I've just gotten my installation running finally (in my Copious Free Time) and hit my first *major* snag:
It appears that Z (or the webclient, whichever is pertinent) generates improper In-Reply-To headers. I will deal with the fact that it doesn't thread *inbound* mail on them later, that only affects me... but rewriting them breaks the RFC -- and threading for everyone else -- and has to be dealt with first.
I replied to a message from a Yahoogroups (irony is great, isn't it? :-) mailing list with this Message-ID:
And the copy of my message which the mailing list sent me back had an In-Reply-To header of this:
In-Reply-To: <31469464.491221407842912.JavaMail.email@example.com icimarketing.com>
Any ideas, folks? Could this be caused by a misconfiguration, or should I open a ticket on it?