IPhone and Exchange Server
Simple troubleshooting steps to start with:
1. Check your version of Exchange. Must be at least 2003 w/SP2.
2. Check your security certificate. If you go to your "https://webmail.yourdomain.com/owa" or "https://webmail.yourdomain.com/exchange" and receive a certificate error, you may want to look into an external certificate from a recognized CA. I used SBS through my registrar.
3. Check to ensure your "Front-End" and "Back-End" server are not both requiring SSL. That will cause issues with OMA.
If these steps don't work, feel free to contact me.
Justin
MacBook PRO 17", Mac OS X (10.4.11)