This weekend I tried to roll back my Mac from a Time Machine backup, only to have the restore fail - TM got stuck on "can't restore files", which left me with an erased HDD and no option but to reinstall Yosemite from scratch. I then used Migration Assistant to bring everything back from my TM back-up, and it restored all my settings, apps and documents. However, Mail is very broken. When I launched it, it said it was importing my mailboxes. The progress bar got right to the end, then it said it was unable to restore and I had to quit Mail. Now Mail is completely broken. This is the main viewer window and a new message: With these windows open, every menu option is grayed out, including Quit. I've deleted the preference files, mail folders, etc, trying to get Mail to reset itself to factory, but nothing happens. In fact, the mail.plist files, etc, do not auto-recreate themselves after I delete them. Any ideas? Can I use Pacifist to extract Mail from the Yosemite installer, without having to reinstall OS X again?