Not in the way most organizations mean “backup.” Microsoft 365 is designed for high availability and continuity of the service and it includes helpful native capabilities (like recycle bins, version history and retention features). However, those features are not the same as an independent, comprehensive backup that lets you restore data on demand across scenarios such as accidental deletion, malicious activity, misconfiguration or tenant-level incidents.
In practice, Microsoft 365 follows a shared responsibility approach: Microsoft secures and operates the cloud service, while your organization remains responsible for protecting its own data and ensuring it can be recovered when needed.

For reliable Microsoft 365 backup, organizations typically choose a dedicated third-party backup that is built specifically for backup and recovery. With Mindtime Microsoft 365 Backup, the goal is straightforward: create an independent copy of your critical Microsoft 365 data and make recovery fast and predictable, whether you need to restore a single email, a folder or larger sets of data.
A good Microsoft 365 backup approach should also support clear scheduling (to meet your RPO/RTO needs), granular restores and strong search to help with operational recovery as well as compliance and eDiscovery-related requests.

Retention in Microsoft 365 depends on the workload and configuration and it often behaves differently than people expect. Exchange Online may retain deleted items for a limited period (often 14 days by default, configurable up to 30 days), while SharePoint Online retains deleted items in the recycle bin for a longer period (commonly up to 93 days).
It’s also important to understand what happens when user accounts change. When an employee leaves and their Microsoft 365 account is removed, the associated data can become unavailable after a grace period—unless it was preserved elsewhere. And because retention configuration can be complex, mistakes or misconfigurations can lead to permanent loss. That’s why many organizations treat an independent Microsoft 365 backup as a practical safety net.

Microsoft’s native and first-party options can be useful in specific situations, but many organizations still choose a dedicated backup for one core reason: independence.

• A separate backup copy (so recovery doesn’t depend on the same environment where the incident occurs)
• Control over restore and retention aligned with your organization’s operational and compliance needs
• A clear fit for organizations operating in the EU market (Netherlands, Belgium, Luxembourg, Germany) where data governance, accountability, and audit readiness matter day-to-day

For Microsoft 365 backup sizing, a “user” typically means a unique Microsoft 365 account you choose to protect. Even if that person uses multiple services (for example Exchange Online, SharePoint Online and OneDrive), they are usually counted once from a protection perspective, because the data belongs to the same identity in your tenant.
(Exact counting can depend on how your tenant is structured, and whether shared mailboxes or service accounts are included in scope.)

In most organizations, the safest answer is: all users that generate or handle business-critical data. Every mailbox, OneDrive and collaboration space can contain information that matters for continuity, legal obligations, customer commitments or simply day-to-day operations. Leaving gaps creates risk, because the one account you didn’t protect can become the one you urgently need during a recovery or compliance request.