Docs: add warning on SNI-dependent certfile expansion needing a good default

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

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index d08a7a040e77c28a6c2b53acb2b00b31deb14a08..45d84571869afdeda6b21ff033d6d85639d5e9e4 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -2627,6 +2627,8 @@ users to set envelope senders.
 
 .cindex "&'From:'& header line"
 .cindex "&'Sender:'& header line"
 
 .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.
 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.


@@ -5031,6 +5033,27 @@ address lists. In Exim 4 these are handled better by named lists &-- see
 section &<<SECTnamedlists>>&.
 
 
 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`&"
 .section "Conditional skips in the configuration file" "SECID46"
 .cindex "configuration file" "conditional skips"
 .cindex "&`.ifdef`&"


@@ -5134,7 +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
 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
 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


@@ -6262,7 +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
 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/)).
 
 Jeffrey Friedl's &'Mastering Regular Expressions'&, which is published by
 O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)).
 


@@ -10156,6 +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.
 
 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"
 
 .vitem &*${eval:*&<&'string'&>&*}*&&~and&~&*${eval10:*&<&'string'&>&*}*&
 .cindex "expansion" "expression evaluation"


@@ -12988,8 +13028,7 @@ or external command, as described above. It is also used during a
 
 .vitem &$verify_mode$&
 .vindex "&$verify_mode$&"
 
 .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.
 
 contains "S" for sender-verification or "R" for recipient-verification.
 Otherwise, empty.
 


@@ -13816,6 +13855,7 @@ See also the &'Policy controls'& section above.
 .table2
 .row &%accept_8bitmime%&             "advertise 8BITMIME"
 .row &%auth_advertise_hosts%&        "advertise AUTH to these hosts"
 .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 &%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"


@@ -14305,11 +14345,15 @@ $primary_hostname-$tod_epoch-testing
 See section &<<CALLaddparcall>>& for details of how this value is used.
 
 
 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.
 
 
 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%&"
 See &%check_spool_space%& below.
 
 .oindex "&%check_rfc2047_length%&"


@@ -14324,11 +14368,15 @@ of the RFC, generates overlong encoded words. If &%check_rfc2047_length%& is
 set false, Exim recognizes encoded words of any length.
 
 
 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.
 
 
 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"
 .cindex "checking disk space"
 .cindex "disk space, checking"
 .cindex "spool directory" "checking space"


@@ -14339,7 +14387,7 @@ message is accepted.
 .vindex "&$log_space$&"
 .vindex "&$spool_inodes$&"
 .vindex "&$spool_space$&"
 .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.
 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.


@@ -14348,7 +14396,7 @@ 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%& 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
 check_spool_inodes = 100
 .endd
 The spool partition is the one that contains the directory defined by


@@ -14367,12 +14415,29 @@ 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
 &%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.
 
 
 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"
 .option daemon_smtp_ports main string &`smtp`&
 .cindex "port" "for daemon"
 .cindex "TCP/IP" "setting listening ports"


@@ -14394,6 +14459,7 @@ See &%daemon_startup_retries%&.
 .option delay_warning main "time list" 24h
 .cindex "warning of delay"
 .cindex "delay warning, specifying"
 .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
 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


@@ -16989,7 +17055,15 @@ larger prime than requested.
 The value of this option is expanded and indicates the source of DH parameters
 to be used by Exim.
 
 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
 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


@@ -17005,23 +17079,39 @@ 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.
 
 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
 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
 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, or "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`&,
 &`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.
 
 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,
 
 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,


@@ -23891,6 +23981,16 @@ connects. If authentication fails, Exim will try to transfer the message
 unauthenticated. See also &%hosts_require_auth%&, and chapter
 &<<CHAPSMTPAUTH>>& for details of authentication.
 
 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 server 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
+

 .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
 .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


@@ -27437,8 +27537,13 @@ 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
 
 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.
 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.
 
 The Exim developers are proceeding cautiously and so far no other TLS options
 are re-expanded.


@@ -27761,6 +27866,17 @@ 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.
 
 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
 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


@@ -28082,7 +28198,7 @@ provides a means of specifying an &"and"& conjunction between conditions. For
 example:
 .code
 deny  dnslists = list1.example
 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
 .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


@@ -28104,8 +28220,8 @@ after &%endpass%&, the ACL returns &"deny"&. Consider this statement, used to
 check a RCPT command:
 .code
 accept domains = +local_domains
 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
 .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


@@ -28756,7 +28872,7 @@ Notice that we put back the lower cased version afterwards, assuming that
 is what is wanted for subsequent tests.
 
 
 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.
 .cindex "&ACL;" "cutthrough routing"
 .cindex "cutthrough" "requesting"
 This option requests delivery be attempted while the item is being received.


@@ -28796,11 +28912,20 @@ 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.
 
 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.
 
 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.
 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.


@@ -31671,6 +31796,11 @@ 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.
 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
 
 .vitem &$spam_action$&
 For SpamAssassin either 'reject' or 'no action' depending on the


@@ -33256,6 +33386,7 @@ incoming SMTP message from a source that is not permitted to send them.
 
 .section "Resent- header lines" "SECID220"
 .cindex "&%Resent-%& header lines"
 
 .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:'&,
 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:'&,


@@ -33312,6 +33443,7 @@ existing &'Bcc:'& is not removed.
 
