Microsoft Defender for Office 365 vs Tessian

Microsoft Defender for Office 365 and Tessian are both cloud email security solutions. Microsoft Defender for Office 365 microsoft's native email security for Microsoft 365 with XDR integration, while Tessian human layer security platform preventing inbound threats and outbound misdirected emails. The best choice depends on your organization's size, technical requirements, and budget.

Updated Feb 2026
How we compare:This comparison is based on official documentation, public pricing, community discussions, and aggregated user feedback, not hands-on testing by our team. We organize what real users and practitioners are saying across the web.

The Bottom Line

Choose Microsoft Defender for Office 365 if deep native integration with Microsoft 365 and Defender XDR ecosystem is your priority and microsoft 365-centric organizations wanting native email security with XDR integration and cost efficiency through E5 licensing. Choose Tessian if unique misdirected email prevention addresses a gap no other tool covers well matters most and organizations concerned about both inbound email threats and accidental data loss from misdirected emails and human error.

Choose Microsoft Defender for Office 365 if:

  • You value deep native integration with Microsoft 365 and Defender XDR ecosystem
  • You value included in Microsoft 365 E5 — significant cost savings for E5 customers
  • You value automated investigation and response reduces analyst workload
  • You want to avoid now part of Proofpoint — future as standalone product uncertain
  • You want to avoid not a full email gateway replacement

Choose Tessian if:

  • You value unique misdirected email prevention addresses a gap no other tool covers well
  • You value behavioral AI catches threats that gateway solutions miss
  • You value real-time coaching helps users make better security decisions
  • You want to avoid only protects Microsoft 365 — does not support Google Workspace or other platforms
  • You want to avoid detection efficacy for advanced threats historically behind Proofpoint and Mimecast

Feature Comparison

FeatureMicrosoft Defender for Office 365Tessian
PricingPlan 1 from $2/user/month / Plan 2 from $5/user/month / included in E5Custom pricing / per-user licensing
Pricing ModelPer-user subscription (bundled with Microsoft 365 E5)Per-user subscription
Open SourceNoNo
DeploymentCloudCloud
Best ForMicrosoft 365-centric organizations wanting native email security with XDR integration and cost efficiency through E5 licensingOrganizations concerned about both inbound email threats and accidental data loss from misdirected emails and human error
Safe Links (URL detonation and rewrit...SupportedNot available
Safe Attachments (sandbox analysis)SupportedNot available
Anti-phishing with impersonation prot...SupportedNot available

Sources

Related

Microsoft Defender for Office 365 AlternativesTessian AlternativesMicrosoft Defender for Office 365 OverviewTessian Overview