Try Get ZOOK MBOX to PST Converter to convert MBOX files in bulk and access all mailbox contents in Outlook. This is the safest method to export MBOX data to PST format for email clients that use MBOX files, including Mac Mail/Apple Mail, Mozilla Thunderbird, Eudora, and Entourage.
Check for more details at: https://www.zooksoftware.com/mbox-to-pst/