How to integrate Bigmailer MCP with CrewAI

This guide walks you through connecting Bigmailer to CrewAI using the Composio tool router. By the end, you'll have a working Bigmailer agent that can create a new welcome campaign for brand x, list all brands i manage in bigmailer, get your bigmailer account user details through natural language commands. This guide will help you understand how to give your CrewAI agent real control over a Bigmailer account through Composio's Bigmailer MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Bigmailer

Api Key

BigMailer is an email marketing platform for managing multiple brands with white-labeling and automation. It helps teams streamline campaigns and simplify integration with Amazon SES.

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Introduction

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

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

Also integrate Bigmailer with

OpenAI Agents SDK Claude Agent SDK Claude Code Claude Cowork Codex OpenClaw Hermes CLI Google ADK LangChain Vercel AI SDK Mastra AI LlamaIndex

TL;DR

Here's what you'll learn:

Get a Composio API key and configure your Bigmailer connection
Set up CrewAI with an MCP enabled agent
Create a Tool Router session or standalone MCP server for Bigmailer
Build a conversational loop where your agent can execute Bigmailer operations

What is CrewAI?

CrewAI is a powerful framework for building multi-agent AI systems. It provides primitives for defining agents with specific roles, creating tasks, and orchestrating workflows through crews.

Key features include:

Agent Roles: Define specialized agents with specific goals and backstories
Task Management: Create tasks with clear descriptions and expected outputs
Crew Orchestration: Combine agents and tasks into collaborative workflows
MCP Integration: Connect to external tools through Model Context Protocol

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

The Bigmailer MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Bigmailer account. It provides structured and secure access to your email marketing platform, so your agent can perform actions like creating transactional campaigns, retrieving your brands, and managing user account details on your behalf.

Automated transactional campaign creation: Have your agent quickly set up new transactional email campaigns for any of your brands, with full control over content, sender details, and subject lines.
Brand management and discovery: Let your agent list and organize all brands associated with your Bigmailer account, providing a clear overview for multi-brand operations.
User account information retrieval: Easily check your authenticated user details to verify API connectivity and view essential account information in real time.
Multi-brand marketing workflow automation: Empower your agent to streamline campaign launches and brand management across multiple business entities from one place.

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:

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

Step-by-step Guide

Step by step08 STEPS

Prerequisites

Before starting, make sure you have:

Python 3.9 or higher
A Composio account and API key
A Bigmailer connection authorized in Composio
An OpenAI API key for the CrewAI LLM
Basic familiarity with Python

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.

Install dependencies

bash

pip install composio crewai crewai-tools[mcp] python-dotenv

What's happening:

composio connects your agent to Bigmailer via MCP
crewai provides Agent, Task, Crew, and LLM primitives
crewai-tools[mcp] includes MCP helpers
python-dotenv loads environment variables from .env

Set up environment variables

bash

COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_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 with Composio
USER_ID scopes the session to your account
OPENAI_API_KEY lets CrewAI use your chosen OpenAI model

Import dependencies

python

import os
from composio import Composio
from crewai import Agent, Task, Crew
from crewai_tools import MCPServerAdapter
import dotenv

dotenv.load_dotenv()

COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set")

What's happening:

CrewAI classes define agents and tasks, and run the workflow
MCPServerHTTP connects the agent to an MCP endpoint
Composio will give you a short lived Bigmailer MCP URL

Create a Composio Tool Router session for Bigmailer

python

composio_client = Composio(api_key=COMPOSIO_API_KEY)
session = composio_client.create(user_id=COMPOSIO_USER_ID, toolkits=["bigmailer"])

url = session.mcp.url

What's happening:

You create a Bigmailer only session through Composio
Composio returns an MCP HTTP URL that exposes Bigmailer tools

Initialize the MCP Server

python

server_params = {
    "url": url,
    "transport": "streamable-http",
    "headers": {"x-api-key": COMPOSIO_API_KEY},
}

with MCPServerAdapter(server_params) as tools:
    agent = Agent(
        role="Search Assistant",
        goal="Help users search the internet effectively",
        backstory="You are a helpful assistant with access to search tools.",
        tools=tools,
        verbose=False,
        max_iter=10,
    )

What's Happening:

Server Configuration: The code sets up connection parameters including the MCP server URL, streamable HTTP transport, and Composio API key authentication.
MCP Adapter Bridge: MCPServerAdapter acts as a context manager that converts Composio MCP tools into a CrewAI-compatible format.
Agent Setup: Creates a CrewAI Agent with a defined role (Search Assistant), goal (help with internet searches), and access to the MCP tools.
Configuration Options: The agent includes settings like verbose=False for clean output and max_iter=10 to prevent infinite loops.
Dynamic Tool Usage: Once created, the agent automatically accesses all Composio Search tools and decides when to use them based on user queries.

