How to integrate Enginemailer MCP with LangChain

This guide walks you through connecting Enginemailer to LangChain using the Composio tool router. By the end, you'll have a working Enginemailer agent that can add new subscriber to newsletter list, pause tomorrow's scheduled marketing campaign, export email delivery report from last week through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Enginemailer account through Composio's Enginemailer MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Enginemailer is an email marketing platform for managing contacts, campaigns, and sending personalized emails. It helps businesses automate outreach and boost engagement with targeted messaging.

38 Tools

Introduction

This guide walks you through connecting Enginemailer to LangChain using the Composio tool router. By the end, you'll have a working Enginemailer agent that can add new subscriber to newsletter list, pause tomorrow's scheduled marketing campaign, export email delivery report from last week through natural language commands.

This guide will help you understand how to give your LangChain agent real control over a Enginemailer account through Composio's Enginemailer MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

Also integrate Enginemailer with

OpenAI Agents SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenClawHermesCLIGoogle ADKVercel AI SDKMastra AILlamaIndexCrewAI

TL;DR

Here's what you'll learn:
  • Get and set up your OpenAI and Composio API keys
  • Connect your Enginemailer project to Composio
  • Create a Tool Router MCP session for Enginemailer
  • Initialize an MCP client and retrieve Enginemailer tools
  • Build a LangChain agent that can interact with Enginemailer
  • Set up an interactive chat interface for testing

What is LangChain?

LangChain is a framework for developing applications powered by language models. It provides tools and abstractions for building agents that can reason, use tools, and maintain conversation context.

Key features include:

  • Agent Framework: Build agents that can use tools and make decisions
  • MCP Integration: Connect to external services through Model Context Protocol adapters
  • Memory Management: Maintain conversation history across interactions
  • Multi-Provider Support: Works with OpenAI, Anthropic, and other LLM providers

What is the Enginemailer MCP server, and what's possible with it?

The Enginemailer MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Enginemailer account. It provides structured and secure access to your email marketing platform, so your agent can perform actions like creating campaigns, managing subscriber lists, exporting reports, and sending personalized email campaigns on your behalf.

  • Campaign creation and scheduling: Direct your agent to set up new email campaigns, configure content, and schedule delivery to your audience.
  • Subscriber management: Have your agent add new subscribers to your lists, including custom fields and segmentation for targeted outreach.
  • Instant campaign delivery and controls: Command your agent to send campaigns immediately or pause scheduled campaigns for last-minute adjustments.
  • Campaign monitoring and reporting: Let your agent export detailed email campaign reports as CSV files and check the status of ongoing exports.
  • Audience segmentation and subcategory retrieval: Guide your agent to fetch subcategories and organize recipients for more personalized and effective campaigns.

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

Composio's Composio SDK helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Composio SDK

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Composio SDK works

The Composio SDK follows a three-phase workflow:

  1. Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
  2. Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
  3. Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Step by step10 STEPS
1

Prerequisites

Before starting this tutorial, make sure you have:
  • Python 3.10 or higher installed on your system
  • A Composio account with an API key
  • An OpenAI API key
  • Basic familiarity with Python and async programming
2

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key. You'll need credits to use the models, or you can connect to another model provider.
  • Keep the API key safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Navigate to your API settings and generate a new API key.
  • Store this key securely as you'll need it for authentication.
3

Install dependencies

npm install @composio/langchain @langchain/core @langchain/openai @langchain/mcp-adapters dotenv

Install the required packages for LangChain with MCP support.

What's happening:

  • @composio/langchain provides Composio integration for LangChain
  • @langchain/mcp-adapters enables MCP client connections
  • @langchain/core is the core agent framework
  • dotenv/config loads environment variables
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_composio_user_id_here
OPENAI_API_KEY=your_openai_api_key_here

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your requests to Composio's API
  • COMPOSIO_USER_ID identifies the user for session management
  • OPENAI_API_KEY enables access to OpenAI's language models
5

Import dependencies

import { Composio } from '@composio/core';
import { LangchainProvider } from '@composio/langchain';
import { MultiServerMCPClient } from "@langchain/mcp-adapters";
import { createAgent } from "langchain";
import * as readline from 'readline';
import 'dotenv/config';

dotenv.config();
What's happening:
  • We're importing LangChain's MCP adapter and Composio SDK
  • The dotenv/config import loads environment variables from your .env file
  • This setup prepares the foundation for connecting LangChain with Enginemailer functionality through MCP
6

Initialize Composio client

const composioApiKey = process.env.COMPOSIO_API_KEY;
const userId = process.env.COMPOSIO_USER_ID;

if (!composioApiKey) throw new Error('COMPOSIO_API_KEY is not set');
if (!userId) throw new Error('COMPOSIO_USER_ID is not set');

async function main() {
    const composio = new Composio({
        apiKey: composioApiKey as string,
        provider: new LangchainProvider()
    });
What's happening:
  • We're loading the COMPOSIO_API_KEY from environment variables and validating it exists
  • Creating a Composio instance that will manage our connection to Enginemailer tools
  • Validating that COMPOSIO_USER_ID is also set before proceeding
7

