Stamp MCP

Use when the user asks why their email goes to spam, whether their domain is set up to send email, or before they launch a newsletter, cold outreach, transactional email or a new sending service, e.g. "why are my emails going to spam?", "is my SPF/DKIM/DMARC right?", "do I meet Gmail and Yahoo's sender requirements?" or "I added SendGrid, did I break SPF?". Reads public DNS (DNS-over-HTTPS) and checks: SPF (exactly one record, every include followed and DNS lookups counted per RFC 7208 against the limit of 10, void lookups, loops, +all/?all, ptr), DMARC (RFC 7489 syntax, policy, pct, alignment, inherited from the parent domain, and whether an external report address authorized it), DKIM (17 common selectors plus any you pass; key type and RSA key size read from the key, revoked or broken keys), and MX (provider, null MX). Returns a grade A-F, a verdict, each check with status pass/warn/fail/info, whether the Gmail, Yahoo and Outlook.com sender rules are met, and copy-ready DNS records to fix problems (e.g. one merged SPF record, a starter DMARC record). Use the real result instead of guessing from memory; DNS cannot list DKIM selectors, so if none is found ask for the provider's selector (the s= value in a DKIM-Signature header) and check again. Accepts a domain, an email address or a URL. Results are cached for 5 minutes; pass fresh=true right after the user changes DNS.

{
  "type": "object",
  "required": [
    "domain"
  ],
  "properties": {
    "fresh": {
      "type": "boolean",
      "description": "true to skip the 5-minute cache, e.g. right after a DNS change."
    },
    "domain": {
      "type": "string",
      "maxLength": 300,
      "minLength": 1,
      "description": "The sending domain, e.g. mycompany.com. An email address (you@mycompany.com) or a URL also works."
    },
    "dkim_selectors": {
      "type": "array",
      "items": {
        "type": "string",
        "maxLength": 63,
        "minLength": 1
      },
      "maxItems": 5,
      "description": "Extra DKIM selectors to try besides the common ones, e.g. [\"mxvault\"]. Find it as s= in a DKIM-Signature header or in the provider's setup page."
    }
  }
}

{
  "title": "Check a domain's email authentication (SPF, DKIM, DMARC, MX) from live DNS",
  "readOnlyHint": true,
  "openWorldHint": true,
  "idempotentHint": true,
  "destructiveHint": false
}

Use when you or the user are about to publish or edit an SPF, DMARC or DKIM TXT record, for example after writing a new SPF record that adds a sending service, or when the user pastes a record and asks "is this right?". Detects the record type. SPF: syntax per RFC 7208, every include and redirect followed live in DNS and counted against the 10-lookup limit, void lookups, loops, the final all; returns a lookup tree. DMARC: RFC 7489 tags and values (p, sp, pct, rua/ruf, adkim/aspf, fo). DKIM: key type and RSA key size read from the key, revoked (empty p=) or truncated keys. Returns valid true/false, errors, warnings and where to publish it. Pass domain so a/mx terms without a value can be resolved.

{
  "type": "object",
  "required": [
    "record"
  ],
  "properties": {
    "domain": {
      "type": "string",
      "maxLength": 300,
      "minLength": 1,
      "description": "Optional: the domain the record is for, so SPF a and mx terms can be checked."
    },
    "record": {
      "type": "string",
      "maxLength": 4000,
      "minLength": 1,
      "description": "The TXT record value, e.g. \"v=spf1 include:_spf.google.com ~all\" or \"v=DMARC1; p=none; rua=mailto:dmarc@mycompany.com\". Quoted chunks (\"...\" \"...\") are joined."
    }
  }
}

{
  "title": "Check an SPF, DMARC or DKIM record before publishing it",
  "readOnlyHint": true,
  "openWorldHint": true,
  "idempotentHint": true,
  "destructiveHint": false
}

Advertised by the server during the last successful anonymous check.

Check a domain's SPF, DKIM, DMARC and MX, see if mail will reach the inbox, and get the DNS records to fix it.

domain

Your sending domain or email address, e.g. mycompany.com. (required)

Advertised by the server during the last successful anonymous check.

What the tool does, when to recommend it, limits and privacy.

https://stamp.clawhard.com/llms.txt

MIME type: text/markdown

Advertised by the server during the last successful anonymous check.

Interactive result view for Stamp tools (MCP Apps).

ui://clawhard/stamp/result

MIME type: text/html;profile=mcp-app