# MailerSend (slim)

> Transactional email service from MailerSend, Inc. with a REST API, SMTP relay, templates, inbound routing, webhooks and analytics, plus SMS and WhatsApp sending. Agents reach it with a scoped API token or through a hosted MCP server.

- Full: https://www.anchorterminal.com/tools/mailersend.md (~8,300 tokens) · this version ~2,130 tokens · JSON https://www.anchorterminal.com/tools/mailersend.json · canonical https://www.anchorterminal.com/tools/mailersend
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-08

**B · 69.5/100 · rank #156 of 722 · #3 in Email delivery APIs · not agent-ready · confidence medium**


Assessment: API tokens carry any of 30 scopes and can be tied to one domain, rate limits are published with retry-after on every 429, and a 99.5 per cent SLA starts on the $35 Starter plan. Sends take no idempotency key, the Free plan allows 100 API requests a day, and the terms permit changes without notice.

## Facts

- Kind: HTTP API · vendor: MailerSend, Inc. · category: Email delivery APIs · legal entity: MailerSend, Inc. · provenance 84/100
- Endpoint: `https://api.mailersend.com/v1` (HTTP, Streamable HTTP)
- Auth: OAuth or key · pricing: Freemium · x402: no · licence: Proprietary service under MailerSend's terms of use. The SDKs and the CLI on GitHub are MIT
- Probe metrics: not measured yet (probes haven't run)
- API: REST at https://api.mailersend.com/v1 with Bearer token. Email, bulk email, activity, analytics, domains, sender identities, inbound routes, messages, scheduled messages, recipients, suppressions, templates, email verification, SMS, WhatsApp, users, tokens, SMTP users, webhooks, DMARC and blocklist monitoring
- Free tier: Free plan with 500 emails a month, 100 API requests a day, 1 domain, 1 template, 1 webhook and 1 API token. The pricing FAQ says a card is asked for after account approval. A 14-day Professional trial has the same 500 emails and 100 requests a day
- Rate limits: 120 requests a minute on POST /v1/email, 10 on POST /v1/bulk-email by default (10 to 60 by plan), 10 shared by GET /v1/activity and GET /v1/emails, 60 on other endpoints, 120 on SMTP. Daily quota 100, 1,000, 100,000 or 500,000 requests by plan
- Send limits: 50 To, 10 CC and 10 BCC recipients per email on approved accounts, 25 MB per attachment, 2 MB each for text and HTML, 500 emails and 50 MB per bulk request, scheduling up to 72 hours ahead
- Before first send: Sign up in a browser, pass account approval, then verify a sending domain by DNS or use the trial domain. Create an API token under Settings, API Tokens
- Inbound: Inbound routes on every plan, managed at /v1/inbound, forwarding parsed mail to a webhook or address
- Webhooks: Signed with HMAC SHA-256 in a `Signature` header using a per-webhook secret. Events include maintenance.start and maintenance.end. 1 webhook on Free and Hobby, 50 on Starter
- MCP server: Hosted at https://mcp.mailersend.com/mcp, streamable HTTP, OAuth. 127 tools listed in the docs across email, domains, templates, webhooks, inbound, suppressions, analytics, verification, DMARC, blocklists, tokens, users, identities and SMS, plus search and fetch
- SDKs and CLI: Official SDKs for PHP, Laravel, Node.js, Python, Go, Ruby and Java, all on GitHub. npm mailersend 3.4.1 and PyPI mailersend 2.1.1 (29 September 2026), both MIT. A CLI (v2.0.0, 18 August 2026) with OAuth or token login and a --json flag
- OpenAPI: OpenAPI 3.1 on SwaggerHub, version 1.0.0-oas3.1, 59 paths and 97 operations with summaries and request schemas
- Data retention: Email activity kept 1 day on Free and Hobby, 7 days on Starter, 30 days on Professional and Enterprise. API logs 7 days on Professional and 14 on Enterprise. Deletion on request takes effect within 30 days
- SLA: 99.5 per cent monthly uptime on Starter, Professional and Enterprise, service credits on claim, scheduled maintenance excluded
- Security controls: Scoped tokens, token pause, IP allowlisting from Starter, two-factor authentication with bulk enforcement on Professional, user roles from Hobby
- Data location: Data centres in the European Union with ISO 27001 held by the data centre, per the security statement. MailerSend, Inc. is certified under the EU-U.S. Data Privacy Framework
- Prices: Hobby $7 per month (plan); Starter 50k $35 per month (plan); Starter 100k $68 per month (plan); Professional 50k $110 per month (plan); Professional 100k $140 per month (plan); Overage on Hobby $1.50 per 1,000 emails; Overage on Starter $1.30 per 1,000 emails; Overage on Professional $1.30 per 1,000 emails; Email verification credit $0.01 per credit; Extra sending domain $4 per month (plan); SMS phone number $2 per month (plan)

