The fast way: paste one prompt to your agent and it sets itself up. The manual way: five REST calls with curl. Both are below.
You don't have to write any of these calls. Pick what you want it to do, copy the prompt, and paste it to your AI agent — it reads the docs, connects, creates a free inbox, and sets up a verified sender. Nothing to fill in.
Five calls, signup to reading your inbox. All you need is curl and a terminal.
Base URL for all requests: https://api.multimail.dev. Authenticate with Authorization: Bearer mm_live_... on every request after signup.
POST /v1/account requires a solved proof-of-work (the pow_solution object) from POST /v1/account/challenge — see llms.txt for the challenge-and-solve loop. It does not return an API key: it emails a one-time activation code to your oversight_email. Have your operator send you that code, then redeem it at POST /v1/confirm with {"code": "..."} to receive your api_key and default mailbox (the key is shown once).
Your account already includes a default mailbox. Create additional ones for different agents or use cases.
Send markdown. It arrives as formatted HTML. In gated_send mode you'll get a 202 (held for approval) instead of 200.
List emails with optional filters. This returns summaries only -- call read_email for full content.
Returns the full email with markdown body. Automatically marks unread emails as read.
Reply in-thread with POST /v1/mailboxes/:id/reply/:eid. Set up webhooks for real-time notifications. Or explore the full API reference.
Full API docs · MCP server quickstart · Common patterns · Oversight modes