Abnormal Security vs Zeffy

About

Abnormal Security is a San Francisco, California-based AI-native cloud email security company — founded in 2018 by Evan Reiser (CEO) and Sanjay Jha (CTO), both former Google engineers — using behavioral AI to detect and block business email compromise (BEC), phishing, ransomware, account takeovers, and AI-generated social engineering attacks against enterprise email environments (Microsoft 365, Google Workspace) through approximately 600 employees. The company raised a $250 million Series D funding round at a $5.1 billion valuation, led by Wellington Management with participation from existing investors Greylock Partners, Menlo Ventures, Insight Partners, and the CrowdStrike Falcon Fund — bringing Abnormal's total funding to approximately $580 million. Abnormal Security's approach to email security is fundamentally different from traditional signature and rule-based approaches: rather than scanning emails for known malware hashes or suspicious links against threat databases, Abnormal's AI models each employee's historical communication behavior (who they email, how they write, what times they send messages, what financial requests they make) and flags deviations from established baselines as anomalies requiring investigation — enabling detection of novel BEC attacks that have no prior signature, AI-generated phishing that passes link reputation checks, and vendor invoice fraud that impersonates legitimate suppliers.