# MailSlurp (slim)

> MailSlurp is a hosted email and SMS API from Pettman OÜ of Estonia. It creates real inboxes and phone numbers for tests and for supervised AI agents, reached over REST, SDKs, IMAP and SMTP, and a hosted MCP server.

- Full: https://www.anchorterminal.com/tools/mailslurp.md (~7,950 tokens) · this version ~1,830 tokens · JSON https://www.anchorterminal.com/tools/mailslurp.json · canonical https://www.anchorterminal.com/tools/mailslurp
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-10

**B · 68.4/100 · rank #215 of 950 · #3 in Agent inbox APIs · not agent-ready · confidence medium**


Assessment: 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.

## Facts

- Kind: HTTP API · vendor: Pettman OÜ · category: Agent inbox APIs · legal entity: Pettman OÜ · provenance 74/100
- Endpoint: `https://api.mailslurp.com` (HTTP, Streamable HTTP)
- Auth: OAuth or key · pricing: Freemium · x402: no · licence: Proprietary service under MailSlurp's terms. The JavaScript client on GitHub is MIT
- Probe metrics: not measured yet (probes haven't run)
- Inbox creation: `POST /inboxes` with no required parameter returns a random address. Options include a chosen address, tags, expiry and `HTTP_INBOX` or `SMTP_INBOX` type. An agent key with account-wide inbox-manager scope can call `POST /agent/inboxes`
- How replies arrive: Signed webhooks (`NEW_EMAIL`, at least once, retried for up to 24 hours), wait endpoints such as `GET /agent/inboxes/{inboxId}/emails/latest`, polling, or IMAP
- Threading: `GET /emails/threads/{threadId}` and `GET /agent/emails/{emailId}/thread`. Agent replies keep the conversation context
- Custom domains: `POST /domains`. Pro and above, one domain included on Growth
- Connected mailboxes: Gmail through Google OAuth, Outlook and others through IMAP and SMTP. The docs say connector credentials are not shown to the agent
- Agent roles: `AGENT_READ_ONLY`, `AGENT_DRAFT_ONLY`, `AGENT_RESPONDER`, `AGENT_SUPPORT`, `AGENT_INBOX_MANAGER`. The OpenAPI file also lists `AGENT_TOTP_MANAGER`
- MCP server: https://api.mailslurp.com/mcp, stateless Streamable HTTP, OAuth or an `x-api-key` header carrying a scoped agent key. 16 tools documented, all prefixed `mailslurp.`
- Free plan: 500 emails received a month, 1,000 sandbox sends to inboxes in the same account, 100 inbox creations, 50 retained inboxes, 200 MB storage
- Rate limits: 150 requests a second per the rate limit guide. Plan quotas for received mail, sends and inbox creations. 429 is also used for plan and sending restrictions
- Errors: Agent errors carry `code`, `message`, `retryable`, `suggestedAction` and `requestId`. Some rate-limit responses add `retryAfterSeconds` and a `Retry-After` header
- SDKs: The docs list JavaScript and TypeScript, Java, C#, Python, PHP, Ruby, Go, Kotlin, Swift and Dart. `mailslurp-client` on npm is 17.6.0, tagged 24 September 2026, MIT
- Status: status.mailslurp.com on updown.io, eight checks (API, email processes, website, dashboard, two logins, IMAP, SMTP), one month of uptime each and no incident log
- Hosting: AWS us-west-2 (Oregon) per the security policy, with optional regional selection for message content only per the DPA
- Prices: Starter plan $19.99 per month (plan); Pro plan $49.99 per month (plan); Growth plan $129.99 per month (plan); Inbox placement test beyond the plan $1 per transaction; Device render beyond the plan $0.50 per transaction

- Scores: Reliability 75, Performance pending, Schema & documentation 72, Agent ergonomics 84, Security & auth 70, Payments & pricing 32, Task success pending, Maintenance & community 75, Transparency & trust 60 · total over the 7 assessed categories
- Why: Reliability, Graded as a hosted service, on the REST API. · Schema & documentation, OpenAPI 3.0.1 at `api.mailslurp.com/v2/api-docs/`, version 6.5.2, 844 operations on 676 paths (25). · Agent ergonomics, Graded on the REST API, with the MCP server noted. · Security & auth, MCP OAuth with client registration, and scoped agent keys with five roles and a scope of inbox IDs, tags or the whole account, shown once, w… · Payments & pricing, No x402, MPP or L402 found (0 of 40). · Maintenance & community, `mailslurp-client` v17.6.0 was tagged on 24 September 2026, 15 days before the check (30). · Transparency & trust, Closed service under published terms, with an MIT JavaScript client (17 of 30).
- Sources: 19, open questions: 11, both in the full twin
- Capabilities: email.inbox, email.inbound, email.send, email.threads, email.domains, messaging.sms, messaging.inbound, hitl.approve
- JSON: https://www.anchorterminal.com/api/v1/tools/mailslurp.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/mailslurp.svg` or a link to https://www.anchorterminal.com/tools/mailslurp from a page on mailslurp.com or one of its subdomains, or the README of github.com/mailslurp/mailslurp-client, then `POST https://www.anchorterminal.com/api/v1/verify` `{"slug", "url"}` or `verify_listing` at /mcp; re-checked weekly, no effect on the grade. Snippets in the full twin.

## Before you call it

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

## Connect

```bash
npm install --save mailslurp-client
```

```bash
curl --request GET \
  --url https://api.mailslurp.com/inboxes \
  --header "x-api-key: $MAILSLURP_API_KEY"
```

```bash
claude mcp add --transport http --scope user mailslurp https://api.mailslurp.com/mcp
claude mcp login mailslurp
```
Full config and headless snippets are in the full page. Through letme (picks today, calling later): https://letme.dev/mailslurp

## Similar tools

| Tool | Grade | Score | Shared capabilities | Slim |
| --- | --- | --- | --- | --- |
| AgentMail API + MCP | BB | 74.9 | email.inbox, email.send, email.inbound, email.threads, email.domains | https://www.anchorterminal.com/tools/agentmail.min.md |
| Robotomail | B | 69.8 | email.inbox, email.send, email.inbound, email.threads, email.domains | https://www.anchorterminal.com/tools/robotomail.min.md |
| MailerSend | B | 69.5 | email.send, email.inbound, email.domains, email.threads, messaging.sms | https://www.anchorterminal.com/tools/mailersend.min.md |
| Mailtrap Email API + MCP | B | 66.8 | email.send, email.inbound, email.domains, email.inbox, email.threads | https://www.anchorterminal.com/tools/mailtrap.min.md |
| mails.ai Agent Email | B | 66.7 | email.inbox, email.send, email.inbound, email.threads, email.domains | https://www.anchorterminal.com/tools/mails-ai.min.md |


## Panel reviews (0, desk reviews from public material, no calls made)