Email remains the number one attack vector, responsible for over 90% of successful cyberattacks. Business email compromise losses exceeded $2.9 billion in 2025, while AI-generated phishing has made traditional signature-based detection obsolete. The market is splitting between legacy secure email gateways (SEGs) that sit inline as MX record proxies and newer API-based platforms that integrate directly with Microsoft 365 and Google Workspace via Graph API. Proofpoint acquired Hornetsecurity for $1.8 billion (2025) to expand its SMB and MSP reach, while Mimecast acquired Code42 to add insider threat and data loss capabilities to its email platform. We evaluated platforms across phishing detection, BEC prevention, integration depth, and operational efficiency.

How We Evaluated

Platforms were assessed on:

  • Phishing detection efficacy against credential harvesting, malware delivery, and AI-generated phishing
  • BEC prevention and ability to detect impersonation, account takeover, and social engineering attacks
  • Integration covering deployment model (SEG vs. API), Microsoft 365/Google Workspace depth, and SIEM/SOAR integration
  • AI capabilities including behavioral analysis, NLP, computer vision, and adaptive detection models
  • Operational efficiency focusing on alert quality, false positive rates, and SOC investigation workflows
  • User protection through security awareness training, real-time coaching, and phishing simulation

1. Proofpoint Email Protection

Score: 95/100

Proofpoint is the undisputed market leader in email security, protecting over 80% of the Fortune 100. The $1.8 billion Hornetsecurity acquisition (2025) extends Proofpoint’s reach into the SMB and MSP segments, adding cloud-native email security, backup, and compliance capabilities. Proofpoint’s Nexus AI platform combines behavioral analysis, threat intelligence from trillions of daily data points, and sandbox detonation to catch threats that bypass all other defenses.

Proofpoint protects 87 of the Fortune 100 with the largest email threat intelligence dataset in the industry. The Nexus AI platform analyzes behavioral, content, and sender signals across 3 trillion daily data points. The Hornetsecurity acquisition adds cloud-native SMB/MSP email security and Microsoft 365 backup. Targeted Attack Protection (TAP) includes URL rewriting, sandbox detonation, and time-of-click analysis. Integrated security awareness training includes phishing simulation and adaptive learning paths.

Best for: Large enterprises requiring best-in-class threat detection, deep threat intelligence, and comprehensive email security across the attack chain

2. Microsoft Defender for Office 365

Score: 93/100

Microsoft’s native email security has matured dramatically, with Defender for Office 365 Plan 2 now providing capabilities that rival dedicated SEGs for Microsoft 365 environments. The tight integration with Entra ID, Defender XDR, and Copilot for Security creates an investigation workflow that no third-party vendor can match within the Microsoft ecosystem.

Native Microsoft 365 integration requires zero MX record changes and provides full Graph API access. Safe Attachments includes real-time sandbox detonation in Microsoft’s cloud infrastructure. Safe Links provides time-of-click URL detonation and post-delivery protection. Copilot for Security integration provides natural language email threat investigation. Attack Simulation Training offers phishing awareness with built-in reporting and analytics.

Best for: Microsoft-centric organizations wanting native email protection tightly integrated with Defender XDR and Entra ID

3. Mimecast Advanced Email Security

Score: 91/100

Mimecast provides a comprehensive email security and resilience platform combining gateway protection, continuity, archiving, and now insider threat detection following the Code42 acquisition. The platform’s strength lies in its breadth. Organizations can consolidate email security, archiving, compliance, and data protection under a single vendor.

The comprehensive platform covers gateway security, continuity, archiving, compliance, and DLP in one solution. The Code42 acquisition adds insider threat detection and data loss prevention via behavioral analysis. Brand Exploit Protect identifies domain spoofing and lookalike domains in real time. CyberGraph AI maps communication patterns to detect impersonation and account takeover. Email continuity ensures access during Microsoft 365 and Google Workspace outages.

Best for: Organizations seeking a comprehensive email resilience platform covering security, archiving, continuity, and insider threat in one vendor

4. Abnormal Security

Score: 89/100

Abnormal Security is the leading API-based email security platform, deploying without MX record changes by connecting directly to Microsoft 365 and Google Workspace via API. The platform uses behavioral AI to build identity models of every employee, vendor, and partner, detecting BEC and social engineering attacks that bypass traditional content-based detection entirely.

API-native deployment connects directly to Microsoft 365 and Google Workspace without MX changes. Behavioral AI builds identity profiles from communication patterns, writing style, and relationship graphs. Industry-leading BEC detection catches impersonation attacks that content-based SEGs miss. VendorBase maps vendor ecosystems to detect supply chain email compromise. Account takeover detection identifies compromised internal mailboxes through behavioral anomalies.

Best for: Organizations prioritizing BEC and social engineering defense with a non-disruptive API-based deployment model

5. Cisco Secure Email Threat Defense

Score: 86/100

Cisco Secure Email combines traditional gateway capabilities with API-based protection and integrated threat intelligence from Talos, one of the largest commercial threat research teams in the world. The platform benefits from Cisco’s broader security ecosystem, correlating email threats with network, endpoint, and identity signals through Cisco XDR.

