Server side, you see the cheap bastards than run the CO where I work are tired of Spam and they didn't like my idea of getting a Barracuda box, so they are looking for freeware solutions and guess who's in charge of the search... Yes! Lord Fake bloody British.
I had been looking and the followings look quite promising:
SPAMAWARE
SPAMPAL
SPAMBAYES
Spamihilator
Spam experts (home)
K9
EMAILSPY
http://www.dirfile.com/no_spam_today__spam_filter_for_mail_servers.htmSpecially the last one. If you know about any please let me know since once I've got it I will need to find the way of integrate it with the NTLM server and that will be simply a pain in the ass.
I know that some of the above are client side but the interfaces look pretty friendly and lamentably everything on server side is expensive and as I said the idea is to get it for free.
Mark my words, never get your ass into a Dutch CO
FB