Anyone can use the eSoftTools MBOX Converter tool to import MBOX emails to Office365 files, which is one of the most reliable software available. It includes advanced features that make conversion of MBOX to Office365 easy. This tool can export bulk MBOX files at once files without any changes in their order, styles, email headers, formatting, etc.
For more info- Import MBOX emails to Office365
For more info- Import MBOX emails to Office365