Microsoft Defender for Office 365 vs Abnormal Security

Abnormal Security and Microsoft Defender for Office 365 are both ai email security solutions. Abnormal Security aI-powered email security platform specializing in behavioral detection of social engineering attacks, while Microsoft Defender for Office 365 microsoft's native email security for Microsoft 365 with XDR integration. 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 Abnormal Security if superior detection of socially-engineered attacks with no malicious payload is your priority and organizations facing sophisticated social engineering and BEC attacks that bypass traditional email gateways. Choose Microsoft Defender for Office 365 if deep native integration with Microsoft 365 and Defender XDR ecosystem matters most and microsoft 365-centric organizations wanting native email security with XDR integration and cost efficiency through E5 licensing.

Choose Microsoft Defender for Office 365 if:

  • You value superior detection of socially-engineered attacks with no malicious payload
  • You value aPI-based deployment requires no MX record changes — deploys in minutes
  • You value behavioral AI catches novel attacks that signature-based tools miss
  • 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

Choose Abnormal Security 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 does not replace a full email gateway — typically layers on top of one
  • You want to avoid less effective against traditional malware and payload-based attacks

Feature Comparison

FeatureMicrosoft Defender for Office 365Abnormal Security
PricingCustom pricing / per-user licensingPlan 1 from $2/user/month / Plan 2 from $5/user/month / included in E5
Pricing ModelPer-user subscriptionPer-user subscription (bundled with Microsoft 365 E5)
Open SourceNoNo
DeploymentCloudCloud
Best ForOrganizations facing sophisticated social engineering and BEC attacks that bypass traditional email gatewaysMicrosoft 365-centric organizations wanting native email security with XDR integration and cost efficiency through E5 licensing
Behavioral AI threat detectionSupportedNot available
Business email compromise preventionSupportedNot available
Vendor and supply chain fraud detectionSupportedNot available

Sources

Related

Microsoft Defender for Office 365 AlternativesAbnormal Security AlternativesMicrosoft Defender for Office 365 OverviewAbnormal Security Overview