You can check the location of your Outlook Data office 365 sync errors fix Files in Outlook.

Repair Outlook Data Files (.pst and .ost)

An Outlook data files are designed to safely handle max space 50GB in Outlook 2010 to 2019 and Office 365 by default. 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 it is converted, you can easily view the contents of the data file.

Outlook - OST file recurring corruption

"Excellent program. Ive used it twice to convert .EML files to .MSG. Thank you." Repair Outlook Profile Online 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.

• Once you re-open Outlook, your OST file is automatically recreated or rebuilt.
• The Lost and Found folder contains any folders and items recovered by the repair tool that Outlook can't place in their original structure.
• To execute this, you need to have a good tool with yourselves.
• OST file corruption is a common problem faced by Outlook users like you.
• Any MS techs can contact me if they need further information or analysis.
• You might be working on something important across it when it happens.
• This article will mention the process to rebuild the OST file in detail.

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

The question mentioned above is thus definite in such a case. It is surely possible to rebuild the OST files at any instant. Although the procedure may differ to some extent, it can be executed. This article will mention the process to rebuild the OST file in detail. Perfectly repair and recover corrupted Outlook PST & OST files.

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 how to fix Outlook not opening today 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.