Talos threat intelligence provides real-time indicators from one of the largest threat research teams globally. Dual deployment offers SEG mode for MX-based protection or API mode for Microsoft 365 integration. Cisco XDR integration correlates email threats with network, endpoint, and identity telemetry. Graymail management and advanced spam filtering reduce inbox noise. Strong outbound DLP and encryption capabilities are included.

Best for: Cisco ecosystem customers wanting email security integrated with network, endpoint, and XDR capabilities

6. Barracuda Email Protection

Score: 84/100

Barracuda provides layered email protection combining a traditional gateway with AI-powered impersonation detection and automated incident response. The platform is particularly strong in the mid-market, offering straightforward deployment and management without the complexity of enterprise-focused competitors.

Layered protection includes gateway filtering, AI impersonation detection, and automated remediation. Incident Response automates post-delivery threat hunting and removal across all mailboxes. Cloud-to-Cloud Backup covers Microsoft 365 data (Exchange, SharePoint, OneDrive, Teams). Link Protection includes time-of-click URL rewriting and sandbox analysis. The platform has a strong mid-market fit with simplified deployment and intuitive management console.

Best for: Mid-market organizations seeking layered email security with straightforward deployment and integrated Microsoft 365 backup

7. Fortinet FortiMail

Score: 82/100

FortiMail integrates tightly with the Fortinet Security Fabric, sharing threat intelligence bidirectionally with FortiGate, FortiSandbox, FortiSIEM, and FortiSOAR. The platform provides both gateway and server modes with strong outbound DLP and encryption capabilities.

Deep integration with Fortinet Security Fabric enables coordinated threat response. FortiSandbox integration provides real-time malware detonation for attachments and URLs. FortiGuard threat intelligence includes AI-driven anti-spam, anti-malware, and URL filtering. Strong outbound email security includes DLP, encryption, and identity-based routing. Hardware and virtual appliance options provide high throughput for large mail volumes.

Best for: Fortinet customers wanting email security tightly integrated with their existing Security Fabric infrastructure

8. Ironscales

Score: 80/100

Ironscales combines AI-powered email security with integrated phishing simulation and security awareness training in a single platform. The self-learning AI adapts to each organization’s communication patterns, while crowdsourced threat intelligence from the Ironscales community accelerates detection of emerging campaigns.

Integrated email security and phishing simulation training come in a single platform. Adaptive AI learns organizational communication patterns to reduce false positives. Crowdsourced threat intelligence from thousands of organizations detects shared campaigns. Themis AI copilot provides mailbox-level investigation and automated classification. Decentralized threat response empowers SOC analysts with one-click remediation across tenants.

Best for: Organizations wanting combined email security and security awareness training with community-driven threat intelligence

9. Cofense

Score: 78/100

Cofense uniquely combines phishing detection with the industry’s largest human-reported phishing intelligence network. The Cofense Reporter button enables employees to flag suspicious emails, creating a crowdsourced detection layer that catches threats automated tools miss. The Cofense Intelligence team analyzes millions of employee-reported emails annually.

The largest human-reported phishing intelligence network processes millions of employee reports annually. The Cofense Reporter button turns every employee into a phishing sensor. Phishing Detection and Response (PDR) provides managed triage of reported emails. Integrated phishing simulation includes adaptive campaigns based on real-world threats. Cofense Intelligence provides curated, human-verified phishing IOCs.

Best for: Organizations building a human-centric phishing defense with employee-reported intelligence and managed response

10. Material Security

Score: 76/100

Material Security takes a unique approach by protecting the data within email rather than just blocking threats at the gateway. The platform redacts sensitive content in archived messages, adds authentication challenges for accessing sensitive emails, and provides post-breach protection that limits the damage of compromised mailboxes.

Data-centric email protection redacts sensitive content in historical messages. Authentication challenges protect access to emails containing sensitive data (PII, financials, credentials). Post-breach protection limits damage from compromised mailboxes by protecting the archive. Message-level DLP identifies and protects sensitive data across the entire mailbox. API-based deployment has no impact on email delivery or user workflows.

Best for: Organizations focused on protecting sensitive data within email archives and limiting the blast radius of account compromise

Several trends are shaping the email security market in 2026.

API-based is displacing gateway. Abnormal, Material, and others are proving that API-based email security can match or exceed SEG efficacy without MX record changes, forcing legacy vendors to offer dual deployment modes.

AI-generated phishing demands AI defense. LLM-crafted phishing emails with perfect grammar and personalized context have rendered signature and content-based detection insufficient. Behavioral AI that models sender identity is now essential.

Email security meets data protection. Mimecast’s Code42 acquisition and Material Security’s approach signal convergence between email security, DLP, and insider threat. The mailbox is both an attack vector and a data repository.

Consolidation continues. Proofpoint’s Hornetsecurity deal ($1.8B) extends enterprise vendors into the MSP/SMB segment, while platform vendors bundle email security into broader XDR and SASE offerings.

QR code and image-based phishing is surging. Quishing attacks using QR codes in emails grew 400% in 2025, driving demand for computer vision and image analysis capabilities in email security platforms.