MailTester Ninja
ninja.mailtester/email-verificationmailtester.ninjastreamable-httpv1.0.1Scanned
Verify email addresses live against their mail server and find work emails. Nothing stored.
2 tools: 1 change things and 1 only read.
- Reads private data · 1
- Reads text others write · 2
- Can send data out · 0
- No findings
Anlyon alternative
1 of these tools change something. Run those as governed actions.
Declare what an action changes, and Anlyon puts it under a shared limit, binds every approval to the exact request, and grades the outcome. It works on any HTTPS API you can describe as an action.
Anlyon does not run, proxy or govern this MCP server. A tool your own code calls directly is not routed through Anlyon and is not governed by it.
Import an OpenAPI spec →Tools
Grouped by what each tool does, most consequential first. Open one for its reasons and full description; descriptions are the publisher's own words.
2 tools
Changes things 1Claude Code: ask
verify_emailCheck in real time whether an email address exists and can receive mail, by asking the recipient's mail server (no message is sent).Reads text others writeNo findings
Why it is in this group
- 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.
What it can reach
- untrusted-inputThe server marks it openWorldHint: true: it reaches things outside the server's own data.
Description, as the server wrote it 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.
Annotations the server declares
- title: Verify an email address
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: true
Only reads 1Show 1 read-only tool
find_emailFind the work email address of a person from their name and their company domain.Reads private dataReads text others writeNo findings
Why it is in this group
- The name "find_email" says "find": a word for reading.
What it can reach
- private-dataThe name "find_email" says "find" and "email": it reads mail.
- private-dataThe description's first sentence says "find" and "email": it reads mail.
- untrusted-inputThe server marks it openWorldHint: true: it reaches things outside the server's own data.
- untrusted-inputThe name "find_email" says "find" and "email": it reads inbound email, which other people can write.
- untrusted-inputThe description's first sentence says "find" and "email": it reads inbound email, which other people can write.
Description, as the server wrote it 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.
Annotations the server declares
- title: Find a professional email address
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: true
This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.
Exfil surface
Which tools read private data, which read text someone else can write, and which can send data out. One of each is a path a prompt injection can use.
No private-data, untrusted-input, outbound path in this server alone: no tool is tagged outbound.
- Reads private data1
- Reads files, mail, messages, databases, secrets, calendars or repositories.
- Reads text others write2
- Brings in text someone else can write: web pages, inbound email, messages, issues and comments.
- Can send data out0
- Can carry data to people or systems: it sends, posts or publishes, or takes a recipient, channel or URL.
Other servers in the same agent add their own tools to these paths. Audit your whole setup to see them together.
Findings
Matches of fixed checks, with the text they matched.
No check matched anything in these tool definitions. That is not a safety guarantee.
History
Changes to its tool definitions and to its remote endpoint, newest first.
No change seen yet. Its tools are rescanned every day, and a remote endpoint is looked at once a week.
Install
Pinned to version 1.0.1. Values in angle brackets are yours to fill in.
claude mcp add --transport http email-verification https://mcp.mailtester.ninja/mcp --header 'X-API-Key: <your-x-api-key>'claude mcp add --transport http email-verification https://mcp.mailtester.ninja/mcp --header 'X-API-Key: <your-x-api-key>'Run in a terminal.
Claude Code permissions
Allow the reads, ask before a change or a way out, deny the deletes. Paste into .claude/settings.json.
{
"permissions": {
"allow": [
"mcp__email-verification__find_email"
],
"ask": [
"mcp__email-verification__verify_email"
],
"deny": []
}
}Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. A read that can send data out (it takes a URL, say) asks first too. It assumes the server is installed as email-verification. Review it before you use it.
Capability tags behind 2 rules
- mcp__email-verification__verify_email untrusted-input
- mcp__email-verification__find_email private-data, untrusted-input
Pin
Keep the decision: fail CI when the tools change, follow every change, or show a badge.
Pin in CI
Fail a build when the tools you reviewed are not the tools the server serves today.
curl -s "https://anlyon.dev/api/v1/servers/ninja.mailtester/email-verification/verify?hash=a70c2ad6a488a2e37209ffb6bf504000c7914cfaaec88c1620604e5e1e68aad0" | jq -e '.changed == false'Pinned hash a70c2ad6a488, from Oct 28, 2026, 20:19 UTC.
Watch
Get told when its tools change: a new tool, a new description, a new class.
https://anlyon.dev/servers/ninja.mailtester/email-verification/changes.xmlAn Atom feed. Works in any feed reader or Slack's RSS app.
Badge
[](https://anlyon.dev/servers/ninja.mailtester/email-verification)Source: MCP Registry. Synced Oct 28, 2026, 20:18 UTC.