AI Email API & Infrastructure for AI Agents | Mails.ai

# Mails.ai > The AI email API for agents and developers. Email infrastructure built specifically for AI — drop ~6 lines into any agent and it gets a working email address with parsing, identity, and reputation built in. Typed reply events, per-agent reputation graph, native prompt-injection scanning, MCP-native distribution. Self-serve signup, no contact-sales gate, and sending works immediately — no approval queue. Each agent can be held to the domains you allow and to its own hourly and daily send caps, which its own key cannot loosen. ## API Base URL https://api.mails.ai — all endpoints under /v1 — auth header: Authorization: Bearer mk_live_<key>. Send: POST /v1/messages with JSON { agent, to, subject, body_text }. Returns the sent message (id, status, cost_usd). Receive: GET /v1/events?event_type=message.received, live tail GET /v1/events/stream (SSE), or register a webhook with POST /v1/webhooks. - [API quickstart](https://mails.ai/docs/quickstart): Key, agent, first send, first reply event — five minutes. - [API reference](https://mails.ai/docs/api-reference): Every REST endpoint with exact request and response fields. - [Docs as Markdown](https://mails.ai/docs/llms.txt): Every docs page as a plain Markdown link, in the docs' own order. Open source (MIT): the MCP server, the TypeScript SDK and the Python SDK are public at https://github.com/mailsai/mailsai, with six runnable examples (first send, inbox loop, the injection firewall, OpenAI Agents SDK, LangGraph, MCP client config). The API implementation itself is closed. - [Source code and examples](https://github.com/mailsai/mailsai): MIT-licensed MCP server, TypeScript and Python SDKs, and six runnable examples you can execute on a test key. ## Background - [Architecture](https://mails.ai/architecture): How sends and replies flow — send pipeline, typed reply events, per-agent reputation graph, multi-vendor failover. - [Use cases](https://mails.ai/use-cases): Four named agents on one primitive