 +9219,13 @@ dependent upon the option for which a value is sought; in this documentation,
 options for which string expansion is performed are marked with &dagger; after
 the data type.  ACL rules always expand strings.  A couple of expansion
 conditions do not expand some of the brace-delimited branches, for security
 options for which string expansion is performed are marked with &dagger; after
 the data type.  ACL rules always expand strings.  A couple of expansion
 conditions do not expand some of the brace-delimited branches, for security

-reasons.
+reasons,
+.new
+.cindex "tainted data" expansion
+.cindex expansion "tainted data"
+and expansion of data deriving from the sender (&"tainted data"&)
+is not permitted.
+.wen

 
 
 
 
 
 


@@ -12756,6 +12770,16 @@ or if not set, the value of &$qualify_domain$&.
 .cindex queues named
 The name of the spool queue in use; empty for the default queue.
 
 .cindex queues named
 The name of the spool queue in use; empty for the default queue.
 

+.new
+.vitem &$r_...$&
+.vindex &$r_...$&
+.cindex router variables
+Values can be placed in these variables by the &%set%& option of a router.
+They can be given any name that starts with &$r_$&.
+The values persist for the address being handled through subsequent routers
+and the eventual transport.
+.wen
+

 .vitem &$rcpt_count$&
 .vindex "&$rcpt_count$&"
 When a message is being received by SMTP, this variable contains the number of
 .vitem &$rcpt_count$&
 .vindex "&$rcpt_count$&"
 When a message is being received by SMTP, this variable contains the number of


@@ -14323,7 +14347,9 @@ listed in more than one group.
 See also the &'Policy controls'& section above.
 
 .table2
 See also the &'Policy controls'& section above.
 
 .table2

-.row &%dkim_verify_signers%&         "DKIM domain for which DKIM ACL is run"
+.row &%dkim_verify_hashes%&          "DKIM hash methods accepted for signatures"
+.row &%dkim_verify_keytypes%&        "DKIM key types accepted for signatures"
+.row &%dkim_verify_signers%&         "DKIM domains for which DKIM ACL is run"

 .row &%host_lookup%&                 "host name looked up for these hosts"
 .row &%host_lookup_order%&           "order of DNS and local name lookups"
 .row &%recipient_unqualified_hosts%& "may send unqualified recipients"
 .row &%host_lookup%&                 "host name looked up for these hosts"
 .row &%host_lookup_order%&           "order of DNS and local name lookups"
 .row &%recipient_unqualified_hosts%& "may send unqualified recipients"


@@ -14368,6 +14394,7 @@ See also the &'Policy controls'& section above.
 .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 &%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 &%pipelining_connect_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"
 .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"


@@ -15067,6 +15094,27 @@ etc. are ignored. If IP literals are enabled, the &(ipliteral)& router declines
 to handle IPv6 literal addresses.
 
 
 to handle IPv6 literal addresses.
 
 

+.new
+.option dkim_verify_hashes main "string list" "sha256 : sha512 : sha1"
+.cindex DKIM "selecting signature algorithms"
+This option gives a list of hash types which are acceptable in signatures,
+and an order of processing.
+Signatures with algorithms not in the list will be ignored.
+
+Note that the presence of sha1 violates RFC 8301.
+Signatures using the rsa-sha1 are however (as of writing) still common.
+The default inclusion of sha1 may be dropped in a future release.
+
+.option dkim_verify_keytypes main "string list" "ed25519 : rsa"
+This option gives a list of key types which are acceptable in signatures,
+and an order of processing.
+Signatures with algorithms not in the list will be ignored.
+
+.option dkim_verify_minimal main boolean false
+If set to true, verification of signatures will terminate after the
+first success.
+.wen
+

 .option dkim_verify_signers main "domain list&!!" $dkim_signers
 .cindex DKIM "controlling calls to the ACL"
 This option gives a list of DKIM domains for which the DKIM ACL is run.
 .option dkim_verify_signers main "domain list&!!" $dkim_signers
 .cindex DKIM "controlling calls to the ACL"
 This option gives a list of DKIM domains for which the DKIM ACL is run.


