Mailing list gateway enhancement

[Peter da Silva <peter-200306@xxxxxxxxxxx>]

If the mailing list gateway added "In-Reply-To" to the end of the references on messages coming in through the gateway, threading would work for mailing list messages. That's what I do with my news-mail gateways and it works pretty well even when mail clients toss the references... there's enough info in even one reference that the threading database can keep track.