I have been trying for hours, and hours to setup ISA 2004 to allow exchange 2003 and IIS to accept connections from an iPhone. Here is the skinny... I can get the phone to connect, verify the account, password and certificate, but it won't download any mail, contacts or calendar, and I'm not sure what to do, from here. I think I've tried everything.
The local domain was set to websiteaddress.local (I'm substitution websiteaddress for the real one)
I figured it out. Installed wire shark and had it listen to the incoming packets. Found that the iPhone was calling to the /exchange-oma/ folder. Checked the server's logs and found an access denied error. Checked the access restrictions on the IIS folder, mentioned above, and BINGO. It was set to listen only internally, on just that folder. Changed the setting and it instantly started working, so my ISA server was setup correctly. IIS was the culprit.