I would like to suggest the DRS PST migration tool. It migrates PST files to MBOX, and many other file formats, as well as email clients like EML, PDF, Gmail, Yahoo, etc. This tool has many advanced features, like removing duplicate files, maintaining folder hierarchy, you can select the files by filtering the date, and creating custom folder names. This tool also gives a free demo trial in which you can convert 50 files per folder at a time, or if you want to migrate more than 50 files per folder at a time, then you can buy the premium version of it.

Read More: https://www.drssoftech.com/pst-converter/