Deliverability Doctor

io.github.Integrity-OsPublished by GitHub account Integrity-Osv1.0.2Updated Oct 24, 2026

Check if a domain can be email-spoofed: SPF, DMARC, DKIM, MX graded from public DNS. Authless.

VerifiedStreamable HTTPWeb executableDeveloper ToolsSecurity & Monitoring

Overview

AI-generated overview

A remote MCP server that grades a domain's email-spoofing defenses (SPF, DMARC, DKIM, MX) from public DNS and suggests fixes.

What you can do
Check one domain's email security: SPF, DMARC policy and reporting, MX, and DKIM at common selectors, returning an A–F grade with concrete fixes; accepts a bare domain, URL, or email address and refuses non-existent domains instead of grading them. Compare two to five domains side by side in a table with per-domain grades, for example your domain against competitors.
When to use it
Useful when you want a quick, read-only assessment of whether a domain can be spoofed, or a side-by-side comparison of several domains' email authentication posture before fixing DNS records.
Requirements
A remote streamable HTTP endpoint; no authentication, API key, or environment variables are declared. The server resolves records over DNS-over-HTTPS, so it needs network access to public DNS resolvers.
Before you install
Read-only: it queries public DNS and stores nothing. Reports may include an upsell line linking a paid written audit when problems are found, so treat that as marketing rather than a finding. Results reflect only public DNS at query time and the selectors checked, not full inbox deliverability.

Installation

In SourceWeft

  1. Open Deliverability Doctor in the dashboard and add it to a workspace.
  2. 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/io.github.Integrity-Os%2Fdeliverability-doctor/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": {
    "deliverability-doctor": {
      "type": "http",
      "url": "https://deliverability-doctor.deliverability-doctor.workers.dev/mcp"
    }
  }
}

README

Deliverability Doctor

Remote MCP server: "Can my domain be email-spoofed?" answered from public DNS, graded, with concrete fixes. Connectable to Claude (custom connector) and ChatGPT (Apps SDK / MCP connector) — both speak MCP, one server serves both.

Tools

  • check_email_security(domain) — SPF (incl. RFC 7208 multiple-record permerror and redirect= handling), DMARC (policy, rua, pct), MX, DKIM at 7 common selectors. Graded A–F report, fixes per finding, upsell line only when problems exist. Accepts bare domain, URL, or email address.
  • compare_email_security(domains[2..5]) — comparison table with grades.

Design decisions

  • Authless: reads public DNS only, stores nothing, takes nothing but a domain. Lowest possible connect friction; nothing sensitive to protect.
  • DNS-over-HTTPS (Cloudflare → Google fallback): identical code runs on local Node and on Cloudflare Workers — no dns module dependency.
  • Stateless streamable HTTP: fresh transport per request, no sessions; safe to scale, trivial for clients.
  • NXDOMAIN is refused, not graded — "domain doesn't exist" ≠ "spoofable".
  • Verified against known postures before first run: gmail.com (redirect= must not be flagged), n8n.io (must grade A on p=reject), missing-everything domain (must grade F), NXDOMAIN (must refuse).

Run

bash
npm installnode server.js          # :8787/mcp

Quick public demo: cloudflared tunnel --url http://localhost:8787 → use https://<random>.trycloudflare.com/mcp as the connector URL.

Status 2026-08-23

  • Local: end-to-end MCP verified (initialize / tools/list / tools/call).
  • Public: live via quick tunnel, initialize verified from the public URL.
  • Durable hosting: pending — Cloudflare Workers deploy needs Kacper's account (~5 min). Tunnel URL dies with the process/PC.
  • Directory submissions (Anthropic connector directory, ChatGPT apps): need the durable URL first, then Kacper's developer accounts.

Monetization path

Free tool = distribution. Report links the $99 written audit (niekonieczny.gumroad.com/l/vscjt) only when problems are found. NOTE: Gumroad payouts currently frozen on Stripe KYC — unfreeze before promoting.

Source: README.md at commit f07454d

Tools

2

check_email_security

Check a domain’s email security

Checks whether a domain can be email-spoofed, using public DNS only. Verifies SPF (including the RFC 7208 multiple-record permerror), DMARC policy and reporting, MX, and DKIM at common selectors. Returns a graded report with concrete fixes. Accepts a bare domain, a URL, or an email address. Nothing is sent to the domain.

Parametersdomainrequired

compare_email_security

Compare email security across domains

Runs the email-security check on 2–5 domains and returns a comparison table with per-domain grades. Useful for checking your domain against competitors.

Parametersdomainsrequired

Version history

1
  1. v1.0.2LatestSep 16, 2026

Score

100% 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
  • License10 pts