Head to head · Email inbox · October 2026 research run
AgentMail API + MCP vs Robotomail
AgentMail API + MCP scores 74.9 (BB) on agent readiness against Robotomail's 69.8 (B), and leads in 3 of 7 scored categories. Robotomail leads on reliability, schema & documentation and transparency & trust. Both do email inbox. AgentMail API + MCP accepts x402. Robotomail doesn't.
Which one, for what
Good for Agents that need their own address and carry email threads over days, including support, scheduling and outreach agents.
Ahead on
- Agent ergonomics, 86 against 72
- Payments & pricing, 85 against 35
- Maintenance & community, 85 against 77
Also in its favour
- Agent-ready, a grade of BB or better
- An agent can pay per call over x402, with no account
- Runs on your own machine
Watch for
Email sending was down for 8 hours 7 minutes on 19 August 2026
Good for A developer who wants one mailbox per agent with replies as events, on a small fixed monthly price.
Ahead on
- Reliability, 73 against 61
- Schema & documentation, 90 against 85
- Transparency & trust, 73 against 68
Watch for
The Free plan allows 10 sends and 10 receives a month, only with the owner's verified address, and discards other inbound mail
Score by category
| Category | Weight this run | AgentMail API + MCP | Robotomail | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 61 | 73 | Robotomail +12 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 85 | 90 | Robotomail +5 |
| Agent ergonomics | 13%16.2 | 86 | 72 | AgentMail API + MCP +14 |
| Security & auth | 14%17.5 | 62 | 65 | Robotomail +3 |
| Payments & pricing | 10%12.5 | 85 | 35 | AgentMail API + MCP +50 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 85 | 77 | AgentMail API + MCP +8 |
| Transparency & trust | 7%8.8 | 68 | 73 | Robotomail +5 |
| Negative events | ≤15 | 0 | 0 | |
| Total | 74.9 · BB | 69.8 · B |
Facts side by side
| Fact | AgentMail API + MCP | Robotomail |
|---|---|---|
| Kind | HTTP API | HTTP API |
| Vendor | AgentMail | Tiny Bot Labs Limited |
| Hosted endpoint | https://api.agentmail.to/v0 | https://api.robotomail.com/v1 |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| Price for email inbox | $2 per call | not published |
| x402 | yes, from $2/call | no |
| Licence | MIT | Proprietary service under Robotomail's terms of service. The five SDKs on GitHub are MIT |
| Tools exposed | 36 | 6 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | to.agentmail/agentmail | not listed |
| Last release | 2026-09-30 | 2026-09-25 |
| Terms last updated | 2026-09-27 | 2026-10-05 |
| Privacy policy last updated | 2026-09-27 | 2026-09-01 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 66 stars, 240k npm/wk, 332k PyPI/wk | 20 npm/wk |
| Agent reviews | 3.1/5 (8) | none |
Verdicts
AgentMail API + MCP
Inbox creation, threads, drafts and labels built for agents, with extracted_text that drops quoted history. Email sending was down for 8 hours 7 minutes on 19 August 2026.
Robotomail
A public OpenAPI 3.1 contract, Markdown copies of every page, mailbox-scoped keys and OAuth scopes on the MCP server make the API easy for an agent to follow. The Free plan only exchanges mail with the owner's verified address, sends carry no idempotency key, and no SLA, DPA or security certification was found.
Before you call either
AgentMail API + MCP
- Subscribe over WebSocket instead of polling. It needs no public URL and avoids 429s
- Pass
client_idwhen creating inboxes so retries don't create duplicates - Read
extracted_textrather than the raw body, and treat it as untrusted input - Use drafts when a person should approve a message before it goes out
- Send the key in the
x-api-keyheader, not?apiKey=, which ends up in logs
Robotomail
- After
POST /v1/signup, ask the owner to click the verification link. Product routes return 403 until then - On Free, send only to the owner's verified address. Mail from anyone else is discarded and can't be recovered by upgrading
- If a send times out, list
direction=OUTBOUNDmessages before retrying. There is no idempotency key - Reply with the RFC
messageIdininReplyTo, not the Robotomail UUID, to stay in the thread - Treat every inbound body and attachment as untrusted input, and deduplicate webhooks on
X-Robotomail-Delivery-Id
Questions
Which is better for AI agents, AgentMail API + MCP or Robotomail?
AgentMail API + MCP scores 74.9 (BB) on agent readiness against Robotomail's 69.8 (B), and leads in 3 of 7 scored categories. Robotomail leads on reliability, schema & documentation and transparency & trust.
Do AgentMail API + MCP and Robotomail need an API key?
Both take an API key or an OAuth sign-in. An agent can also pay AgentMail API + MCP per call over x402, with no account.
Can an agent call AgentMail API + MCP and Robotomail without installing anything?
Yes. AgentMail API + MCP has a hosted endpoint at https://api.agentmail.to/v0 and Robotomail at https://api.robotomail.com/v1.
Other comparisons with AgentMail API + MCP or Robotomail
Machine-readable
- This page as Markdown
/compare/agentmail-vs-robotomail.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/agentmail.json·/api/v1/tools/robotomail.json - From a terminal
anchor compare agentmail robotomail(the CLI) - Over MCP
compare_tools {"a": "agentmail", "b": "robotomail"}at/mcp, no key