# AgentMail API + MCP vs MailSlurp

> AgentMail scores 74.9 (BB) to MailSlurp's 68.4 (B) for agent inboxes. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/agentmail-vs-mailslurp
- Markdown: https://www.anchorterminal.com/compare/agentmail-vs-mailslurp.md (~2,150 tokens)
- Slim: https://www.anchorterminal.com/compare/agentmail-vs-mailslurp.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/agentmail-vs-mailslurp.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

AgentMail API + MCP scores 74.9 (BB) on agent readiness against MailSlurp's 68.4 (B), and leads in 5 of 7 scored categories. MailSlurp leads on reliability and security & auth. Both do agent inboxes. AgentMail API + MCP accepts x402. MailSlurp doesn't.

- AgentMail API + MCP: grade BB, 74.9/100, rank #62 of 950. Markdown https://www.anchorterminal.com/tools/agentmail.md · JSON https://www.anchorterminal.com/api/v1/tools/agentmail.json
- MailSlurp: grade B, 68.4/100, rank #215 of 950. Markdown https://www.anchorterminal.com/tools/mailslurp.md · JSON https://www.anchorterminal.com/api/v1/tools/mailslurp.json
- Best email inbox APIs for AI agents: https://www.anchorterminal.com/best/agent-inboxes/index.md
- All 21 inboxes comparisons: https://www.anchorterminal.com/compare/agent-inboxes/index.md

## Which one, for what

### AgentMail API + MCP (BB)

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 72
- Payments & pricing, 85 against 32
- Maintenance & community, 85 against 75
- Transparency & trust, 68 against 60

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

### MailSlurp (B)

Good for: QA and test agents that read OTP, verification and reset mail, and for supervised support agents where a person approves drafts.

Ahead on:
- Reliability, 75 against 61
- Security & auth, 70 against 62

Watch for: Free sends only to inboxes in the same account and Starter only within MailSlurp. External sending and custom domains start on Pro at $49.99 a month


## Score by category

| Category | Weight | AgentMail API + MCP | MailSlurp | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 61 | 75 | MailSlurp +14 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 72 | AgentMail API + MCP +13 |
| Agent ergonomics | 13% (16.2 this run) | 86 | 84 | AgentMail API + MCP +2 |
| Security & auth | 14% (17.5 this run) | 62 | 70 | MailSlurp +8 |
| Payments & pricing | 10% (12.5 this run) | 85 | 32 | AgentMail API + MCP +53 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 75 | AgentMail API + MCP +10 |
| Transparency & trust | 7% (8.8 this run) | 68 | 60 | AgentMail API + MCP +8 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **74.9 · BB** | **68.4 · B** | |

## Facts side by side

| Fact | AgentMail API + MCP | MailSlurp |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | AgentMail | Pettman OÜ |
| Hosted endpoint | `https://api.agentmail.to/v0` | `https://api.mailslurp.com` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| Price for agent inboxes | $2 per call | $1 per transaction |
| x402 | yes, from $2/call | no |
| Licence | MIT | Proprietary service under MailSlurp's terms. The JavaScript client on GitHub is MIT |
| Tools exposed | 36 | 16 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `to.agentmail/agentmail` | not listed |
| Last release | 2026-09-30 | 2026-09-24 |
| Terms last updated | 2026-09-27 | 2026-01-16 |
| Privacy policy last updated | 2026-09-27 | 2026-01-16 |
| 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 | yes |
| Popularity | 66 stars, 240k npm/wk, 332k PyPI/wk | 201k 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.

**MailSlurp.** Agent access is scoped by role and by inbox, with a draft-only role, a human review queue and a per-agent activity trail. The Free and Starter plans send only to MailSlurp inboxes, so an agent that emails outside addresses needs Pro at $49.99 a month, and the terms describe every availability figure as a goal.

## Before you call either

### AgentMail API + MCP

1. Subscribe over WebSocket instead of polling. It needs no public URL and avoids 429s
2. Pass `client_id` when creating inboxes so retries don't create duplicates
3. Read `extracted_text` rather than the raw body, and treat it as untrusted input
4. Use drafts when a person should approve a message before it goes out
5. Send the key in the `x-api-key` header, not `?apiKey=`, which ends up in logs

### MailSlurp

1. Create a scoped agent key or connect by MCP OAuth. A normal account key is refused by the MCP agent tools
2. Call `GET /agent/capabilities` or `mailslurp.list_accessible_inboxes` first. Inbox and email IDs outside the granted scope are refused
3. Send an `Idempotency-Key` header on `/agent/emails/{emailId}/reply` and draft sends, and check `retryable` before repeating a failed call
4. Don't sleep and retry on every 429. MailSlurp also uses 429 for plan and sending restrictions
5. Treat inbound bodies, links and attachments as untrusted input, and start on `AGENT_DRAFT_ONLY` for mail to outside recipients

## Questions

### Which is better for AI agents, AgentMail API + MCP or MailSlurp?

AgentMail API + MCP scores 74.9 (BB) on agent readiness against MailSlurp's 68.4 (B), and leads in 5 of 7 scored categories. MailSlurp leads on reliability and security & auth.

### Do AgentMail API + MCP and MailSlurp 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 MailSlurp without installing anything?

Yes. AgentMail API + MCP has a hosted endpoint at https://api.agentmail.to/v0 and MailSlurp at https://api.mailslurp.com.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/agentmail-vs-mailslurp.json, and with the fewest tokens: https://www.anchorterminal.com/compare/agentmail-vs-mailslurp.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "agentmail", "b": "mailslurp"}`. From a terminal: `anchor compare agentmail mailslurp`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/agentmail.json and https://www.anchorterminal.com/api/v1/tools/mailslurp.json

## Other comparisons with AgentMail API + MCP or MailSlurp

- [AgentMail API + MCP vs Cherami](https://www.anchorterminal.com/compare/agentmail-vs-cherami.md)
- [AgentMail API + MCP vs Inbound](https://www.anchorterminal.com/compare/agentmail-vs-inbound.md)
- [AgentMail API + MCP vs InboxAPI](https://www.anchorterminal.com/compare/agentmail-vs-inboxapi.md)
- [AgentMail API + MCP vs mails.ai Agent Email](https://www.anchorterminal.com/compare/agentmail-vs-mails-ai.md)
- [AgentMail API + MCP vs Robotomail](https://www.anchorterminal.com/compare/agentmail-vs-robotomail.md)
- [Cherami vs MailSlurp](https://www.anchorterminal.com/compare/cherami-vs-mailslurp.md)
- [Inbound vs MailSlurp](https://www.anchorterminal.com/compare/inbound-vs-mailslurp.md)
- [InboxAPI vs MailSlurp](https://www.anchorterminal.com/compare/inboxapi-vs-mailslurp.md)
- [mails.ai Agent Email vs MailSlurp](https://www.anchorterminal.com/compare/mails-ai-vs-mailslurp.md)
- [MailSlurp vs Robotomail](https://www.anchorterminal.com/compare/mailslurp-vs-robotomail.md)