Microsoft Defender for Office 365
Microsoft's native email security for Microsoft 365 with XDR integration
Pricing: Plan 1 from $2/user/month / Plan 2 from $5/user/month / included in E5
Reviewed by the CyberSecTool editorial team against the public sources cited below · Last reviewed February 2026 · How we review listings
What is Microsoft Defender for Office 365?
Microsoft Defender for Office 365 is Microsoft's native email security solution that provides protection against phishing, malware, and business email compromise for Microsoft 365 environments. It integrates deeply with the Microsoft security ecosystem including Microsoft Sentinel, Defender XDR, and Entra ID to provide cross-domain threat detection and automated investigation. For organizations heavily invested in Microsoft 365, Defender for Office 365 offers strong protection without requiring a third-party email security gateway.
- ✓ Deep native integration with Microsoft 365 and Defender XDR ecosystem
- ✓ Included in Microsoft 365 E5. Significant cost savings for E5 customers
- ✓ Automated investigation and response reduces analyst workload
- ✓ Cross-domain detection correlates email threats with identity and endpoint signals
- ✓ Continuous improvement from Microsoft's massive threat intelligence network
- • Only protects Microsoft 365. Does not support Google Workspace or other platforms
- • Detection efficacy for advanced threats historically behind Proofpoint and Mimecast
- • Configuration complexity across multiple Microsoft security portals
- • Plan 1 lacks important features like AIR and Threat Explorer
- • Less effective at catching novel social engineering attacks
Reported in public reviews and vendor documentation. See sources below.
Key Features
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Quick Info
| Pricing | Plan 1 from $2/user/month / Plan 2 from $5/user/month / included in E5 |
| Model | Per-user subscription (bundled with Microsoft 365 E5) |
| Founded | 2015 |
| Cloud | Yes |
| Self-Hosted | No |
Last updated: Feb 20, 2026
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