@@ -15158,6 +15206,11 @@ domain matches this list.
 This is a fudge to help with name servers that give big delays or otherwise do
 not work for the AAAA record type. In due course, when the world's name
 servers have all been upgraded, there should be no need for this option.
 This is a fudge to help with name servers that give big delays or otherwise do
 not work for the AAAA record type. In due course, when the world's name
 servers have all been upgraded, there should be no need for this option.

+.new
+Note that all lookups, including those done for verification, are affected;
+this will result in verify failure for IPv6 connections or ones using names
+only valid for IPv6 addresses.
+.wen

 
 
 .option dns_retrans main time 0s
 
 
 .option dns_retrans main time 0s


@@ -15887,6 +15940,7 @@ and no &'Sender:'& header is ever added. If, in addition, you want to retain
 &'Sender:'& header lines supplied by untrusted users, you must also set
 &%local_sender_retain%& to be true.
 
 &'Sender:'& header lines supplied by untrusted users, you must also set
 &%local_sender_retain%& to be true.
 

+.cindex "envelope from"

 .cindex "envelope sender"
 These options affect only the header lines in the message. The envelope sender
 is still forced to be the login id at the qualify domain unless
 .cindex "envelope sender"
 These options affect only the header lines in the message. The envelope sender
 is still forced to be the login id at the qualify domain unless


@@ -16373,6 +16427,19 @@ for each SMTP command and response. When PIPELINING is advertised, Exim assumes
 that clients will use it; &"out of order"& commands that are &"expected"& do
 not count as protocol errors (see &%smtp_max_synprot_errors%&).
 
 that clients will use it; &"out of order"& commands that are &"expected"& do
 not count as protocol errors (see &%smtp_max_synprot_errors%&).
 

+.new
+.option pipelining_connect_advertise_hosts main "host list&!!" *
+.cindex "pipelining" "early connection"
+.cindex "pipelining" PIPE_CONNECT
+If Exim is built with the SUPPORT_PIPE_CONNECT build option
+this option controls which hosts the facility is advertised to
+and from which pipeline early-connection (before MAIL) SMTP
+commands are acceptable.
+When used, the pipelining saves on roundtrip times.
+
+Currently the option name &"X_PIPE_CONNECT"& is used.
+.wen
+

 
 .option prdr_enable main boolean false
 .cindex "PRDR" "enabling on server"
 
 .option prdr_enable main boolean false
 .cindex "PRDR" "enabling on server"


@@ -17904,6 +17971,7 @@ See &%unknown_login%&.
 .cindex "sender" "setting by untrusted user"
 .cindex "untrusted user setting sender"
 .cindex "user" "untrusted setting sender"
 .cindex "sender" "setting by untrusted user"
 .cindex "untrusted user setting sender"
 .cindex "user" "untrusted setting sender"

+.cindex "envelope from"

 .cindex "envelope sender"
 When an untrusted user submits a message to Exim using the standard input, Exim
 normally creates an envelope sender address from the user's login and the
 .cindex "envelope sender"
 When an untrusted user submits a message to Exim using the standard input, Exim
 normally creates an envelope sender address from the user's login and the


@@ -18054,6 +18122,10 @@ file = ${extract{mailbox}{$address_data}}
 This makes the configuration file less messy, and also reduces the number of
 lookups (though Exim does cache lookups).
 
 This makes the configuration file less messy, and also reduces the number of
 lookups (though Exim does cache lookups).
 

+.new
+See also the &%set%& option below.
+.wen
+

 .vindex "&$sender_address_data$&"
 .vindex "&$address_data$&"
 The &%address_data%& facility is also useful as a means of passing information
 .vindex "&$sender_address_data$&"
 .vindex "&$address_data$&"
 The &%address_data%& facility is also useful as a means of passing information


@@ -18306,6 +18378,7 @@ Not effective on redirect routers.
 
 
 .option errors_to routers string&!! unset
 
 
 .option errors_to routers string&!! unset

+.cindex "envelope from"

 .cindex "envelope sender"
 .cindex "router" "changing address for errors"
 If a router successfully handles an address, it may assign the address to a
 .cindex "envelope sender"
 .cindex "router" "changing address for errors"
 If a router successfully handles an address, it may assign the address to a


@@ -18834,11 +18907,24 @@ latter kind.
 
