MailerSend API + MCP (2026): official remote MCP, v1 REST, 6 SDKs

MailerSend’s public API is a single-version REST surface at api.mailersend.com/v1 with 6 official SDKs, a Go-based CLI, and, since August 2025, an official first-party MCP server at mcp.mailersend.com/mcp. That MCP coverage is unusual for a mid-market ESP: as of August 2026, MailerSend, Resend, and SendGrid are the shortlist of transactional providers shipping an official remote MCP endpoint, while Postmark, SparkPost and Amazon SES still rely on community wrappers. If you are picking an API-first ESP that AI agents can drive out of the box, MailerSend earns a serious look. If you need a mature bulk-marketing API with campaign automations, keep Brevo or Mailchimp on the shortlist instead.

At a glance

MCP integration in 2026

The Model Context Protocol lets AI clients. Claude Desktop, Claude Code, Cursor, VSCode, Gemini CLI, ChatGPT Developer mode, call MailerSend as a first-class tool with the same auth and observability as any human integration. MailerSend was one of the first transactional ESPs to ship a first-party server; the spin-off from MailerLite in 2019 kept the developer-tooling DNA, and it shows here.

Available MCP servers

Four MCP entry points are usable in production today. Prefer the official server for anything sensitive; the others are useful when you need agent orchestration layers or GTM-specific workflow packaging.

MailerSend API essentials

The REST surface is intentionally small: one base URL, one version prefix, JSON in and JSON out, Bearer-token auth, cursor-and-page pagination. There is no GraphQL variant and no separate marketing/transactional split, every resource lives under /v1/.

Resources map cleanly to product concepts: domains, templates, webhooks, suppressions, activity, analytics, inbound, sms. If you are used to the SendGrid or Postmark shape, MailerSend feels closer to Postmark: one send endpoint per intent, no verbose personalizations DSL, envelope kept small. Compared with SendGrid’s /v3/mail/send payload, a MailerSend send body is roughly half the JSON for the same outcome.

Authentication methods

MailerSend uses a single auth model: a Bearer API token issued from the dashboard. There is no OAuth 2.0 flow, no legacy Basic Auth on API keys, and no per-domain sub-credentials for the REST surface.

Bearer API token

Create a token under Integrations › API tokens, scope it to a domain if you want to blast-radius it, and pass it as:

Authorization: Bearer <YOUR_API_TOKEN>
Content-Type: application/json
X-Requested-With: XMLHttpRequest

Tokens can be paused via PUT /v1/token/{token_id}/settings and revoked via DELETE /v1/token/{token_id}. The free plan allows 1 token, Hobby 3 tokens, Starter and above lift the cap. Tokens are shown once at creation, write them to a secrets manager immediately.

SMTP user credentials (separate)

The SMTP relay uses its own username and password pair, generated per SMTP user under Domains › SMTP users. These are not the API token and cannot be regenerated from the token list, see the SMTP settings tab for the full setup.

Rate limits

MailerSend publishes per-minute API limits (not per-hour) and plan-tiered daily quotas. Every rate-limited response returns 429 Too Many Requests with a Retry-After header in seconds and x-ratelimit-* response headers to inspect budget mid-flight.

Workaround pattern for the bulk throttle: batch 500 messages into one POST /v1/bulk-email call and poll the returned bulk id via GET /v1/bulk-email/{id}. On Free/Hobby that is 5,000 messages/minute theoretical ceiling (10 bulk calls x 500 messages) versus 12,000 for single-send at 120 rpm, bulk is cheaper on your rate budget once you cross ~4 recipients per call.

Official SDKs

MailerSend maintains six official SDKs directly on GitHub, all released under the mailersend org and covering the same endpoint surface. Compared with Postmark (7 SDKs) or SendGrid (7+), the coverage is competitive; the Go SDK doubles as the source for the official CLI.

Notable community SDKs

Community coverage is thinner than for SendGrid or Mailgun-expect to reach for the framework-native drivers first: the official Laravel driver, the Symfony Mailer transport, the Django Anymail backend, and the official Firebase extension. For .NET, Elixir and Rust there is no first-party or actively maintained community SDK as of August 2026, use the raw HTTP API.

Endpoints reference

Full API reference lives at developers.mailersend.com/api/v1. The 15 resources below cover 95%+ of production traffic; less common surfaces (identities, templates variables, activity exports) are documented in the reference but omitted here for scannability.

Code examples

Python · single transactional send

# pip install mailersend
import os
from mailersend import emails

mailer = emails.NewEmail(os.environ['MAILERSEND_API_KEY'])

body = {}
mailer.set_mail_from({'email': 'you@your-verified-domain.com', 'name': 'SMTPedia Bot'}, body)
mailer.set_mail_to([{'email': 'alaa@example.com', 'name': 'Alaa'}], body)
mailer.set_subject('Hello from MailerSend', body)
mailer.set_html_content('<p>Ping from Python SDK.</p>', body)
mailer.set_plaintext_content('Ping from Python SDK.', body)

response = mailer.send(body)
print(response)  # HTTP status + x-message-id header

Node.js · async send with typed payload

// npm install mailersend
import { MailerSend, EmailParams, Sender, Recipient } from 'mailersend';

const mailerSend = new MailerSend({ apiKey: process.env.MAILERSEND_API_KEY });

const sentFrom = new Sender('you@your-verified-domain.com', 'SMTPedia Bot');
const recipients = [new Recipient('alaa@example.com', 'Alaa')];

const emailParams = new EmailParams()
  .setFrom(sentFrom)
  .setTo(recipients)
  .setSubject('Hello from MailerSend')
  .setHtml('<p>Ping from Node SDK.</p>')
  .setText('Ping from Node SDK.');

const response = await mailerSend.email.send(emailParams);
console.log(response.statusCode, response.headers['x-message-id']);

Common gotchas

Deprecations and changelog

MailerSend publishes release notes at mailersend.com/changelog. Highlights that affect API and MCP integrators (most recent first):

• June 30, 2026-Template Translations released: one-click translate drag-and-drop templates into 9 languages without duplicating template IDs.
• March 9, 2026-Blocklist Monitoring shipped: automated periodic checks of your sending IPs and domains against major blocklists, exposed via the API and MCP server.
• February 26, 2026-MailerSend CLI GA: Go-based command-line tool to send emails and manage domains/tokens from the terminal (Homebrew tap available).
• December 9, 2025-DMARC Monitoring released: ingests aggregate DMARC reports and visualizes authentication results per source.
• September 22, 2025-Webhooks 2.0: new lighter payload envelope and versioned webhook subscriptions.
• August 5, 2025-MailerSend MCP Server (Beta) launched at mcp.mailersend.com/mcp with 30+ tools across email, domains, suppressions, SMS and analytics.

Frequently asked questions