an ARC set of headers. The textually-first Authentication-Results: header
is used as a basis (you must have added one on entry to the ADMD).
Expanded as a whole; if unset, empty or forced-failure then no signing is done.
an ARC set of headers. The textually-first Authentication-Results: header
is used as a basis (you must have added one on entry to the ADMD).
Expanded as a whole; if unset, empty or forced-failure then no signing is done.
Caveats:
* There must be an Authentication-Results header, presumably added by an ACL
while receiving the message, for the same ADMD, for arc_sign to succeed.
This requires careful coordination between inbound and outbound logic.
Caveats:
* There must be an Authentication-Results header, presumably added by an ACL
while receiving the message, for the same ADMD, for arc_sign to succeed.
This requires careful coordination between inbound and outbound logic.
* If passing a message to another system, such as a mailing-list manager
(MLM), between receipt and sending, be wary of manipulations to headers made
by the MLM.
+ For instance, Mailman with REMOVE_DKIM_HEADERS==3 might improve
deliverability in a pre-ARC world, but that option also renames the
Authentication-Results header, which breaks signing.
* If passing a message to another system, such as a mailing-list manager
(MLM), between receipt and sending, be wary of manipulations to headers made
by the MLM.
+ For instance, Mailman with REMOVE_DKIM_HEADERS==3 might improve
deliverability in a pre-ARC world, but that option also renames the
Authentication-Results header, which breaks signing.
* Even if you use multiple DKIM keys for different domains, the ARC concept
should try to stick to one ADMD, so pick a primary domain and use that for
AR headers and outbound signing.
* Even if you use multiple DKIM keys for different domains, the ARC concept
should try to stick to one ADMD, so pick a primary domain and use that for
AR headers and outbound signing.