How to Archive Mozilla Thunderbird Mail Folders

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by Heinz Tschabitscher
An independent writer who has reviewed hundreds of email programs and services since 1997.
Updated February 18, 2019

Mozilla Thunderbird is a great place to store mail. Add a big "Archive" folder or one for every year, and all your messages are quickly available without slowing down your everyday email handling.

Of course, you want to back up mail, in particular, the messages that have been worthy of keeping in the first place. Why not combine that backing up with cleaning up your local Mozilla Thunderbird and archive old mail remotely — especially if you primarily need or want to keep these messages, not to access them?

Archive Mozilla Thunderbird Mail Folders

To back up or archive Mozilla Thunderbird folders:

  1. Make sure Mozilla Thunderbird is not running.

  3. Open the Mail folder.

  4. Look for the file named like the Mozilla Thunderbird folder you want to archive in the Local Folders or an account-specific sub-folder (such as pop.gmail.com, for example).

    • Make sure you pick the file that has no extension no the identically named file with the .msf extension. (The right file is Archive, for example, not Archive.msf.)

  5. Highlight the desired file (or files; hold down the Ctrl (Windows) or Command (Mac) key to highlight multiple files).

  6. Drag and drop the files to the desired archive location (on a removable medium such as a DVD, an external hard drive, a network drive or internet storage, for example).

  7. Open Mozilla Thunderbird.

  8. Delete the folders whose corresponding files you have just copied to the archive location by dragging and dropping to the Trash, clicking OK, and selecting File: Empty Trash from the menu bar.

To open a folder you have archived:

  1. Make sure Mozilla Thunderbird is not running.

  2. Open your Mozilla Thunderbird profile directory.

  3. Go to the Mail folder.

  4. Drag and drop the archived folder file (Archive, for example) from its remote location to the Local Folders folder.

    Make sure you do not overwrite existing files. If a file with the same name already exists under Local Folders, rename the archived folder file before copying.


  5. Open Mozilla Thunderbird.

  6. The archived folder should appear under Local Folders in the folder list.