Import MBOX into macOS Mail
The Mail app on macOS allows you to import the email messages you have exported from the Xfinity Export Portal.
Step 1: Open the Mail application on your Mac
Step 2: Click on “File” in the menu bar and select "Import Mailboxes"
Step 3: In the import window, choose "Files in mbox format”. Then, click on “Continue”.
Step 4: Select your mbox files, then click on “Continue”.
Once finished, the imported emails will appear in a new mailbox called “Import” in the sidebar.