It is technically not possible to open OST files in Thunderbird or import them, like you can do for MBOX. OST means ‘Offline Storage Table’ and is slight variant of PST file. PST is however a personal file used in many ways as users need. OST is different.
Convert OST files to Thunderbird
To convert OST files to Thunderbird, you would need a software that can do that. There is no manual way to either convert the files or rename their extensions; it does not work like that. Only through a third-party app can you convert the files in their needed formats and also restructure the information within them.
And while there are many converters, not all of them are simple to use or effective, or even safe for your emails. Except OST Extractor Pro (for Mac & Windows).
If you have any worries about converting OST files to Thunderbird, ‘OST Extractor Pro‘ is the answer.
It can also convert OST to PST, MBOX, EML, Apple Mail, Postbox etc.

It works simply enough that you do not need any experience or to read any tutorial. It’s greatest feature is that it does the job quickly without asking for any confusing input from the user. It does not indulge in technical sidesteps that are unnecessary but part of many methods and software. The simplicity you get is what makes the tool one of the best.
How to Convert OST files to Thunderbird using ‘OST Extractor Pro?’ As said above, there is not much need for a tutorial to use it. Once you have installed and launched it, anyone can understand what needs to be done. To put it in few words: just load your OST files, choose the folders you want to convert, and click ‘Convert.’

Therefore, the steps outlined below are more for the purpose of showing the functionality and giving you a clearer idea of its workings. It comes in both Mac and Windows, but the way it works is same for both.
How to convert OST to Thunderbird
- Click the link given at the bottom of this article to download the setup. Double-click the setup file, follow the instructions for installation.
- Once installed, you can launch it by double-clicking the launch icon from your “Programs” list or “Applications” list.
- Click on “Add OST” at the top. Browse to the OST files for conversion and select them. You can select more than one.
- The tool displays all the folders within those files. And you are free to remove any folder you don’t want to convert.
- Choose the output format (which is ‘Thunderbird’ in this case, but you can also choose PST, Apple Mail, MBOX, and EML).
- Click ‘Start’
That’s all. It works in less than 10 minutes for 1 GB of data, which is much quicker than any other app out there.
Try It Today!
‘OST Extractor Pro‘ carries specialized logic for your Unicode headers, large files as attachments, embedded images, and for the folders’ hierarchy. So you can also let go of all the concerns regarding incomplete conversion and data errors.

You can find the download link below.
Download now at https://www.uslsoftware.com/ost-to-thunderbird-converter-for-mac-and-windows/