So I got a new rMBP and swapped everything from my other MBP. The original one is also running mavericks. I did the migration assistant, everything transferred. Then I open mail, and it prompts for an account setup. Upon entering account info, it either crashes or freezes mail. If you look in the accounts menu, all of the previous accounts did transfer, just mail did not pick them up. In Mail, under the Mail menu, preferences is greyed out. It doesn't matter if they are gmail or "AOL" accounts Mail doesn't recognize them. I contacted Apple Care, they did a screen share, and didn't have any idea either, and were going to escalate to an engineer. Anyone have any idea of a way around this? What is very interesting, is if I create a new user on the machine, and log in there, I can set up Mail properly. Which tells me something stupid got tweaked during the transfer. This is my main machine for business, so I really would like to get my email working.