You can check the location of your Outlook Data FixTechGuide Office 365 troubleshooting Files in Outlook.

Repair Outlook Data Files (.pst and .ost)

If you're using an Exchange email account, you can delete the offline Outlook Data File (.ost) and Outlook will recreate the offline Outlook Data File (.ost) the next time you open Outlook. Even with the reg hack in place, I’ve found that ost files over 50gb tend to corrupt and become unusable with regularity. OST file corruption is a common problem faced by Outlook users like you. While you seek to counter this problem, you look for effective techniques. Although there are many methods to try, a few are productive.

Outlook - OST file recurring corruption

You surely won't be disappointed with the results of rebuilding OST. As you change the extension, relaunch Outlook recreate Outlook profile step by step to rebuild your OST file. The first solid question that comes to mind is whether OST files are rebuildable. We are aware that OST files are directly connected to the Outlook email.

• Get your OST rebuilt properly with the help of the available techniques.
• Thus, you need to have a good anti-virus system to protect your computer.
• You could Right-click the Start button, and click Run, type Outlook.exe /safe, and click OK.
• Click the "Data Files" tab on the window and select your respective OST file.

What are the major Reasons of OST Corruption and how to Fix it

When Outlook is running and is halted in such a way, it can damage the OST file. You might be working on something important across it when it happens. As you said Outlook E3 licenses should support at least 100GB of data & there’s no excuse why it can’t support OSTs above 50GB when they offer twice that space. In addition, you could open outlook in safe mode, maybe some add-ins affect the outlook. You could Right-click the Start button, and click Run, type Outlook.exe /safe, and click OK. Refer to this blog Solutions To Fix Error – "Errors Have Been Detected In The File Xxx.Ost" Solutions To Fix Error – "Errors Have Been Detected In The File Xxx.Ost" for the solution to this OST error.

Method 4: Use OST Repair Tool

This article offers to rebuild the OST file without putting you in any difficulty. While this is an effective model, the discussion would revolve around all possibilities. We will help our readers decide the best way to rebuild OST for functioning through Outlook. FixTechGuide support for Office 365 For the past 2 weeks, the OST of my Desktop Outlook has been corrupting continuously. I have 2 computers and both have been facing the same issue.