 This option controls whether the local part is used to form the key for retry
 hints for addresses that suffer temporary errors while being handled by this
 
 This option controls whether the local part is used to form the key for retry
 hints for addresses that suffer temporary errors while being handled by this

-router. The default value is true for any router that has &%check_local_user%&
+.new
+router. The default value is true for any router that has any of
+&%check_local_user%&, 
+&%local_parts%&,
+&%condition%&,
+&%local_part_prefix%&,
+&%local_part_suffix%&,
+&%senders%& or
+&%require_files%&
+.wen

 set, and false otherwise. Note that this option does not apply to hints keys
 for transport delays; they are controlled by a generic transport option of the
 same name.
 
 set, and false otherwise. Note that this option does not apply to hints keys
 for transport delays; they are controlled by a generic transport option of the
 same name.
 

+Failing to set this option when it is needed
+(because a remote router handles only some of the local-parts for a domain)
+can result in incorrect error messages being generated.
+

 The setting of &%retry_use_local_part%& applies only to the router on which it
 appears. If the router generates child addresses, they are routed
 independently; this setting does not become attached to them.
 The setting of &%retry_use_local_part%& applies only to the router on which it
 appears. If the router generates child addresses, they are routed
 independently; this setting does not become attached to them.


@@ -18967,6 +19053,32 @@ SMTP VRFY command is enabled, it must be used after MAIL if the sender address
 matters.
 
 
 matters.
 
 

+.new
+.option set routers "string list" unset
+.cindex router variables
+This option may be used multiple times on a router;
+because of this the list aspect is mostly irrelevant.
+The list separator is a semicolon but can be changed in the
+usual way.
+
+Each list-element given must be of the form $"name = value"$
+and the names used must start with the string &"r_"&.
+Values containing a list-separator should have them doubled.
+When a router runs, the strings are evaluated in order,
+to create variables which are added to the set associated with
+the address.
+The variable is set with the expansion of the value.
+The variables can be used by the router options
+(not including any preconditions)
+and by the transport.
+Later definitions of a given named variable will override former ones.
+Varible use is via the usual &$r_...$& syntax.
+
+This is similar to the &%address_data%& option, except that
+many independent variables can be used, with choice of naming.
+.wen
+
+

 .option translate_ip_address routers string&!! unset
 .cindex "IP address" "translating"
 .cindex "packet radio"
 .option translate_ip_address routers string&!! unset
 .cindex "IP address" "translating"
 .cindex "packet radio"


@@ -21752,6 +21864,7 @@ on a remote transport in the current implementation.
 
 .option return_path transports string&!! unset
 .cindex "envelope sender"
 
 .option return_path transports string&!! unset
 .cindex "envelope sender"

+.cindex "envelope from"

 .cindex "transport" "return path; changing"
 .cindex "return path" "changing in transport"
 If this option is set, the string is expanded at transport time and replaces
 .cindex "transport" "return path; changing"
 .cindex "return path" "changing in transport"
 If this option is set, the string is expanded at transport time and replaces


@@ -22746,6 +22859,15 @@ sometimes add other information onto the ends of message filenames.
 
 Section &<<SECID136>>& contains further information.
 
 
 Section &<<SECID136>>& contains further information.
 

+.new
+This option should not be used when other message-handling software
+may duplicate messages by making hardlinks to the files.  When that is done Exim
+will count the message size once for each filename, in contrast with the actual
+disk usage.  When the option is not set, calculating total usage requires
+a system-call per file to get the size; the number of links is then available also
+as is used to adjust the effective size.
+.wen
+

 
 .option quota_warn_message appendfile string&!! "see below"
 See below for the use of this option. If it is not set when
 
 .option quota_warn_message appendfile string&!! "see below"
 See below for the use of this option. If it is not set when


@@ -22798,6 +22920,7 @@ percentage.
 
 
 .option use_bsmtp appendfile boolean false
 
 
 .option use_bsmtp appendfile boolean false

+.cindex "envelope from"

 .cindex "envelope sender"
 If this option is set true, &(appendfile)& writes messages in &"batch SMTP"&
 format, with the envelope sender and recipient(s) included as SMTP commands. If
 .cindex "envelope sender"
 If this option is set true, &(appendfile)& writes messages in &"batch SMTP"&
 format, with the envelope sender and recipient(s) included as SMTP commands. If


@@ -23682,7 +23805,7 @@ inserted in the argument list at that point &'as a separate argument'&. This
 avoids any problems with spaces or shell metacharacters, and is of use when a
 &(pipe)& transport is handling groups of addresses in a batch.
 
 avoids any problems with spaces or shell metacharacters, and is of use when a
 &(pipe)& transport is handling groups of addresses in a batch.
 

