AegisAI closed a $36 million Series A led by Battery Ventures to expand its AI-powered email security platform that combats sophisticated spear phishing attacks.

The startup was founded by former Google security executives Cy Khormaee and Ryan Luo, who previously developed safe browsing technology and reCAPTCHA. The pair launched AegisAI in 2025 after recognizing that traditional rule-based email security systems cannot keep pace with AI-generated threats.

Accel and Foundation Capital participated in the round, bringing AegisAI's total funding to $49 million since its $13 million seed round in September 2025.

The company's AI agents analyze incoming emails using human-like reasoning rather than simple "if-then" logic. The technology can detect malicious PDF attachments with built-in passwords and CAPTCHA systems designed to bypass standard spam filters.

Why AI-powered attacks are winning

Hackers now use AI to aggregate personal information about targets, including coworker details, active projects, and recent travel plans. This allows them to craft highly personalized phishing messages that appear authentic.

"AI-powered attacks bypass existing controls more than half the time now, which means they're almost twice as effective as they used to be," Khormaee said. "They've researched you, they understand everything about you, and they're targeting attacks that are perfectly bespoke to you."

AegisAI has signed dozens of customers including crypto payments company Mesh, AI startup LangChain, and privacy compliance platform Lokker. The company claims its agents spot threats that traditional email security systems miss entirely.

Battery Ventures general partner Dharmesh Thakker led the investment after noticing an increase in email attacks targeting his portfolio companies. He sought a startup that could "defend against AI with AI" and replace legacy email security tools with agent-driven defense systems.

The funding will support AegisAI's expansion as enterprises face mounting pressure from increasingly sophisticated email-based cyberattacks powered by generative AI tools.