AgentMail

AgentMail: Gmail-style inboxes, built for AI agents instead of humans

AgentMail is an email API with a simple premise: AI agents need their own email addresses. One API call creates an inbox, and the agent gets a real address with full two-way communication — sending, receiving, threading, replying, searching, and labeling. That's a different animal from transactional email APIs, which fire one-way notifications; AgentMail is built for agents that carry on actual conversations with vendors, carriers, customers, and other agents.

The platform handles the unglamorous parts of email infrastructure so agent builders don't have to: custom domains with DKIM, SPF, and DMARC, real-time delivery via webhooks and WebSockets, attachment handling, and IMAP/SMTP access for compatibility with existing tooling. Python and TypeScript SDKs plus an MCP server make it drop-in for most agent stacks, and it works out of the box with LangChain, LlamaIndex, CrewAI, and anything else that can make an API call.

Key Features

• Inbox-per-agent API: create real email inboxes programmatically, with threading, labels, search, and attachments
• Real-time events via webhooks and WebSockets, so agents react to incoming mail instantly
• Custom domains with DKIM, SPF, and DMARC authentication built in
• Python and TypeScript SDKs, an MCP server, and IMAP/SMTP access
• Multi-tenant Pods for platform builders provisioning inboxes across many customers
• Free tier: 3 inboxes and 3,000 emails/month; Developer at $20/month, Startup at $200/month, Enterprise custom

Ideal Use Case

AgentMail fits developers building agents whose work happens over email: supply-chain agents coordinating dozens of carriers, collections agents handling payment-plan follow-ups, support agents managing an inbox autonomously, or procurement bots negotiating with vendors. If your agent needs a persistent identity and a conversation history — not just the ability to fire a notification — this is the infrastructure layer for it, and the free tier covers prototyping.

How AgentMail differentiates

AgentMail (Y Combinator Summer 2025) raised a $6M seed led by General Catalyst in March 2026, with angels including Paul Graham, HubSpot CTO Dharmesh Shah, Supabase CEO Paul Copplestone, and Ramp CTO Karim Atiyeh. By the raise it counted more than 500 B2B customers and hundreds of thousands of agent users, with over 100 million emails delivered. Transactional providers like Resend or SendGrid optimize for humans sending to humans; AgentMail is the first provider designed around agents as first-class inbox owners.

FAQ

How is this different from a transactional email API? Transactional APIs send one-way notifications. AgentMail gives agents full inboxes — receiving, threading, replying, and searching — for genuine two-way conversations.

Is there a free plan? Yes: 3 inboxes and 3,000 emails/month, no credit card required. Paid plans start at $20/month.

Can I use my own domain? Yes, with DKIM, SPF, and DMARC configured through the platform.

Does it work with my agent framework? Yes — SDKs for Python and TypeScript, an MCP server, and REST APIs work with LangChain, LlamaIndex, CrewAI, or any custom stack.

tl;dr

AgentMail gives AI agents their own real email inboxes via API — send, receive, thread, search — with a free tier and paid plans from $20/month, backed by a $6M General Catalyst-led seed.

Related

Looking for more options? Browse the AI Infrastructure directory or read our best AI infrastructure tools listicle. AgentMail is also tracked on Crunchbase.