I wonder how easy it would be to implement Citadel it in NS. Citadel as the exchange replacement that I use at work.
It seems like the effort of a single man right now and with some help from enthusiastic users, yet what he has accomplished is great.
By the way, I use an old version and it still works miracles. I guess the little issues I have will already be solved in the latest version.
P.D. I remember I even tried it with Outlook many years ago and it worked.