Want to take all your cherished emails? Find out here how to copy “On My Mac” email folders to another computer using Apple Mail on macOS.

First, No Sooner Had She Stepped Ashore Than Asking for a Cup of Tea

Alas, such a refreshment was not to be yet for Catherine, the Portuguese princess that had arrived in Portsmouth on 13 May 1662 to become wife of Charles II and queen of—Britain.

This, story has it, is how the British tradition of drinking tea got started. Together with a few other culinary customs, Catherine of Braganza brought tea to the British Isles.

Want to pack up, step ashore—and ask for your On My Mac email folders in Apple Mail?

How to Copy On My Mac Email Folders to a New Computer with Apple Mail

To move and copy an On My Mac email folder to a new computer from one Apple Mail to another:

On the old Mac:

  1. Open the folder you want to copy under On My Mac in Apple Mail on macOS.
    • Note: Mail will export any sub-folders to that folder as well. You can choose whether you want to import them on the new Mac.
  2. Select Mailbox | Export Mailbox… from the menu.
  3. Choose a location that will allow you to move the created file to the new Mac.
    • Tip: An online drive such as iCloud Drive, OneDrive or Google Drive work well; you can also use an external hard drive, a phone or tablet or AirDrop, for example.
  4. Click Choose.

Now transfer the created .mbox files to the new Mac.

To avoid issues during copying, you can compress the files: click on the .mbox file with the right mouse button and select Compress “___.mbox” from the context menu.

On the new Mac:

  1. Open Mail.
  2. Select File | Import Mailboxes… from the menu.
  3. Make sure Apple Mail is selected under Import data from:.
  4. Click Continue.
  5. Highlight the .mbox file (or files; you can import more than one folder at a time).
  6. Now click Choose.
  7. Make sure all folders you do want to import are checked.
  8. Click Continue.
  9. Now click Done.
  10. Find the imported folders under the Import in the On My Mac section.

How to Copy All On My Mac Email Folders to a New Computer

Have a whole slew of folders under On My Mac in Apple Mail? You need not export them all individually.

To copy email folders from one computer’s On My Mac section in macOS Mail to another:

  1. In Finder, press Command Shift Q.
  2. Type ~/Library/Mail/V6.
    • Note: For versions of Mail other than 12 (from macOS Mojave 10.14), the last folder may be different, e.g. “V5” instead of “V6”.
  3. Click Go.
  4. Go through the folders named with random strings until you find one that has .mbox files whose names correspond to the folders under On My Mac in Mail.
  5. Highlight and copy all .mbox files to the new computer.
    • Note: To turn all files into one document you can copy easily, highlight the .mbox files, click with the right mouse button on one of them and select Compress __ Items from the context menu that has appeared.
  6. See above for importing all On My Mac folders on a new computer.

(How to copy “On My Mac” email folders to a new computer with Apple Mail tested with Mail 12.2 under macOS Mojave 10.14; updated January 2019)