Running postfix on CentOS 6 as an edge relay for a while now, so all our outgoing mail is routed through one point with
opendkim signing the mail. This works great. I was originally using
dkim-filter/dkim-milter (I believe) but switched to
opendkim a couple of years back.
But one thing I've been meaning to get around to for a long time is getting the
DomainKey-Signature header added in addition to the
DKIM-Signature. I realise that
DomainKeys is the older spec and is technically replaced by
DKIM but I think there's still a reasonable number of systems that verify both (e.g.: Gmail).
Would this involve multiple milters, one for
DKIM and another for the older
I'm not too happy about the idea of having to maintain 2 sets of configurations and signing tables etc, as I have to add/remove relay domains reasonably frequently.
Anyone know if it's possible to add both signatures within