-If &%force_command%& is enabled on the transport, Special handling takes place
+If &%force_command%& is enabled on the transport, special handling takes place

 for an argument that consists of precisely the text &`$address_pipe`&.  It
 is handled similarly to &$pipe_addresses$& above.  It is expanded and each
 argument is inserted in the argument list at that point
 for an argument that consists of precisely the text &`$address_pipe`&.  It
 is handled similarly to &$pipe_addresses$& above.  It is expanded and each
 argument is inserted in the argument list at that point


@@ -24553,6 +24676,30 @@ facilities such as AUTH, PIPELINING, SIZE, and STARTTLS.
 Exim will not use the SMTP PIPELINING extension when delivering to any host
 that matches this list, even if the server host advertises PIPELINING support.
 
 Exim will not use the SMTP PIPELINING extension when delivering to any host
 that matches this list, even if the server host advertises PIPELINING support.
 

+.new
+.option hosts_pipe_connect smtp "host list&!!" unset
+.cindex "pipelining" "early connection"
+.cindex "pipelining" PIPE_CONNECT
+If Exim is built with the SUPPORT_PIPE_CONNECT build option
+this option controls which to hosts the facility watched for
+and recorded, and used for subsequent connections.
+
+The retry hints database is used for the record,
+and records are subject to the &%retry_data_expire%& option.
+When used, the pipelining saves on roundtrip times.
+It also turns SMTP into a client-first protocol
+so combines well with TCP Fast Open.
+
+Note:
+When the facility is used, the transport &%helo_data%& option
+will be expanded before the &$sending_ip_address$& variable
+is filled in.
+A check is made for the use of that variable, without the
+presence of a &"def:"& test on it, but suitably complex coding
+can avoid the check and produce unexpected results.
+You have been warned.
+.wen
+

 
 .option hosts_avoid_tls smtp "host list&!!" unset
 .cindex "TLS" "avoiding for certain hosts"
 
 .option hosts_avoid_tls smtp "host list&!!" unset
 .cindex "TLS" "avoiding for certain hosts"


@@ -25269,6 +25416,7 @@ When an address is being routed, either for delivery or for verification,
 rewriting is applied immediately to child addresses that are generated by
 redirection, unless &%no_rewrite%& is set on the router.
 
 rewriting is applied immediately to child addresses that are generated by
 redirection, unless &%no_rewrite%& is set on the router.
 

+.cindex "envelope from"

 .cindex "envelope sender" "rewriting at transport time"
 .cindex "rewriting" "at transport time"
 .cindex "header lines" "rewriting at transport time"
 .cindex "envelope sender" "rewriting at transport time"
 .cindex "rewriting" "at transport time"
 .cindex "header lines" "rewriting at transport time"


@@ -28385,6 +28533,13 @@ transport provide the client with a certificate, which is passed to the server
 if it requests it. If the server is Exim, it will request a certificate only if
 &%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client.
 
 if it requests it. If the server is Exim, it will request a certificate only if
 &%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client.
 

+.new
+Do not use a certificate which has the OCSP-must-staple extension,
+for client use (they are usable for server use).
+As TLS has no means for the client to staple before TLS 1.3 it will result
+in failed connections.
+.wen
+

 If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it
 specifies a collection of expected server certificates.
 These may be
 If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it
 specifies a collection of expected server certificates.
 These may be


@@ -30864,7 +31019,7 @@ client host, and its contents have been verified. If there has been no previous
 attempt to verify the HELO/EHLO contents, it is carried out when this
 condition is encountered. See the description of the &%helo_verify_hosts%& and
 &%helo_try_verify_hosts%& options for details of how to request verification
 attempt to verify the HELO/EHLO contents, it is carried out when this
 condition is encountered. See the description of the &%helo_verify_hosts%& and
 &%helo_try_verify_hosts%& options for details of how to request verification

-independently of this condition.
+independently of this condition, and for detail of the verification.

 
 For SMTP input that does not come over TCP/IP (the &%-bs%& command line
 option), this condition is always true.
 
 For SMTP input that does not come over TCP/IP (the &%-bs%& command line
 option), this condition is always true.


