According to an article I found on Apple's site, you need to do the following:
Open port 993
Installl a digital certificate
Open port 587, 465, or 25
No problem, sounds easy, right? WRONG. Our network guys refuse to do the first one, assuring me that I should be able to use ActiveSync. Of course, ActiveSync isn't available yet for the Iphone really, but when it is, this should all work quite nicely.
What a pain!! I am still searching to make sure I haven't missed something. . .but for now. . .I have told my user he is out of luck, but I just hate that answer.