2014-03-18 Migration issue Mac Mail
From ITSwiki
When migration from an older MacBookPro to a newer one - with Migrations Assistant - the Mac Mail accounts were gone ?!
Googeling found others that had same experience:
https://discussions.apple.com/thread/5483863?start=45&tstart=0
so - SHOULD you have this issue after migrating - removing the
Container.plist from Library/Containers/com.apple.mail might do the trick.