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How to integrate Postmark MCP with CrewAI

Connect CrewAI to Postmark MCP. Send a password reset email to user, get delivery status for last 10 emails, and more using natural language, with authentication handled for you.

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Postmark is an email delivery service for sending transactional emails with reliable deliverability. It delivers detailed analytics and fast, secure email delivery for developers.

46 Tools

Introduction

This guide walks you through connecting Postmark to CrewAI using the Composio tool router. By the end, you'll have a working Postmark agent that can send templated emails in batches, search inbound and outbound messages, track opens and clicks, manage suppressions, and check spam scores through natural language commands.

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

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

Also integrate Postmark with

Claude CodeClaude CoworkOpenAI Agents SDKClaude Agent SDKGrok BotCodexOpenClawHermesAtomic AgentGoogle ADKLangChainVercel AI SDKMastra AILlamaIndexPydantic AIAutoGen

TL;DR

Here's what you'll learn:
  • Get a Composio API key and configure your Postmark connection
  • Set up CrewAI with an MCP enabled agent
  • Create a Tool Router session or standalone MCP server for Postmark
  • Build a conversational loop where your agent can execute Postmark 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 Postmark MCP server, and what's possible with it?

The Postmark MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Postmark account. It provides structured and secure access to transactional email sending and analytics, so your agent can perform actions like delivering transactional emails, monitoring delivery status, managing templates, and analyzing engagement metrics on your behalf.

  • Automated transactional email delivery: Let your agent send password resets, confirmations, and notification emails with high deliverability and reliability.
  • Template management and customization: Enable your agent to create, update, or select dynamic email templates for consistent, branded communications.
  • Email delivery status monitoring: Ask your agent to track sent messages, check delivery receipts, and identify bounced or failed emails in real time.
  • Engagement and analytics tracking: Have your agent retrieve open and click data, analyze engagement trends, and provide actionable insights from your email campaigns.
  • Suppression list and recipient management: Direct your agent to manage suppression lists, process unsubscribes, and maintain healthy recipient lists automatically.

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 step08 STEPS
1

Prerequisites

Before starting, make sure you have:
  • Python 3.9 or higher
  • A Composio account and API key
  • A Postmark connection authorized in Composio
  • An OpenAI API key for the CrewAI LLM
  • Basic familiarity with Python
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

bash
pip install composio crewai crewai-tools[mcp] python-dotenv
What's happening:
  • composio connects your agent to Postmark via MCP
  • crewai provides Agent, Task, Crew, and LLM primitives
  • crewai-tools[mcp] includes MCP helpers
  • python-dotenv loads environment variables from .env
4

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
5

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 Postmark MCP URL
6

Create a Composio Tool Router session for Postmark

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

url = session.mcp.url
What's happening:
  • You create a Postmark only session through Composio
  • Composio returns an MCP HTTP URL that exposes Postmark tools
7

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.
8

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 Postmark 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=["postmark"],
)
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 Postmark through Composio's Tool Router. The agent can perform Postmark 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 Postmark action and event your agent gets out of the box.

Archive Message Stream

Tool to archive a message stream (soft delete).

Check Spam Score

Assess the spam score of a raw email via the SpamCheck API.

Create Inbound Rule

Tool to create a new inbound rule trigger to block email from a specific sender or domain.

Create Message Stream

Tool to create a new message stream.

Create Suppressions

Tool to add email addresses to the suppression list for a message stream.

Create Template

Tool to create a new email template.

Create Webhook

Tool to create a new webhook configuration for Postmark.

Delete Inbound Rule

Tool to delete a specific inbound rule trigger.

Delete Suppressions

Tool to remove email addresses from the suppression list for a message stream.

Delete Template

Tool to delete a template by its ID or alias.

Delete Webhook

Tool to delete a specific webhook.

Edit Server

Update settings for the current Postmark server.

Edit Template

Tool to update an existing Postmark template by its ID.

Edit Webhook

Update an existing webhook by ID, supplying its URL and triggers.

Get Bounce Counts

Tool to get total counts of emails that have been returned as bounced.

Get Bounces

Tool to retrieve a list of bounces for a server with optional filters.

Get Browser Platform Usage

Retrieve browser platform usage statistics for clicked links, including desktop, mobile, and unknown platform counts.

Get Browser Usage

Retrieve browser usage statistics for clicked links to analyze browsers and platforms used.

Get Click Counts

Tool to retrieve total click counts across all links in emails.

Get Clicks By Browser Family

Tool to retrieve click statistics grouped by browser family.

Get Clicks by Location

Tool to get an overview of which part of the email links were clicked from (HTML or Text).

Get Delivery Stats

Retrieve delivery statistics consisting of inactive recipient counts and bounce counts by type, including spam complaints.

Get Email Client Usage

Retrieve statistics on email clients used to open outbound emails.

Get Email Open Counts

Tool to retrieve counts of opened emails.

Get Message Stream

Tool to retrieve details of a specific message stream by its ID.

Get Opens by Platform

Tool to retrieve email open statistics by platform type.

Get Outbound Overview

Tool to retrieve outbound email statistics overview.

Get Sent Counts

Tool to retrieve total count of emails sent out.

Get Server

Tool to retrieve details of the current Postmark server.

Get Spam Complaints

Tool to retrieve counts of spam complaints.

Get Template

Tool to retrieve details of a specific template by its ID.

Get Tracked Email Counts

Tool to retrieve counts of emails with tracking enabled.

Get Webhook

Tool to retrieve details of a specific webhook by its ID.

List Inbound Rules

Tool to list all inbound rules (triggers) configured for blocking senders.

List Message Streams

Tool to list all message streams for a Postmark server with optional type and archive filtering.

List Outbound Message Clicks

Tool to list clicks for outbound messages with filtering options.

List Outbound Message Opens

Tool to retrieve opens for outbound messages with filtering options.

List Suppressions

Tool to retrieve the suppression list for a message stream with optional filtering.

List Templates

List templates for a Postmark server, with pagination and optional type and active-status filters.

List Webhooks

List current webhook configurations for the Postmark server associated with the authenticated server token.

Search Inbound Messages

Tool to search inbound messages received with optional filtering.

Search Outbound Messages

Tool to search outbound messages with filtering by recipient, tag, status, and date range.

Send Batch Templated Emails

Send up to 500 templated emails in a single batch API call.

Unarchive Message Stream

Tool to unarchive a previously archived message stream.

Update Message Stream

Tool to update a message stream configuration in Postmark.

Validate Template

Tool to validate a Postmark template.

FRAMEWORKS

How to build Postmark MCP Agent with another framework

Claude Code logo

Claude Code

Use Postmark MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Postmark MCP with Claude Cowork

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Postmark MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Postmark MCP with Claude Agent SDK

Grok Bot logo

Grok Bot

Use Postmark MCP with Grok Bot

Codex logo

Codex

Use Postmark MCP with Codex

OpenClaw logo

OpenClaw

Use Postmark MCP with OpenClaw

Hermes logo

Hermes

Use Postmark MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Postmark MCP with Atomic Agent

Google ADK logo

Google ADK

Use Postmark MCP with Google ADK

LangChain logo

LangChain

Use Postmark MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Postmark MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Postmark MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Postmark MCP with LlamaIndex

Pydantic AI logo

Pydantic AI

Use Postmark MCP with Pydantic AI

AutoGen logo

AutoGen

Use Postmark MCP with AutoGen

FAQ

Frequently asked questions

With a standalone Postmark MCP server, the agents and LLMs can only access a fixed set of Postmark tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Postmark 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 Postmark tools.

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

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