Postbox Tools MCP Server

by postboxservices Your server? Claim it

answering

Postbox Tools is answering right now. Last checked 3 min ago. It exposes 8 tools.

Free email checks: 24 blacklists, spoofing/BEC grade, redirect tracing, email spam test, WHOIS.

Uptime history 21 days of history · worst day 99%

21 days agonow

100.0%

Uptime 24h

92 of 92 checks

Tools

read from the server

468 ms

Response time

average over 24h

open, no key

Access

streamable-http

What changed 11

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 27 September 2026. No other catalogue keeps this.

28 Sep 7 tool descriptions were rewritten8 times that day analyze_eml, check_blacklist, check_spoofability and 4 more

27 Sep a tool description was rewritten2 times that day check_blacklist

27 Sep a tool changed the parameters it asks for check_blacklist

and 2 more, back to 27 September 2026

Nothing serious here today

Today is the operative word: we check Postbox Tools every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 3 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add postbox-tools --transport http https://mcp.postboxservices.com/mcp

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "postbox-tools": {
      "url": "https://mcp.postboxservices.com/mcp"
    }
  }
}

~/.codex/config.toml

[mcp_servers.postbox-tools]
url = "https://mcp.postboxservices.com/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "postbox-tools": {
      "url": "https://mcp.postboxservices.com/mcp"
    }
  }
}

.vscode/mcp.json

{
  "mcpServers": {
    "postbox-tools": {
      "url": "https://mcp.postboxservices.com/mcp"
    }
  }
}

Available tools 8

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

mailtest

create_mailtest

Create a disposable test address for a full email deliverability audit (score /10: SPF, DKIM, DMARC + alignment, blacklists, reverse DNS, SpamAssassin content, Gmail/Yahoo bulk-sender compliance). The USER must then send an email from the system they want to test to the returned address, after which get_mailtest_result returns the score.

get_mailtest_result

Fetch the score and breakdown of a mail test created with create_mailtest, once the user has sent their email to the disposable address.

analyze

analyze_eml

Run a deliverability/content analysis on a raw RFC 822 email (.eml source: full headers + body). IMPORTANT LIMITS: with no live SMTP session, SPF, blacklist and reverse-DNS cannot be verified from a file - for the authoritative score use create_mailtest instead.

blacklist

check_blacklist

Check a domain against domain blacklists (Spamhaus DBL, SURBL, URIBL and others), or an IP address against 24 IP blacklists including Spamhaus ZEN, Barracuda and SpamCop. Checks the exact target given: domains are not resolved to IPs. Returns per-list listing status.

domain

get_domain_age

Get a domain's registration date and age (young domains have weak sending reputation).

spoofability

check_spoofability

Grade how exposed a domain is to email spoofing and business email compromise, from its public DNS (SPF, DMARC policy strength, alignment, live lookalike domains). Returns an A-F grade with findings.

trace

trace_redirect

Follow a URL server-side through every HTTP redirect hop to its real final destination - per-hop status, IP, TLS and timing, plus phishing/deliverability flags (cross-domain jumps, https downgrades, meta/JS redirects). Fetching is SSRF-hardened (private ranges blocked, HTTPS-only, per-hop validation); how it works: https://redirect.postboxservices.com/

whois

whois_lookup

WHOIS summary for a domain: registrar, created/updated/expires dates, nameservers, DNSSEC, status flags.

Endpoints

URL	Transport	State	Latency	Checked
https://mcp.postboxservices.com/mcp	streamable-http	answering	474 ms	3 min ago

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Postbox Tools — questions

Answers built from our own checks of this server.

What can Postbox Tools do?

It exposes 8 tools, read directly from the server on our last check. Among them: analyze_eml, check_blacklist, check_spoofability, create_mailtest, get_domain_age, get_mailtest_result and 2 more. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is Postbox Tools working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 92 of 92 checks got a reply (100.0%), average response time 468 ms. The bar chart above shows every period we have measured.

How do I connect Postbox Tools?

Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does Postbox Tools need an API key?

No. Postbox Tools completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 8 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is Postbox Tools?

It answers our handshake in 468 ms on average, which is faster than 25% of all working MCP servers we measure. That is on the slow side — worth knowing if the tool sits inside an interactive loop. The comparison comes from our own checks across the whole registry, every 15 minutes.