&`fail`& keyword causes a &'forced expansion failure'& &-- see section
&<<SECTforexpfai>>& for an explanation of what this means.
- The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, and TXT,
+ The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, TLSA and TXT,
and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is also
configured). If no type is given, TXT is assumed. When the type is PTR,
the data can be an IP address, written as normal; inversion and the addition of
list. The effect of each one lasts until the next, or until the end of the
list.
-To explain the host/ip processing logic a different way for the same ACL:
+.new
+.section "Mixing wildcarded host names and addresses in host lists" &&&
+ "SECTmixwilhos"
+.cindex "host list" "mixing names and addresses in"
+
+This section explains the host/ip processing logic with the same concepts
+as the previous section, but specifically addresses what happens when a
+wildcarded hostname is one of the items in the hostlist.
.ilist
If you have name lookups or wildcarded host names and
&`+ignore_unknown`&, which was discussed in depth in the first example in
this section.
.endlist
-
+.wen
.section "Temporary DNS errors when looking up host information" &&&
-.section "Mixing wildcarded host names and addresses in host lists" &&&
- "SECTmixwilhos"
-.cindex "host list" "mixing names and addresses in"
-If you have name lookups or wildcarded host names and IP addresses in the same
-host list, you should normally put the IP addresses first. For example, in an
-ACL you could have:
-.code
-accept hosts = 10.9.8.7 : *.friend.example
-.endd
-The reason for this lies in the left-to-right way that Exim processes lists.
-It can test IP addresses without doing any DNS lookups, but when it reaches an
-item that requires a host name, it fails if it cannot find a host name to
-compare with the pattern. If the above list is given in the opposite order, the
-&%accept%& statement fails for a host whose name cannot be found, even if its
-IP address is 10.9.8.7.
-
-If you really do want to do the name check first, and still recognize the IP
-address, you can rewrite the ACL like this:
-.code
-accept hosts = *.friend.example
-accept hosts = 10.9.8.7
-.endd
-If the first &%accept%& fails, Exim goes on to try the second one. See chapter
-&<<CHAPACL>>& for details of ACLs.
-
-
-
.section "Address lists" "SECTaddresslist"
- .option headers_add routers string&!! unset
+ .option headers_add routers list&!! unset
.cindex "header lines" "adding"
.cindex "router" "adding header lines"
- This option specifies a string of text that is expanded at routing time, and
- associated with any addresses that are accepted by the router. However, this
+ This option specifies a list of text headers, newline-separated,
+ that is associated with any addresses that are accepted by the router.
+ Each item is separately expanded, at routing time. However, this
option has no effect when an address is just being verified. The way in which
the text is used to add header lines at transport time is described in section
&<<SECTheadersaddrem>>&. New header lines are not actually added until the
&"see"& the added header lines.
The &%headers_add%& option is expanded after &%errors_to%&, but before
- &%headers_remove%& and &%transport%&. If the expanded string is empty, or if
- the expansion is forced to fail, the option has no effect. Other expansion
+ &%headers_remove%& and &%transport%&. If an item is empty, or if
+ an item expansion is forced to fail, the item has no effect. Other expansion
failures are treated as configuration errors.
Unlike most options, &%headers_add%& can be specified multiple times
- .option headers_remove routers string&!! unset
+ .option headers_remove routers list&!! unset
.cindex "header lines" "removing"
.cindex "router" "removing header lines"
- This option specifies a string of text that is expanded at routing time, and
- associated with any addresses that are accepted by the router. However, this
+ This option specifies a list of text headers, colon-separated,
+ that is associated with any addresses that are accepted by the router.
+ Each item is separately expanded, at routing time. However, this
option has no effect when an address is just being verified. The way in which
the text is used to remove header lines at transport time is described in
section &<<SECTheadersaddrem>>&. Header lines are not actually removed until
&"see"& the original header lines.
The &%headers_remove%& option is expanded after &%errors_to%& and
- &%headers_add%&, but before &%transport%&. If the expansion is forced to fail,
- the option has no effect. Other expansion failures are treated as configuration
+ &%headers_add%&, but before &%transport%&. If an item expansion is forced to fail,
+ the item has no effect. Other expansion failures are treated as configuration
errors.
Unlike most options, &%headers_remove%& can be specified multiple times
&%user%& (see below).
- .option headers_add transports string&!! unset
+ .option headers_add transports list&!! unset
.cindex "header lines" "adding in transport"
.cindex "transport" "header lines; adding"
- This option specifies a string of text that is expanded and added to the header
+ This option specifies a list of text headers, newline-separated,
+ which are (separately) expanded and added to the header
portion of a message as it is transported, as described in section
&<<SECTheadersaddrem>>&. Additional header lines can also be specified by
routers. If the result of the expansion is an empty string, or if the expansion
checked, since this option does not automatically suppress them.
- .option headers_remove transports string&!! unset
+ .option headers_remove transports list&!! unset
.cindex "header lines" "removing"
.cindex "transport" "header lines; removing"
- This option specifies a string that is expanded into a list of header names;
+ This option specifies a list of header names, colon-separated;
these headers are omitted from the message as it is transported, as described
in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
- routers. If the result of the expansion is an empty string, or if the expansion
+ routers.
+ Each list item is separately expanded.
+ If the result of the expansion is an empty string, or if the expansion
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 added.
+ for a router; all listed headers are removed.
the transport cannot refer to the modified header lines, because such
expansions all occur before the message is actually transported.
- For both routers and transports, the result of expanding a &%headers_add%&
+ For both routers and transports, the argument of a &%headers_add%&
option must be in the form of one or more RFC 2822 header lines, separated by
newlines (coded as &"\n"&). For example:
.code
Exim does not check the syntax of these added header lines.
Multiple &%headers_add%& options for a single router or transport can be
- specified; the values will be concatenated (with a separating newline
- added) before expansion.
+ specified; the values will append to a single list of header lines.
+ Each header-line is separately expanded.
- The result of expanding &%headers_remove%& must consist of a colon-separated
+ The argument of a &%headers_remove%& option must consist of a colon-separated
list of header names. This is confusing, because header names themselves are
often terminated by colons. In this case, the colons are the list separators,
not part of the names. For example:
.endd
Multiple &%headers_remove%& options for a single router or transport can be
- specified; the values will be concatenated (with a separating colon
- added) before expansion.
+ specified; the arguments will append to a single header-names list.
+ Each item is separately expanded.
- When &%headers_add%& or &%headers_remove%& is specified on a router, its value
- is expanded at routing time, and then associated with all addresses that are
+ When &%headers_add%& or &%headers_remove%& is specified on a router,
+ items are expanded at routing time,
+ and then associated with all addresses that are
accepted by that router, and also with any new addresses that it generates. If
an address passes through several routers as a result of aliasing or
forwarding, the changes are cumulative.
git://git.exim.org / exim.git / commitdiff