MailerLite API + MCP (2026): Marketing v2 + MailerSend MCP for Transactional

MailerLite’s API story is a two-part answer. For marketing operations (subscribers, campaigns, automations, forms) you use the MailerLite API v2 at connect.mailerlite.com/api — stable since 2022, 5 official SDKs, generous 120 req/min rate limit. For transactional email operations (send, templates, webhooks, delivery tracking) you route to MailerLite’s companion product MailerSend, which ships an official MCP server BETA at mcp.mailersend.com/mcp. Single sign-on links both accounts, so you can operate the marketing + transactional split from one login. This tab inventories both surfaces and the MCP capabilities a buyer needs to evaluate before committing.

At a glance

MCP integration in 2026

Model Context Protocol is the emerging standard for connecting LLM agents to external tools. MailerLite’s MCP story splits: no official MCP for the Marketing API (yet), but its companion transactional product MailerSend ships a hosted MCP server in BETA that covers the transactional email surface plus SMS.

Available MCP servers for MailerLite + MailerSend

Three ways to reach the MailerLite ecosystem from an AI agent as of August 2026, ordered by maturity. Only one is first-party.

Marketing API v2 essentials

The MailerLite API v2 follows REST conventions with clean JSON payloads and predictable pagination. Scope covers everything you can do in the MailerLite UI plus a few developer-only endpoints (batching, webhooks).

API v2 is the current focus. Classic v1 remains available for legacy integrations that have not migrated, but new development should target v2. The migration path from v1 to v2 is documented but not zero-effort (endpoint paths and response shapes changed).

Authentication methods

Single mechanism, straightforward setup.

Bearer token (API key)

Generate an API key under Integrations › API in the MailerLite UI. Send it in the Authorization header on every request:

Authorization: Bearer YOUR_API_KEY
Content-Type: application/json
Accept: application/json

API keys are account-scoped and inherit the permission set of the user who created them. There is no granular scope system (no “read-only” or “campaigns-only” tokens). To limit blast radius of a leaked token, best practice is to generate per-integration keys and revoke individually when unused.

Rate limits

The 120 req/min general ceiling is generous for interactive dashboards and low-volume automation. The 5 req/min import ceiling catches teams off guard when migrating large subscriber lists — use the batch endpoint with large payloads instead of looping single-add calls. For genuinely high-volume operations (>10K subscribers/minute processing), reach out to MailerLite support to discuss dedicated infrastructure options.

Official SDKs

Five official client libraries for the Marketing API v2. All maintained by MailerLite.

No official .NET, Java, or Rust SDKs. Community wrappers exist for .NET; teams building in Java or Rust typically call the API directly with their language’s standard HTTP client. For AI-agent access via natural language, the native Claude integration and ChatGPT integration cover most operational asks without writing code.

Endpoints reference

The endpoint groups you will actually use in production. Full reference at developers.mailerlite.com/docs.

Code examples

Two representative snippets covering the most common first-day tasks: add a subscriber, then send a campaign to a group.

Node.js: add or update a subscriber

const MailerLite = require('@mailerlite/mailerlite-nodejs').default;

const mailerlite = new MailerLite({ api_key: 'YOUR_API_KEY' });

const params = {
  email: 'subscriber@example.com',
  fields: {
    name: 'Alaa',
    last_name: 'Touil'
  },
  groups: ['GROUP_ID_HERE'],
  status: 'active'
};

mailerlite.subscribers.createOrUpdate(params)
  .then(response => {
    console.log('Subscriber upserted:', response.data.data.id);
  })
  .catch(error => {
    console.error('Error:', error.response?.data || error.message);
  });

Python: create and send a campaign

from mailerlite import Client

client = Client({'api_key': 'YOUR_API_KEY'})

# 1. Create the campaign
campaign = client.campaigns.create({
    'name': 'Weekly Newsletter',
    'type': 'regular',
    'emails': [{
        'subject': 'Test from the API',
        'from_name': 'SMTPedia',
        'from': 'hello@smtpedia.com',
        'content': '<h1>Hello</h1><p>This is a test.</p>'
    }],
    'groups': ['GROUP_ID_HERE']
})

# 2. Schedule immediate delivery
client.campaigns.schedule(
    campaign_id=campaign['data']['id'],
    delivery='instant'
)

print(f"Campaign {campaign['data']['id']} scheduled")

Common gotchas

Deprecations and changelog

MailerLite maintains a changelog on the developers portal at developers.mailerlite.com. Key items to know:

• API v2 is current. Stable since 2022. Focus of all new SDK work and documentation.
• Classic API v1 is still supported at developers-classic.mailerlite.com. No formal deprecation date announced, but new integrations should target v2.
• MailerSend MCP Server released in BETA late 2025 / early 2026 with wide tool coverage from launch (email, SMTP, templates, webhooks, analytics, SMS).
• Native Claude and ChatGPT integrations shipped 2026 for the Marketing API side — unusually early for an ESP at MailerLite’s price point.
• Multi-user token management introduced 2024 for team accounts (previously all tokens were account-owner scoped).

Frequently asked questions