SPF check

Fetch and validate a domain's SPF record (RFC 7208). Parses mechanisms (ip4/ip6/include/a/mx/all), counts DNS lookups against the famous 10-lookup limit, and flags the qualifier on `all` (-/fail, ~/softfail, ?/neutral). The first stop when an email is hitting the spam folder.

Input

Example output

{
  "domain": "google.com",
  "hasRecord": true,
  "raw": "v=spf1 include:_spf.google.com ~all",
  "mechanisms": [
    {
      "type": "include",
      "qualifier": "pass",
      "value": "_spf.google.com"
    },
    {
      "type": "all",
      "qualifier": "softfail"
    }
  ],
  "lookupCount": 1,
  "all": "softfail",
  "valid": true,
  "warnings": []
}

Try it - see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/spf-check \
  -H "Content-Type: application/json" \
  -d '{"domain":"google.com"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/spf-check", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "domain": "google.com"
  }),
});

Part of these workflows

This tool is one step in 4 curated multi-tool workflows - agents can fetch the whole sequence as an MCP prompt or call https://agent402.tools/api/skill-packs/{slug}/prompt.

• Security audit - Enumerate a domain's external attack surface in one workflow: certs, DNS posture, email auth, HTTP security headers, and tech stack.
• Email deliverability - Diagnose why a domain's email lands in spam: SPF posture, DMARC policy, DKIM key strength, MX targets, and a composite 0–100 score.
• Email security - Full email auth posture: SPF, DMARC, DKIM, and composite deliverability score in one call.
• Contact verification - Verify an email address is deliverable - syntax validation plus MX record check on the domain.

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