Save Office 365 Mailboxes using Office 365 Backup Tool. The tool supports Mac OS Machines.
Select Office 365 Account and Enter the Office 365 Account credentials to the software Panel. Press login button.
Select the email folder to convert and choose the respective format from PST, EML, MBOX, HTML, MHT, CSV, OLM, Thunderbird, IMAP, etc.
Click on the browse button in order to store the resultant file in the required location else save the file in default location - Desktop.