Not in the way most people assume. Microsoft keeps the service running and holds deleted items for a limited time. Once that time passes, a deleted mailbox or folder is gone unless you have your own backup.
What Microsoft looks after
Microsoft is responsible for keeping Microsoft 365 available: the datacenters, the servers and the software. If one of their systems fails, your data is still there.
What is left to you
The data itself is your responsibility. Recycle bins and retention settings give you a window to recover something deleted by mistake, but they aren't designed as a long-term backup.
- An employee deletes a folder and nobody notices for months
- A departing employee's mailbox is removed with their license
- Ransomware encrypts files that then sync to the cloud
- An account is compromised and emails are deleted on purpose
What a separate backup adds
A separate backup keeps its own copy of your mailboxes and files, on a schedule, outside Microsoft's systems. You can restore a single message, a folder or a whole account from any point you kept.
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