I am Vipin, and I work as a Software Developer in MacSonik Software. If you need a good way to change your OST files into PST files, I recommend a professional method using the MacSonik OST to PST Converter for Mac. It is specifically designed to migrate OST files to PST file format including emails, contacts, notes, attachments, etc. The utility is capable of converting single or multiple OST files without losing data loss. Users can specify where they want to export their OST files in PST format. It is compatible with any version of Mac OS Device. You can download its free trial version and convert 50 emails per folder for free.