What are you looking to do with it? I have used Exchange 5.5 (without Active Directory) and Exchange 2000 (with Active Directory) and liked both of them. Are you looking for calendar sharing and collaboration, or simple POP access?

Also, here's a link with some free email server software applications:
 
http://www.webattack.com/Freeware/server/fwmailserver.shtml

just regular post office access. nothing special. so exchange server then. pretty stable? i'll give it a try.
 
thanks for the link as well.
 
is there any way i can email you coffee Clutch?
 

 
thanks again.

Exchange server is quite stable. I haven't had any problems, and using NTBACKUP (Win2K's built-in backup software) is MUCH better than many of the backup agents on the market, plus it supports online restoration of the databases and directory services as opposed to shutting it all down and doing a flat file restore. If you are looking at Exchange 2K, you will need Active Directory installed first, as Exchange 2K doesn't have its own directory service (which Exchange 5.5 did).
 
As for the coffee, you gotta get a mail server first, bud...