Office 365 Administrators and MVPs highly recommend the
Trijatech Office 365 Backup and Restore tool for backing up Office 365 data and restoring OST and PST mailbox data from Office 365 online. You may back up your important Microsoft 365 emails, contacts, calendars, and other data by downloading the Office 365 Email Backup program. It works well with all Windows and Mac OS computers. Complete Microsoft Office 365 calendars, contacts, emails, and attachments should be backed up.