Convert multiple MBOX files in bulk I suggest utilizing BetaVare MBOX to PST Converter App to convert multiple Thunderbird MBOX files to Outlook PST file format. Convert MBOX emails to PST, EML, EMLX, MSG, and other formats using the MBOX to PST Online Tool. It can also convert several MBOX files in a single process. The trial version allows you to test the application's performance. Email clients such as Thunderbird, Apple Mail, Eudora, Cone, Sylpheed, Gnu, Postbox, SeaMonkey, and others are supported. It works with all Windows versions, including Windows 8, 8.1, 10, 11, Vista, and XP.