iOS4 with MS Exchange 2003 inbox “Server is unavailable”

Archilies has the solution. “I had the same issue. It appears that the mail client in iOS 4 does not like CNAMEs. I had to change our DNS zone to use A records instead of CNAMEs for our mail server.”  This is verified by other posters on the thread.”

via Apple – Support – Discussions – iOS4 with MS Exchange 2003 issue ….