@@ -34372,6 +34527,7 @@ headers remove "Old-Subject"
 
 
 .section "Setting an errors address in a system filter" "SECID217"
 
 
 .section "Setting an errors address in a system filter" "SECID217"

+.cindex "envelope from"

 .cindex "envelope sender"
 In a system filter, if a &%deliver%& command is followed by
 .code
 .cindex "envelope sender"
 In a system filter, if a &%deliver%& command is followed by
 .code


@@ -34605,6 +34761,7 @@ other words, such qualification is also controlled by
 .cindex "sender" "address"
 .oindex "&%uucp_from_pattern%&"
 .oindex "&%uucp_from_sender%&"
 .cindex "sender" "address"
 .oindex "&%uucp_from_pattern%&"
 .oindex "&%uucp_from_sender%&"

+.cindex "envelope from"

 .cindex "envelope sender"
 .cindex "Sendmail compatibility" "&""From""& line"
 Messages that have come from UUCP (and some other applications) often begin
 .cindex "envelope sender"
 .cindex "Sendmail compatibility" "&""From""& line"
 Messages that have come from UUCP (and some other applications) often begin


@@ -36053,6 +36210,7 @@ the address, giving a suitable error message.
 .section "Variable Envelope Return Paths (VERP)" "SECTverp"
 .cindex "VERP"
 .cindex "Variable Envelope Return Paths"
 .section "Variable Envelope Return Paths (VERP)" "SECTverp"
 .cindex "VERP"
 .cindex "Variable Envelope Return Paths"

+.cindex "envelope from"

 .cindex "envelope sender"
 Variable Envelope Return Paths &-- see &url(https://cr.yp.to/proto/verp.txt) &--
 are a way of helping mailing list administrators discover which subscription
 .cindex "envelope sender"
 Variable Envelope Return Paths &-- see &url(https://cr.yp.to/proto/verp.txt) &--
 are a way of helping mailing list administrators discover which subscription


@@ -37380,6 +37538,15 @@ The field is a single "L".
 
 On accept lines, where PIPELINING was offered but not used by the client,
 the field has a minus appended.
 
 On accept lines, where PIPELINING was offered but not used by the client,
 the field has a minus appended.

+
+.new
+.cindex "pipelining" "early connection"
+If Exim is built with the SUPPORT_PIPE_CONNECT build option
+accept "L" fields have a period appended if the feature was
+offered but not used, or an asterisk appended if used.
+Delivery "L" fields have an asterisk appended if used.
+.wen
+

 .next
 .cindex "log" "queue run"
 .cindex "queue runner" "logging"
 .next
 .cindex "log" "queue run"
 .cindex "queue runner" "logging"


@@ -39427,6 +39594,11 @@ was received from the client, this records the Distinguished Name from that
 certificate.
 .endlist
 
 certificate.
 .endlist
 

+.new
+Any of the above may have an extra hyphen prepended, to indicate the the
+corresponding data is untrusted.
+.wen
+

 Following the options there is a list of those addresses to which the message
 is not to be delivered. This set of addresses is initialized from the command
 line when the &%-t%& option is used and &%extract_addresses_remove_arguments%&
 Following the options there is a list of those addresses to which the message
 is not to be delivered. This set of addresses is initialized from the command
 line when the &%-t%& option is used and &%extract_addresses_remove_arguments%&


@@ -39773,15 +39945,28 @@ RFC 6376 lists these tags as RECOMMENDED.
 
 Verification of DKIM signatures in SMTP incoming email is done for all
 messages for which an ACL control &%dkim_disable_verify%& has not been set.
 
 Verification of DKIM signatures in SMTP incoming email is done for all
 messages for which an ACL control &%dkim_disable_verify%& has not been set.

+.new
+.cindex DKIM "selecting signature algorithms"
+Individual classes of signature algorithm can be ignored by changing
+the main options &%dkim_verify_hashes%& or &%dkim_verify_keytypes%&.
+The &%dkim_verify_minimal%& option can be set to cease verification
+processing for a message once the first passing signature is found.
+.wen
+

 .cindex authentication "expansion item"
 Performing verification sets up information used by the
 &$authresults$& expansion item.
 
 .cindex authentication "expansion item"
 Performing verification sets up information used by the
 &$authresults$& expansion item.
 