Create a CLI Chatloop and define the Crew

python

print("Chat started! Type 'exit' or 'quit' to end.\n")

conversation_context = ""

while True:
    user_input = input("You: ").strip()

    if user_input.lower() in ["exit", "quit", "bye"]:
        print("\nGoodbye!")
        break

    if not user_input:
        continue

    conversation_context += f"\nUser: {user_input}\n"
    print("\nAgent is thinking...\n")

    task = Task(
        description=(
            f"Conversation history:\n{conversation_context}\n\n"
            f"Current request: {user_input}"
        ),
        expected_output="A helpful response addressing the user's request",
        agent=agent,
    )

    crew = Crew(agents=[agent], tasks=[task], verbose=False)
    result = crew.kickoff()
    response = str(result)

    conversation_context += f"Agent: {response}\n"
    print(f"Agent: {response}\n")

What's Happening:

Interactive CLI Setup: The code creates an infinite loop that continuously prompts for user input and maintains the entire conversation history in a string variable.
Input Validation: Empty inputs are ignored to prevent processing blank messages and keep the conversation clean.
Context Building: Each user message is appended to the conversation context, which preserves the full dialogue history for better agent responses.
Dynamic Task Creation: For every user input, a new Task is created that includes both the full conversation history and the current request as context.
Crew Execution: A Crew is instantiated with the agent and task, then kicked off to process the request and generate a response.
Response Management: The agent's response is converted to a string, added to the conversation context, and displayed to the user, maintaining conversational continuity.

Complete Code

Here's the complete code to get you started with Bigmailer and CrewAI:

python

from crewai import Agent, Task, Crew, LLM
from crewai_tools import MCPServerAdapter
from composio import Composio
from dotenv import load_dotenv
import os

load_dotenv()

GOOGLE_API_KEY = os.getenv("GOOGLE_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not GOOGLE_API_KEY:
    raise ValueError("GOOGLE_API_KEY is not set in the environment.")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set in the environment.")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set in the environment.")

# Initialize Composio and create a session
composio = Composio(api_key=COMPOSIO_API_KEY)
session = composio.create(
    user_id=COMPOSIO_USER_ID,
    toolkits=["bigmailer"],
)
url = session.mcp.url

# Configure LLM
llm = LLM(
    model="gpt-5",
    api_key=os.getenv("OPENAI_API_KEY"),
)

server_params = {
    "url": url,
    "transport": "streamable-http",
    "headers": {"x-api-key": COMPOSIO_API_KEY},
}

with MCPServerAdapter(server_params) as tools:
    agent = Agent(
        role="Search Assistant",
        goal="Help users with internet searches",
        backstory="You are an expert assistant with access to Composio Search tools.",
        tools=tools,
        llm=llm,
        verbose=False,
        max_iter=10,
    )

    print("Chat started! Type 'exit' or 'quit' to end.\n")

    conversation_context = ""

    while True:
        user_input = input("You: ").strip()

        if user_input.lower() in ["exit", "quit", "bye"]:
            print("\nGoodbye!")
            break

        if not user_input:
            continue

        conversation_context += f"\nUser: {user_input}\n"
        print("\nAgent is thinking...\n")

        task = Task(
            description=(
                f"Conversation history:\n{conversation_context}\n\n"
                f"Current request: {user_input}"
            ),
            expected_output="A helpful response addressing the user's request",
            agent=agent,
        )

        crew = Crew(agents=[agent], tasks=[task], verbose=False)
        result = crew.kickoff()
        response = str(result)

        conversation_context += f"Agent: {response}\n"
        print(f"Agent: {response}\n")

Conclusion

You now have a CrewAI agent connected to Bigmailer through Composio's Tool Router. The agent can perform Bigmailer operations through natural language commands.

