How to integrate Mailtrap MCP with Claude Code

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Introduction

Manage your Mailtrap directly from Claude Code with zero worries about OAuth hassles, API-breaking issues, or reliability and security concerns.

You can do this in two different ways:

  1. Via Rube - Direct and easiest approach
  2. Via Composio SDK - Programmatic approach with more control

Why Rube?

Rube is a universal MCP server with access to 850+ SaaS apps. It ensures just-in-time tool loading so Claude can access the tools it needs, a remote workbench for programmatic tool calling and handling large tool responses out of the LLM context window, ensuring the LLM context window remains clean.

Connect Mailtrap to Claude Code with Rube

1. Get the MCP URL

Copy and paste the below command in Claude Code to add Rube MCP.

Terminal

2. Authenticate Rube

Run /mcp to view Rube

bash
/mcp
Run /mcp to view Rube in Claude Code
Click on Rube to authenticate
Authentication flow complete

3. Ensure it's connected

Run /mcp again to verify the connection. Now, do whatever you want with Claude Code and Mailtrap.

Rube connected successfully

Supported Tools & Triggers

Tools
Clean InboxTool to clean an inbox in Mailtrap by deleting all messages.
Create ContactTool to create a new contact in Mailtrap.
Create Contact EventTool to create a contact event in Mailtrap.
Create Contact ExportTool to create a contact export job for a Mailtrap account.
Create Contact FieldTool to create a custom contact field in Mailtrap.
Create Contact ListTool to create a new contact list in Mailtrap.
Create Email TemplateTool to create a new email template in Mailtrap account.
Create Sending DomainTool to create a new sending domain in Mailtrap.
Delete ContactTool to delete a contact from a Mailtrap account.
Delete Contact FieldTool to delete a contact field by its ID.
Delete Contact ListTool to delete a contact list by its ID.
Delete Email TemplateTool to delete an email template from a Mailtrap account.
Delete ProjectTool to delete a project from Mailtrap.
Delete Sending DomainTool to delete a sending domain from a Mailtrap account.
Get Billing UsageTool to retrieve current billing cycle usage for an account.
Get ContactTool to retrieve a contact by UUID or email address from Mailtrap.
Get Contact ExportTool to retrieve the status of a contact export.
Get Contact FieldTool to retrieve contact field details by field ID.
Get Contact Import StatusTool to retrieve the status of a contact import operation.
Get Contact ListTool to retrieve a specific contact list by its ID.
Get Email TemplateTool to retrieve details of a specific email template by ID.
Get Inbox AttributesTool to retrieve inbox attributes from Mailtrap.
Get Message HTML BodyTool to retrieve the HTML body of a message from Mailtrap.
Get Permission ResourcesTool to retrieve all resources in account for permission management.
Get Project by IDTool to retrieve project details from Mailtrap by project ID.
Get Sending DomainTool to retrieve sending domain details from Mailtrap.
Get Sending StatsTool to retrieve email sending statistics from Mailtrap for a specific account.
Get Sending Stats by CategoriesTool to retrieve email sending statistics grouped by categories.
Get Sending Stats by DateTool to retrieve email sending statistics aggregated by date.
Get Sending Stats by DomainsTool to retrieve sending statistics grouped by domains for a Mailtrap account.
Get Sending Stats by ESPTool to retrieve email sending statistics grouped by email service providers (ESPs) for a specified date range.
Import ContactsTool to import contacts in bulk to Mailtrap.
List AccountsTool to list all Mailtrap accounts you have access to.
List Contact FieldsTool to get all contact fields for a Mailtrap account.
List Contact ListsTool to retrieve all contact lists for a Mailtrap account.
List Email TemplatesTool to retrieve all email templates for a Mailtrap account.
List InboxesTool to get a list of inboxes for a Mailtrap account.
List Messages in InboxTool to get messages from a Mailtrap inbox.
List ProjectsTool to get a list of projects for a Mailtrap account.
List Sending DomainsTool to list all sending domains for a Mailtrap account.
List Email SuppressionsTool to list suppressed email addresses for a Mailtrap account.
Mark Inbox as ReadTool to mark all messages in a Mailtrap inbox as read.
Reset Inbox CredentialsTool to reset SMTP credentials for a Mailtrap inbox.
Update contactTool to update an existing contact in Mailtrap.
Update Contact FieldTool to update a contact field in Mailtrap.
Update Contact ListTool to update a contact list's name in Mailtrap.
Update Email TemplateTool to update an existing email template in Mailtrap account.
Update inboxTool to update an inbox's settings in Mailtrap.
Update projectTool to update a project's name in Mailtrap.

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

The Mailtrap MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mailtrap account. It provides structured and secure access so your agent can perform Mailtrap operations on your behalf.

Connecting Mailtrap via Tool Router

Tool Router is the underlying tech that powers Rube. It's a universal gateway that does everything Rube does but with much more programmatic control. You can programmatically generate an MCP URL with the app you need (here Mailtrap) for even more tool search precision. It's secure and reliable.

