The best, secure and most reliable tool for Mac OS that helps backup and migrate Zoho mails to Office 365 is MacSonik Zoho Backup Tool for Mac. By using this tool you can download Zoho mails in PST, OST, EML, EMLX, MSG, and many more formats on macOS. The software has a capability to backup and migrate Zoho mail to Office 365, Gmail, iCloud, Hostgator Emails, etc. It allows a free-up server space after the backup or migration of Zoho emails and maintains the folder hierarchy.