Next steps:

Add role-specific instructions to customize agent behavior
Plug in more toolkits for multi-app workflows
Chain tasks for complex multi-step operations

TOOLS

Supported Tools

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

Create Brand

Tool to create a new brand in BigMailer.

Create Brand Property

Tool to create a brand property in BigMailer.

Create Bulk Campaign

Tool to create a bulk email campaign in BigMailer.

Create Contact

Tool to create a new contact in BigMailer within a specified brand.

Create Contact Batch

Tool to create a batch of contacts in BigMailer for a specific brand.

Create Field

Tool to create a custom field in a BigMailer brand.

Create List

Creates a new contact list within a specified brand in BigMailer.

Create Segment

Tool to create a segment in BigMailer for a specific brand.

Create Suppression List

Tool to upload a suppression list for a brand in BigMailer.

Create Template

Tool to create a new email or page template in BigMailer.

Create Transactional Campaign

Creates a new transactional campaign within a specified brand in BigMailer.

Create User

Tool to create a new user in BigMailer.

Delete Brand Property

Tool to delete a brand property from a brand in BigMailer.

Delete Contact

Tool to delete a contact from a brand in BigMailer.

Delete Custom Field

Deletes a custom field from a specified brand in BigMailer.

Delete List

Tool to delete a list from BigMailer.

Delete Segment

Tool to delete a segment from a brand in BigMailer.

Delete Template

Tool to delete a template from BigMailer.

Delete User

Tool to delete a user from BigMailer.

Get Brand

Tool to retrieve detailed information about a specific brand by its ID.

Get Brand Property

Tool to retrieve a specific brand property by its ID for a given brand.

Get Bulk Campaign

Tool to retrieve detailed information about a specific bulk campaign in BigMailer.

Get Contact

Tool to retrieve detailed information about a specific contact from BigMailer.

Get Contact Batch Status

Tool to retrieve the status and results of a contact batch upload in BigMailer.

Get Custom Field

Tool to retrieve a custom field from a BigMailer brand.

Get List

Tool to retrieve details of a specific list within a brand.

Get Segment

Tool to retrieve a specific segment from BigMailer by brand ID and segment ID.

Get Suppression List

Tool to retrieve details of a specific suppression list for a brand in BigMailer.

Get Template

Tool to retrieve detailed information about a specific template by its ID.

Get Transactional Campaign

Tool to retrieve detailed information about a specific transactional campaign in BigMailer.

Get User

Tool to retrieve detailed information about a specific user by their ID.

Get User Information

This tool retrieves information about the authenticated user in BigMailer using the GET /me endpoint.

List All Brands

This tool retrieves a list of all brands associated with the authenticated BigMailer account.

List Brand Properties

Tool to retrieve a list of brand properties for a specific brand in BigMailer.

List Bulk Campaigns

Tool to list bulk campaigns for a specified brand in BigMailer.

List Connections

Tool to list all connections in your BigMailer account.

List Contacts

Tool to list contacts for a brand in BigMailer.

List Fields

Tool to list custom fields for a brand in BigMailer.

List Contact Lists

Tool to retrieve all contact lists for a specified brand in BigMailer.

List Message Types

Tool to list message types for a specific brand in BigMailer.

List Segments

Tool to list segments for a brand in BigMailer.

List Senders

Tool to list all senders configured for a specific brand in BigMailer.

List Suppression Lists

Tool to list suppression lists for a specific brand.

List Templates

Tool to list templates for a brand in BigMailer.

List Transactional Campaigns

Tool to list transactional campaigns for a specified brand in BigMailer.

List Users

Tool to list all users in your BigMailer account.

Update Brand

Tool to update a brand in BigMailer.

Update Brand Property

Tool to update a brand property in BigMailer.

Update Bulk Campaign

Tool to update an existing bulk campaign in BigMailer.

Update Contact

Tool to update an existing contact in BigMailer.

Update Field

Tool to update a custom field in BigMailer.

Update List

Tool to update a list in BigMailer.

Update Segment

Tool to update an existing segment in BigMailer.

Update Template

Tool to update an existing email or page template in BigMailer.

Update Transactional Campaign

Tool to update a transactional campaign in BigMailer.

Update User

Tool to update a user in BigMailer.

Upsert Contact

Tool to create or update a contact in a BigMailer brand.

