I am currently attempting to migrate from SBS2003 to Server 2012 R2 Hyper-V host with several Server 2012 R2 VMs and Exchange 2013. I understand that there is no direct migration of Exchange 2003 to 2013. I have setup a VM running Server 2008 and installed Exchange 2010.
I have got Exchange 2010 running and migrated a test user's mailbox. I had to 'repair' Outlook for the user but got it working with internal and external email as well as OWA. Next I moved my own mailbox and had the same result; I had to repair Outlook (to get it to look at the new Exchange server instead of the old one) but it works for internal and external email as well OWA.
However, I can't get my iPhone to sync with Outlook anymore. I have deleted account on the iPhone and recreated, but still can't connect.