This is a simple MCP server that sends emails using Resend's API. Why? Now you can let Cursor or Claude Desktop compose emails for you and send it right away without having to copy and paste the email content.

As an example, you could use this to run local scripts, chat with Claude, or process data and send the results to yourself or your team.

Built with:

• Resend
• Anthropic MCP
• Cursor

• Send plain text and HTML emails
• Schedule emails for future delivery
• Add CC and BCC recipients
• Configure reply-to addresses
• Customizable sender email (requires verification)
• List Resend audiences

Currently, you must build the project locally to use this MCP server. Then add the server in Cursor or Claude Desktop to use it in any Cursor or Claude Desktop chat.

1. Clone this project locally.

git clone https://github.com/resend/mcp-send-email.git

2. Build the project

npm install
npm run build

3. Setup Resend

Create a free Resend account and Create an API Key. To send to other addresses, you'll also need to verify your own domain.

1. Open Cursor Settings.

Open the command palette (cmd+shift+p on macOS or ctrl+shift+p on Windows) and choose "Cursor Settings".

2. Add the MCP server

Select "MCP" from the left sidebar and click "Add new global MCP server".

Add the following config:

{
  "mcpServers": {
    "resend": {
      "type": "command",
      "command": "node ABSOLUTE_PATH_TO_MCP_SEND_EMAIL_PROJECT/build/index.js --key=YOUR_RESEND_API_KEY"
    }
  }
}

You can get the absolute path to your build script by right-clicking on the /build/index.js file in Cursor and selecting Copy Path.

Possible arguments

• --key: Your Resend API key (required)
• --sender: Your sender email address from a verified domain (optional)
• --reply-to: Your reply-to email address (optional)
• --transport: Transport type - stdio (default) or http
• --port: HTTP server port when using --transport=http (default: 3000)
• --host: Bind address when using --transport=http (default: localhost)
• --cors-origin: Allowed origin for CORS when using --transport=http (optional)

3. Test the sending

Now you can test out sending emails by going to email.md.

• Replace the to: email address with your own
• Select all text in email.md, and press cmd+l
• Tell cursor to "send this as an email" in the chat (make sure cursor is in Agent mode by selecting "Agent" on lower left side dropdown).

1. Open Claude's Developer config file

Open Claude Desktop settings and navigate to the "Developer" tab. Click Edit Config.

2. Add the MCP server

Add the following config:

{
  "mcpServers": {
    "resend": {
      "command": "node",
      "args": [
        "ABSOLUTE_PATH_TO_MCP_SEND_EMAIL_PROJECT/build/index.js"
      ],
      "env": {
        "RESEND_API_KEY": "YOUR_RESEND_API_KEY",
      }
    }
  }
}

You can get the absolute path to your build script by right-clicking on the /build/index.js file in your IDE and selecting Copy Path.

Possible environment variables

• RESEND_API_KEY: Your Resend API key (required)
• SENDER_EMAIL_ADDRESS: Your sender email address from a verified domain (optional)
• REPLY_TO_EMAIL_ADDRESS: Your reply-to email address (optional)

3. Test the sending

Close and reopen Claude Desktop. Verify that the resend tool is available in the Claude developer settings.

Chat with Claude and tell it to send you an email using the resend tool.

The MCP Send Email server now supports HTTP transport with Server-Sent Events (SSE) for web-based integration and multiple concurrent clients.

1. Build the project (same as above)

npm install
npm run build

2. Start the server with HTTP transport

node build/index.js --transport=http --key=YOUR_RESEND_API_KEY

HTTP-specific arguments:

• --transport=http: Enable HTTP transport instead of stdio
• --port=3000: HTTP server port (default: 3000)
• --host=localhost: Bind address (default: localhost)
• --cors-origin=https://your-domain.com: Allowed origin for CORS (optional)

Complete example:

node build/index.js \
  --transport=http \
  --port=3000 \
  --host=localhost \
  --key=YOUR_RESEND_API_KEY \
  [email protected] \
  --cors-origin=https://your-web-app.com

When running with HTTP transport, the server exposes:

• GET /sse: Establishes Server-Sent Events connection for receiving messages
• POST /message: Sends JSON-RPC messages to the server

Web clients can connect to the MCP server using the streaming HTTP transport:

// Establish SSE connection
const eventSource = new EventSource('http://localhost:3000/sse');
let sessionId = null;

eventSource.onopen = () => {
  console.log('Connected to MCP server');
};

eventSource.onmessage = (event) => {
  const message = JSON.parse(event.data);

  // Extract session ID from first message
  if (!sessionId && event.lastEventId) {
    sessionId = event.lastEventId;
  }

  // Handle MCP responses
  console.log('Received:', message);
};

// Send JSON-RPC message
async function sendMessage(jsonRpcMessage) {
  const response = await fetch('http://localhost:3000/message', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Mcp-Session-Id': sessionId
    },
    body: JSON.stringify(jsonRpcMessage)
  });

  return response.json();
}

• Origin Validation: Prevents DNS rebinding attacks by validating the Origin header
• CORS Configuration: Configurable allowed origins for web client integration
• Localhost Binding: Binds to localhost by default for enhanced security
• Session Management: Each SSE connection gets a unique session ID

• Multiple Clients: Support concurrent connections from multiple clients
• Web Integration: Enable direct integration with web applications
• Session Management: Better state management for long-running operations
• Scalability: HTTP transport scales better than stdio for multiple users