I’ve used the repair tool when this started and it did not really repair the file. I used the following combination of techniques to get the user working. In the diagnose Office activation conflicts Folder Pane, you might see a folder named Recovered Personal Folders that contains your default Outlook folders or a Lost and Found folder.

Repair Outlook Data Files (.pst and .ost)

Click the "Data Files" tab on the window and select your respective OST file. Click the "Open File Location" button to lead to the folder automatically. Outlook OST is directly connected and synchronized to the email client. If the problems occur across the synchronization of the OST file, it would be damaging. The file would get inaccessible and won't update in any case. To the ones that said 50Gb are more than enough for most people,… well we are in 2020 & I can assure you that more than half of the accounts we manage are way above 50Gb, close to 100Gb actually.

Outlook - OST file recurring corruption

"Excellent program. Ive used it twice to convert .EML files to .MSG. Thank you." Exchange connectivity diagnostic 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.

• 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.
• There may be items in the backup file that you might be able to recover that the Inbox Repair tool couldn't.
• 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.
• Confirmed user can log on to OWA (Office 365 webmail) without issue.

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

Fwiw, responding to my original post and how we addressed it for this user - we ended up creating new Outlook profile and limiting the amount of cached mail to 2 years. If the OST still gets corrupted when you have reduced the size there is something in the mailbox causing the problem. You must re-select "Account Settings" when it opens across a drop-down menu. There, lead into the "Data Files" tab and select your OST file. After selecting the file, click on "Open File Location" to redirect to the folder.

Method 4: Use OST Repair Tool

In certain cases, you must go for other methods to recover the data across OST files. If the respective file is not rebuilding from the above methods, there are other ways to get its data. This can be done with the help of PST files, another Outlook data file form. While they act as the basic backup data file for the user, the OST file online Outlook email repair utility can be easily converted to this form. Also, I forgot to mention that normally when the OST is corrupted you normally delete the file and recreate it.