How the Tool Router works

The Tool Router 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

Prerequisites

Before starting, make sure you have:
  • Claude Pro, Max, or API billing enabled Anthropic account
  • Composio API Key
  • A Mailtrap account
  • Basic knowledge of Python or TypeScript

Install Claude Code

bash
# macOS, Linux, WSL
curl -fsSL https://claude.ai/install.sh | bash

# Windows PowerShell
irm https://claude.ai/install.ps1 | iex

# Windows CMD
curl -fsSL https://claude.ai/install.cmd -o install.cmd && install.cmd && del install.cmd

To install Claude Code, use one of the following methods based on your operating system:

Set up Claude Code

bash
cd your-project-folder
claude

Open a terminal, go to your project folder, and start Claude Code:

  • Claude Code will open in your terminal
  • Follow the prompts to sign in with your Anthropic account
  • Complete the authentication flow
  • Once authenticated, you can start using Claude Code
Claude Code initial setup showing sign-in prompt
Claude Code terminal after successful login

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here

Create a .env file in your project root with the following variables:

  • COMPOSIO_API_KEY authenticates with Composio (get it from Composio dashboard)
  • USER_ID identifies the user for session management (use any unique identifier)

Install Composio library

pip install composio-core python-dotenv

Install the Composio Python library to create MCP sessions.

  • composio-core provides the core Composio functionality
  • python-dotenv loads environment variables from your .env file

Generate Composio MCP URL

import os
from composio import Composio
from dotenv import load_dotenv

load_dotenv()

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

composio_client = Composio(api_key=COMPOSIO_API_KEY)

composio_session = composio_client.create(
    user_id=USER_ID,
    toolkits=["mailtrap"],
)

COMPOSIO_MCP_URL = composio_session.mcp.url

print(f"MCP URL: {COMPOSIO_MCP_URL}")
print(f"\nUse this command to add to Claude Code:")
print(f'claude mcp add --transport http mailtrap-composio "{COMPOSIO_MCP_URL}" --headers "X-API-Key:{COMPOSIO_API_KEY}"')

Create a script to generate a Composio MCP URL for Mailtrap. This URL will be used to connect Claude Code to Mailtrap.

What's happening:
  • We import the Composio client and load environment variables
  • Create a Composio instance with your API key
  • Call create() to create a Tool Router session for Mailtrap
  • The returned mcp.url is the MCP server URL that Claude Code will use
  • The script prints this URL so you can copy it

Run the script and copy the MCP URL

python generate_mcp_url.py

Run your Python script to generate the MCP URL.

  • The script connects to Composio and creates a Tool Router session
  • It prints the MCP URL and the exact command you need to run
  • Copy the entire claude mcp add command from the output

Add Mailtrap MCP to Claude Code

bash
claude mcp add --transport http mailtrap-composio "YOUR_MCP_URL_HERE" --headers "X-API-Key:YOUR_COMPOSIO_API_KEY"

# Then restart Claude Code
exit
claude

In your terminal, add the MCP server using the command from the previous step. The command format is:

  • claude mcp add registers a new MCP server with Claude Code
  • --transport http specifies that this is an HTTP-based MCP server
  • The server name (mailtrap-composio) is how you'll reference it
  • The URL points to your Composio Tool Router session
  • --headers includes your Composio API key for authentication

After running the command, close the current Claude Code session and start a new one for the changes to take effect.

Verify the installation

bash
claude mcp list

Check that your Mailtrap MCP server is properly configured.

  • This command lists all MCP servers registered with Claude Code
  • You should see your mailtrap-composio entry in the list
  • This confirms that Claude Code can now access Mailtrap tools

If everything is wired up, you should see your mailtrap-composio entry listed:

Claude Code MCP list showing the toolkit MCP server

Authenticate Mailtrap

The first time you try to use Mailtrap tools, you'll be prompted to authenticate.

  • Claude Code will detect that you need to authenticate with Mailtrap
  • It will show you an authentication link
  • Open the link in your browser (or copy/paste it)
  • Complete the Mailtrap authorization flow
  • Return to the terminal and start using Mailtrap through Claude Code

Once authenticated, you can ask Claude Code to perform Mailtrap operations in natural language. For example:

  • "Send a test email to marketing team"
  • "List all emails sent from Mailtrap today"
  • "Create a new inbox for transactional testing"

Complete Code

Here's the complete code to get you started with Mailtrap and Claude Code:

import os
from composio import Composio
from dotenv import load_dotenv

load_dotenv()

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

composio_client = Composio(api_key=COMPOSIO_API_KEY)

composio_session = composio_client.create(
    user_id=USER_ID,
    toolkits=["mailtrap"],
)

COMPOSIO_MCP_URL = composio_session.mcp.url

print(f"MCP URL: {COMPOSIO_MCP_URL}")
print(f"\nUse this command to add to Claude Code:")
print(f'claude mcp add --transport http mailtrap-composio "{COMPOSIO_MCP_URL}" --headers "X-API-Key:{COMPOSIO_API_KEY}"')

Conclusion

You've successfully integrated Mailtrap with Claude Code using Composio's MCP server. Now you can interact with Mailtrap directly from your terminal using natural language commands.

Key features of this setup:

  • Terminal-native experience without switching contexts
  • Natural language commands for Mailtrap operations
  • Secure authentication through Composio's managed MCP
  • Tool Router for dynamic tool discovery and execution

Next steps:

  • Try asking Claude Code to perform various Mailtrap operations
  • Add more toolkits to your Tool Router session for multi-app workflows
  • Integrate this setup into your development workflow for increased productivity

You can extend this by adding more toolkits, implementing custom workflows, or building automation scripts that leverage Claude Code's capabilities.

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FAQ

What are the differences in Tool Router MCP and Mailtrap MCP?

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

Can I use Tool Router MCP with Claude Code?

Yes, you can. Claude Code 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 Mailtrap tools.

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

Yes, absolutely. You can configure which Mailtrap 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.

How safe is my data with Composio Tool Router?

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 Mailtrap data and credentials are handled as safely as possible.

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