MailTester Ninja MCP ServerVerifiedFeatured

MailTester Ninja MCP server

Real-time email verification for AI agents, from the team behind the MailTester Ninja API. The agent asks, the server talks to the recipient's mail server over SMTP, stops before any message is sent, and returns a plain verdict. Nothing is stored.

Tools

Tool	What it does
verify_email	Checks one address live. Returns ok (valid), ko (invalid) or mb (uncertain, for example a catch-all domain), plus a message: Accepted, Rejected, Catch-All, No MX, Disposable, Timeout...
find_email	Finds a person's work address from first name, last name and company domain by trying the usual patterns until the mail server accepts one. Stops early on catch-all domains and domains without a mail server. Paid key only.

Connect

• Endpoint: https://mcp.mailtester.ninja/mcp (Streamable HTTP)
• Auth: X-API-Key: YOUR_KEY header (also accepted: Authorization: Bearer YOUR_KEY or ?key=YOUR_KEY)

{
  "mcpServers": {
    "mailtester-ninja": {
      "url": "https://mcp.mailtester.ninja/mcp",
      "headers": { "X-API-Key": "YOUR_KEY" }
    }
  }
}

Claude Code:

claude mcp add --transport http mailtester-ninja https://mcp.mailtester.ninja/mcp --header "X-API-Key: YOUR_KEY"

Keys and pricing

• Free API token: 50 checks a day, one request every 30 seconds, no card: https://mailtester.ninja/free-email-verification-api/
• Paid plans from $6.99 a week for 100,000 checks a day, flat rate, no credits: https://mailtester.ninja/verify-emails-unlimited/

Good to know

• The agent is told to report the verdict it received and to treat mb as uncertain, never as valid.
• Typical uses: cleaning a list before a campaign, checking signups, finding a contact's email before outreach.
• Listed in the official MCP Registry as ninja.mailtester/email-verification.

Setup guide for Claude, Cursor and VS Code: https://mailtester.ninja/integrations/mcp/