Proven Ways to Convert OST Files to Thunderbird MBOX

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  • Published on
    March 14th, 2023
  • Read Time
    4 minutes
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Summary:- All the data of MS Outlook is stored in an OST file whenever you work offline on it. It is impossible to view the emails of an OST file without converting it to any other file format. Many Outlook users shifting to Thunderbird need to convert OST to MBOX to migrate all emails. So here you can explore an easy way to move all emails from an Outlook OST file to Thunderbird MBOX. You can make use of the OST Converter Software and do the migration.

Difference Between an OST and MBOX File

Basis OST Files MBOX Files
Definition Offline folders that aid users in working in offline mode are called OST files. It stores account information and data like tasks, email messages, contacts, calendars, etc. MBOX files are file formats that are used for the collection of electronic mail messages. It stores entire messages of a desired folder in a separate database file.
Supports Two email clients support OST files, Microsoft Outlook and Exchange Server. Various email clients support MBOX files, Apple Mail, Mozilla Thunderbird, Eudora, and many more.
Size Limits There is a preconfigured limit of 50 GB on the size of OST files. Yes, there is also a limitation of 4.7 GB on the size of MBOX files.


Reasons for Converting OST Files to Thunderbird

  • When an Outlook user is shifting from Outlook to Thunderbird.
  • When you want to sync all emails of the Exchange OST file to Thunderbird.
  • OST files can’t be opened unless OST Files are converted to PST.
  • Thunderbird offers many updated features that are not available in Outlook.

So, you have seen the differences between the OST file and MBOX and the reason why people want to convert OST to MBOX. Now you can check the method to migrate all emails from an OST file to MBOX.

Method to Convert all Emails from an OST file to Thunderbird MBOX

The only way to transfer OST file emails to Thunderbird is to use the OST Converter Software. This software allows you to move every single OST file email with its attachments to the Thunderbird MBOX File. You will just have to instal and Launch Software>Add OST File>Mark OST File Emails>Choose Saving Format as MBOX>Define the location and Convert. Your OST File will be converted to MBOX and now you can import it easily to any Thunderbird account.

Quick Steps for OST to MBOX Conversion

  • Launch and Open OST Converter Software and Add the OST File.
  • Then you can preview all the emails present in the OST file.
  • Mark the emails that you want to move to the MBOX file.
  • Now in the Save As option, choose MBOX and define the location.
  • Finally, click on the Convert button and all your OST files will be converted to MBOX.

After having an MBOX file, you can import it to any Thunderbird account and view the OST file emails. If in case your OST file is corrupted and you want to convert it to MBOX then you can make use of the OST Recovery Software and recover and convert the OST File emails to MBOX.

Features of Automated Software

  • You can convert any type of OST file to MBOX created on any Outlook Version.
  • There is no file size limitation and this software can even large OST files.
  • Even if you have multiple OST files then al you can convert them to MBOX at once.
  • You can use this software on all versions of Windows.
  • You will love the interface of this software and easily convert OST to MBOX.


You have seen the simplest method to import all emails of an OST file to Thunderbird by converting them to MBOX. This software does the full email migration without missing any emails from the MBOX File. You can download this software and do the OST to MBOX Migration.

Frequently Asked Questions

Q. Can I migrate an OST file of 50 GB to MBOX?

Ans – Yes, with the help of an OST Converter, you can easily migrate an OST file of 50 GB to Thunderbird MBOX.

Q. I have 20 different OST files, can I migrate all of them at once to MBOX?

Ans – Yes, this software will help you to do the conversion of unlimited OST files to MBOX at once with all the email attachments.

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