FreeCustom.Email MCP — AI Email + OTP Automation for Agents

FreeCustom.Email MCP Server

The official Model Context Protocol (MCP) server for FreeCustom.Email API.

This server provides the ultimate temp mail API and temp mail automation capabilities specifically designed for AI agents (Claude, Cursor, Windsurf, Kilo Code, etc.). Instead of building complex polling logic to wait for emails and extract OTPs, your AI agents can now create inboxes, wait for emails, and extract verification codes in a single tool call.

The Ultimate Temp Mail for AI Agents

Traditional temporary email API providers (like Mailinator, Maildrop, 1secmail, or Guerrilla Mail) are built for human consumption or basic REST polling. They lack the context and connection needed for advanced AI workflows.

Why FreeCustom.Email is better for AI:

Feature	Traditional Temp Mail APIs	FreeCustom.Email MCP
Agent Interface	Manual HTTP REST requests	Native MCP (Model Context Protocol) Tools
Wait for Email	Constant polling (hits rate limits)	Long-polling & Pub/Sub (Zero extra requests)
Action Economy	3-5 operations to get an OTP	1-shot tool (create_and_wait_for_otp)
Data Parsing	AI must parse messy HTML/Text	Server automatically extracts 4-6 digit OTPs

Whether you are doing temp mail testing, automated QA, or autonomous AI agent signups, this MCP server handles the complexity behind the scenes.

Prerequisites

To use this MCP server, you must have a Growth or Enterprise plan on FreeCustom.Email, as this is a premium AI automation feature.

You will need your API key, which can be found in your FreeCustom.Email dashboard.

Want to use MCP in web-based AI tools? We host a public MCP endpoint at https://mcp.freecustom.email/mcp that works with Claude Web, OpenAI Playground, Replit Agent, and any other cloud AI platform—no local installation required. Just pass your API key via the Authorization: Bearer header or use OAuth.

Installation & Configuration

For Claude Desktop (Local Stdio)

1. Open your Claude Desktop configuration file based on your Operating System:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Add the following to the configuration:

{
  "mcpServers": {
    "fce-mcp": {
      "command": "npx",
      "args": ["-y", "fce-mcp-server"],
      "env": {
        "FCE_API_KEY": "your_api_key_here"
      }
    }
  }
}

For Claude Web Chat (claude.ai)

The Claude web interface requires a Remote MCP Server URL. We provide a hosted MCP endpoint at https://mcp.freecustom.email/mcp that works directly with Claude Web using OAuth.

1. Open Claude Web (or the Claude app on mobile).
2. Go to Settings > Integrations > Add Custom Connector.
3. Fill in the details:
   • Name: FreeCustom.Email MCP
   • Remote MCP Server URL: https://mcp.freecustom.email/mcp
4. Under Advanced settings, add your API key as the OAuth Client ID (or just paste your FreeCustom.Email API key).
5. Click Connect.

For Cursor

1. Open Cursor Settings.
2. Navigate to Features > MCP Servers.
3. Click Add New MCP Server.
4. Set the Type to command.
5. Name it fce-mcp.
6. Command: npx -y fce-mcp-server
7. In your system environment variables, ensure FCE_API_KEY is set.

For Windsurf / Windsurf Editor

{
  "mcpServers": {
    "fce-mcp": {
      "command": "npx",
      "args": ["-y", "fce-mcp-server"],
      "env": {
        "FCE_API_KEY": "your_api_key_here"
      }
    }
  }
}

For Kilo CLI & Kilo Code

{
  "mcp": {
    "fce-mcp": {
      "type": "local",
      "command": ["npx", "-y", "fce-mcp-server"],
      "environment": {
        "FCE_API_KEY": "your_api_key_here"
      },
      "enabled": true
    }
  }
}

For Web-Based AI Platforms

Many AI platforms require an HTTP endpoint. Use our hosted MCP endpoint:

Platform	How to Configure
Claude.ai (Web)	Settings → Integrations → Add Custom Connector → URL: https://mcp.freecustom.email/mcp
OpenAI Playground	Use custom "OpenAI Agents" with our MCP URL
Replit Agent	Add MCP server with URL: https://mcp.freecustom.email/mcp + Bearer token auth
Agentops / LangChain	Configure MCP client with our URL, pass Authorization: Bearer <YOUR_API_KEY>

Available Tools

Once connected, your AI agent will have access to the following tools:

Email Operations

create_and_wait_for_otp (🔥 GOLD FEATURE)

Generates a random inbox and holds the connection open until an OTP arrives.

• domain (optional): Domain to use (defaults to ditube.info)
• timeout (optional): Max wait time in seconds (10-60, defaults to 45)

get_latest_email

Retrieves the most recent email for a given inbox.

• inbox (required): Full email address (e.g. [email protected])

extract_otp

Directly retrieves the latest 4-6 digit code or verification link.

• inbox (required): Full email address of the inbox

watch_email

Long-polling wait for new emails on an existing inbox.

• inbox (required): Full email address of the inbox to watch
• timeout (optional): Max wait time in seconds (10-60, defaults to 30)
• since (optional): Message ID to wait for newer messages after

get_messages

Fetches multiple messages from an inbox.

• inbox (required): Full email address
• limit (optional): Number of messages (1-100, default 10)
• unread_only (optional): Only fetch unread messages

delete_email

Deletes a specific email from an inbox.

• inbox (required): Full email address
• `message_id (required): The message ID to delete

Inbox Management

list_inboxes

Lists all inboxes owned by the API key's account. (no args)

Custom Domain Management

list_custom_domains

Lists all custom domains associated with the account. (no args)

add_custom_domain

Adds a new custom domain to the account.

• domain (required): The custom domain (e.g. mail.yourdomain.com)

verify_custom_domain

Initiates DNS verification for a custom domain.

• domain (required): The custom domain to verify

delete_custom_domain

Deletes a custom domain from the account.

• domain (required): The custom domain to delete

Plan Requirements

MCP access requires a Growth or Enterprise plan:

• Growth: 60 ops/minute, 5 concurrent sessions
• Enterprise: 200 ops/minute, 10 concurrent sessions

Troubleshooting

"I don't have tools available" If your AI agent says it doesn't have tools, the MCP server failed to load.

• Restart the App: Desktop agents only read the config on startup. Quit completely and reopen.
• Check Logs: For Claude on macOS: tail -n 50 ~/Library/Logs/Claude/mcp*.log

"Using Claude Web (claude.ai)" If getting OAuth/token errors:

• Use Remote MCP Server URL: https://mcp.freecustom.email/mcp (not /sse)
• Ensure your API key is valid and you have a Growth/Enterprise plan

"npx: command not found" GUI apps may not inherit your $PATH. Use absolute paths:

{
  "mcpServers": {
    "fce-mcp": {
      "command": "/usr/local/bin/node", 
      "args": ["/absolute/path/to/fce-mcp-server/build/index.js"],
      "env": { "FCE_API_KEY": "your_api_key_here" }
    }
  }
}

License

MIT