How do I correctly back up my email files on my old computer and then restore them to my new MacBook Pro?
When you set up your new laptop, connect your old Mac to the MacBook Pro via a FireWire cable and let Apple’s Migration Assistant do the dirty work. You’ll be prompted automatically to use Migration Assistant, and then provided with instructions on how to set it up. (If you choose not to migrate when you first set up the laptop, you can do so later by running Migration Assistant, which lives in the /Applications/Utilities folder.) When the utility copies your user data, it will bring along your email settings and messages.
You can also do the job manually by archiving your messages within Mail and then transferring those archives. Ctrl-click (or right-click) on the Inbox in Mail and choose Archive Mailbox from the contextual menu. In the sheet that appears, you’ll be asked to choose a destination for the exported mailbox files (called mbox files). Pick a location and click on the Choose button. Mail will create as many mbox files as you have accounts listed under Inbox.
On the laptop, choose File?Import Mailboxes in the Mail application. In the Import window that appears, choose Mail For Mac OS X and click on Continue. In the resulting sheet, select the folder that contains your mailbox archives and click on Choose. A list of all the mailbox archives Mail is able to import will appear. Deselect those you don’t want and then click on Continue. Mail will place the archives in an Import folder under the On My Mac heading in Mail’s Mailboxes list.
At this point, you’ll want to click on each mailbox to see what it contains and then rename the mailboxes to accurately reflect the account they’re linked to – AOL Archive, for example.