MBOX to Office 365 migration is not a common task for everyone and doing the migration manually is a failsafe process.
For best result, various users know that MBOX data file is created by many email clients like Thunderbird, EML, Gmail, Webmail, Apple Mail, Entourage, etc. So we suggest user to download MailsDaddy MBOX to Office 365 migration tool to transfer data MBOX to Office 365 migration in few simple clicks. The free version allows the user to easily change the first 20 emails from each mailbox.
Read more: Import MBOX to Office 365