MailTester Ninja

ninja.mailtesterPublished by mailtester.ninjaOfficial publisherv1.0.1Updated Oct 30, 2026

Verify email addresses live against their mail server and find work emails. Nothing stored.

VerifiedStreamable HTTPWeb executableCommunication & CollaborationBusiness & Commerce

Overview

AI-generated overview

Remote MCP server that verifies email addresses live against their mail server and finds a person's work email from name and company domain.

What you can do
  • Verify a single address in real time against the recipient's mail server, with no message sent, and get a verdict of ok, ko or mb plus a reason such as Accepted, Rejected, Catch-All, No MX or Disposable.
  • Guess a person's work email from their name and company domain by trying common address patterns and returning the first one the mail server accepts.
When to use it
Useful when cleaning contact lists, checking whether an address will bounce before sending, or trying to find a colleague's or prospect's work email from a name and company domain.
Requirements
A remote endpoint reached over streamable HTTP; no local runtime or package. Requires a MailTester Ninja API key sent in the X-API-Key header; a free token allows 50 checks a day, and a paid key is needed for find_email.
Before you install
The API key is a secret passed in the X-API-Key header. Every check, including each pattern tried by find_email, counts against the daily quota, so lookups can consume paid credits. Addresses and names are sent to a third-party service, and find_email requires a paid key.

Installation

In SourceWeft

  1. Open MailTester Ninja in the dashboard and add it to a workspace.
  2. Connect X-API-Key credentials. They are stored privately and never shown on public pages.
  3. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/ninja.mailtester%2Femail-verification/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

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

Tools

2

verify_email

Verify an email address

Check in real time whether an email address exists and can receive mail, by asking the recipient's mail server (no message is sent). Returns code "ok" (valid), "ko" (invalid) or "mb" (uncertain, such as a catch-all domain) with a message.

Parametersemailrequired

find_email

Find a professional email address

Find the work email address of a person from their name and their company domain. Tries the usual patterns (first.last, flast, first...) one by one and returns the first address the mail server accepts. Each pattern tried counts as one verification. Requires a paid MailTester Ninja key.

Parametersdomainrequiredlast_namerequiredfirst_namerequiredmiddle_name

Version history

1
  1. v1.0.1LatestOct 30, 2026

Score

83% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts

    Declare a GitHub repository with a README, or serve resource_documentation in the OAuth protected-resource metadata.

  • LicenseNot applicable

    A hosted service is used under its provider's terms, so no license is expected here. This check is left out of the percentage.