If you want to migrate convert an OST file to a PST file then I would like to recommend you to try MacMister Mac OST Converter. It is an all-in-one and effective email migration utility for Mac users. This application is capable to export unlimited OST mailboxes to PST file in a single go. You can use this software to convert an OST file to a PST file format including emails, contacts, calendars, notes, tasks, and journals. Furthermore, users can utilize this utility for OST to Gmail, Yahoo, Thunderbird, Office 365, PDF, MBOX, MSG, EML, DOC, HTML, and more. One can try the free demo version on any Mac OS including latest macOS 14.