For MBOX to Office 365 migration various tools available on the web which claim to migrate MBOX to Office 365 account, but choosing the best tool is always a typical task for users. Here I suggest a tool named Shoviv MBOX to Office 365 Migrator which easily export MBOX files into Office 365 account. Besides the Office 365 migration, the tool also exports MBOX to PST and Live Exchange server. This tool support MBOX format over many email clients such as Apple Mail, Thunderbird, Eudora, Seamonkey and many more.
For more info visit here: https://www.shoviv.com/mbox-to-office365.html