Exchange Server by Microsoft is aggravating.
First, Microsoft re-writes the rules for e-mail. It seems the RFC's that everyone lives by is quite good enough for Microsoft's view of the Internet, but I can live with that. One has to make compromises in this world, and this is one of them.
Second, like SQL server, Exchange eats up most of the CPU resources of a computer, so you need to run it on its own. I still find it amazing that MS sells SBS (Small Business Server, but that's another rant, another time).
Thirdly, and this is the new corker I just found out about. Exchange Server has a store limit. All the e-mail, the logs, the incoming and outgoing mail, and the saved e-mail can not exceed, get this, 16GB.
Now some of you are saying to yourselves, "16 Gigs, that's a tremendous amount of data". You'd be right, but when you have multiple users, who get large amounts of e-mail, it really isn't.