I'll elaborate on some of the popular methods and tools people use:

1. Third-Party Backup Solutions: This is by far the most common and recommended approach for serious Exchange Online backup. These solutions connect to your Microsoft 365 tenant via APIs and allow you to:

• Perform automated backups of mailboxes, SharePoint, and OneDrive data.
• Store backups independently (e.g., on-premises, in another cloud, or the vendor's cloud).
• Offer granular recovery (single email, folder, or entire mailbox).
• Provide various recovery options (restore in-place, export to PST, restore to different mailbox).
• Examples include Shoviv Backup for Microsoft 365, Weeom, Rubrik, AvePoint, Acronis, and many more. Do your research and get demos!

1. PST Exports (Manual/Scripted):

While not a true backup solution for an enterprise, some smaller organizations or for specific long-term archive needs might consider: * eDiscovery Export: You can use Content Search in the Microsoft Purview compliance portal to export mailbox data to PST files. This can be cumbersome for large-scale operations and ongoing backups. * PowerShell: New-MailboxExportRequest (though this typically requires an on-premises Exchange server or specific configurations to work with Exchange Online). This is less common for direct Exchange Online backups. * Pros: Simple, can be done for individual mailboxes. * Cons: Not automated, difficult to manage at scale, no granular restore without re-importing, security risks with PST files. I generally don't recommend this as a primary backup strategy.

1. Litigation Hold/In-Place Archive (as part of a broader strategy): As CloudGuru_88 mentioned, these are for preservation rather than backup. However, they play a vital role. Ensure critical mailboxes are on Litigation Hold if you need to retain all data for a specific period for legal or compliance reasons. In-Place Archiving can help users manage their mailbox size without deleting older emails.

My strong recommendation is to evaluate third-party backup solutions. They provide peace of mind and significantly reduce recovery time in a disaster scenario.

Resources: 1. https://www.shoviv.com/blog/export-office365-mailbox-to-pst/ 2. https://www.linkedin.com/pulse/how-delete-restore-mailboxes-o365-exchange-online-pradeep-katiyar-aw8tf 3. https://www.shoviv.com/blog/how-to-download-emails-from-outlook-web-app/ 4. https://www.linkedin.com/pulse/how-archive-emails-outlook-web-app-windows-pradeep-katiyar-wgzwf 5. https://www.shoviv.com/blog/how-to-migrate-sharepoint-site-to-another-site/ 7. https://www.shoviv.com/blog/backup-sharepoint-online-in-microsoft-365/ 8. https://www.shoviv.com/sharepoint-migrator.html 9. https://www.shoviv.com/onedrive-migrator.html 10. https://www.shoviv.com/blog/export-pst-from-owa-outlook-web-app/ 11. https://www.shoviv.com/blog/sharepoint-migration-manager-uses-benefits-alternatives/ 12. https://www.shoviv.com/blog/ediscovery-pst-export-tool-alternatives-to-get-pst-file/ 13. https://www.shoviv.com/sharepoint-backup.html 14. https://www.shoviv.com/blog/migrate-shared-mailbox-to-microsoft-365-exchange-online/ 15. https://www.shoviv.com/blog/move-files-from-onedrive-to-sharepoint/