Create a Tool Router session

const session = await composio.create(
    userId as string,
    {
        toolkits: ['enginemailer']
    }
);

const url = session.mcp.url;
What's happening:
  • We're creating a Tool Router session that gives your agent access to Enginemailer tools
  • The create method takes the user ID and specifies which toolkits should be available
  • The returned session.mcp.url is the MCP server URL that your agent will use
  • This approach allows the agent to dynamically load and use Enginemailer tools as needed
8

Configure the agent with the MCP URL

const client = new MultiServerMCPClient({
    "enginemailer-agent": {
        transport: "http",
        url: url,
        headers: {
            "x-api-key": process.env.COMPOSIO_API_KEY
        }
    }
});

const tools = await client.getTools();

const agent = createAgent({ model: "gpt-5", tools });
What's happening:
  • We're creating a MultiServerMCPClient that connects to our Enginemailer MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • getTools() retrieves all available Enginemailer tools that the agent can use
  • We're creating a LangChain agent using the GPT-5 model
9

Set up interactive chat interface

let conversationHistory: any[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
console.log("Ask any Enginemailer related question or task to the agent.\n");

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: 'You: '
});

rl.prompt();

rl.on('line', async (userInput: string) => {
    const trimmedInput = userInput.trim();

    if (['exit', 'quit', 'bye'].includes(trimmedInput.toLowerCase())) {
        console.log("\nGoodbye!");
        rl.close();
        process.exit(0);
    }

    if (!trimmedInput) {
        rl.prompt();
        return;
    }

    conversationHistory.push({ role: "user", content: trimmedInput });
    console.log("\nAgent is thinking...\n");

    const response = await agent.invoke({ messages: conversationHistory });
    conversationHistory = response.messages;

    const finalResponse = response.messages[response.messages.length - 1]?.content;
    console.log(`Agent: ${finalResponse}\n`);
        
        rl.prompt();
    });

    rl.on('close', () => {
        console.log('\n👋 Session ended.');
        process.exit(0);
    });
What's happening:
  • We initialize an empty conversationHistory list to maintain context across interactions
  • A readline interface is used to continuously accept user input from the command line
  • When a user types a message, it's added to the conversation history and sent to the agent
  • The agent processes the request using the invoke() method with the full conversation history
  • Users can type 'exit', 'quit', or 'bye' to end the chat session gracefully
10

Run the application

main().catch((err) => {
    console.error('Fatal error:', err);
    process.exit(1);
});
What's happening:
  • We call the main() function to start the application

Complete Code

Here's the complete code to get you started with Enginemailer and LangChain:

import { Composio } from '@composio/core';
import { LangchainProvider } from '@composio/langchain';
import { MultiServerMCPClient } from "@langchain/mcp-adapters";  
import { createAgent } from "langchain";
import * as readline from 'readline';
import 'dotenv/config';

const composioApiKey = process.env.COMPOSIO_API_KEY;
const userId = process.env.COMPOSIO_USER_ID;

if (!composioApiKey) throw new Error('COMPOSIO_API_KEY is not set');
if (!userId) throw new Error('COMPOSIO_USER_ID is not set');

async function main() {
    const composio = new Composio({
        apiKey: composioApiKey as string,
        provider: new LangchainProvider()
    });

    const session = await composio.create(
        userId as string,
        {
            toolkits: ['enginemailer']
        }
    );

    const url = session.mcp.url;
    
    const client = new MultiServerMCPClient({
        "enginemailer-agent": {
            transport: "http",
            url: url,
            headers: {
                "x-api-key": process.env.COMPOSIO_API_KEY
            }
        }
    });
    
    const tools = await client.getTools();
  
    const agent = createAgent({ model: "gpt-5", tools });
    
    let conversationHistory: any[] = [];
    
    console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
    console.log("Ask any Enginemailer related question or task to the agent.\n");
    
    const rl = readline.createInterface({
        input: process.stdin,
        output: process.stdout,
        prompt: 'You: '
    });

    rl.prompt();

    rl.on('line', async (userInput: string) => {
        const trimmedInput = userInput.trim();
        
        if (['exit', 'quit', 'bye'].includes(trimmedInput.toLowerCase())) {
            console.log("\nGoodbye!");
            rl.close();
            process.exit(0);
        }
        
        if (!trimmedInput) {
            rl.prompt();
            return;
        }
        
        conversationHistory.push({ role: "user", content: trimmedInput });
        console.log("\nAgent is thinking...\n");
        
        const response = await agent.invoke({ messages: conversationHistory });
        conversationHistory = response.messages;
        
        const finalResponse = response.messages[response.messages.length - 1]?.content;
        console.log(`Agent: ${finalResponse}\n`);
        
        rl.prompt();
    });

    rl.on('close', () => {
        console.log('\nSession ended.');
        process.exit(0);
    });
}

main().catch((err) => {
    console.error('Fatal error:', err);
    process.exit(1);
});

Conclusion

You've successfully built a LangChain agent that can interact with Enginemailer through Composio's Tool Router.

