MachineMail
Email inboxes and an API that let AI agents sign up, receive mail, and reply safely.
✓ Verified against machinemail.dev · Nov 5, 2026Free tier · from $9/moWeb · API · Command line
What it does
MachineMail is an AI tool for building AI agents. It has a free plan, and paid plans start at $9 per month.
MachineMail is an email service built for AI agents rather than people. Each agent gets its own address that can be created with a single API call, and every inbound message comes back as structured JSON with a cleaned body and a trust report attached, so the agent never parses raw HTML from a stranger. Agents reach it from an MCP client such as Claude Code, Codex, Cursor, OpenCode or Copilot through a hosted Streamable HTTP server, or through the /v0 API, a command line tool and a web dashboard. An agent can register itself with auth.md, receive a sandbox key and a temporary inbox, then show a code that a person enters to claim the inbox for their organization. Before an agent reads anything, the trust layer checks SPF, DKIM and DMARC alignment, sender history, allow and block lists, hidden text and zero-width characters, links and attachments, and runs a classifier for prompt injection and phishing. Each message gets a trust level from verified down to withheld, and the agent acts on that level instead of on what the sender claims. Webhooks are signed and retried, and the MCP wait call holds until mail lands. Inboxes cost nothing on every plan; you pay for mail sent, received and stored. Usage past an allowance is billed in arrears at published rates, spam and quarantined mail are never billed, and any inbox can be exported as mbox or JSONL.
- Per-agent inboxes on a free shared domain
- Trust report and level on every inbound message
- Hosted MCP server for agent clients
- REST API, CLI and web dashboard
- auth.md self-registration with human claiming
- Catch-all domains and expiring inboxes
- Signed, replayable webhooks plus SSE and WebSocket events
- AgentMail-compatible API paths and field names
Verified facts
Each row links to the page we checked it on.| API | Yes | machinemail.dev | ✓ Nov 5, 2026 |
|---|---|---|---|
| Free plan | Yes, 3,000 messages a month | machinemail.dev | ✓ Nov 5, 2026 |
| Paid plans from | $9 per month | machinemail.dev | ✓ Nov 5, 2026 |
| Platforms | Web dashboard, API, and CLI | machinemail.dev | ✓ Nov 5, 2026 |
| Pricing | Free plan plus paid plans; pay for mail sent, received, and stored | machinemail.dev | ✓ Nov 5, 2026 |
What you can do with it
Good at
- Inboxes are free on every plan
- Mail arrives as agent-safe text with a verdict the agent can act on
- Paid plans keep working past their allowance, billed in arrears
Watch out for
- Free plan has a daily message cap and one custom domain
- Inboxes on the shared domain are capped per organization
- On Free, mail over the allowance is held until the allowance resets
Common questions
- What is MachineMail used for?
- MachineMail is used for building AI agents. On AIToolMaps it ranks #1 of 23 for building AI agents.
- Is MachineMail free?
- Yes. MachineMail has a free plan, and paid plans start at $9 per month.
- What platforms does MachineMail run on?
- MachineMail runs on Web, API and Command line.
- Does MachineMail have an API?
- Yes. MachineMail offers an API, so developers can use it from their own code.
- What are the best alternatives to MachineMail?
- The closest alternatives are Base44, Hugging Face and Notion, which do most of the same jobs. Base44 is the closest one with a free plan.
Reviews
No reviews yetListing history
- Nov 5, 2026Checked against machinemail.dev
- Nov 6, 2026Listed