If you’ve ever needed to transfer email from a Windows PC to a Mac, you know how intensive the process is. It can take hours, and there has never been a clearly documented way to cleanly convert the email and mailbox files from Outlook Express’ format to Apple Mail’s.
Dbxconv is a great and simple utility that utilizes the command line on your PC to convert the .dbx files Outlook Express (5.0-6.0) uses by default to the .mbx format which Apple Mail can use. It’s available for download (along with detailed instructions) for free here.
After downloading, run Dbxconv at the command line on the PC, after exporting your emails from Outlook Express in their native .dbx format. The utility will then convert the .dbx files into .mbx files. These files can be transferred to your Mac via a MS-DOS (FAT) formatted USB drive. Once transferred, these files can be imported into Apple Mail by choosing “Import Mailboxes…” under the File menu.
After the import is complete, you will see the mailboxes appear in Mail under “Imports.” If preferred, those mailboxes and messages can easily be selected and dragged over to any other pre-existing mailboxes.