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How to Convert OST to PST with Stellar Converter for OST

Updated: Dec 29, 2023

We are going to look at the application called Stellar Converter for OST and what we think of it when it comes to recovering data from inaccessible and old OST files. We will be looking at the installation, ease of use, features and of course the end result of the application. We all know that OST is a proprietary format of Microsoft which in comparison to a PST file it cannot be transferred to another computer or device and opened with another Outlook. An OST file is a synchronized copy of your live mailbox and cannot be opened even on the same machine with a different profile. From Microsoft Office 2013 onwards we also see the use of OST file format in IMAP accounts also.

Since it’s a sync, why would anyone want to recover from it and who cares if it’s get corrupt, right? Well that is where you’re wrong. If you have travelling users and these work offline on their device writing emails, creating tasks and calendar invites while something happens to their computer… the only way to retrieve the time spent and those particular emails is from the OST file. When you create a draft, send emails which go into the outbox, create task or create new calendar entries, these all go into the OST file and once there is a connection to the Exchange Server, these changes will be synchronized to the mailbox in the server and vice versa.If Outlook would get corrupted before the synchronization, then retrieving from the OST is pretty much your only option… apart from accepting data loss. Try to explain that to the angry user who was working in offline mode for the last two hours.

If you have an old computer of a user who left the company and the mailbox was deleted from the Exchange Server, the only way to get the data back is by retrieving from the OST file.

Another most drastic thing you would need to recover from an OST file if the server is compromised and lost and restoring from backup is useless or even your backup is lost. The only copies of the mailboxes is in the OST file. Thou drastic there were cases where an IMAP server was compromised and deleted, and to top it off the backup servers where on the same network and were deleted along with the live server.

As you can see above an OST file although useless it can be indispensable at times and your only hope in extreme and day to day cases.

Like this we have a basic on what an OST file is and the importance of the file. Let’s talk about the application Stellar Converter for OST. The installation was fairly easy and with a few clicks I had the application installed in a few minutes.

Once I opened the application I was immediately greeted with the window to choose the OST file manually or search for any OST files in my drive. This is a good part as usually OST files are hidden in the user’s profile and can be tricky to find.



When the OST file is selected, it will execute a scan of the file before getting started. Mind you, depending on the size of the OST file the application will take its course in scanning it, but with the tests I ran it was quite efficient. Once the scan is ready, you will have an interface that looks like this.


If you scan a large OST file which could take some time to finish you can always click on the Save Scan to save a copy of the scan job so that next time you can just load the scan to skip the scanning. Taking a look at the UI it’s very neat and all is in one screen. The one thing I hate is to have to go through a lot of screens and windows to do something in an application. On the left hand side you will see all the structure of your mailbox along with other information which Exchange saves in the OST file. In the middle pane you will have the list of items in the selected folder and on the right pane you will have the preview pane which will show the highlighted email contents in HTML format. On the bottom left you can also find the icons of the mail, calendar, tasks, journal and contact. This is a very good interface as it resembles the one you would find in Outlook meaning that you will easily adapt to the application.

In the middle pain I have also noticed that the search is integrated in the same screen i.e. you can search for emails by sender, recipient, date and subject on the file and results will show while you type.


Each folder on the structure on the left has a tick box. This is because you can choose what to export or not. If you tick some folders and click the Save Converted File on the bottom right, it will export all the items you selected and save them to PST.


There is a refined search in the application by clicking the Find Message in the toolbar on top. This includes searching for messages with dates. This will be show you the results and you can even more fine-tune them with the search bar in the results area. While in this view, you can explicitly export the emails to other formats such as MSG,EML, HTML or PDF.


If you export the whole OST file to PST or the emails in the draft or any other folder at your discretion you will be asked to select the format and destination. Once you click OK, voila the magic is done and your data is being exported to PST format or other.

Taking a look at the bottom of the right pane you can change over to the other items in the mailbox like Calendar,tasks, people and journal where you can also search and export accordingly.


In Conclusion

Stellar Converter for OST comes really handy in those sticky situations and those drastic and disastrous ones. Setting up the application was fairly easy and the interface felt comfortable and very easy to get going with it. Stellar Converter for OST was great and performed really well on corrupted and large OST files. It supports any version of Office from 2000 till 2019 and with the Technician licence you can export from OST files directly to a live Exchange Server database or to an Office 365 tenant,so you can use it also as a migration tool. The application is highly recommended for those one time disaster cases and the day to day recovery of an Exchange Administrator.

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