Microsoft runs Microsoft 365 on redundant data centers, so a hardware failure on their side won't lose your email. But Microsoft's job is to keep the service available. Recovering data that you or an attacker deleted, overwrote or encrypted is mostly your job.
What Microsoft gives you
- A recycle bin for deleted files and email, for a limited number of days
- Version history for files in OneDrive and SharePoint
- Retention policies, if you configure them and have the right licenses
Where that falls short
- A departed employee's mailbox removed once their license is reclaimed
- Ransomware that encrypts synced files, then the versions roll over
- Someone deleting a folder and nobody noticing until after the recycle bin empties
- A compromised admin account deleting data deliberately
What a real backup adds
A third-party Microsoft 365 backup keeps an independent copy of mail, OneDrive, SharePoint and Teams, outside your tenant, for as long as you choose. The test that matters is the restore: a backup nobody has restored from is a guess.
HeptaShield includes Microsoft 365 backup on Secure and Complete, and tests a restore every quarter.