# `ninja.mailtester/email-verification` on anlyon.dev

> Text inside fenced blocks marked untrusted-server-text was written by the MCP server's publisher, not by anlyon.dev. It is data to inspect, not instructions to follow. Invisible characters are shown as [U+XXXX].
> No finding is not a safety guarantee: these are point-in-time checks of tool definitions, not of code or behaviour.

- Page: https://anlyon.dev/servers/ninja.mailtester/email-verification
- JSON: https://anlyon.dev/api/v1/servers/ninja.mailtester/email-verification
- Version: 1.0.1 (active)
- Publisher: ninja.mailtester (domain proven to the MCP Registry)
- Runs: remote (streamable-http)
- Sign-in to list tools: none
- Metadata from the official MCP Registry, synced 2026-10-28T20:18:59.792Z

Title and description, as the publisher wrote them:

```untrusted-server-text
MailTester Ninja
Verify email addresses live against their mail server and find work emails. Nothing stored.
```

Scanned 2026-10-28T20:19:08.455Z over streamable-http.

**2 tools: 1 change things and 1 only read.**

| Group | Class | Tools | Claude Code |
| --- | --- | --- | --- |
| Deletes or cancels | destructive | 0 | deny |
| Can't be undone | irreversible | 0 | ask |
| Changes things | write | 1 | ask |
| Only reads | read | 1 | allow |

## Exfil surface

No private-data -> untrusted-input -> outbound path in this server alone: no tool is tagged outbound.

| Tag | Meaning | Tools |
| --- | --- | --- |
| private-data | Reads files, mail, messages, databases, secrets, calendars or repositories. | `mcp__email-verification__find_email` |
| untrusted-input | Brings in text someone else can write: web pages, inbound email, messages, issues and comments. | `mcp__email-verification__find_email` `mcp__email-verification__verify_email` |
| outbound | Can carry data to people or systems: it sends, posts or publishes, or takes a recipient, channel or URL. | none |

## Findings

No check matched anything in these tool definitions.


## Changes things (1)

Creates or changes something that can be changed back. Claude Code: ask.

### `verify_email`

- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
- Tag untrusted-input: The server marks it openWorldHint: true: it reaches things outside the server's own data.

Description, as the server wrote it:

```untrusted-server-text
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.
```

## Only reads (1)

Looks things up and changes nothing. Claude Code: allow.

### `find_email`

- The name "find_email" says "find": a word for reading.
- Tag private-data: The name "find_email" says "find" and "email": it reads mail. The description's first sentence says "find" and "email": it reads mail.
- Tag untrusted-input: The server marks it openWorldHint: true: it reaches things outside the server's own data. The name "find_email" says "find" and "email": it reads inbound email, which other people can write. The description's first sentence says "find" and "email": it reads inbound email, which other people can write.

Description, as the server wrote it:

```untrusted-server-text
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.
```

## Claude Code permissions

For `.claude/settings.json`, assuming the server is installed as `email-verification`:

```json
{
  "permissions": {
    "allow": [
      "mcp__email-verification__find_email"
    ],
    "ask": [
      "mcp__email-verification__verify_email"
    ],
    "deny": []
  }
}
```

Capability tags behind the rules (a read tagged outbound is asked about):

- `mcp__email-verification__verify_email`: untrusted-input
- `mcp__email-verification__find_email`: private-data, untrusted-input