How to Recover Data from Orphaned OST Files using Free OST Converter?

2026-03-28 - 00:43

An OST file becomes orphaned when it lost connection with the mailbox server or the mailbox account is deleted from the server. You cannot access such a file through Outlook. However, you can convert your orphaned OST file to PST by using a reliable free OST converter tool to recover your mailbox data. In this article, we will discuss why OST files become orphaned and explain the step-by-step process to recover mailbox data from orphaned OST file by using a free online OST to PST converter tool. Understanding the OST File Offline Storage Table or OST is a type of Outlook data file that is created automatically when you configure your email account with Exchange, IMAP, or Microsoft 365 in Cached Exchange Mode. This file acts as a copy of your mailbox data saved locally on your device. It contains all your mailbox items, such as emails, calendar, attachments, tasks, contacts, etc. This file facilitates to work offline, i.e. when Outlook is not connected to the server or internet connection. Any changes you do, like composing emails, updating contacts, etc. will be synced automatically as soon as the connectivity is restored‍​‌‍​‍‌. There is another attribute of OST file – it is encrypted with the MAPIEntry GUID key. This means that it is closely tied to the specific Outlook profile and mail account in which it is created. Therefore, you cannot open the file directly in any Outlook profile or account. Why does an OST File become Orphaned? An OST file becomes orphaned when it loses connection with the mailbox on the server, making it inaccessible. This happens when: The Outlook profile is deleted. Exchange or Microsoft 365 account is removed. Mailbox is deleted from the server. There are domain changes in organization. The Exchange Server is decommissioned or crashed. Recovering Data from Orphaned OST File using Free OST to PST Converter Tool As already mentioned, you cannot open and access the orphaned OST directly in another Outlook account. In this situation, the only practical solution is to convert the OST file to PST format using a specialized OST to PST converter tool. There are many such tools available in the market but free OST to PST converter online by Stellar is one of the most trusted and recommended tools. This tool can convert orphaned OST files (up to 500 MB file size) to PST online for free. You can also go for premium version of this tool that allows you to convert OST file of up to 5 GB. Below are the top features of the online OST to PST converter tool by Stellar: Free online OST to PST conversion No Outlook installation required Convert OST file to PST in 3 simple steps No Exchange Server needed Preserves folder structure after conversion No data retention for user privacy Real-time progress tracking Steps to convert OST to PST using this free online OST converter tool: Open a web browser on your computer, like Chrome. Now, visit this: Stellar OST Convertor Online Sign up before starting the conversion. Select Upload OST File. Locate and select the OST file (<500 MB). Click on Open and wait until the file is uploaded. Click on Start Conversion. Wait for the process to complete. Once the process is complete, select Save PST file. Now, you can open or import this PST file into any Outlook account or profile to access your orphaned OST file data. Follow the steps given below to import the PST file into Outlook: Launch Outlook on your device. Go to File > Open & Export. Click on Import/Export. Select the option – Import from another program or file. Click on Next. Select Outlook Data File (.pst). Click Next. Click Browse and choose the location of your PST file. Click Next. Select the folder to import from and select the Include subfolders checkbox. Choose the destination folder and then click Finish. Conclusion In this article, we have explained how to recover data from an orphaned OST file by using the free OST converter tool by Stellar. With its user-friendly interface, you can easily convert the orphaned OST file into PST. This tool can recover your data from orphaned OST file in a few simple steps. But if your OST file is large, then you can opt for the desktop version, called Stellar Converter for OST. This tool can convert inaccessible or orphaned OST file without any file size limitations. In addition to PST, it can save the OST file data in various other formats, such EML, MSG, etc.