How to Open OST file in Thunderbird? 2 Ways Discussed

  Rollins Duke
Rollins Duke   
Published: December 22nd, 2025 • 7 Min Read

Summary: Searching for the best and most reliable technique to open OST file in Thunderbird? Are you stuck in a situation where you have a folder having many OST files and want to import OST to Thunderbird without losing crucial data? If yes, this blog will surely help you out! Read this entire write-up to know how to open OST file in Thunderbird in batch.

Switching from one email client to another is now easier. Though there are numerous manual solutions available for doing so, it is a little bit techie. Today, for business organizations as well as for other personal uses, individuals prefer to work with a free email client such as Thunderbird. However, the problem occurs when users can’t transfer their data from one email client to another. Recently, our technical team received a query from a client where the user wants to import OST file into Thunderbird.

Does Thunderbird Import OST File? User Query

I am currently working for an IT MNC Company where almost all co-workers and management use Microsoft Outlook 2021, 2019, and 2016 versions. Due to some reason, I have decided to shift to another job location, but all my crucial emails are stored in MS Outlook in OST (Offline Storage Table). Now, I want to open OST file in Thunderbird client. The main reason is that Thunderbird is a freeware email client, and I don’t want to spend money on purchasing any email client. Along with emails, a few attachments are embedded with them. Can someone please suggest a workable solution so that I can access Outlook OST file in Thunderbird? Your help will be appreciated!

– Austin, USA

#1 Manual Method to Open OST File in Thunderbird

Various users prefer to import OST file into Thunderbird manually without purchasing any external software. If you are one of those who is looking for a manual solution to convert OST to Thunderbird, then you can do this using a Microsoft Outlook desktop client.

If your OST file is linked to Microsoft Outlook, you can manually import Outlook mails to Thunderbird. Unfortunately, if you have orphaned OST files, you cannot open them directly in Thunderbird.

Follow the complete instructions below to open OST file manually.

How to Import OST to Thunderbird Manually?

  1. Launch the Thunderbird email client on your computer.
  2. Then, choose Tools > Import option from Thunderbird.
    Import option
  3. Next, enable Import from Outlook and tap Continue.
    Import from Outlook
  4. Select the required items to import from OST and click Continue.
    Select Mail messages
  5. Press the Start Import button to import OST to Thunderbird.
    Import OST file into Thunderbird
  6. Thunderbird import OST process completed successfully.
    Thunderbird Import OST File

Unavoidable Setting: Please don’t forget to set MS Outlook desktop as your default email client to access OST file in Thunderbird. This is a mandatory setting so if you are facing any error then do this immediately.

Limitations of the Manual Method

  • The OST file must be linked to Microsoft Outlook.
  • No dedicated support, you only need to rely on the forums.
  • Outlook should be a licensed version.
  • Minor mistakes during this process can lead to permanent data loss.
  • To use this solution, you need to install MS Outlook on your computer.

Note: If you are a professional user, the above-described section is not suggested for you. Since it has more limitations, including data corruption. Therefore, to overcome the challenges, you can check more trusted solution in the other section.

#2 Automated Method to Import OST File into Thunderbird

Now we understood the limitations of the method described above and know that the user cannot open OST file in Thunderbird easily. Therefore, we’re recommending you use a professional solution. i.e., OST file converter software that allows you to directly import OST files into Thunderbird local folder. Follow the steps provided below to access OST file in Thunderbird.

How to Open OST File in Thunderbird? Watch Video

How to Convert OST to Thunderbird? See Screenshots

  1. Start the Thunderbird Import OST tool and add OST files in the software GUI.
    Add OST files
  2. Select the required items to import from the OST file to Thunderbird.
    Select OST file items
  3. Navigate to the saving options tab and choose Thunderbird as a file-saving format.
    Choose Thunderbird
  4. See the tool automatically chooses the default storage location, don’t change it.
    Destination path
  5. Press the Convert button to start importing OST files Thunderbird.
    Import OST to Thunderbird
  6. Open the Thunderbird client and see the imported OST into Thunderbird.
    Open OST file in Thunderbird

Thunderbird Import OST Tool Features

Batch Open OST Files in Thunderbird: With the usage of this software, one can view OST files in batch in a single folder and load them for conversion into Thunderbird.

Preserver All Attachments: During this conversion process, you don’t need to worry about attachments. The tool will access OST file in Thunderbird with respective attachments.

Open with Exact Formatting: During this conversion process, there is no loss of originality of data. The utility will automatically open OST file in Thunderbird with preserved email components like Subject, To, From, font formatting, hyperlinks, etc.

Dual Modes for Adding OST Files: The user has the freedom to select the desired option for loading OST items into the software panel. With Select Files, you can add desired OST files and with the Select Folder option, you can load the entire Outlook offline data file folder.

No Requirement to Install Outlook: Using this Thunderbird Import OST wizard, the user need not install MS Outlook for the entire process. One can even open OST file without Outlook in the Thunderbird email client.

Saving features: With this tool, you can also convert OST to PST, PDF, EML, MBOX and 39+ Saving options.

Why Do Users Add OST to Thunderbird?

Best for Personal Use: MS Outlook is a widely known email client service that comes up with MS Office pack. However, various organizations don’t prefer to use it as it is costly. Thunderbird, on the other hand, is a freeware and open-source email client thus, individuals want to access OST file in Thunderbird.

Cross-platform Availability: Thunderbird is available for various platforms such as Windows, Linux, macOS, Unix, and BSD.

Data Compatibility: If users have OST files in their system and want to add them to Thunderbird they can simply, download this software. It will efficiently import OST files into Thunderbird.

Final Thoughts

In the above blog, we have described the top 2 ways to open OST file in Thunderbird. So, if MS Outlook is configured and connected with OST file then you can go with a manual solution as mentioned above. You can even try the demo version of this Thunderbird Import OST Tool to evaluate the proficiency of the software.

This demo edition allows importing the first 25 items from each OST folder to a selected format or email service. Once you test the tool’s efficiency, switch to the full pro version of the tool. It permits to import OST to Thunderbird without any limitations. If you still have any queries regarding this, you can contact our technical team.

Frequently Asked Questions

Q 1: How do I open an OST file in Thunderbird?

  1. Download and run Thunderbird import OST Wizard.
  2. Then, add OST files in the software window.
  3. Select the required items that you want to open.
  4. Choose Thunderbird from the list of saving options.
  5. Tap on Convert to open OST file into Thunderbird.

Q 2: Can I import OST to Thunderbird with all email items?

Yes, both manual and automated approaches allow us to convert OST to Thunderbird including complete items and attributes.

Q 3: Is Thunderbird installation mandatory to use software?

This is a standalone software that works without installing any supported email program. However, if you have a desire to import OST to Thunderbird then Thunderbird installation is required.


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