I have faced many problems converting PST files to MBOX, but I searched the internet so I found the best
KDETools PST to MBOX Converter software. This tool allows you to easily convert all email items such as emails, notes, contacts, calendars, drafts, tasks, journals, hyperlinks, email attachments, etc. The advanced tool supports the 'Message Filtering' option which allows the user to select the files between two dates.
READ MORE: https://www.kdetools.com/pst/mbox/
