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How to Import MBOX Files to Thunderbird? - Complete Guide

A comprehensive guide on importing MBOX files into Thunderbird using a free add-on and a software.
Last edited 106 days ago by Nilesh Kumar Singh
Did you know that Mozilla Thunderbird, an excellent email client, can manage multiple email accounts with ease? Despite being free and having a large user base, many users are unaware of how to import MBOX files into Thunderbird. Whether it's an old backup file or an MBOX file downloaded from email services like Gmail, Thunderbird has got you covered. In this guide, we will provide you with a reliable method to import MBOX files to Thunderbird using both a free and a professional solution.

MBOX File Types You Can Process

There are quite a few kinds of MBOX file. Here is a list of what MBOX type the methods will support:
File with .mbox extension (like Apple Mail MBOX file)
File without extension (Mozilla Thunderbird MBOX file)
Gmail MBOX file containing multiple mailboxes
File with .mbx extension (Eudora, Pocomail file)
If you have any of these files, you can import them in Thunderbird using the given methods.

How to Import MBOX into Thunderbird Application?

Solution: To conveniently transfer the MBOX data into Thunderbird desktop program, you can use either of these two methods:
Method 1: Download an Add-on from Thunderbird store
Method 2: Execute the import process via Thunderbird Importer Software.
Here are the detailed steps.
Note: Before we start, keep in mind that it is impossible to directly add MBOX file in an IMAP-based email account configured in Thunderbird. You must use the methods to import the file in either a POP-based account or simply in the Local Folders mailbox. Afterward, you can move the data to the IMAP-based account, if that’s what you require.

Method 1. Download Add-on in Thunderbird to Import MBOX File

Initially, open Thunderbird, go to Tools menu and click on the Add-ons and Themes option. If the menu is not visible, hit the Alt key to make it visible.
Search for “importexporttools” in the Search bar inside the Extensions tab.
In the search results, find ImportExportTools NG and click on Add to Thunderbird and proceed to install this add-on to your Thunderbird client.
Once installed, go to the mailbox folder where you want to import the data and right-click on it.
Choose ImportExportTools NG > Import mbox file.
In the window that appears, select Import directly one or more mbox files and click OK button.
Now, choose the MBOX file that you want to add and click the Open button.
Voila! The job is complete.
Please note that these steps were performed on Thunderbird version 102.4.0 (32-bit). They should also work for earlier versions. Just ensure you choose either the ImportExportTools NG or the older ImportExportTools add-on, depending on your version of Thunderbird.
While this method is free, some users prefer to use professional tools. This is because there have been instances where the metadata of the imported emails was altered during the manual process. For professionals, this is a significant concern. Therefore, many users prefer not to take this risk and opt for professional tools like the one we will discuss below.

Method 2. Import MBOX File into Thunderbird using Pro Tool

To keep the email properties, metadata and attachments intact during the process, using a reputable is a must. With this software, a user can easily transfer MBOX files into Mozilla Thunderbird email account in bulk.

Steps to Import MBOX to Thunderbird

Start Thunderbird Import Tool. Start the importer and read the instructions.
Add MBOX files into software. Click on Select Files button to import MBOX files.
Select MBOX folder you want to add in Thunderbird. The software will process and display all the added MBOX files that you can choose.
Import the selected MBOX file(s) into Thunderbird. In the next window, start the process as the tool already selects the default location where Thunderbird keeps its data file.
Open Thunderbird to view MBOX files. Finally, open Thunderbird application to view the files under “Local Folders”.


Thunderbird users want a solution to import MBOX files into Thunderbird when they wish to access their emails in the Thunderbird application. We tried to provide you with the most feasible options available to get the job done. The step-by-step process is easy to understand and easier to execute. It will definitely solve your needs without fail.

Common Queries & Their Answers

Q - What is an MBOX file and how is it used in Thunderbird?
MBOX is a mailbox format that stores email messages. Thunderbird uses it for the same purpose. Do note that Thunderbird MBOX files have no extension.
Q - Can I import MBOX files from other email clients into Thunderbird?
Yes, it is possible to do so. Simply generate MBOX files from these email clients, then use one of the methods described in this article to import MBOX into Thunderbird.
Q - Are there any size limitations related to the methods?
No, there are no restrictions on the size of the MBOX files that can be imported.
Q - How can I find the location of the MBOX file I want to import into Thunderbird?
In Thunderbird, go to Help >> Troubleshooting information >> Open folder.
Q - Can I import MBOX files to Thunderbird on both Windows and Mac?
Yes, both the given methods are available for Windows & Mac.
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