Key features of this implementation:

  • Dynamic tool loading through Composio's Tool Router
  • Conversation history maintenance for context-aware responses
  • Async Python provides clean, efficient execution of agent workflows
You can extend this further by adding error handling, implementing specific business logic, or integrating additional Composio toolkits to create multi-app workflows.
TOOLS

Supported Tools

Every Enginemailer action and event your agent gets out of the box.

Activate Subscriber

Tool to activate an inactive subscriber in EngineMailer.

Add or Update Subscriber

Tool to add or update a subscriber with custom fields via N8N integration.

Check Batch Update Status

Tool to check the status of a batch subscriber update operation.

Batch Update Subscribers

Tool to add or update multiple subscribers with custom fields in a single batch operation.

Check Export Status V2

Tool to check status of a previously requested CSV report export.

Test API Connection

Tool to test API connection and verify authentication.

Create Campaign

Tool to create a new email campaign.

Delete Campaign

Tool to delete an undelivered email campaign.

Delete Recipient List

Tool to delete an existing recipient list from a targeted campaign.

Delete Subscriber

Tool to remove a subscriber from the system by email address.

Export CSV Report V2

Tool to export a transactional email report as CSV.

Find Subscriber

Tool to find a subscriber by email address via N8N integration.

Get Custom Field List

Tool to retrieve the list of custom fields configured for subscribers.

Get List Campaign

Tool to get a list of undelivered campaigns.

Get New Subscribers

Tool to retrieve new subscribers with optional filtering by source, form, page, or popup.

Get Subcategories

Tool to retrieve subcategories for a given category.

Get Subscriber

Tool to retrieve subscriber information by email address.

Get Subscriber Autoresponder Completed

Tool to retrieve subscribers who completed autoresponders with optional filtering by autoresponder ID.

Get Subscriber Autoresponder Triggered

Tool to retrieve subscribers who triggered autoresponders with optional filtering by autoresponder ID.

Get Deleted Subscribers

Tool to retrieve deleted subscribers since last polling date.

Get Subscribers Modified

Tool to retrieve modified subscribers since last polling date with optional limit.

Get Subscribers Tagged

Tool to retrieve subscribers who were tagged with optional filtering by subcategory.

Get Untagged Subscribers

Tool to retrieve subscribers who were untagged from subcategories.

Get Unsubscribe Events

Tool to retrieve unsubscribe events with optional filtering by campaign or autoresponder.

Insert Subscriber

Tool to add a new subscriber with optional custom fields.

List Autoresponders

Tool to retrieve a list of all autoresponders.

List Campaigns

Tool to retrieve a list of all campaigns.

List Forms

Tool to retrieve a list of available forms in Enginemailer.

List Pages

Tool to retrieve a list of all pages.

List Popups

Tool to retrieve a list of popups from Enginemailer.

List Templates

Tool to retrieve a list of all email templates.

Pause Campaign

Tool to pause a scheduled email campaign.

Create/Update Category

Tool to create or update a category for subscriber segmentation.

Update Subscriber

Tool to update data for an existing subscriber in EngineMailer.

Send Campaign

Tool to send an email campaign immediately.

Tag Subscriber to Subcategory

Tool to tag a subscriber to a specific subcategory via N8N API endpoint.

Unsubscribe (N8N)

Tool to unsubscribe a subscriber via N8N API endpoint.

Unsubscribe Subscriber

Tool to unsubscribe a subscriber from the email list.

FRAMEWORKS

How to build Enginemailer MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Enginemailer MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Enginemailer MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Enginemailer MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Enginemailer MCP with Claude Cowork

Codex logo

Codex

Use Enginemailer MCP with Codex

OpenClaw logo

OpenClaw

Use Enginemailer MCP with OpenClaw

Hermes logo

Hermes

Use Enginemailer MCP with Hermes

CLI logo

CLI

Use Enginemailer MCP with CLI

Google ADK logo

Google ADK

Use Enginemailer MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Enginemailer MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Enginemailer MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Enginemailer MCP with LlamaIndex

CrewAI logo

CrewAI

Use Enginemailer MCP with CrewAI

FAQ

Frequently asked questions

With a standalone Enginemailer MCP server, the agents and LLMs can only access a fixed set of Enginemailer tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Enginemailer and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. LangChain fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Enginemailer tools.

Yes, absolutely. You can configure which Enginemailer scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Enginemailer data and credentials are handled as safely as possible.

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A lot of students tell us that the moment their connected tools start talking to each other inside Opennote feels almost magical. The agent just knows them, and it's immensely helped keep new users on the platform.

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Before Composio, adding tool integrations was slow and resource-intensive. Each one could take weeks of engineering time, and maintaining them meant constantly keeping up with API changes.

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