The SysInspire PST Converter software recovers both English or Non-English Outlook emails, It can recover your mailbox data(emails, contacts, calendar, and appointments) that has been damaged and is capable to convert PST into MBOX, HTML, EML, EMLX, MSG, and ICS, etc. This is a very advanced third-party tool and it has all the advanced features. You can also try the demo version of this software, on which you can convert twenty-five emails from each mailbox.
Read more;-Convert PST into MBOX
You can try BitVare PST to MBOX tool that is for Mac & Windows both OS and capable for unlimited PST files data to MBOX in single round processing. Using it, you can maintains all mail properties & data integrity without any change. Download it and also try its free demo that helps to understand complete working process. Read more >> https://www.bitvare.com/blog/how-to-convert-pst-files-to-mbox-format/