Cutthrough: Reflect 5xx recipient reject from target to originator

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

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index cd06de8d980256ec8411f9b1cb5cd1b4f527ce42..a67f486751ad8ec6346f719d8c9faa60ff4194b8 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -3151,6 +3151,11 @@ using one of the words &%router_list%&, &%transport_list%&, or
 settings can be obtained by using &%routers%&, &%transports%&, or
 &%authenticators%&.
 
 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 supresses 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
 .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


@@ -7739,7 +7744,7 @@ 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
 expansion must be a list, possibly containing empty items, which is split up
 .cindex "expansion" "of lists"
 Each list is expanded as a single string before it is used. The result of
 expansion must be a list, possibly containing empty items, which is split up


@@ -9677,7 +9682,8 @@ ${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
 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
 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


@@ -13946,6 +13952,14 @@ 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.
 
 This option defines the ACL that is run when an SMTP VRFY command is
 received. See chapter &<<CHAPACL>>& for further details.
 

+.new
+.option add_environment main "string list" empty
+.cindex "environment" "inherited"
+This option allows to set individual environment variables that the
+currently linked libraries and programs in child processes use. The
+default list is empty,
+.wen
+

 .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
 .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


@@ -15033,6 +15047,30 @@ 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 ignore_fromline_local main boolean false
 See &%ignore_fromline_hosts%& above.
 

+.new
+.option keep_environment main "string list" unset
+.cindex "environment" "inherited"
+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 startupif you do not mention
+&%keep_environment%& or &%add_environment%& in your runtime configuration
+file.
+.wen
+

 
 .option keep_malformed main time 4d
 This option specifies the length of time to keep messages whose spool files
 
 .option keep_malformed main time 4d
 This option specifies the length of time to keep messages whose spool files


@@ -16071,6 +16109,12 @@ 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.
 
 &%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"
 
 .option slow_lookup_log main integer 0
 .cindex "logging" "slow lookups"


@@ -23417,6 +23461,15 @@ 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%&.
 
 
 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
 .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


@@ -24059,7 +24112,7 @@ 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"
 .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
 certificate verification must succeed.
 The &%tls_verify_certificates%& option must also be set.
 If both this option and &%tls_try_verify_hosts%& are unset


@@ -27450,9 +27503,6 @@ 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.
 .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"
 
 
 .section "Specifying when ACLs are used" "SECID189"


@@ -28596,7 +28646,11 @@ 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.
 
 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
+.new
+(with use_sender)
+.wen
+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.
 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.


@@ -28607,6 +28661,14 @@ 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.
 
 modified by any of the post-data ACLs (DATA, MIME and DKIM).
 Headers may be modified by routers (subject to the above) and transports.
 

+.new
+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.
+.wen
+

 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.
 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.


@@ -30895,14 +30957,6 @@ 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.
 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
 
 
 .ecindex IIDacl
 
 


@@ -35574,7 +35628,7 @@ the following table:
 &`    `&        on &"Completed"& lines: time spent on queue
 &`R   `&        on &`<=`& lines: reference for local bounce
 &`    `&        on &`=>`&  &`**`& and &`==`& lines: router name
 &`    `&        on &"Completed"& lines: time spent on queue
 &`R   `&        on &`<=`& lines: reference for local bounce
 &`    `&        on &`=>`&  &`**`& and &`==`& lines: router name

-&`S   `&        size of message
+&`S   `&        size of message in bytes

 &`SNI `&        server name indication from TLS client hello
 &`ST  `&        shadow transport name
 &`T   `&        on &`<=`& lines: message subject (topic)
 &`SNI `&        server name indication from TLS client hello
 &`ST  `&        shadow transport name
 &`T   `&        on &`<=`& lines: message subject (topic)


@@ -38005,7 +38059,7 @@ where you accept mail from relay sources (internal hosts or authenticated
 senders).
 
 
 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.
 .cindex "DKIM" "signing"
 
 Signing is implemented by setting private options on the SMTP transport.


@@ -38020,7 +38074,7 @@ 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
 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
 option along with &%$dkim_domain%&.
 
 .option dkim_private_key smtp string&!! unset