Best Methods to Convert OST to MBOX Format

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You must be familiar with OST files as a Microsoft Outlook user, which stores mailbox data locally on a user’s device. What if you want to use another email client like Thunderbird that uses MBOX file format? It will be hard to convert OST to MBOX as there is no straightforward method.

In this article, we have shown the difference between MBOX and OST, and we will discuss the simplest method of using an OST to PST Converter to get an MBOX file from an OST. So you can easily access your email data in Mozilla Thunderbird. A manual method uses a tricky approach to convert OST to MBOX format.

Difference Between OST and MBOX

AboutIt is an email archive used to archive and migrate email data.Offline Storage Table used by MS Outlook to store a local copy of the user mailbox.
Data Format Stores email data in a Plain-text formatStores email data in proprietary Outlook, Binary file format.
CompatibilityCompatible with Mozilla Thunderbird, Apple Mail, and more.Only compatible with Microsoft Outlook.
Size LimitThis file format doesn’t have a size limit.It has a size limit of 2 to 20 GB.
ConvertWe can convert this file format into almost every other format.It can only be converted into PST format.

#1. Manual Method to Convert OST to MBOX Format

In this method, we will convert Outlook OST to MBOX using a unique technique. First, We will export OST file to PST file using the Microsoft Outlook application, and then We will get the MBOX file using Mozilla Thunderbird.

Step 1. Export OST file to PST file

To convert your OST files to PST, follow these steps:

  • First, Run the Microsoft Outlook on your device.
  • Next, go to the “File” menu and tap on “Open and Export” → “Import/Export”.
  • Now, click on “Import/Export” → “Export to a file” and click “Next”.
  • Choose “Outlook Data File (.pst)” as the file type and click Next.
  • Select the folder you want to export from Outlook.
  • Then, set the Name and destination for the exported file and click “Finish”.

Step 2. Convert the PST File to MBOX file

To convert PST to MBOX file format, follow the below steps:

  • Run Microsoft Outlook, and then import the PST file into it.
  • Next, run the Thunderbird application, tap on Tools, and select Import options
  • Now choose Mail and hit Next.
  • After that, opt for Outlook from the list and click Next.
  • You will see an Outlook Import folder containing all the emails under Local Folders.
  • Now close the Import window.
  • Next, open Thunderbird and install the ImportExportTools NG extension.
  • Then, go to “Tools” → “Import Export Tools” → “Export all the Folders”.
  • Here, set the location to save the resultant file and click “Select Folder”.
  • Finally, you will get the MBOX file.

Now we will see an alternate method to convert OST to MBOX, which uses OST to MBOX Converter. The method will be straightforward, no need to perform any manual steps described above.

#2 Professional Method to Convert OST to MBOX

The OST to PST Converter simplifies the process of importing an OST file to MBOX in simple steps. Its simple user interface ensures that any user with/without technical expertise can easily complete the conversion without worrying about data loss. Additionally, users will easily remove duplicate emails, offer bulk import, and support for various file formats and email clients. This is an ideal solution for those users who want to save time and effort by converting large OST files into an insignificant amount of time.

Steps to Import OST to MBOX

  • First, download and start the OST to PST Converter on the device.
  • Next, select the Single File/Multiple Files option to add an OST file.
  • Then, choose the OST file to add it.
  • Now, you can see the files/folders under the preview panel.
  • At this point, choose the MBOX from the drop-down menu.
  • Soon after, you must authenticate your MBOX account to move forward.
  • Click the Convert button to start converting.

Also Read: Import PST File To Gmail Email


In this article, we have mentioned the overview and difference between OST and MBOX, and also we have described the efficient and hassle-free approach to converting OST to MBOX file format. The manual method uses the Outlook application, and the professional method uses an OST to PST converter software. The manual method is a time-consuming process and requires technical knowledge. The professional method has an intuitive interface and doesn’t take much time, which makes it an ideal way to solve the conversion process.

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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