You can check the location of your Outlook Data Outlook data file cannot be accessed 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

"Excellent program. Ive used it twice to convert .EML files to .MSG. Thank you." Outlook profile repair and recovery steps If anyone can get an answer from microsoft on this issue I’d appreciate it. Any MS techs can contact me if they need further information or analysis. I’ve created a ticket today with Rackspace to see if their other customers are having this issue but I’m not hopeful on hearing back from them.

• Open the OST file as per the location provided in the table.
• When Outlook is running and is halted in such a way, it can damage the OST file.
• You can try syncing outlook file 6 to 12 months or through archiving email using retention policy, could be a better way to protect the .ost size from corrupt.
• 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.
• The Inbox Repair tool creates a backup file with the same name as the original, but with a .bak extension, and saves it in the same folder.
• The file would get inaccessible and won't update in any case.
• You can use the Inbox Repair tool (SCANPST.EXE) to diagnose and repair errors in your Outlook data 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

Only way to restore Outlook 2016 (Windows) functionality was to create a new profile; this worked, and a new OST file was created. On the next screen, access the "Find File" option if you are unaware Fix Outlook Not Opening After Windows Update of the location. If you know the location, click on the "Add File" tab and browse it.