OST commonly known as Offline Storage Table is the copy of the Exchange Server mailbox which is stored locally on the user’s hard drive. OST file is used so that the user can work offline when the connection to the Exchange Server is not available. User is able to compose new emails, read emails or delete emails and the changes made to emails are synced once the connection is established with the Exchange. As the OST file is stored locally the damage to Exchange Server mailbox doesn’t affect OST file hence you have a copy of your mailbox items safe which can be imported later to Exchange Server.
But sometimes due to various reasons like error during synchronizing or some virus attack the OST file gets corrupted and the data stored is lost. In such situations you don’t need to panic as Microsoft has provided a tool called OST Integrity Check Tool (Scanost.exe) which can repair the damaged OST file. Scanost.exe is a built in tool which comes with MS Outlook and used to diagnose the damaged OST file for possible error and repair the same. Follow he steps to Repair OST File With Scanost.exe
You need to connect to Exchange account to run Scanost.exe The default location of Scanost.exe is Drive:Program Files>Microsoft Office>Officeversion
Step by Step Process to Run Scanost.exe
- Exit MS Outlook
- Double Click Scanost.exe
- Tool will prompt for Outlook profile, Select the profile for which you want to repair OST file
- Select Connect when you are prompted to Connect or Work Offline
- Select “Repair Errors” option to Scanost.exe automatically correct errors while
- At last click “Begin Scan”
The other simple method is to use third party OST Repair Tool for repairing damaged OST file, Stellar Phoenix OST to PST Converter is one such application available to download for free from 