You should use one of the best and popular third-party applications eSoftTools MBOX Converter Software. With this software, you can quickly import MBOX files into Outlook for Mac. It also converts all emails from MBOX files to PST, EML, EMLX, MSG, HTML, MHTML, and a lot of other formats. It has a split PST file function that helps you to divide a large PST file into multiple small-size PST files.

Get more:- Import MBOX File Into Outlook For Mac