AgentMail

AgentMail is an API-first email platform built for AI agents. Founded in 2025 and part of Y Combinator's S25 batch, the company gives each autonomous agent a dedicated, persistent mailbox - functioning much like Gmail, but designed for programmatic use. Inboxes are created via a REST API with no OAuth flows, and support full two-way communication: sending, receiving, threading, replying, searching and labelling.

The platform's technical scope is broad. It provides real-time eventing through webhooks and WebSockets, automatic spam detection, structured data extraction from emails, semantic search across messages and threads, and multi-tenancy for enterprise deployments. Its infrastructure has processed more than 100m emails, and customers range from individual developers to enterprises running tens of thousands of inboxes. Sectors served include AI and developer tools, software development, enterprise IT and agentic automation.

AgentMail raised a $6m seed round led by General Catalyst. Its angel investors include Paul Graham, Dharmesh Shah (CTO of HubSpot), Paul Copplestone (CEO of Supabase) and Karim Atiyeh (CTO of Ramp). The company describes its product philosophy as developer-first and API-first, with a focus on AI-native and agentic workflows.