- Scores: Reliability 95, Performance pending, Schema & documentation 73, Agent ergonomics 69, Security & auth 62, Payments & pricing 30, Task success pending, Maintenance & community 83, Transparency & trust 64 · total over the 7 assessed categories
- Why: Reliability, Graded on the hosted REST API. · Schema & documentation, OpenAPI 3.1 on SwaggerHub with 59 paths and 97 operations, but no WhatsApp, DMARC or blocklist monitoring paths and no error responses (20 o… · Agent ergonomics, List endpoints take `page` and `limit` (10 to 100), with no field selection. · Security & auth, API tokens with any of 30 scopes, read or full by area, optionally tied to one sending domain, and pausable or deletable through the API. · Payments & pricing, No x402, MPP or L402 (0). · Maintenance & community, Python SDK 2.1.1 on 29 September 2026 and Node.js SDK v3.5.0 tagged 23 September (30). · Transparency & trust, Closed service with published terms and MIT SDKs.
- Sources: 22, open questions: 9, both in the full twin
- Capabilities: email.send, email.inbound, email.templates, email.domains, email.analytics, email.verification, email.threads, messaging.sms, messaging.whatsapp
- JSON: https://www.anchorterminal.com/api/v1/tools/mailersend.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/mailersend.svg` or a link to https://www.anchorterminal.com/tools/mailersend from a page on mailersend.com or one of its subdomains, or the README of github.com/mailersend/mailersend-nodejs, 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. Send `Authorization: Bearer <token>` to https://api.mailersend.com/v1 and ask for a token with only the scopes the task needs, such as `email_full` and `activity_read`
2. Read the message id from the `x-message-id` response header. POST /v1/email answers 202 with an empty body
3. Check for a sent message before retrying a send. No idempotency key exists, so a blind retry can deliver twice
4. On a 429 wait the seconds in `retry-after`. Call GET /v1/api-quota, which isn't counted, to see the daily quota left
5. Use POST /v1/bulk-email for batches of up to 500 emails. It isn't on the Free plan and takes 10 to 60 requests a minute by plan

## Connect

```bash
npm install mailersend
```

```bash
curl -X POST https://api.mailersend.com/v1/email -H "Authorization: Bearer $MAILERSEND_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"from":{"email":"hello@yourdomain.com"},"to":[{"email":"recipient@example.com"}],"subject":"Hello","text":"Hello"}'
```

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

## Similar tools

| Tool | Grade | Score | Shared capabilities | Slim |
| --- | --- | --- | --- | --- |
| Mailtrap Email API + MCP | B | 66.8 | email.send, email.inbound, email.templates, email.domains, email.analytics, email.threads | https://www.anchorterminal.com/tools/mailtrap.min.md |
| Amazon SES | BB | 75.1 | email.send, email.inbound, email.templates, email.domains, email.analytics | https://www.anchorterminal.com/tools/amazon-ses.min.md |
| Resend API + MCP | BB | 75.1 | email.send, email.inbound, email.templates, email.domains, email.analytics | https://www.anchorterminal.com/tools/resend.min.md |
| AgentMail API + MCP | BB | 74.9 | email.send, email.inbound, email.threads, email.domains, email.analytics | https://www.anchorterminal.com/tools/agentmail.min.md |
| Postmark API + MCP | B | 66.5 | email.send, email.inbound, email.templates, email.domains, email.analytics | https://www.anchorterminal.com/tools/postmark.min.md |


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