the same lookup again. Otherwise, because each Exim process caches the results
of lookups, you will just get the same result as before.
+.new
+Macro processing is done on lines before string-expansion: new macros can be
+defined and macros will be expanded.
+Because macros in the config file are often used for secrets, those are only
+available to admin users.
+.wen
+
.vitem &%-bem%&&~<&'filename'&>
.oindex "&%-bem%&"
.cindex "testing" "string expansion"
.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&!! per RFC
+.option dkim_sign_headers smtp string&!! "per RFC"
.option dkim_hash smtp string&!! sha256
.option dkim_identity smtp string&!! unset
DKIM signing options. For details see section &<<SECDKIMSIGN>>&.
unsigned. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion
variables here.
-.option dkim_sign_headers smtp string&!! see below
+.option dkim_sign_headers smtp string&!! "see below"
If set, this option must expand to a colon-separated
-list of header names. Headers with these names will be included in the message
-signature.
-When unspecified, the header names recommended in RFC4871 will be used.
+list of header names.
+.new
+Headers with these names, or the absence or such a header, will be included
+in the message signature.
+When unspecified, the header names listed in RFC4871 will be used,
+whether or not each header is present in the message.
The default list is available for the expansion in the macro
"_DKIM_SIGN_HEADERS".
+.wen
.section "Verifying DKIM signatures in incoming mail" "SECID514"