How to integrate Smtp2go MCP with Claude Code

Manage your Smtp2go 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: Via Composio Connect - Direct and easiest approach Via Composio SDK - Programmatic approach with more control

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Api Key

Smtp2go is a dependable email delivery service that ensures your messages are sent and received reliably. It's designed to give your business fast, secure, and hassle-free transactional email delivery.

32 Tools

Introduction

Manage your Smtp2go 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 Composio Connect - Direct and easiest approach
  2. Via Composio SDK - Programmatic approach with more control

Also integrate Smtp2go with

Why use Composio?

  • Only one MCP URL to connect multiple apps with Claude Code with zero auth hassles.
  • Programmatic tool calling allows LLMs to write its code in a remote workbench to handle complex tool chaining. Reduces to-and-fro with LLMs for frequent tool calling.
  • Handling Large tool responses out of LLM context to minimize context rot.
  • Dynamic just-in-time access to 20,000 tools across 1000+ other Apps for cross-app workflows. It loads the tools you need, so LLMs aren't overwhelmed by tools you don't need.

Connecting Smtp2go to Claude Code using Composio

1. Add the Composio MCP to Claude

Terminal

2. Start Claude Code

bash
claude

3. Open your MCP list

bash
/mcp

4. Select Composio and click on Authenticate

Select Composio and click Authenticate

5. This will redirect you to the Composio OAuth page. Complete the flow by authorizing Composio and you're all set.

Composio OAuth authorization page
Composio authorization complete
Ask Claude to connect to your account and authenticate via the link

What is the Smtp2go MCP server, and what's possible with it?

The Smtp2go MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Smtp2go account. It provides structured and secure access to your email sending and management infrastructure, so your agent can perform actions like searching email activity, managing allowed senders, updating sender domains, and controlling IP allow lists on your behalf.

  • Comprehensive email activity search: Ask your agent to filter and retrieve email events such as sends, opens, clicks, and bounces by recipient, date, or message ID.
  • Allowed sender management: Have your agent add, update, remove, or view allowed sender email addresses to control who can send emails from your account.
  • Sender domain configuration: Let the agent register new sender domains for SPF/DKIM verification and manage domain-related settings seamlessly.
  • IP allow list control: Direct your agent to add or remove IP addresses or CIDR ranges in your account’s IP allow list, enhancing security for sending sources.
  • Email delivery monitoring: Enable your agent to search and analyze sent emails, helping you monitor delivery, troubleshoot issues, and ensure reliable communication.

Connecting Smtp2go via Composio SDK

Composio SDK 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 Smtp2go) for even more tool search precision. It's secure and reliable.

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, make sure you have:
  • Claude Pro, Max, or API billing enabled Anthropic account
  • Composio API Key
  • A Smtp2go account
  • Basic knowledge of Python or TypeScript
2

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:

3

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
4

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)
5

Install Composio library

npm install @composio/core dotenv

Install the Composio TypeScript library to create MCP sessions.

  • @composio/core provides the core Composio functionality
  • dotenv loads environment variables from your .env file
6

Generate Composio MCP URL

import 'dotenv/config';
import { Composio } from '@composio/core';

const { COMPOSIO_API_KEY, USER_ID } = process.env;

if (!COMPOSIO_API_KEY || !USER_ID) {
  throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
}

const composioClient = new Composio({ apiKey: COMPOSIO_API_KEY });

const composioSession = await composioClient.create(USER_ID, {
  toolkits: ['smtp2go'],
});

const composioMcpUrl = composioSession?.mcp.url;

console.log(`MCP URL: ${composioMcpUrl}`);
console.log(`\nUse this command to add to Claude Code:`);
console.log(`claude mcp add --transport http smtp2go-composio "${composioMcpUrl}" --headers "X-API-Key:${COMPOSIO_API_KEY}"`);

Create a script to generate a Composio MCP URL for Smtp2go. This URL will be used to connect Claude Code to Smtp2go.

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 Smtp2go
  • The returned mcp.url is the MCP server URL that Claude Code will use
  • The script prints this URL so you can copy it
7

Run the script and copy the MCP URL

node --loader ts-node/esm generate_mcp_url.ts
# or if using tsx
tsx generate_mcp_url.ts

Run your TypeScript 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
8

Add Smtp2go MCP to Claude Code

bash
claude mcp add --transport http smtp2go-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 (smtp2go-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.

9

Verify the installation

bash
claude mcp list

Check that your Smtp2go MCP server is properly configured.

