MailProbe MCP server

mailprobe-mcp

Official Model Context Protocol server of the MailProbe API. Your AI assistant checks whether email addresses exist and can receive mail, in real time and without sending anything: one address, or a list before a campaign. Verification runs on OVHcloud servers in France, and the API stores no address.

Installation · Tools · How it behaves · Development

There are two ways to reach it, with the same two tools:

• the remote server that MailProbe runs at https://mailprobe.dev/mcp, for a client that connects to a remote server and can send a header: nothing to install;
• the local server of this package, npx -y mailprobe-mcp, for a client that starts its servers on your computer.

This repository also holds the Claude Code plugin and the skill that tells an assistant how to read a result and how to go through a list.

Installation

1. Create an account on mailprobe.dev. It comes with 100 free credits; see pricing for more.
2. Create an API key, which starts with mplive, under Developer in your account. MailProbe shows it only once, at creation.
3. Add one of the two servers to your MCP client.

Remote server

The key goes in the Authorization header. In Claude Code:

claude mcp add --transport http mailprobe https://mailprobe.dev/mcp --header "Authorization: Bearer mp_live_..."

In Cursor, in .cursor/mcp.json:

{
  "mcpServers": {
    "mailprobe": {
      "url": "https://mailprobe.dev/mcp",
      "headers": { "Authorization": "Bearer mp_live_..." }
    }
  }
}

Any other client that connects to a remote MCP server and can send a header works the same way.

Local server

The key goes in the MAILPROBEAPIKEY environment variable, and the server needs Node.js 22 or later. In Claude Desktop and the other clients configured with a JSON file:

{
  "mcpServers": {
    "mailprobe": {
      "command": "npx",
      "args": ["-y", "mailprobe-mcp"],
      "env": { "MAILPROBE_API_KEY": "mp_live_..." }
    }
  }
}

The Claude and ChatGPT apps connect to a remote server only through an OAuth sign-in, which MailProbe does not offer yet. Claude Desktop takes the local server above; elsewhere, MailProbe is available through Zapier MCP.

Claude Code plugin

The plugin connects Claude Code to the remote server and adds a skill that tells the assistant how to read a result, what a call costs, and how to go through a list.

/plugin marketplace add jamalofski/mailprobe-mcp
/plugin install mailprobe@mailprobe

Claude Code asks for the API key when the plugin is enabled, and keeps it in the credential store of the system, not in a settings file. To set it later, run /plugin configure mailprobe@mailprobe, or open /plugin, Installed tab, mailprobe, Configure options. A remote server you added by hand at the same address takes precedence over the one of the plugin.

For another agent that loads SKILL.md skills, add one of the two servers above and take the skill alone: plugin/skills/mailprobe/SKILL.md in this repository, also listed on Agensi.

Then ask for what you need: "does jane@example.com exist?", "check the addresses of contacts.csv before I send the newsletter", "which of these sign-ups are disposable?".

Tools

Shortened. The full README is on GitHub.