2. Choose Import Mailboxes from the File menu.
3. Choose either Mail for Mac OS X or Standard mbox files depending on the method you used to back up (Figure 1)
4. Navigate to the location of your backed up mailboxes and select the folder where the backup of your mailbox is located.
5. Mail will list all of the available mailboxes that can be imported from the selected directory. Check the mailboxes to import, and click the forward button to import the mailboxes.
2. Drag your old Mail preferences file "com.apple.mail.plist" that was part of your backup, into the Users preferences folder (~/Library/Preferences).