  • This command lists all MCP servers registered with Claude Code
  • You should see your smtp2go-composio entry in the list
  • This confirms that Claude Code can now access Smtp2go tools

If everything is wired up, you should see your smtp2go-composio entry listed:

Claude Code MCP list showing the toolkit MCP server
10

Authenticate Smtp2go

The first time you try to use Smtp2go tools, you'll be prompted to authenticate.

  • Claude Code will detect that you need to authenticate with Smtp2go
  • It will show you an authentication link
  • Open the link in your browser (or copy/paste it)
  • Complete the Smtp2go authorization flow
  • Return to the terminal and start using Smtp2go through Claude Code

Once authenticated, you can ask Claude Code to perform Smtp2go operations in natural language. For example:

  • "Search for bounced emails this week"
  • "Add marketing@mydomain.com as allowed sender"
  • "List all verified sender domains"

Complete Code

Here's the complete code to get you started with Smtp2go and Claude Code:

import 'dotenv/config';
import { Composio } from '@composio/core';

const { COMPOSIO_API_KEY, USER_ID } = process.env;

if (!COMPOSIO_API_KEY || !USER_ID) {
  throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
}

const composioClient = new Composio({ apiKey: COMPOSIO_API_KEY });

const composioSession = await composioClient.create(USER_ID, {
  toolkits: ['smtp2go'],
});

const composioMcpUrl = composioSession?.mcp.url;

console.log(`MCP URL: ${composioMcpUrl}`);
console.log(`\nUse this command to add to Claude Code:`);
console.log(`claude mcp add --transport http smtp2go-composio "${composioMcpUrl}" --headers "X-API-Key:${COMPOSIO_API_KEY}"`);

Conclusion

You've successfully integrated Smtp2go with Claude Code using Composio's MCP server. Now you can interact with Smtp2go directly from your terminal using natural language commands.

Key features of this setup:

  • Terminal-native experience without switching contexts
  • Natural language commands for Smtp2go 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 Smtp2go 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.

TOOLS

Supported Tools

Every Smtp2go action and event your agent gets out of the box.

Search Email Activity

Tool to search activity events like sends, opens, clicks, and bounces.

Add Allowed Sender

Tool to add a new allowed sender email address.

Remove Allowed Sender

Tool to remove a sender email address from the allowed senders list.

Update Allowed Senders

Tool to update (replace) the entire allowed senders list in your SMTP2GO account.

View Allowed Senders

Tool to view the list of allowed senders configured in your account.

Add Sender Domain

Tool to add a new sender domain for SPF/DKIM verification.

Search SMTP2GO Emails

Tool to search sent emails.

Add IP Allow List

Tool to add a public IP address to your account's IP allow list.

Remove IP from Allow List

Tool to remove an IP address from your account's IP allow list.

View IP Allow List

Tool to view the list of IP addresses in your IP allow list.

View Received SMS

Tool to retrieve received SMS replies for your SMTP2GO account.

Get Email Bounces Stats

Tool to retrieve email bounces statistics.

Email Cycle Statistics

Tool to retrieve current email cycle/quota statistics.

Email History Statistics

Tool to retrieve email history statistics.

Email Spam Statistics

Tool to retrieve email spam report statistics.

Email Unsubscription Stats

Tool to retrieve email unsubscribe statistics.

Search Subaccounts

Tool to search subaccounts.

Subaccounts Usage

Tool to retrieve usage statistics for subaccounts.

Add to Suppression List

Tool to add email addresses or domains to the suppression list.

Remove suppression entry

Tool to remove an email address or domain from the suppression list.

View Suppression List

Tool to view the suppression list.

Edit Email Template

Tool to edit details of an existing email template.

Search Email Templates

Tool to search your collection of email templates by ID or name.

View Email Template

Tool to view details of a specific email template.

Add SMTP User

Tool to add a new SMTP user.

Edit SMTP User

Tool to edit details of an existing SMTP user.

Remove SMTP User

Tool to remove an SMTP user from your account.

View SMTP Users

Tool to list all SMTP users configured on your account.

Add Webhook

Tool to create a new webhook.

Edit Webhook

Tool to edit an existing webhook’s settings.

Remove webhook

Tool to remove a webhook.

View Webhooks

Tool to view all webhooks configured in your account.

FAQ

Frequently asked questions

With a standalone Smtp2go MCP server, the agents and LLMs can only access a fixed set of Smtp2go tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Smtp2go and many other apps based on the task at hand, all through a single MCP endpoint.

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 Smtp2go tools.

Yes, absolutely. You can configure which Smtp2go 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 Smtp2go data and credentials are handled as safely as possible.

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