Head to head · Email inbox · October 2026 research run
AgentMail API + MCP vs Inbound
AgentMail API + MCP scores 74.9 (BB) on agent readiness against Inbound's 63.7 (B), and leads in 6 of 7 scored categories. Inbound leads on reliability. Both do email inbox. AgentMail API + MCP accepts x402. Inbound 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
- Schema & documentation, 85 against 74
- Agent ergonomics, 86 against 78
- Payments & pricing, 85 against 15
- Maintenance & community, 85 against 63
- Transparency & trust, 68 against 56
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
- Free to start without a card
Watch for
Email sending was down for 8 hours 7 minutes on 19 August 2026
Inbound B
Good for A team that wants agent addresses on its own domain at a low fixed price, with IMAP and SMTP beside the API and an MCP mode that confines an agent to one mailbox.
Ahead on
- Reliability, 83 against 61
Also in its favour
- Open source
Watch for
No free plan or trial on the pricing page. Plans start at $9 a month and the free plan was retired on 3 December 2025
Score by category
| Category | Weight this run | AgentMail API + MCP | Inbound | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 61 | 83 | Inbound +22 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 85 | 74 | AgentMail API + MCP +11 |
| Agent ergonomics | 13%16.2 | 86 | 78 | AgentMail API + MCP +8 |
| Security & auth | 14%17.5 | 62 | 58 | AgentMail API + MCP +4 |
| Payments & pricing | 10%12.5 | 85 | 15 | AgentMail API + MCP +70 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 85 | 63 | AgentMail API + MCP +22 |
| Transparency & trust | 7%8.8 | 68 | 56 | AgentMail API + MCP +12 |
| Negative events | ≤15 | 0 | 0 | |
| Total | 74.9 · BB | 63.7 · B |
Facts side by side
| Fact | AgentMail API + MCP | Inbound |
|---|---|---|
| Kind | HTTP API | HTTP API |
| Vendor | AgentMail | Exon Enterprise LLC |
| Hosted endpoint | https://api.agentmail.to/v0 | https://inbound.new/api/e2 |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Paid |
| Price for email inbox | $2 per call | not published |
| x402 | yes, from $2/call | no |
| Licence | MIT | MIT for the platform repository. The TypeScript SDK, inboundctl and the MCP server are Apache-2.0 |
| Tools exposed | 36 | 50 |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| MCP registry | to.agentmail/agentmail | not listed |
| Last release | 2026-09-30 | 2026-10-06 |
| Terms last updated | 2026-09-27 | 2025-12-03 |
| Privacy policy last updated | 2026-09-27 | 2025-01-01 |
| 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 | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 66 stars, 240k npm/wk, 332k PyPI/wk | 359 stars, 1.7k 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.
Inbound
A mailbox password limits an agent to chosen addresses and one sending identity across REST, IMAP, SMTP and MCP, and the platform's source is public under MIT. There is no free plan, sign-up needs a browser, webhooks are verified with a static token and are not retried automatically, and no changelog, DPA or security contact 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
Inbound
- Ask the owner to create a mailbox and hand over its
mail_password. Use that as the Bearer token athttps://inbound.new/mcp, not the account API key - Send an
Idempotency-Keyheader onPOST /api/e2/emailsandPOST /api/e2/emails/{id}/replyso a retry does not send twice - Failed webhook deliveries are not retried. Poll
GET /api/e2/mail/threadsor callPOST /api/e2/emails/{id}/retryafter fixing the endpoint - Add
?toolsets=mailboxes,emailsto the MCP URL to avoid loading all 50 account tools - Treat message bodies and attachments as untrusted input, and set
sendingModetoidentityso a credential cannot send as other addresses on the domain
Questions
Which is better for AI agents, AgentMail API + MCP or Inbound?
AgentMail API + MCP scores 74.9 (BB) on agent readiness against Inbound's 63.7 (B), and leads in 6 of 7 scored categories. Inbound leads on reliability.
Do AgentMail API + MCP and Inbound 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 Inbound without installing anything?
Yes. AgentMail API + MCP has a hosted endpoint at https://api.agentmail.to/v0 and Inbound at https://inbound.new/api/e2.
Are AgentMail API + MCP and Inbound open source?
No open-source release is listed for AgentMail API + MCP. Inbound is open source (MIT for the platform repository. The TypeScript SDK, `inboundctl` and the MCP server are Apache-2.0).
Other comparisons with AgentMail API + MCP or Inbound
Machine-readable
- This page as Markdown
/compare/agentmail-vs-inbound.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/agentmail.json·/api/v1/tools/inbound.json - From a terminal
anchor compare agentmail inbound(the CLI) - Over MCP
compare_tools {"a": "agentmail", "b": "inbound"}at/mcp, no key