How to Import MBOX to Thunderbird? Top 4 Simple Methods

  Rollins Duke
Rollins Duke   
Published: August 25th, 2025 • 8 Min Read

This post defines the best strategies to import MBOX to Thunderbird step-by-step. It is a vital task for users who are looking to migrate their emails or back up important communication. Whether you are switching from another email client, changing your account, or organising your messages, read this article and follow the steps mentioned here to easily open MBOX file in Thunderbird in a hassle-free manner.

Like different email applications, Apple Mail, Eudora, Entourage, Opera Mail, and SeaMonkey, Thunderbird also supports the MBOX format. This file format is used to store a collection of email messages in a single file. Each email is stored sequentially, which makes it a popular choice among users to archive and transfer emails. You can export MBOX files from Thunderbird, which stores a whole folder’s emails with components.

Hence, to learn in-depth the right solution to how to add MBOX file to Thunderbird, read this complete blog to the very end. In this informational guide, we will walk you through the different methods and step-by-step procedures to easily import MBOX to Thunderbird, including attachments and all other data. Moreover, we will also understand a few causes behind this process. Let’s begin.

Why Open MBOX File in Thunderbird Account?

As such, the reasons to import MBOX to Thunderbird could vary from one user to another. But the primary reason to open an MBOX data file is without its native email client. Therefore, to get a gist of the possible situations that make the user seek a solution for how to add MBOX file to Thunderbird are as follows:

  • If you are willing to access file data without its parent email application, then you need an MBOX-compatible email client. Since Thunderbird runs on both Windows and Mac, many of you choose Thunderbird for opening MBOX files. This is one of the most prominent reasons to import MBOX to Thunderbird.
  • Sometimes users export MBOX from Gmail using the Google Takeout utility, and later they prefer to import MBOX to Thunderbird desktop client because it is available at no cost and has various features.
  • There are some situations when MacBook users want to switch to Windows. So, they export MBOX from Apple Mail and later want to open MBOX file in Thunderbird on Windows, as Thunderbird is compatible with both Windows and Mac platforms.

How to Add MBOX File to Thunderbird Account Manually?

There are three manual methods to open MBOX file in Thunderbird account using the ImportExportToolsNG add-on and import methods as well. Also, if the user have a Gmail MBOX file, then there is also a way to import MBOX to Thunderbird.

#1: Import MBOX to Thunderbird Using Add-ons

  1. Install and set up Thunderbird on your computer.
  2. Now, start Thunderbird, and choose “Tools”.
  3. There, click on “Add-Ons and Themes”.
  4. Next, search for ImportExportTools NG add-ons
  5. And click on the “Add to Thunderbird” icon.
  6. Then again, choose the “Tools” menu button.
  7. After that, select the “ImportExportToolsNG” option.
  8. Select the “Import MBOX Files” and click on the “Individual MBOX Files” option.

    import mbox to thunderbird

  9. After that, browse the MBOX file from your computer and tap the “Open” button.

    browse the MBOX file

  10. See the imported MBOX file under Local Folder in Thunderbird.

    uploaded

  11. With this, the process to open MBOX file in Thunderbird completes successfully. 

Constraints Of This Method

While you try to import MBOX to Thunderbird with this manual technique, you may suffer from the following issues:

  • In this way, the possibilities to get broken inline images present in the MBOX file are very high.
  • You can get misplaced MBOX mailboxes and erroneous header information.
  • May get some missing email attachments of MBOX files during the process to open MBOX file in Thundebird.
  • This solution of how to add MBOX file to Thunderbird does not maintain the actual folder structure.

#2: Use Default Import Option

Before you begin to import MBOX to Thunderbird, you first need to ZIP the MBOX file and then import it using the following steps.

  1. First of all, start Thunderbird and go to “Tools”.
  2. Then, select the “Import” option and click on Import from a file option.
  3. Browse the ZIP file of MBOX data and hit the “Next” button.
  4. Finally, click on the “Start Import” option to open MBOX file in Thunderbird.

Constraints Of This Method

  • This method to import MBOX to Thunderbird is not available in older Thunderbird versions.
  • The user must need to ZIP the MBOX file before importing, otherwise the solution cannot be performed.
  • In order to open MBOX file in Thunderbird using this method, the file size must be under 2 GB.
  • Also, this manual way doesn’t support all platforms’ exported MBOX files.

