Convert OST to MBOX

How to Convert OST File into MBOX Format Step by Step Instantly?


Query: I am switching from Microsoft Outlook 2016 to Mozilla Thunderbird due to some reasons. So, I am searching for a solution which can perform OST to MBOX conversion. Please suggest me the best way to convert offline OST file into MBOX format so that I can access my emails and other data in Mozilla Thunderbird.

Solution: Definitely, I will help you out from this situation. Let me share the methods by which you can convert OST to MBOX file format. So basically, there are 2 methods to export data from Microsoft Outlook data file (.ost) into Mozilla Thunderbird email client are:

So, let’s start explaining both the methods one by one.

Method 1: Export Offline OST File into MBOX File Format Using Automated Solution

Following are the below steps to convert offline storage file (.ost) into MBOX file format in few steps:

download OST to MBOX Converter

OST to MBOX Converter

  • Step 2: Install, run it and check it’s all prerequisite.
  • Step 3: Open the application, under Add files tab, click on Browse button to open Offline OST file.

Browse OST File

  • Step 4: Select the Outlook.ost file from the location wherever you have saved it in your machine to perform OST file MBOX conversion.

Location of OST File

  • Step 5: After adding the OST file, the software will start scanning the offline Exchange OST file.

Scanning OST File

  • Step 6: Once the completion scanning, all the emails and other data will appear on the left side of the software panel.


  • Step 7: No select the folder where all the emails are saved. Select the Inbox folder. If you have emails in any other folders, then you may select that folder too.

Select Inbox Folder

  • Step 8: Click on Next button to start exporting OST into MBOX file format.
  • Step 9: The screen will be appearing you five output formats, select MBOX option.

Choose MBOX Option

  • Step 10: Click on Browse button to select the destination path to save the resultant MBOX file.

Browse Destination

  • Step 11: Finally, click on Export button to begin the OST file to MBOX conversion.

Click Export

  • Step 12: After the completion of process, the software will show that you have successfully converter Microsoft Outlook / Exchange account offline OST file into MBOX file format.

Successfully Completed OST to MBOX Conversion

The above automated solution is the best way for converting mailboxes from OST into MBOX file format easily, quickly and safely without any data loss.

Point to be Remember: If your OST file is not healthy, means corrupted, then first repair it using free SCANPST or Inbox Repair Tool. Afterward, add the health OST file in the above application. Otherwise, you may face some problem to perform OST to MBOX conversion.

Method 2: Step by Step Guide to Convert OST file into MBOX format Manually

In this manual method, you have to use 2 steps for exporting mailboxes from Exchange OST file into MBOX file format. Let’s start free OST to MBOX procedure.

Step 1: Using Import/Export Option of Microsoft Outlook

  • Firstly, Login your Microsoft Outlook 2019 with the Exchange account.
  • Now, go to the File >> Account Settings.

File Tab

Account Settings

  • Click on Data Files tab.
  • Now, click on Open File Location folder to locate the OST File.

Open File Location

Now, follow the steps to export mailboxes from Outlook data file (.ost) to PST format.

  • Again, open MS Outlook with your Exchange account and visit to File tab.
  • Click on Open & Export and hit on Import/Export option.

Import and Export

  • Select Export to a file option >> hit on Next.

Export to a File Option

  • A new window will open, choose the 2nd option i,e; Outlook Data File (.pst) >> hit on Next.

Outlook Data File

  • Next, select the folder from which you want to export the data and click Next.

Select Inbox Folder

  • Browse the destination path wherever you want to save the exported or resultant Outlook data file (.pst) and select “Do not import duplicate items” option or you can select as per your requirement. Click on Finish button.

Destination Select

  • You can find the exported Outlook data file (.pst) at the destination.

Now, import the exported Outlook PST file into Mozilla Thunderbird account.

Note: If you have orphan Outlook PST file, then you don’t need to open Microsoft Outlook account. Just follow the below step.

Step 2: Import Resultant PST File into Mozilla Thunderbird Account

  • Initially, you need to download, install and rum Mozilla Thunderbird on your computer.
  • After the successful completion of Mozilla Thunderbird, open it.
  • Now, go to the File Menu and then Import option.
  • Next, start importing resultant Outlook data file (.pst) which you want to convert in MBOX file format.
  • After doing so, Mozilla Thunderbird will convert your resultant or selected Outlook PST file into MBOX format.

As we all know that, Mozilla Thunderbird creates .mbox file format. So, finally we have got an MBOX file using manual solutions.


In the above article, we have explained the two methods for OST to MBOX conversion and a really query of a user for the better understanding. In the first method, you will get the automated solution to convert OST file into MBOX format. For that, you just need to use Ignissta OST to PST converter.

And, in the second method, you will know how to export Offline storage file (.ost) into MBOX file format manually. To do so, you need to use Import/Export function of Outlook and Mozilla Thunderbird.

But the manual solution is time taken process, and also there is no guarantee of data loss and security. So, experts always say that you should use automated solution i.e; Ignissta OST Converter. It will easily export all the data from OST file into MBOX format without any data loss.

Leave a Reply