Bob- Can you please provide the whitepaper or methodology of how you accomplished this feat, since even with 2 TAMS and 3 Microsoft internal resources assisting us we were unable to do the same for just 1700 mailboxes. We had constant problems up the yin yang and are still having to delete and re-create OAB IIS directories and other such nonsense every few weeks. Applying the CU3 patch was a horrific experience for us much like Night of the Living dead as OWA simply stopped working. Please provide us with a link or some other documentation on how you managed to migrate 3000 users to Exchange 2013 with "NO issues". I don't believe you. Might as well tell us Harry Potter waved his magic wand over your servers too.