#3: Import Gmail MBOX Files to Thunderbird Account

If you want to import MBOX to Thunderbird generated by a Gmail account, then there is no need to follow the lengthy and time-consuming process to export data through Google Takeout. You can follow the given steps to open  MBOX file in Thunderbird for a Gmail account, as Thunderbird allows you to connect to cloud-based email services just by providing IMAP and account details. The steps to follow this method are as follows:

  1. Start and run Thunderbird on your device.
  2. Hit on the “Tools” and choose “Account Settings” option.

    settings

  3. Select the “Account Actions” and click on “Add Mail Account” icon.

    account actions

  4. Put in the account credentials of the Gmail account.

    account credentials

  5. After that, provide IMAP details.

    imap details

  6. At last, select the “Finish” button to open MBOX file in Thunderbird.

    import mbox to thunderbird

Now, locate the folder of connected Gmail accounts in Thunderbird, right-click on it, and choose the “Move To” option. After that, select the Thunderbird profile.

Troubleshooting Tips

  • Large Files: If you are trying to import large MBOX files to Thunderbird, be patient and ensure Thunderbird is not interrupted during the import process.
  • Compatibility Issues: Please ensure you are importing MBOX into Thunderbird without having any corruption in files. If you encounter issues, then use free software to repair MBOX files.

How to Import MBOX to Thunderbird Account Professionally?

To escape the shortcomings of the above manual process, use the Thunderbird Import Tool. With the help of this software, you can open MBOX file in Thunderbird. All you need to do is download and install the utility on the computer. This software allows you to batch import MBOX to Thunderbird account without any limitations or restrictions. Hence, it is the best solution of how to add MBOX file to Thunderbird for all those users who want to safely, accurately, and easily do this drill. 

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Working Steps to Open MBOX File in Thunderbird Account

  1. Firstly, launch the recommended software and choose one option from “Select Files” or “Select Folders” for adding .mbox files.

    open mbox files in thunderbird

  2. Choose the required files, and press the “Next” button.

    preview all selected files

  3. Thereafter, the tool will automatically choose the default destination path of the Thunderbird profile.

    destination path

  4. After that, tap on the “Next” button to import MBOX to Thunderbird profile.

    next icon

  5. Finally, after completing the task, run your Thunderbird to preview the imported emails.

    import mbox to thunderbird

Why Expert Solutions Over Manual Methods?

  • Compatible with MBOX files of all desktop and cloud-based email programs such as Apple Mail, Eudora, Opera Mail, Spicebird, Postbox, Claws Mail, Alpine, Netscape, Mail Copa, Earthlink, Pocomail, and all.
  • The software is skilled enough to import MBOX to Thunderbird in bulk, together with attachments. Also, not only the current MBOX emails, but they can also import old emails to Thunderbird without any hitches.
  • This tool can simply add multiple data files and folders in bulk at one time without losing any information or details.
  • Also, it maintains the original data and components like email headers and email body details with attachments.
  • The best thing is that it also offers a trial edition which is completely free of cost and let the user test the tools’ efficiency before getting the paid one.
FAQs

1. Can Thunderbird open MBOX files?

Yes, Thunderbird can open MBOX file data with attachments because it supports and exports its data in this file extension.

2. Where are Thunderbird MBOX files located?

Often, the location of Thunderbird MBOX files is “AppData\Roaming” or “~/.Thunderbird.

3. Does the expert solution import my MBOX files directly into my Thunderbird account?

Yes, just don’t change the location during the process. It will locate the path and open MBOX file in Thunderbird account.

4. Does this software support corrupted or inaccessible Thunderbird profiles?

Yes, it will load the default location and will save your data, whether your profile is working or not. You can even change any other path as per your choice.

Bringing All Together

Finally, the above blog describes four proper solutions to import MBOX to Thunderbird. Hence, if you are willing to perform a bulk open MBOX files in Thunderbird. Then, the above-mentioned solutions are best for you!

These solutions provide 100% precise results and enable you to add MBOX to Thunderbird without losing a single bit of information. For more doubts, feel free to get in touch with our technical support team.

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