How to Open MSG Files in Thunderbird in Bulk Securely?

  

Rollins Duke   
Published: July 16th, 2026 • 9 Min Read

Are you trying to open MSG file in Thunderbird but getting nowhere? Don’t overthink, you are not alone. Thunderbird itself does not support MSG format because it is a proprietary email format for Microsoft Outlook. This is the reason, to access these Outlook MSG files, you need to use a compatible import method or convert it into Thunderbird supported format.

In this guide, we will explain to you why MSG files are not supported and help you walk you through the available manual method and their limitations. Additionally, you’ll get familiar with the easiest way to open single as well as batch MSG files in Thunderbird directly through a dedicated MSG to Thunderbird Converter without losing any important email data. So let’s get started.

Can Thunderbird Open MSG Files?

Yes, but not directly. Thunderbird cannot open MSG files because it is an Outlook support format. But Thunderbird supports standard email format i.e. EML and MBOX, which stores email content in simpler and structured form. So to access MSG files in Thunderbird you must first need to convert MSG to EML and then directly import them.

While the manual method is available, they are suitable to open only a small amount of files without attachments and formatting. For a professional method and results, choose the automated solution. It will import MSG to Thunderbird without requiring any conversion in between, saving your time and effort.

Reasons to Open MSG File in Thunderbird

Users choose Thunderbird to access MSG files for several reasons. We have discussed some of the most common ones below.

• Switching from Microsoft Outlook to Thunderbird helps in reducing licensing costs as it is an open-source email client.
• Organizations and individuals often preserve important emails as MSG files to keep them available in future. Importing them in Thunderbird makes it easier to search and organize from one place.
• Users who no longer use Microsoft Outlook usually need an alternative way to read and manage their emails. Thunderbird becomes a reliable option for this, as it is a commonly used email client for business purposes.
• Export MSG files to Thunderbird to organize and store email backups in a more accessible and searchable format especially for long-term email preservation needs.
• Thunderbird email client is available for Windows, macOS and Linux, that makes it easier for users to access emails across platforms without depending upon one system.

Manual Method to Open MSG file in Thunderbird

This method is only applicable if you want to read the basic email content and especially for a few MSG files. It involves opening MSG file in Outlook Classic, saving it to TXT format, then renaming the TXT file to EML and then opening it in Thunderbird because Thunderbird supports importing EML files only.

However for a clear view this is not a true MSG-to-Thunderbird approach and should be used for temporary access. Don’t rely on this approach if you want professional results with maintained formatting.

Follow these steps:

1. First locate your MSG files that you want to import. Select one file, right click and open it with Outlook Classic.
   
   
2. After that, go to File, select Save As and in the saving type choose TXT format.
   
3. Thereafter, set the destination path to store file and save it.
4. Once done till here, navigate to the location where you have saved MSG files in plain text format i.e. TXT.
5. Simply, right-click on them > choose Rename option > change the file extension from .txt to .eml.
6. Now, right-click the output EML file and click on Open With. From the menu, select Thunderbird.
7. You can now access MSG files in Thunderbird and view their content.

With this you can only view data of an individual MSG file and have to repeat the same steps for each MSG file.

How to Bulk Import MSG files to Thunderbird Manually?

1. Once you have saved all the MSG files in EML format using Outlook Classic.
2. Open Thunderbird on the same device.
3. Go to Menu > click on Add-ons and Themes > Search ImportExportTools NG and press on Add to Thunderbird option.
   
4. After that, simply right-click on the folder where you want to import MSG files.
5. Select ImportExportTools NG option > Import EML messages > All EML messages from a directory and subdirectories from the list.
   
6. Finally, choose the above renamed .eml files to open and view them in Thunderbird.

That’s it, you are done. Now let’s discuss the drawbacks of this manual approach to have a clear understanding about it before proceeding and choosing it as a practical solution.

Limitations of the Manual Method

• Saving MSG file to TXT will only show the email data with no fixed formatting.
• HTML fonts, colors, hyperlinks, tables and other elements are lost during the process.
• In this process, renaming .txt to .eml only changes the file extension. It does not recreate the original email structure.
• The original folder structure is not maintained properly even when you perform the bulk Thunderbird import process.
• Moreover, this is a lengthy and time-consuming process to import MSG to Thunderbird.
• The user having New Outlook cannot directly open MSG files, as it will throw an error.
• Most importantly, attachments are not preserved. They get lost while saving MSG files to TXT and then renaming it to EML.
• Important email properties are not maintained such as Internet headers, message ID, categories, flags, read/unread status, voting buttons and other Outlook-specific MAPI attributes.
• Last, this method is not suitable for business and large enterprise users who work with large MSG files.

Simple Steps to Import Outlook MSG files in Thunderbird

1. Install & run the MSG to Thunderbird Converter on your machine.
   
2. Choose single or multiple MSG files from the database that you want to import.
   
3. Thereafter, preview the message files before moving towards the next step.
   
4. Navigate towards the saving formats provided in the GUI and pick Thunderbird as the saving format.
   
   
5. Now, the tool will automatically set a default destination folder of Thunderbird.
   
6. Hit the Convert tab to start the process. Once the Conversion is done, the tool will show this message on the screen: “Conversion Completed Successfully.”
   
   
7. After file migration, the software will automatically show the default storage location where your MSG emails are saved. Lastly, start the Thunderbird email client to open MSG File in Thunderbird.
   

Bonus Point: You can also just view the MSG files through the MSG file viewer tool. Without the installation of any application like Outlook or Thunderbird, you can directly open and view MSG files in bulk.

Manual Method vs Professional Tool Comparison

This table will help you understand both the methods clearly and in short. Plus, with this you will get an idea which approach is most beneficial for you depending upon your data.

Final Words

As we reach the end of this blog post, I hope you get the answer to all your queries regarding how to open MSG file in Thunderbird. The every method discussed in this article serves a different purpose and use cases depending on the needs. The manual technique is useful for temporary access and few MSG files whereas the robust MSG to Thunderbird Converter is best suited for users who value accuracy and efficiency in the results and handle large collections of data. In addition, it provides a direct way with complete security. Now, the last decision is yours, so always choose the right method after reviewing everything.

FAQs

Q1. Can I directly access MSG files in Thunderbird?

No, Thunderbird does not support MSG file format. To access it in Thunderbird, you must first convert them into EML or MBOX format or use a dedicated professional solution for direct import.

Q2. Can I open MSG files without Microsoft Outlook?

Yes, you can. But the available options are very limited. The manual method requires Outlook Classic installation as a must. Whereas if you don’t want to use MS Outlook then you can use the above suggested MSG to Thunderbird Converter that opens and imports MSG files without requiring Outlook or any other application.

Q3. Will my metadata and data attributes be preserved while opening MSG manually?

No, there is no guarantee or support for your data security. Manual ways are risky, whereas an automated approach provides users with a guarantee of data security and 24/7 customer support.