Import .MBOX Files into Mozilla Thunderbird

While ITS does not assist with importing email to third-party mail clients, you will find self-service instructions below for importing and viewing Gmail .MBOX files in Mozilla Thunderbird (free, open-source email client). Use this service at your own risk.

Install & Set Up Thunderbird


On a personally-owned computer

  1. Go to the Mozilla Thunderbird download page.
  2. Click the Download button in the middle of the page.
  3. Open the downloaded file, Thunderbird Setup 115.9.0.exe (Windows) or Thunderbird 115.9.0.dmg (Mac).

Note: The version you download may be different than the version listed above.

For Windows users:

  1. Click Run and then Yes in the pop-ups that appear to allow the program to begin the installation.
  2. Proceed with following the steps in the Mozilla Thunderbird Setup Wizard (default settings should work fine).

Note: Uncheck the “Use Thunderbird as my default mail application” box in the Summary section.

For Mac users:

  1. Drag the Thunderbird icon into the Applications folder.
  2. Open the Applications folder, double-click the Thunderbird icon, and click Open.

On a MiWorkspace managed computer

If MiWorkspace manages your computer, you can download Mozilla Thunderbird from the Software Center (Windows) or Managed Software Center (Mac).

Account setup

Note: In order to import your U-M Gmail archive (.MBOX) into Local Folders within Thunderbird for searching and viewing purposes, you need to temporarily configure at least one account in Thunderbird. For this reason, we recommend using a personal, non-UM email (e.g.,, especially one that’s empty, to avoid downloading any mail in that account. However, if you do not have a personal account, your email will work, as you’ll be removing the account after completing the steps anyway.

The first time Thunderbird runs, you will be taken to the Account Setup tab.

  1. Enter your name, personal email address, and email password in their respective fields and click Continue.
  2. Thunderbird will attempt to automatically configure the account based on the email address that you provide. If successful, you will see a green banner. Click Done.

Note: If the green banner does not appear, click Configure manually and enter the email account settings that are provided by your email provider.

  1. Click Confirm Security Exception (if applicable), click Finish, and finally, click Skip Integration.

Install Thunderbird Import Tool

You will need to install a third-party import add-on within Thunderbird.

  1. Click the hamburger/grid icon in the top right corner and select Add-ons and Themes from the drop-down menu.
  2. Enter Import in the search field at the top and press ENTER.
  3. Click the green Add to Thunderbird button next to “ImportExportTools NG."
  4. Click Add and OK! in the dialog boxes that appear
  5. Navigate back to the main Email tab (tab with your email address at the top).
  6. Right-click Local Folders in the left sidebar and select New Folder.
  7. Enter U-M Google Imported Email in the Name field and click Create Folder.

Import Your .MBOX File(s)

You will now import your U-M Google emails (in .MBOX format) from your Google Takeout export into a local Thunderbird folder, which is stored on your computer’s hard drive.

Note: Ensure you’ve extracted the contents of your Google Takeout .ZIP archives to regular folders before proceeding. More information: (Windows / Mac).

  1. Right-click the “U-M Google Imported Email” folder you just created, hover over “ImportExportTools NG” in the drop-down menu, and select Import mbox file.
  2. Select “Import directly one or more mbox files” from the dialog box that appears and click OK.
  3. Navigate to the folder where your Google Takeout .MBOX file(s) is stored, select one or more of the files, and click Open. The contents of your .MBOX files will be imported into Thunderbird.

It may take several minutes to import your .MBOX file(s). Import times depend on how much hard drive space your computer has, how large the file is, and how many files you’re importing at once. If you have more than one large .MBOX file to import, we recommend importing them one at a time.

After your file(s) has been imported, you can click the “U-M Google Imported Email” folder to view all of the emails included in the file. The .MBOX file imports should include the name of the U-M Google label followed by “.mbox” (e.g., Inbox.mbox, Drafts.mbox, etc.).

Remove Your Email Account

After importing your .MBOX file(s), you can proceed with removing the email account you used to set up Thunderbird.

  1. Click the hamburger/grid icon in the top right corner and select Account Settings from the drop-down menu.
  2. Click Account Actions from the bottom of the left sidebar and select Remove Account from the drop-down menu.
  3. Check the “Remove message data” box and click Remove.
Last Updated: 
Wednesday, March 20, 2024