So you have installed Lion and imported your mail back from a TimeMachine backup you did in Snow Leopard. You click Mail and it updates/imports the messages and then… nothing. I got the menu bar at the top of the screen but no actual application window. Bum.

Here’s how I fixed the problem. Your mileage may vary.

First of all, try dragging the Mail icon out of the dock and starting the app by clicking the Mail icon from the Applications folder (or Launch Control) instead. That work? No? OK…

Force Quit Mail and try running SpeedMail – it’s a free install so give it a go. Any joy? No, me neither…

Assuming you still have the TimeMachine backup:

  1. You’ll need to show the Library (hidden by default in Lion). To do this, launch Terminal (it’s in Applications, Utilities) and enter the following command: 
    chflags nohidden ~/Library
  2. Now you can see the Library folder under your username, move the ‘Mail’ folder from your-username/Library/ to the Desktop (or somewhere else, does’t matter where).
  3. Launch Mail again, it will now load (honest) but you will be forced to enter a mail account details. Once you have done that, the Mail window will open (I know, about friggin’ time, right).
  4. Now, with Mail running, you can either enter TimeMachine, select the folders that were there in Snow Leopard and click Restore. Or, from the Mail menubar, click File, then Import Mailboxes and then choose the ‘Apple Mail’ option and then browse to the Mail folder on your Desktop (or wherever you saved it), and then import all the mailboxes it finds.
  5. Either way you’ll probably have to drag some messages back and forth but at least you have Mail back and working. If you use IMAP only, then these last two steps aren’t actually necessary as once you add the account settings, it should pull down all your mail as it was before anyway.

Hope that helps someone, wasted a good couple of hours on that today. On the plus side, the new Mail is rather nice…