I’ve spent a fair bit of time today trying to sort out my iPhone sync to my Exchange Server, failing miserably. It used to work, pre-upgrade to iOS4, but for some reason fails to sync.
The server was configured as per http://support.microsoft.com/kb/817379/en-us to allow OWA/ActiveSync with SSL on OWA.
The iPhone was configured to accept the SSL certificate on the Exchange Server.
My brother Tom sent me this Apple KB (http://support.apple.com/kb/TS3398) which he’d found from the other side – Exchange servers he was managing were under very heavy load, which is another symptom of this issue.
I installed the new configuration as per the article, restarted the phone and the issue was fixed!