MailboxValidator

MailboxValidator MCP server

This is a simple Model Context Protocol (MCP) server implementation for MailboxValidator API. It will return validation result for an email address.

Features

• Comprehensive Email Validation: Checking an email address to see if an email is reachable by checking the syntax, DNS, MX server, high risk, suppressed list, and more.
• Disposable Email: Checking an email address to see if it's from a temporary/disposable email provider.
• Free Email: Checking an email address to see if it's from a free email provider.

Requirement

This MCP server requires an API key. You can also sign up for a free API key and enjoy up to 300 queries per month.

The local MCP server setup also uses Node.js and npm, which can be downloaded at Node.js website.

Setup

There are two ways to use this MCP server:

• Cloud-hosted MCP server: Connect directly to the hosted MailboxValidator MCP server. Nothing needs to be installed locally.
• Local MCP server: Download and run the server on your own machine.

Option 1: Cloud-hosted MCP server

Use this if you want to connect directly to the hosted server.

Method A: Direct HTTP connection

Use this if your MCP client supports remote servers over HTTP. No Node.js, npm, or npx is needed.

{
  "mcpServers": {
    "mailboxvalidator": {
      "type": "http",
      "url": "https://mcp.mailboxvalidator.com/mcp",
      "headers": {
        "X-API-Key": "<YOUR_API_KEY>"
      }
    }
  }
}

If your client is configured from the command line, such as Claude Code, you can add the server with:

claude mcp add --transport http mailboxvalidator https://mcp.mailboxvalidator.com/mcp --header "X-API-Key: <YOUR_API_KEY>"

Method B: Connection through npx

Use this if your MCP client only supports local (stdio) servers. The mcp-remote package runs locally and forwards requests to the hosted server. Node.js is required.

{
  "mcpServers": {
    "mailboxvalidator": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote@latest",
        "https://mcp.mailboxvalidator.com/mcp",
        "--header",
        "X-API-Key:<YOUR_API_KEY>"
      ]
    }
  }
}

To get your API key, just login to your dashboard and get it from there, then replace <YOUR_API_KEY> in the example above with your actual API key.

Restart the Claude Desktop after saving the changes, and you should see it appear in the Search and tools menu.

Option 2: Local MCP server

Follow the steps to run the MCP server on your own machine:

1. Download the repository to your local.
2. Run the following commands while inside the project folder to install dependencies and build the server.

npm install
npm run build

1. Make sure you have installed Claude Desktop. If you haven't, kindly download from here for Windows and macOS users, or follow this guide for Linux users.
2. Open claude_desktop_config.json. If you don't have that file yet, follow this guide to create one.
3. Add the following to your claude_desktop_config.json:

{
  "mcpServers": {
    "mailboxvalidator": {
      "command": "node",
      "args": [
        "C:\\path\\to\\mcp-mailboxvalidator\\build\\index.js"
      ],
      "env": {
        "MAILBOXVALIDATOR_API_KEY": "<YOUR_API_KEY>"
      }
    }
  }
}

1. Remember to replace the path for the index.js with your actual path to your MailboxValidator MCP server on your local machine.
2. To get your API key, just login to your dashboard and get it from there. Replace the <YOUR_API_KEY> in the above with your actual API key.
3. Restart the Claude Desktop after saving the changes, and you should see it appear in the Search and tools menu.

Usage

Just enter your query about the email address in a chat in Claude Desktop. Some of example queries are:

• Is (email) a valid email address?
• Is (email) a fake email?
• Is (email) a free email?

In Claude Desktop, the model will automatically generate the output based on the result returned by MailboxValidator MCP server.

Environment Variable

MAILBOXVALIDATOR_API_KEY

The free MailboxValidator API key allows you to query up to 300 emails per month. If you require more, you can sign up for a paid API plan.

Tool

validate_email

Description Validates the email address given. It helps users to determine if an email address is potentially reachable by checking the syntax, DNS, MX server, disposable list and more.

Arguments email (str): The email address to validate.

Returns A JSON string containing the validation data. The result includes the following fields:

• Syntax: Checks that the email address conforms to how an email address should look like.
• DNS & MX Server: Checks that the domain DNS has an MX server specified.
• Network & Connectivity: Attempts connection to the MX server to make sure it's operational.
• Greylisting: Checks if MX server is using greylisting that could cause email sent to that address to bounce.
• Disposable List: Checks if the email domain is from a temporary or disposable email provider.
• High Risk & Suppressed List: Checks if email username looks high-risk or if the email address is found in a suppression list.
• Others: Checks the reputation score for the email and more..

If the request fails, the tool will return an error message as a string.

check_disposable_email

Description Checks if the email address given is from a disposable email provider.

Arguments email (str): The email address to check.

Returns A JSON string containing the disposable email data. The result includes the following fields:

• Disposable List: Checks if the email domain is from a temporary or disposable email provider.

If the request fails, the tool will return an error message as a string.

check_free_email

Description Checks if the email address given is from a free email provider.

Arguments email (str): The email address to check.

Returns A JSON string containing the free email data. The result includes the following fields:

• Free Email List: Checks if the email domain is from a free email provider.

If the request fails, the tool will return an error message as a string.

License

See the LICENSE file.