If you want to import PST files to Office 365, you can do it simply by going to ‘File’ → Open & Export → Import/Export → Import from another program or file → Outlook Data File (*.pst). However, you will notice that there is no option to import OST to Office 365.
Import OST to Office 365 for Mac & Windows
Even though OST is a variant file of PST, Office 365 offers no way to import it. It serves another purpose while storing data. Contrary to the PST file which is more suited for personal and manual data operations, OST is an internal file for Office 365 that works automatically with its functions.
But there are cases where that internal relation between the Office 365 client and OST file may disrupt. That can render the OST file inaccessible but with the important data stuck in them.
Example of cases where that may happen:
- You deleted the original email account without taking backup. Now all the data is in the OST file, but you cannot use it in anyway, at least not directly.
- Virus attacks can also have the same effect.
- Network failures can disrupt the data synchronization process and may isolate the OST file from the main account
- Hard drive failures, power failures, and other similar events are often the cause of inaccessible OST file.
You may have gone through one of these above situations. And now you have the OST file with you that you cannot import to Office 365.
Do not worry. We have a simple solution.
Solution to Import OST to Office 365
By using “OST Extractor Pro,” you can convert the OST file to PST and then import PST like normal. The tool features essential options and functionality along with a UI that is easy to interact with and follow.

There are other similar tools as well but most of them have one or more missing features that can make a huge negative impact in your experience. OST file to PST conversion may sound simple at first but it can be quite complicated. And the modern-day complexity of email databases that contain more than just words/text make it a rather trickier task to undergo. Without a professional set of algorithms to extract information, you can end up with fragmented files with data integrity errors.
Mostly, it is the Unicode content, headers, large attachments, folders hierarchy, and graphics that can be tough to convert. In subpar tools, there are no proper scripts to handle these kinds of information, giving you incomplete results. It can be devastating with work-related OST files where every little item can be very important, such as clients’ contact details.

Only “OST Extractor Pro” has those dedicated and meticulous algorithms at its core that can work with any complex database easily. Every little detail is preserved during the data transfer from OST to PST.
How to import OST to Office 365
- Launch ‘OST Extractor Pro‘
- Click on “Add OST“.
- Browse and select ost file and click “Open”.
- Optional Settings
- Ignore Empty Folders
- Check/uncheck folders to convert.
- Select output format – PST File (*.pst) for Office 365.
- Click on “Convert“.
- After conversion, you can easily import the converted PST file into Office 365 (MS Outlook),

Try it free to import OST to Office 365
Find out how it works in more detail through the free trial version that USL Software offers. You can download it below instantly, without signing up, giving any information, or anything like that. It’s also very small and does not require any significant CPU resource.
Click the download button below, get the file, and you can begin converting OST to PST files in no time.
Also get in touch with the always available support team if you face any issues or have any queries.