The word &"set"& at the start of a line, followed by a single space,
is recognised specially as defining a value for a variable.
+.new
+.cindex "tainted data" "expansion testing"
+If the sequence &",t"& is inserted before the space,
+the value is marked as tainted.
+.wen
The syntax is otherwise the same as the ACL modifier &"set ="&.
.cmdopt -bem <&'filename'&>
The &%acl_smtp_dkim%& ACL is available only when Exim is compiled with DKIM support
enabled (which is the default).
+If, for a specific message, an ACL control
+&*dkim_disable_verify*&
+has been set, this &%acl_smtp_dkim%& ACL is not called.
+
The ACL test specified by &%acl_smtp_dkim%& happens after a message has been
received, and is executed for each DKIM signature found in a message. If not
otherwise specified, the default action is to accept.
.olist
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.
+(including transport filters) except cutthrough delivery.
+.new
+However, signing options may not depend on headers modified by
+routers, the transport or a transport filter.
+.wen
.next
Verifying signatures in incoming messages: This is implemented by an additional
ACL (acl_smtp_dkim), which can be called several times per message, with