MTA-STS policy parser API

Input

A JSON body with content-type: application/json.

Example request

curl -i -X POST https://api.lookproof.dev/v1/mail/mta-sts-parse \
  -H 'content-type: application/json' \
  -d '{"policy": "version: STSv1\nmode: testing\nmx: mx1.example.com\nmx: *.mail.example.com\nmax_age: 604800\n"}'

import asyncio
import os

from eth_account import Account
from x402 import x402Client
from x402.http.clients import x402HttpxClient
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact import register_exact_evm_client


async def main() -> None:
    signer = EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"]))
    client = register_exact_evm_client(x402Client(), signer, networks="eip155:8453")
    async with x402HttpxClient(client) as http:
        response = await http.post('https://api.lookproof.dev/v1/mail/mta-sts-parse', json={'policy': 'version: STSv1\nmode: testing\nmx: mx1.example.com\nmx: *.mail.example.com\nmax_age: 604800\n'})
        response.raise_for_status()
        print(response.json())


asyncio.run(main())

import { wrapFetchWithPaymentFromConfig } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY);
const fetchWithPayment = wrapFetchWithPaymentFromConfig(fetch, {
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }],
});

const response = await fetchWithPayment("https://api.lookproof.dev/v1/mail/mta-sts-parse", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({"policy": "version: STSv1\nmode: testing\nmx: mx1.example.com\nmx: *.mail.example.com\nmax_age: 604800\n"}),
});
console.log(await response.json());

curl: unpaid request — returns 402 with the price (PAYMENT-REQUIRED). The Python and JavaScript clients pay it and send the request again. Only ordinary wallets (EOA) can pay; smart-contract wallets get a 402 without charge. See payments.

Example response

{
  "checked_at": "2026-10-24T12:00:00Z",
  "data": {
    "mx_count": 2,
    "notes": [
      "Only the policy text is read. Whether the domain publishes an _mta-sts record, serves this file at https://mta-sts.<domain>/.well-known/mta-sts.txt and lists matching MX hosts needs the MTA-STS check."
    ],
    "policy": {
      "max_age": 604800,
      "mode": "testing",
      "mx": [
        "mx1.example.com",
        "*.mail.example.com"
      ],
      "version": "STSv1"
    },
    "problems": [],
    "valid": true
  },
  "endpoint": "mail.mta_sts_parse",
  "findings": [
    {
      "code": "MTASTS_MODE_TESTING",
      "evidence": {
        "count": 1,
        "items": [
          {}
        ]
      },
      "explanation": "In testing mode senders report TLS failures through TLS-RPT but still deliver the mail, so the policy does not yet protect against downgrade attacks.",
      "message": "The MTA-STS policy is in testing mode.",
      "recommendation": "Move to mode enforce once TLS-RPT reports show that all MX hosts pass.",
      "severity": "warning"
    }
  ],
  "meta": {
    "cache_hit": false,
    "duration_ms": 42,
    "fresh_until": "2026-10-24T12:05:00Z",
    "observed_at": "2026-10-24T12:00:00Z",
    "resolver": null,
    "source": "offline"
  },
  "request_id": "req_aaaaaaaaaaaaaaaaaaaaaaaaaa",
  "schema_version": "1.0",
  "status": "warning"
}

Response fields

Fields in data

Status codes

Errors use the common error body. See errors.

Findings this endpoint can return