Enterprise email security platform for advanced threat protection, compliance, and data loss prevention
Pricing: Per-user subscription
Deployment: Cloud
Certifications: SOC 2, ISO 27001, FedRAMP, ISO 42001
Microsoft Defender for Office 365 alternatives (2026)
9 email security tools listed alongside Microsoft Defender for Office 365 for side-by-side comparison on capabilities, pricing, and deployment. No editorial ranking.
Why look for Microsoft Defender for Office 365 alternatives?
Microsoft Defender for Office 365 is a strong option for email security, but it's not the right fit for every team. Common reasons teams look elsewhere: only protects microsoft 365. does not support google workspace or other platforms; detection efficacy for advanced threats historically behind proofpoint and mimecast.
Below we list 9 alternatives, broken down by deployment model. All data is aggregated from official documentation and community feedback.
Head-to-Head Comparisons
- Microsoft Defender for Office 365 vs Proofpoint
- Microsoft Defender for Office 365 vs Mimecast
- Microsoft Defender for Office 365 vs Abnormal AI
- Microsoft Defender for Office 365 vs Barracuda Email Security
- Microsoft Defender for Office 365 vs Cisco Secure Email
- Microsoft Defender for Office 365 vs Trend Micro Email Security
- Microsoft Defender for Office 365 vs IRONSCALES
- Microsoft Defender for Office 365 vs Tessian
- Microsoft Defender for Office 365 vs Acronis Email Security
Cloud-Managed Alternatives
Cloud email security platform with threat protection, archiving, and continuity
Pricing: Per-user subscription
Deployment: Cloud
Certifications: ISO 27001, SOC 2 Type II, ISO 27701
AI-powered email security platform specializing in behavioral detection of social engineering attacks
Pricing: Per-user subscription
Deployment: Cloud
Certifications: SOC 2 Type II, ISO 27001, ISO 27701, ISO 42001 +5
Cloud email security gateway with AI-powered BEC detection and XDR integration
Pricing: Per-user subscription
Deployment: Cloud
Certifications: ISO 27001, SOC 2 Type II
AI-powered anti-phishing platform with crowdsourced threat intelligence
Pricing: Per-user subscription (tiered plans)
Deployment: Cloud
Certifications: ISO 27001, SOC 2 Type II
Human layer security platform preventing inbound threats and outbound misdirected emails
Pricing: Per-user subscription
Deployment: Cloud
Acronis Cyber Protect Cloud with Acronis Email Security protects Microsoft 365, Google Workspace, and other mailboxes against phishing, BEC, account takeover, malware, and zero-day threats, integrated with backup, endpoint protection, and DLP.
Pricing: Subscription-based, priced per unique protected mailbox/user as an add-on to Acronis Cyber Protect Cloud. Varies by licensing model, protected workloads, mailboxes, and region. One-month trial available. Contact an Acronis partner for current pricing.
Deployment: Cloud
Certifications: SOC 2, ISO/IEC 27001, ISO 9001, PCI DSS +5
Self-Hosted Alternatives
Email threat protection platform available as gateway appliance or cloud service
Pricing: Per-user subscription or appliance license
Deployment: Cloud, Self-hosted
Certifications: SOC 2 Type II, ISO 27001
Enterprise email security gateway with Cisco Talos threat intelligence integration
Pricing: Per-user subscription or appliance license
Deployment: Cloud, Self-hosted