If the email app you're switching from isn't listed, click Cancel.If you're importing messages from a Windows or UNIX computer, select 'Files in mbox format' and locate the folder containing the files.Make sure the app you're importing from is open and running, because some of the options require this.Follow the instructions that appear onscreen.Select the email app you want to import messages from.If you're importing a mailbox exported from Mail, choose Apple Mail.Mail can import messages from other email apps or messages from mailboxes that you exported using Mail.
