This item inserts &"basic"& header lines. It is described with the &%header%&
expansion item below.
+
+.vitem "&*${acl{*&<&'name'&>&*}{*&<&'arg'&>&*}...}*&"
+.cindex "expansion" "calling an acl"
+.cindex "&%acl%&" "call from expansion"
+The name and zero to nine argument strings are first expanded separately. The expanded
+arguments are assigned to the variables &$acl_arg1$& to &$acl_arg9$& in order.
+Any unused are made empty. The variable &$acl_narg$& is set to the number of
+arguments. The named ACL (see chapter &<<CHAPACL>>&) is called
+and may use the variables; if another acl expansion is used the values
+are overwritten. If the ACL sets
+a value using a "message =" modifier and returns accept or deny, the value becomes
+the result of the expansion.
+If no message was set and the ACL returned accept or deny
+the value is an empty string.
+If the ACL returned defer the result is a forced-fail. Otherwise the expansion fails.
+
+
.vitem "&*${dlfunc{*&<&'file'&>&*}{*&<&'function'&>&*}{*&<&'arg'&>&*}&&&
{*&<&'arg'&>&*}...}*&"
.cindex &%dlfunc%&
10M, not if 10M is larger than &$message_size$&.
+.vitem &*acl&~{{*&<&'name'&>&*}{*&<&'arg1'&>&*}&&&
+ {*&<&'arg2'&>&*}...}*&
+.cindex "expansion" "calling an acl"
+.cindex "&%acl%&" "expansion condition"
+The name and zero to nine argument strings are first expanded separately. The expanded
+arguments are assigned to the variables &$acl_arg1$& to &$acl_arg9$& in order.
+Any unused are made empty. The variable &$acl_narg$& is set to the number of
+arguments. The named ACL (see chapter &<<CHAPACL>>&) is called
+and may use the variables; if another acl expansion is used the values
+are overwritten. If the ACL sets
+a value using a "message =" modifier the variable $value becomes
+the result of the expansion, otherwise it is empty.
+If the ACL returns accept the condition is true; if deny, false.
+If the ACL returns defer the result is a forced-fail.
+
.vitem &*bool&~{*&<&'string'&>&*}*&
.cindex "expansion" "boolean parsing"
.cindex "&%bool%& expansion condition"
If the result is any other value, the router is run (as this is the last
precondition to be evaluated, all the other preconditions must be true).
-This option is unique in that multiple &%condition%& options may be present.
+This option is unusual in that multiple &%condition%& options may be present.
All &%condition%& options must succeed.
The &%condition%& option provides a means of applying custom conditions to the
the expansion is forced to fail, the option has no effect. Other expansion
failures are treated as configuration errors.
+Unlike most options, &%headers_add%& can be specified multiple times
+for a router; all listed headers are added.
+
&*Warning 1*&: The &%headers_add%& option cannot be used for a &(redirect)&
router that has the &%one_time%& option set.
the option has no effect. Other expansion failures are treated as configuration
errors.
+Unlike most options, &%headers_remove%& can be specified multiple times
+for a router; all listed headers are removed.
+
&*Warning 1*&: The &%headers_remove%& option cannot be used for a &(redirect)&
router that has the &%one_time%& option set.
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_add%& can be specified multiple times
+for a transport; all listed headers are added.
+
.option headers_only transports boolean false
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.
+
.option headers_rewrite transports string unset
.vitem &*acl&~=&~*&<&'name&~of&~acl&~or&~ACL&~string&~or&~file&~name&~'&>
.cindex "&ACL;" "nested"
.cindex "&ACL;" "indirect"
+.cindex "&ACL;" "arguments"
.cindex "&%acl%& ACL condition"
The possible values of the argument are the same as for the
&%acl_smtp_%&&'xxx'& options. The named or inline ACL is run. If it returns
condition false. This means that further processing of the &%warn%& verb
ceases, but processing of the ACL continues.
+If the argument is a named ACL, up to nine space-separated optional values
+can be appended; they appear in $acl_arg1 to $acl_arg9, and $acl_narg is set
+to the count of values. The name and values are expanded separately.
+
If the nested &%acl%& returns &"drop"& and the outer condition denies access,
the connection is dropped. If it returns &"discard"&, the verb must be
&%accept%& or &%discard%&, and the action is taken immediately &-- no further
.endd
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.
+
The result of expanding &%headers_remove%& 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,
.code
headers_remove = return-receipt-to:acknowledge-to
.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.
+
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
accepted by that router, and also with any new addresses that it generates. If