You can also use the eSoftTools OST to PST Converter program to convert bulk Outlook OST files to PST format, which includes addresses, contacts, calendars, projects, notes, and other items, as well as attachments. It has a very basic user interface, but even non-techies can appreciate the software's operating process and capabilities. The OST user can convert the OST file to a PST file without MS Outlook installed and try a free demo version to export 25 emails or items from every Exchange OST file.
Read more:- Convert OST to PST files
Read more:- Convert OST to PST files