My Institution is transitioning from FirstClass to Zimbra. And one of the most difficult issues we face is replacing the forum/Bulletin Board functionality of FirstClass to provide community announcements, classroom collaboration and threaded messaging. We are looking for a product that can authenticate off of CAS and provide RSS feeds.

It sure would be nice if Zimbra had the forum features built in ... and I view it as necessary if they want to be "the leader or next-generation messaging and collaboration"

Any thoughts? Any suggestions for such BBS/forum software?