Lion’s Mail brings many new features, but it still won’t magically back up and restore your messages when you move to a new Mac or reinstall OS X. But don’t worry. It’s easy to transfer mail to a new copy of Mail, even if you don’t use Time Machine or another method to back up your Mac’s drive. Difficulty Level: Easy
What You Need:
>> Lion’s Mail client
>> An external drive to which you can back up your data
1. Show Your Mailboxes
First, connect your external drive to your Mac. To back up one or more mailboxes, smart mailboxes, or folders, launch Mail, then click Show in the Favorites Bar to see them in Mail’s sidebar. Select each item you want to back up. Shift-click to select multiple adjacent items, or Command-click to select multiple nonadjacent items.
2. Export Your Messages
Next, select Mailbox > Export Mailbox in the Menu Bar, or click the gear icon at the bottom of the sidebar and choose Export Mailbox. Select your external drive in the Devices section of the Export sheet’s sidebar as the destination for your exported selections.
Check the Export All Subfolders box at the bottom of the sheet to export items complete with subfolders, then click Choose to export the data to your backup drive and eject your drive, which now contains your exported .mbox files.
3. Import Back to Mail
Launch Mail on your new Mac or a new installation of OS X and set up an account as prompted. Connect your drive, then choose Import > Import Mailboxes in Mail’s Menu Bar. In the resulting window, choose Apple Mail as the application you’ll be importing from. Select your external drive in the Import window, then select each .mbox file you want to import, and click Choose.
Confirm the import in the next window, then click Continue. Congratulations! Your imported mail will now appear in the Import folder in Mail’s sidebar.