Guys,
I came across fudforum, in case you've never heard of it.
It is a discussion forum, but has support for mailing list
integration/syncronisation and can even send incoming posts, be that
from the lists or by online posts, to a newsgroup. (and can of course
syncronize with a newsgroup too)
It has a built in search engine, threaded tree views, and of course
supports PostgreSQL.
Might be worth going for this, as it is well maintained, and fairly easy
to set up / configure.
Supports themes too...
... John