We recently transitioned from Exchange 2003 to Exchange 2010. I can get ALL of our newly created mail accounts to work on the iPhone using the Mail on the iPhone. However, MOST (not all) of our old mailboxes, which were moved from Exchange 2003 to Exchange 2010 wil not work. The error I get is: 'Cannot Get Mail - The connection to the server failed'.
This applies to the Calendar, Contacts and all other folders in the mailbox; none of the will connect.
I should mention that we had never used iPhones before the upgrade from Exchange 2003 to Exchange 2010 so it may not have anything to do with this issue.
I've checked all settings and they are identical between the new and the old mailboxes.