 .section "The Date: header line" "SECID223"
 .cindex "&'Date:'& header line"
 
 .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.
 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.


@@ -33329,6 +33461,7 @@ messages.
 
 .section "The Envelope-to: header line" "SECID225"
 .cindex "&'Envelope-to:'& header line"
 
 .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
 .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


@@ -33340,6 +33473,7 @@ messages.
 
 .section "The From: header line" "SECTthefrohea"
 .cindex "&'From:'& header line"
 
 .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"
 .cindex "Sendmail compatibility" "&""From""& line"
 .cindex "message" "submission"
 .cindex "submission mode"


@@ -33383,6 +33517,7 @@ name as described in section &<<SECTconstr>>&.
 
 .section "The Message-ID: header line" "SECID226"
 .cindex "&'Message-ID:'& header line"
 
 .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
 .cindex "message" "submission"
 .oindex "&%message_id_header_text%&"
 If a locally-generated or submission-mode incoming message does not contain a


@@ -33398,6 +33533,7 @@ in this header line by setting the &%message_id_header_text%& and/or
 
 .section "The Received: header line" "SECID227"
 .cindex "&'Received:'& header line"
 
 .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.
 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.


@@ -33414,6 +33550,7 @@ 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"
 
 .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
 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


@@ -33428,6 +33565,7 @@ 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"
 
 .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%&
 .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%&


@@ -33440,6 +33578,7 @@ default), Exim removes &'Return-path:'& header lines from incoming messages.
 .section "The Sender: header line" "SECTthesenhea"
 .cindex "&'Sender:'& header line"
 .cindex "message" "submission"
 .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
 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


@@ -35408,6 +35547,7 @@ picked out by the distinctive two-character flags that immediately follow the
 timestamp. The flags are:
 .display
 &`<=`&     message arrival
 timestamp. The flags are:
 .display
 &`<=`&     message arrival

+&`(=`&     message fakereject

 &`=>`&     normal message delivery
 &`->`&     additional address in same delivery
 &`>>`&     cutthrough message delivery
 &`=>`&     normal message delivery
 &`->`&     additional address in same delivery
 &`>>`&     cutthrough message delivery


@@ -35640,10 +35780,12 @@ the following table:
 &`F   `&        sender address (on delivery lines)
 &`H   `&        host name and IP address
 &`I   `&        local interface used
 &`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
 &`id  `&        message id for incoming message
 &`P   `&        on &`<=`& lines: protocol used
 &`    `&        on &`=>`& and &`**`& lines: return path

-&`PRX `&        on &'<='& and&`=>`& lines: proxy address
+&`PRDR`&        PRDR extension used
+&`PRX `&        on &`<=`& and &`=>`& lines: proxy address

 &`Q   `&        alternate queue name
 &`QT  `&        on &`=>`& lines: time spent on queue so far
 &`    `&        on &"Completed"& lines: time spent on queue
 &`Q   `&        alternate queue name
 &`QT  `&        on &`=>`& lines: time spent on queue so far
 &`    `&        on &"Completed"& lines: time spent on queue


@@ -38042,14 +38184,14 @@ DKIM is documented in RFC 4871.
 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_&.
 
 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
 .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
 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
 ACL (acl_smtp_dkim), which can be called several times per message, with
 different signature contexts.
 .endlist


@@ -38188,6 +38330,7 @@ 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).
 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 &%$dkim_verify_status%&
 A string describing the general status of the signature. One of
 .ilist
 .vitem &%$dkim_verify_status%&
 A string describing the general status of the signature. One of
 .ilist


@@ -38202,6 +38345,7 @@ available in &%$dkim_verify_reason%&.
 .next
 &%pass%&: The signature passed verification. It is valid.
 .endlist
 .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
 .vitem &%$dkim_verify_reason%&
 A string giving a little bit more detail when &%$dkim_verify_status%& is either
 "fail" or "invalid". One of


@@ -38221,51 +38365,73 @@ 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
 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 &%$dkim_domain%&
 The signing domain. IMPORTANT: This variable is only populated if there is
 an actual signature in the message for the current domain or identity (as
 reflected by &%$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 &%$dkim_identity%&
 The signing identity, if present. IMPORTANT: This variable is only populated
 if there is an actual signature in the message for the current domain or
 identity (as reflected by &%$dkim_cur_signer%&).

+

 .vitem &%$dkim_selector%&
 The key record selector string.
 .vitem &%$dkim_selector%&
 The key record selector string.

+

 .vitem &%$dkim_algo%&
 The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'.
 .vitem &%$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_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_canon_headers%&
 The header canonicalization method. One of 'relaxed' or 'simple'.

+

 .vitem &%$dkim_copiedheaders%&
 A transcript of headers and their values which are included in the signature
 (copied from the 'z=' tag of the signature).
 .vitem &%$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_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_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_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_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_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_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_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_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_notes%&
 Notes from the key record (tag n=).

+

 .vitem &%$dkim_key_length%&
 Number of bits in the key.
 .endlist
 .vitem &%$dkim_key_length%&
 Number of bits in the key.
 .endlist


@@ -38280,13 +38446,18 @@ 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
 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
 
      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
 .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