How to Import Outlook OST to Thunderbird Mail? – Ultimate Guide

  •  Pradeep Kumar
  • Published on:  June 11th, 2024
  • Updated on:  June 12, 2024
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Microsoft Outlook is a popular email client, whose proprietary file is OST (Offline Storage Table) that stores a copy of Outlook mailbox data. On the other hand, Mozilla Thunderbird is a free and open-source email client. Many users want to import OST to Thunderbird, so they can easily access both email clients (Microsoft Outlook and Mozilla Thunderbird) in a single place.

Importing OST files into Thunderbird is a difficult process. As we know, Thunderbird supports MBOX file format and there is no direct way to open an OST file to Thunderbird instead of our software “OST to PST Converter”. Don’t worry, we will help you with the entire import process. In this article, we will cover two methods: a manual method and a professional method.

Why Users Want to Import OST to Thunderbird Mail?

There are several reasons why a user decides to import an OST file into Thunderbird. Some of them are mentioned below.

  • Free of cost: A preference for open-source and cost-effectiveness doesn’t require any subscription or any purchase.
  • Security: Known for its strong security features that include encryption and spam filtering.
  • Accessibility: Thunderbird can be used on Windows, Linux, and MacOS.

Manual Method to Import OST Files to Thunderbird

The manual approach is not a straightforward method to import OST files in Mozilla Thunderbird. Importing OST to Thunderbird involves three steps, 

  • Export OST to PST files
  • Import PST to Thunderbird

Now we will explore the three steps in detail to provide you with concept knowledge about Import OST File in Mozilla Thunderbird

Step 1. Export OST file to PST file format

A user can convert OST to PST easily just by using Microsoft Outlook.

  • Open Microsoft Outlook on your device.
  • Then, go to File > Open and Export > Import/Export.
  • Select Export to a file from the drop-down and click Next.
  • Choose Outlook Data File (.pst) in the file type option.
  • Now choose the folder the user wants to export.
  • Set the Name and destination for the exported file and click Finish.

Step 2. Import PST file into Thunderbird Account

  • First, make sure Outlook is your default setting for sending and receiving email by clicking on the Default Programs >> Set your default programs, then choose Outlook.
  • Run the Thunderbird app, tap on Tools, and select Import options
  • Now, pick Import from Outlook and click Continue.
  • Now, choose what to import from Outlook and click on Continue.
  • Finally, click on Import. It will take several minutes to complete the process.

Here, we have completed the manual method to import OST to Thunderbird. However, the upper method contains some drawbacks. Now, we will see some limitations of the manual method.

Limitations of Manual Method

There are several limitations of the Manual Method, which are listed below in points.

  • Time-consuming: The manual method requires a user to manually perform all the processes. Importing all mailboxes can be lengthy as it contains tons of files.
  • Risk of data loss: During the conversion process, there is a risk of data corruption, when a user is not familiar with technical aspects.
  • Bulk Conversion: You have to perform all the manual steps again and again for every email if you have multiple files.

Direct Way to Import Outlook OST File into Thunderbird

The Cigati OST to PST Converter can directly import OST data files into Thunderbird within a few steps. Because of its simple and intuitive user interface, any user can perform the conversion very easily without losing any data. Even it keeps all the email data organized as it was before, including attachments and other data. With the help of our software, users can remove duplicates, filter their emails using a date range, and import emails without attachments. Below are the steps on how a user can perform the importing process.

Steps to Import OST to Thunderbird

  • First, download and run the Cigati OST to PST Converter on your device.
  • Then, Choose Single/Multiple Files to add an OST file.
  • Next, select the OST file to add them.
  • Then, you can view the files/folders in the preview panel.
  • Now, choose the Thunderbird client from the drop-down list.
  • After that, you need to authenticate your Thunderbird account to proceed further.
  • Finally, tap on the Convert button to start the conversion.


In the above blog, we discussed how you can import OST files into Thunderbird using a professional tool that directly imports to Thunderbird. However, there is also a manual method available to do the same, but it has some limitations that can cause data loss and corruption. That is why we recommend opting for an effective method that works for you and helps you import OST into Thunderbird hassle-free.

About The Author:

Pradeep is a dedicated technical content writer who thrives on the intersection of technology and storytelling. With a background in engineering and a passion for writing, he brings a unique blend of technical expertise and creativity to his work. Pradeep’s articles not only educate but also entertain, making complex technical subjects approachable and intriguing for a broad audience. His work has been featured in numerous tech blogs, making him a trusted source for tech enthusiasts and novices alike.

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