How to Open MBOX File in Thunderbird – Comprehensive Guide

In this post, we will show you EXACTLY how to open MBOX file in Thunderbird.

In fact, this is the same process thousands of users have used to import their MBOX files in Mozilla Thunderbird.

So, if you want to open your files without any hassle, you’ll love this how-to guide.

• Method #1: Using Thunderbird add-on (basic import)
  • Step #1: Install the add-on
  • Step #2: Open MBOX file using Thunderbird
• Method #2: Using Import Tool (for folder structure)
  • Step #1: Install the tool
  • Step #2: Open MBOX file in Thunderbird

Method #1: Using Thunderbird add-on (basic import)

This is a basic import option, so you will be able to import your MBOX files in Mozilla Thunderbird and read the emails easily.

Step #1: Install the add-on

First, launch the Mozilla Thunderbird email application on your system.

Click on the Menu icon located at the top-right corner of the Thunderbird screen and select Add-ons and Themes option.

Type “importexport” in the search bar and press the Enter key.

Find the ImportExportTools NG add-on and click on the “Add to Thunderbird” button.

Click on “Add” when it asks for access to Thunderbird.

Finally, click on the “OK” button.

Now, the add-on is installed. You will have to restart the Mozilla Thunderbird to avoid any complications in its working.

Step #2: Open MBOX file using Thunderbird

Here, we will finally open MBOX file in Thunderbird application. First, we will confirm that the add-on is properly installed.

Right-click on the Local folders mailbox, select the ImportExportTools NG option and then, click on Import mbox file option.

Here, you have 4 different ways to import MBOX file:

1. Import directly one or more mbox files – A basic option to simply select and import MBOX files in Thunderbird.
2. Import with its/their subdirectory – Import the entire directory/subdirectory with emails (Only applicable for Thunderbird SBD folders).
3. Search files in a directory – Search a folder for MBOX files.
4. Search files in a directory including all subdirectories – Search a folder and all its sub-folders for MBOX files.

Select the first option and click on the OK button.

Browse and choose the MBOX file(s), then click the Open button.

The MBOX data is successfully imported into Thunderbird. Now, you can view the emails in the newly added files.

This is how you open MBOX file in Thunderbird using the free add-on.

A note: You cannot directly import MBOX files in IMAP account. No software, application, thread, or trick supports this function. Therefore, you need to open the mailbox file in the Local folder and then move it to an IMAP account within the Thunderbird app, if that’s what you want.

Any Complications?

It is evident that the entire process is simple and easy to use. So there are no complications, per se. But, yes there are certain things that users want but the add-on does not provide them. For example:

• There is no facility to maintain the on-disk folder hierarchy of the MBOX files. Yes, there is an option that looks like importing files with a subdirectory, but it’s addressed towards Thunderbird SBD folders.
• Many users do not want to open the complete MBOX data in Thunderbird. They only require the data of a certain time period. The add-on provides no such option to filter emails during the import process.
• The add-on has bugs that often lead to missing inline images and attachments.

So, to resolve such problems, we are including the second method – a professional tool, as explained next.

Method #2: Using Import Tool (for folder structure)

This method will maintain folder hierarchy, if that’s what you want, and also provide optional date-range filters.

Step #1: Install the tool

First, you need to download, install and activate the Mozilla Thunderbird Import Tool. The free version of the tool will open only 25 emails per folder in Thunderbird.

Download Tool Purchase Now

You can use it to test the tool’s working and functionality as well as the imported results. Once satisfied, activate its full version for complete functionality.

Step #2: Open MBOX file in Thunderbird

Launch the software on the Windows system.

Click on Add folder button on the main screen.

Select the folder containing one or more MBOX files and click the OK button.

After that, click the Next button.

Select Local Folders in the Select identities section (please avoid selecting any IMAP account).

You can apply date-range filters with the Set button and also choose to maintain the on-disk folder hierarchy with the Maintain folder hierarchy.

Finally, click the Import button to open MBOX file in Mozilla Thunderbird application.

Wait for the process to complete and click the OK button.

Run Mozilla Thunderbird to view the emails (restart if necessary). As you can see, the complete folder structure is successfully kept intact.

Also Read: How to Import PST files to Thunderbird?

What to do if you:

Cannot open file in IMAP account?

It is technically not possible to directly open mailboxes in a configured IMAP account. So, make sure to choose the Local Folders as the destination account in the software.

Afterward, you can simply drag and drop all the emails from the added file to the IMAP account within Thunderbird, if that’s what you want.

Cannot see the imported data in Thunderbird?

Mozilla Thunderbird supports multiple profiles. The software auto-locates the default profile and allows you to open MBOX in Thunderbird profile. So, make sure the intended profile is same as the default destination path as shown in the software.

You can open/delete other profiles by running Thunderbird from CMD. To do that, follow these steps:

1. Press Start button + R
2. Type “thunderbird.exe -p” without quotes.
3. Click the OK

Open other profile to see if the data has been moved into it. You can also delete other profiles from here.

Important: Please double-check before deleting any profile. You can also choose to keep all the data intact but only delete the profile from Thunderbird, if that’s what you want.

People also ask:

How do I open an MBOX file in Thunderbird?

For manual method, read this article.

Brief steps to open MBOX file in Thunderbird using tool are:

1. Run the professional tool.
2. Click “Add Folder” to add multiple MBOX files.
3. Select “Local Folders” and apply other settings.
4. Click “Import” to open MBOX in Thunderbird.

Can Thunderbird read MBOX files?

Yes, Mozilla Thunderbird can easily read such files as it itself uses an MBOX variant (without extension files) to store its mailbox data. The methods and steps to do so are included in this post.