MCP Server | Reloop Docs

What is an MCP Server?

The Model Context Protocol (MCP) is an open standard that lets AI models connect to external tools and data sources. An MCP server acts as a bridge between your AI agent and the Reloop API, allowing the agent to send emails, manage contacts, handle domains, and more — all through natural language.

What can Reloop's MCP Server do?

The Reloop MCP Server exposes the full Reloop API as MCP tools:

Emails — Send, list, get, cancel, update, and batch send emails. Supports HTML, plain text, attachments (local file, URL, or base64), CC/BCC, reply-to, scheduling, tags, and topic-based sending.
Received Emails — List and read inbound emails. List and download received email attachments.
Contacts — Create, list, get, update, and remove contacts. Manage segment memberships and topic subscriptions. Supports custom contact properties.
Broadcasts — Create, send, list, get, update, and remove broadcast campaigns. Supports scheduling, personalization placeholders, and preview text.
Domains — Create, list, get, update, remove, and verify sender domains. Configure tracking, TLS, and sending/receiving capabilities.
Segments — Create, list, get, and remove audience segments.
Topics — Create, list, get, update, and remove subscription topics.
Contact Properties — Create, list, get, update, and remove custom contact attributes.
API Keys — Create, list, and remove API keys.
Webhooks — Create, list, get, update, and remove webhooks for event notifications.
Templates — Create, list, get, update, and remove email templates.

Prerequisites

You'll need a supported MCP client and npx installed on your machine.

How to use the MCP Server

Replace rl_xxxxxxxxx with your actual Reloop API key.

Stdio Transport (Default)

claude mcp add reloop -e RELOOP_API_KEY=rl_xxxxxxxxx -- npx -y reloop-mcp

codex mcp add reloop \
  --env RELOOP_API_KEY=rl_xxxxxxxxx \
  -- npx -y reloop-mcp

{
  "mcpServers": {
    "reloop": {
      "command": "npx",
      "args": ["-y", "reloop-mcp"],
      "env": {
        "RELOOP_API_KEY": "rl_xxxxxxxxx"
      }
    }
  }
}

{
  "mcpServers": {
    "reloop": {
      "command": "npx",
      "args": ["-y", "reloop-mcp"],
      "env": {
        "RELOOP_API_KEY": "rl_xxxxxxxxx"
      }
    }
  }
}

Add the following to your VS Code settings.json:

{
  "mcp": {
    "servers": {
      "reloop": {
        "command": "npx",
        "args": ["-y", "reloop-mcp"],
        "env": {
          "RELOOP_API_KEY": "rl_xxxxxxxxx"
        }
      }
    }
  }
}

{
  "mcpServers": {
    "reloop": {
      "command": "npx",
      "args": ["-y", "reloop-mcp"],
      "env": {
        "RELOOP_API_KEY": "rl_xxxxxxxxx"
      }
    }
  }
}

Add to your opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "reloop": {
      "type": "local",
      "command": ["npx", "-y", "reloop-mcp"],
      "enabled": true,
      "environment": {
        "RELOOP_API_KEY": "rl_xxxxxxxxx"
      }
    }
  }
}

{
  "mcpServers": {
    "reloop": {
      "command": "npx",
      "args": ["-y", "reloop-mcp"],
      "env": {
        "RELOOP_API_KEY": "rl_xxxxxxxxx"
      }
    }
  }
}

HTTP Transport

For HTTP transport, the API key is passed via the Authorization header instead of an environment variable.

Start the server:

npx -y reloop-mcp --http --port 3000

The server will be available at http://127.0.0.1:3000 with the MCP endpoint at /mcp.

Claude Code
Cursor

claude mcp add reloop --transport http http://127.0.0.1:3000/mcp --header "Authorization: Bearer rl_xxxxxxxxx"

{
  "mcpServers": {
    "reloop": {
      "url": "http://127.0.0.1:3000/mcp",
      "headers": {
        "Authorization": "Bearer rl_xxxxxxxxx"
      }
    }
  }
}

You can customize the port with the MCP_PORT environment variable:

MCP_PORT=3000 npx -y reloop-mcp --http

Options

CLI flags:

--key: Your Reloop API key (stdio mode only; HTTP mode uses the Bearer token from the client)
--sender: Default sender email address from a verified domain
--reply-to: Default reply-to email address (can be specified multiple times)
--http: Use HTTP transport instead of stdio (default: stdio)
--port: HTTP port when using --http (default: 3000, or MCP_PORT env var)

Environment variables:

RELOOP_API_KEY: Your Reloop API key (required for stdio, optional for HTTP)
SENDER_EMAIL_ADDRESS: Default sender email address from a verified domain (optional)
REPLY_TO_EMAIL_ADDRESSES: Comma-separated reply-to email addresses (optional)
MCP_PORT: HTTP port when using --http (optional)

Local Development

git clone https://github.com/reloop-labs/reloop-mcp.git
pnpm install
pnpm run build

Replace npx commands above with direct node commands.

Stdio

Claude Code
Codex
Cursor / Claude Desktop / Gemini CLI

claude mcp add reloop -e RELOOP_API_KEY=rl_xxxxxxxxx -- node ABSOLUTE_PATH_TO_PROJECT/dist/index.js

codex mcp add reloop \
  --env RELOOP_API_KEY=rl_xxxxxxxxx \
  -- node ABSOLUTE_PATH_TO_PROJECT/dist/index.js

{
  "mcpServers": {
    "reloop": {
      "command": "node",
      "args": ["ABSOLUTE_PATH_TO_PROJECT/dist/index.js"],
      "env": {
        "RELOOP_API_KEY": "rl_xxxxxxxxx"
      }
    }
  }
}

HTTP

node ABSOLUTE_PATH_TO_PROJECT/dist/index.js --http --port 3000

Claude Code
Cursor

claude mcp add reloop --transport http http://127.0.0.1:3000/mcp --header "Authorization: Bearer rl_xxxxxxxxx"

{
  "mcpServers": {
    "reloop": {
      "url": "http://127.0.0.1:3000/mcp",
      "headers": {
        "Authorization": "Bearer rl_xxxxxxxxx"
      }
    }
  }
}

Testing with MCP Inspector

Follow the Local Development steps above first.

Using Stdio Transport

Set your API key:
```
export RELOOP_API_KEY=rl_your_key_here
```
Start the inspector:
```
pnpm inspector
```
Configure in the browser:
- Choose stdio (launch a process)
- Command: node
- Args: dist/index.js (or the full path to dist/index.js)
- Env: RELOOP_API_KEY=rl_your_key_here
- Click Connect, then use "List tools" to verify the server is working

Using HTTP Transport

Start the HTTP server:
```
node dist/index.js --http --port 3000
```
Start the inspector:
```
pnpm inspector
```
Configure in the browser:
- Choose Streamable HTTP (connect to URL)
- URL: http://127.0.0.1:3000/mcp
- Add a custom header: Authorization: Bearer rl_your_key_here and activate the toggle
- Click Connect, then use "List tools" to verify the server is working