Convert OST to MBOX File Format – Know the Top Methods

convert ost to mbox

Handling large email data is a tedious task and can become a huge problem for users. The user decided to migrate their data into another email client but it doesn’t support the current file format. The user must have to convert OST emails into MBOX format. If you are in one of them, this article is specially for you. I know you must have a query “How do I convert Outlook data to MBOX?” Don’t worry we will resolve your query. 

Both OST and MBOX file formats are important and popular file formats in their perspective. But it is not compatible with each other. So if you are converting from  Office 365 to an email client that doesn’t support .ost file and is suitable in .mbox file format. You really need to change your email client. Well, we are going to share with you the two most important methods to convert OST to MBOX Files with Attachments. 

Manual Method to Convert OST to MBOX

This method contains two prominent approaches. Directly you can not convert. You have to first convert your .ost files into the .pst file format after that you have to change your .pst file into Mozilla Thunderbird. Follow these steps to convert OST to MBOX Files with Attachments 

#1  OST to PST Conversion

  • Launch the MS Outlook application.
  • Select the Open & Export option.
  • Choose the Import/Export option and then choose Export to a file from Import and Export Wizard, and click on the Next button.
  • Select Outlook Data File (.pst) from Export to a File window and hit the Next button.
  • Select the folders that you want to Export and click on the Next button.
  • Assign a path to save PST and select the include subfolder checkbox.
  • Hit the Finish button.

And it’s done you have successfully converted from .ost to .pst. Now you have to change your file format from OST to Thunderbird.

#2  PST to Thunderbird Conversion

  • Launch The Outlook application.
  • Make your Outlook the default program.
  • Open the Thunderbird to OST to MBOX conversion.
  • Go to the Tools section and choose the Import option.
  • Select Mail from the Import window, and click on the Next button.
  • Select the Outlook and click on the Next button to start the conversion process.
  • When the process is complete, All the imported emails will be displayed.
  • Now click on the Finish button.

After the process, your all emails will be stored in the Outlook Import folder in the local folders directory. Through this method, the User can easily convert OST to MBOX free. Now we will see the professional approach for OST to MBOX conversion

Professional Method to Convert OST to MBOX

We must suggest a third-party tool OST to PST Converter. This tool perfectly suits to your needs. Along with OST to PST conversion you can also convert Outlook OST files to distinct File Formats and Email Providers in a few simple steps. Apart from this users also can migrate from Outlook to Office 365, Gmail, AOL, IMAP, Thunderbird, Zoho etc. The software is highly recommended for exporting Outlook OST to various file formats. It gives you the advanced features to convert OST files to PST. You can convert email attachments to MBOX file format. It is compatible with all Windows OS including Win 11. It comes with a Free demo version and Technical support. Follow these mentioned steps to convert OST to MBOX.

  • Download OST to PST Converter Tool.  And install the application and run it as administrator.
  • Now go for  Single File/Multiple Files options to add OST files.
  • You have a mailbox preview of the OST file. Tick the desired mailbox items.
  • Now, choose MBOX as the saving option from the drop-down menu.
  • Select the Convert button to convert OST emails to MBOX format.

All done. You have changed your file format from .ost to .pst without any problem. I will recommend you to use this tool personally. You can use this tool so well because it has so simple user interface and no need for extra technical expertise. 


We hope this article has provided all the required information related to your query.  The manual method to convert OST to MBOX is good for the user who has technical expertise. A better alternative is to use the professional approach. It will provide you with various advanced features to simplify the migration process. Also, it gives you a wide range of options to modify the migration as per your needs.