FRAMEWORKS

How to build Bigmailer MCP Agent with another framework

OpenAI Agents SDK

Use Bigmailer MCP with OpenAI Agents SDK

Claude Agent SDK

Use Bigmailer MCP with Claude Agent SDK

Claude Code

Use Bigmailer MCP with Claude Code

Claude Cowork

Use Bigmailer MCP with Claude Cowork

Codex

Use Bigmailer MCP with Codex

OpenClaw

Use Bigmailer MCP with OpenClaw

Hermes

Use Bigmailer MCP with Hermes

CLI

Use Bigmailer MCP with CLI

Google ADK

Use Bigmailer MCP with Google ADK

LangChain

Use Bigmailer MCP with LangChain

Vercel AI SDK

Use Bigmailer MCP with Vercel AI SDK

Mastra AI

Use Bigmailer MCP with Mastra AI

LlamaIndex

Use Bigmailer MCP with LlamaIndex

MORE TOOLKITS

Explore Other Toolkits

Toolkit marketplace

Oauth2

Reddit is a social news platform with thriving user-driven communities (subreddits). It's the go-to place for discussion, content sharing, and viral marketing.

Facebook

Oauth2

Facebook is a social media and advertising platform for businesses and creators. It helps you connect, share, and manage content across your public Facebook Pages.

Oauth2

LinkedIn is a professional networking platform for connecting, sharing content, and engaging with business opportunities. It's the go-to place for building your professional brand and unlocking new career connections.

Active campaign

Api Key

ActiveCampaign is a marketing automation and CRM platform for managing email campaigns, sales pipelines, and customer segmentation. It helps businesses engage customers and drive growth through smart automation and targeted outreach.

FAQ

Frequently asked questions

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

Yes, you can. CrewAI 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 Bigmailer tools.

Yes, absolutely. You can configure which Bigmailer 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 Bigmailer data and credentials are handled as safely as possible.

Start with Bigmailer.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Bigmailer tool your agent needs.Free to start.

Start building

Customer stories

Teams ship real agents on Composio

GET STARTED FOR FREE BOOK A DEMO

Karan skipped his own birthday party to fix our critical issue. It was 10pm and he diverted his Waymo to help us instead. This really sets the bar — it shows the commitment you need when users rely on your software.

Harsha Gaddipati

Co-founder, Slashy

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.

Abhi Arya

Co-founder, Opennote

We chose Composio over Pipedream because it delivered depth where it mattered — niche tools and tricky edge cases other platforms simply ignored. That gave us confidence to scale without compromising.

Nirman Dave

CEO, Zams

As a solo builder, shipping fast is life or death. The only way I can outcompete incumbents is by outmanoeuvring them. Getting bogged down managing agent auth would have been a death sentence.

Ryan Yu

Founder, Extra Thursday

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.

Tomisin Jenrola

Founder & CEO, SwarmZero

With hands-on help from their founder, we integrated Gmail and Google Drive in just 30 minutes. This level of personal support and commitment is exactly what startups should strive for.

Jerome Leclanche

Co-Founder, Ingram Technologies

How to integrate Bigmailer MCP with CrewAI

Connect Bigmailer without auth hassles

Introduction

Also integrate Bigmailer with

TL;DR

What is CrewAI?

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

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

What is Composio SDK?

How the Composio SDK works

Step-by-step Guide

Prerequisites

Getting API Keys for OpenAI and Composio

Install dependencies

Set up environment variables

Import dependencies

Create a Composio Tool Router session for Bigmailer

Initialize the MCP Server

Create a CLI Chatloop and define the Crew

Complete Code

Conclusion

Supported Tools

How to build Bigmailer MCP Agent with another framework

OpenAI Agents SDK

Claude Agent SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

Google ADK

LangChain

Vercel AI SDK

Mastra AI

LlamaIndex

Explore Other Toolkits

Reddit

Facebook

Linkedin

Active campaign

Frequently asked questions

What are the differences in Tool Router MCP and Bigmailer MCP?+

Can I use Tool Router MCP with CrewAI?+

Can I manage the permissions and scopes for Bigmailer while using Tool Router?+

How safe is my data with Composio Tool Router?+

Start with Bigmailer.It takes 30 seconds.

Teams ship real agents on Composio