If you want to convert PST file into MBOX file format. Then you should try PST to MBOX conversion software. This software allows the user to convert PST file into multiple file formats like PST to MBOX, EML, EMLX, MSG, HTML, etc. User can feely use the Batch conversion to quickly convert single and bulk files without any data loss.

Visit here: https://www.kdetools.com/pst/mbox/