Tessian

Tessian was an AI-powered email security platform that used machine learning and behavioral analysis to protect organizations from email threats caused by human error. Unlike traditional rule-based secure email gateways, Tessian analyzed communication patterns to detect anomalies, catching misdirected emails before they were sent, identifying spear-phishing attempts that bypassed conventional filters, and preventing accidental data exfiltration.

In December 2023, Proofpoint completed its acquisition of Tessian, integrating the company's behavioral AI technology into Proofpoint's email security platform to enhance data loss prevention (DLP) capabilities. The integration resulted in Proofpoint's Adaptive Email DLP offering, announced in March 2024, which combines Tessian's behavioral detection with Proofpoint's threat intelligence and enterprise infrastructure.

Tessian's core technology worked by building behavioral models of how each person in an organization normally communicates: who they email, what they send, and how they write. When an email deviated from these patterns—wrong recipient, unusual attachment, suspicious request—Tessian flagged it with contextual warnings that helped users make better decisions in real-time rather than simply blocking messages.

Key capabilities that Tessian brought to Proofpoint include: Human Layer Security for detecting misdirected emails before they leave the organization, advanced spear-phishing protection using behavioral and content analysis, business email compromise (BEC) detection for CEO fraud and wire transfer scams, and real-time security coaching that educated users at the point of risk rather than through generic annual training.

Tessian supported organizations including NHS, Schroders, Arm, and Greenhill. The platform offered seamless deployment with Microsoft 365 and Google Workspace through API integration, requiring no MX record changes and achieving protection within 24 hours of implementation by analyzing historical email data.

The acquisition eliminated Tessian as a standalone product, but preserved its behavioral AI innovations within Proofpoint's enterprise email security suite. Organizations seeking Tessian's capabilities must now purchase Proofpoint's email protection products, which incorporate the acquired technology alongside Proofpoint's existing threat detection and data loss prevention features.

Tessian's approach to email security represented a significant advancement over traditional rule-based systems by focusing on human behavior patterns rather than just content analysis, making it particularly effective against sophisticated social engineering attacks that leverage real business context to bypass conventional filters.