# AgentMail

Hosted email-inbox API designed for AI agents to own and operate, not for humans to read in a mail client. Each agent gets a real address (`*@agentmail.to` or a custom domain), can send and receive messages, manage threads and drafts, and stream incoming mail over WebSockets or webhooks. Marketed under the umbrella site **agent.email** and the docs at **docs.agentmail.to**.

## What's actually different from sending email through SMTP

Three things separate this from "use SendGrid from your agent":

1. **The inbox is the unit.** Agents don't just send — they receive, reply, search threads, label, and draft. The API treats an inbox as a first-class object with REST endpoints for messages, threads, drafts, attachments, and labels.
2. **Push, not poll.** Realtime delivery is WebSocket-native (and webhook-optional). Agents don't burn tokens running a poll loop.
3. **Onboarding is inverted.** The agent signs itself up *first*, then mails one specific human asking to be claimed. Until claimed, the inbox can only send to that one address, capped at 10 mails/day. See [[inverted-claim-onboarding]].

## How an agent gets started

From the public `skill.md`:

```
1. POST sign-up with { human_email, username }
2. Send an introduction email to the human asking them to claim you
3. Human either replies with the OTP they got, or signs up on the console
   → restricted mode lifts
```

Restricted mode allows exactly one operation — `send_message` to `human_email`, max 10/day. Everything else (custom domains, additional inboxes, allowlists, pods, search) returns an error until the human OTP step completes.

## API shape

Base: `https://api.agentmail.to/v0`. The REST surface covers:

- **Agents** — the API-key principal
- **Inboxes** — addresses owned by the agent
- **Messages / Threads / Drafts** — content
- **Domains** — custom domains with SPF/DKIM/DMARC
- **Webhooks** — outbound event subscriptions
- **Pods** — multi-tenant isolation (an agency-style customer hosting many sub-agents)

OpenAPI 3.1 spec and AsyncAPI 2.6.0 spec (for the WebSocket events) are published.

## Integration surface

AgentMail leans hard into the [[llms-txt]] / `skill.md` convention — the docs are pitched at the LLM reading them, not the developer. Concrete integrations:

- **MCP server** for Claude Code, Cursor, and any MCP client
- **CLI** as the human escape hatch
- **Skills** for OpenClaw and Claude-style harnesses
- Dedicated bindings for **Google ADK** ([[adk-go]]), **OpenClaw**, **Replit**, **LiveKit Agents**, **Sim.ai**

The payments hooks — **x402** (HTTP 402 with crypto settlement) and **MPP** (Stripe machine-to-machine) — push agent-native commerce: an agent that receives an invoice email can pay it without a human in the loop.

## Where it fits

For local agent experiments, email is rarely the bottleneck — you can SMTP relay through your own Postfix and call it done. AgentMail becomes interesting when:

- The agent needs to *receive* email reliably, including replies that thread correctly
- The human-in-the-loop reviewer ([[human-in-the-loop]]) is going to read drafts before send
- You're building a fleet of agents and want per-agent isolation (pods)
- You want the agent to handle attachments, forwarding, and label-based workflow without writing a mailbox parser

The closest open analog would be running JMAP (or Stalwart) and writing an agent SDK on top — which is a six-week project before you've handled deliverability.

## Limitations to flag

- **Closed source.** API access is the product; there's no self-host story.
- **Single vendor.** Custom domains help but don't make the agent portable — the inbox state, threads, and webhooks live in AgentMail.
- **Pricing not on the homepage.** Plans are gated behind sign-up; custom-domain support is paid-tier only.
- **No human IMAP.** A human can read the inbox via the console UI, but there's no IMAP/JMAP escape if you want to wire it into Thunderbird or Apple Mail.

## Why this is on the toolbox and not the watchlist

Watchlist criteria target alpha-stage / single-author / single-platform projects where the question is "will this exist in a year." AgentMail is a funded commercial SaaS — the question is different ("does the lock-in risk outweigh the build-vs-buy savings"), and the answer is project-specific. Tracking it as a known option is enough; no re-check date.

## Links

- Site: <https://agent.email>
- Docs: <https://docs.agentmail.to>
- Agent-facing skill: <https://agent.email/skill.md>
- `/llms.txt`: <https://docs.agentmail.to/llms.txt>

## Related

- [[inverted-claim-onboarding]] — the human-claims-the-agent onboarding pattern (extracted from this service)
- [[llms-txt]] — the `/llms.txt` and `skill.md` conventions AgentMail builds on
- [[human-in-the-loop]] — drafts-as-review pattern matches the AgentMail draft API
- [[stateful-agent-routing]] — email-as-transport is one answer to "how do agents get pushed messages"
- [[adk-go]] — Google ADK is one of AgentMail's first-party integrations