-The results of that verification are then made available to the
+.new
+For most purposes the default option settings suffice and the remainder
+of this section can be ignored.
+.wen
+
+The results of verification are made available to the

 &%acl_smtp_dkim%& ACL, which can examine and modify them.
 &%acl_smtp_dkim%& ACL, which can examine and modify them.

-By default, this ACL is called once for each
-syntactically(!) correct signature in the incoming message.

 A missing ACL definition defaults to accept.
 A missing ACL definition defaults to accept.

+By default, the ACL is called once for each
+syntactically(!) correct signature in the incoming message.

 If any ACL call does not accept, the message is not accepted.
 If a cutthrough delivery was in progress for the message, that is
 summarily dropped (having wasted the transmission effort).
 If any ACL call does not accept, the message is not accepted.
 If a cutthrough delivery was in progress for the message, that is
 summarily dropped (having wasted the transmission effort).


@@ -39792,11 +39977,11 @@ containing the signature status and its details are set up during the
 runtime of the ACL.
 
 Calling the ACL only for existing signatures is not sufficient to build
 runtime of the ACL.
 
 Calling the ACL only for existing signatures is not sufficient to build

-more advanced policies. For that reason, the global option
-&%dkim_verify_signers%&, and a global expansion variable
+more advanced policies. For that reason, the main option
+&%dkim_verify_signers%&, and an expansion variable

 &%$dkim_signers%& exist.
 
 &%$dkim_signers%& exist.
 

-The global option &%dkim_verify_signers%& can be set to a colon-separated
+The main option &%dkim_verify_signers%& can be set to a colon-separated

 list of DKIM domains or identities for which the ACL &%acl_smtp_dkim%& is
 called. It is expanded when the message has been received. At this point,
 the expansion variable &%$dkim_signers%& already contains a colon-separated
 list of DKIM domains or identities for which the ACL &%acl_smtp_dkim%& is
 called. It is expanded when the message has been received. At this point,
 the expansion variable &%$dkim_signers%& already contains a colon-separated


@@ -39834,7 +40019,7 @@ If multiple signatures match a domain (or identity), the ACL is called once
 for each matching signature.
 
 
 for each matching signature.
 
 

-Inside the &%acl_smtp_dkim%&, the following expansion variables are
+Inside the DKIM ACL, the following expansion variables are

 available (from most to least important):
 
 
 available (from most to least important):
 
 


@@ -39928,8 +40113,12 @@ DKIM signatures identified as having been signed with historic
 algorithms (currently, rsa-sha1) have permanently failed evaluation
 .endd
 
 algorithms (currently, rsa-sha1) have permanently failed evaluation
 .endd
 

-To enforce this you must have a DKIM ACL which checks this variable
-and overwrites the &$dkim_verify_status$& variable as discussed above.
+To enforce this you must either have a DKIM ACL which checks this variable
+and overwrites the &$dkim_verify_status$& variable as discussed above,
+.new
+or have set the main option &%dkim_verify_hashes%& to exclude
+processing of such signatures.
+.wen

 
 .vitem &%$dkim_canon_body%&
 The body canonicalization method. One of 'relaxed' or 'simple'.
 
 .vitem &%$dkim_canon_body%&
 The body canonicalization method. One of 'relaxed' or 'simple'.


@@ -40196,7 +40385,11 @@ would relax host matching rules to a broader network range.
 .cindex SPF "lookup expansion"
 .cindex lookup spf
 A lookup expansion is also available. It takes an email
 .cindex SPF "lookup expansion"
 .cindex lookup spf
 A lookup expansion is also available. It takes an email

-address as the key and an IP address as the database:
+address as the key and an IP address
+.new
+(v4 or v6)
+.wen
+as the database:

 
 .code
   ${lookup {username@domain} spf {ip.ip.ip.ip}}
 
 .code
   ${lookup {username@domain} spf {ip.ip.ip.ip}}


@@ -40204,7 +40397,6 @@ address as the key and an IP address as the database:
 
 The lookup will return the same result strings as can appear in
 &$spf_result$& (pass,fail,softfail,neutral,none,err_perm,err_temp).
 
 The lookup will return the same result strings as can appear in
 &$spf_result$& (pass,fail,softfail,neutral,none,err_perm,err_temp).

-Currently, only IPv4 addresses are supported.