If you are unable to open the OST file directly in Microsoft Outlook, the most reliable solution is to use eSoftTools OST to PST Converter. This software scans orphaned or inaccessible OST files and converts them to PST format, which can be easily imported into Outlook. After the conversion, you can access your emails, contacts, calendar and attachments without data loss. The tool's interface is simple and the process is fast and secure.

Read More:- Open an OST file to Outlook