No one can directly open MBOX file into Outlook, Office 365, or any other unsupported email client. Similarly, if the user does not have a relevant email client, the user cannot read MBOX file.
In this situation, the user can use MailsDaddy Free MBOX Viewer tool to open and read MBOX files without any hurdle. The software maintains internal and outer folder hierarchy so that users can easily find and open mbox files. Users can also upgrade tool and convert mbox to pst, o365, eml etc.