MachineMail gives every AI agent its own real email inbox. Mail arrives as agent-safe text with a trust level attached, and your agent reads it over MCP wherever it runs. Inboxes cost $0 on every plan, and an agent can even sign itself up through a documented auth flow that you confirm with a six-digit claim code.
What it does
Each inbound message gets a trust report before the agent ever sees it: verified, known, unknown, suspicious, or quarantined. Hidden instructions are stripped out of the body, which matters because prompt injection via email is one of the main attack paths against agent workflows. Agents then read, wait on, and reply from their inbox through one Streamable HTTP MCP server.
Key features
- Trust layer on every message: each inbound delivery carries a trust level and report, so agents can treat suspicious mail differently.
- One inbox per agent: create inboxes with one API call or a catch-all domain; ephemeral inboxes self-delete with an inbox.expired event.
- MCP access: a single Streamable HTTP MCP server serves every inbox, plus an AgentMail-compatible API for portability.
- Agent self-signup: an agent can register itself via /auth.md; the human binds the account with a 6-digit code at /claim.
- Reliable delivery: signed webhooks retried for 5 days with replay support, and long-poll waits of up to a minute for new mail.
Who it is for
MachineMail is built for developers running multi-agent systems: customer-support agents that need a real address, research agents that subscribe to newsletters and alerts, or any automation that must send and receive mail without sharing a human inbox.
Pricing
The Free plan ($0) covers 3,000 messages per month; paid plans start at $9, though the official site does not publicly list exact paid tier names or prices. A message counts as each inbound delivery and each outbound send; spam, quarantined, and rejected mail do not count. Pricing from the official machinemail.dev homepage, checked 2026-11-04; see the official MachineMail website for current details.
Information in this post is based on the official MachineMail website, checked on 2026-11-04. MachineMail launched on Product Hunt on 2026-11-02.
