{"uid":"cap_6R89KO7gjF7-XJWBw5kts","slug":"lookproof-mta-sts-checker-a66f4c17","name":"Lookproof MTA-STS Checker","description":"Check SPF, DMARC, DKIM, MTA-STS, DNSSEC and more, with results that explain what was found and why. Free browser checks and a pay-per-request API with x402.","url":"https://api.lookproof.dev/v1/mail/mta-sts?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"queryParams":{"type":"object","title":"DomainInput","required":["domain"],"properties":{"domain":{"type":"string","title":"Domain","examples":["example.com"],"maxLength":1024,"minLength":1}},"additionalProperties":false}},"additionalProperties":false}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_4IQDFXqZEwTh0ZhqkKyEY","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Checks a domain's full MTA-STS setup (RFC 8461) including DNS record, HTTPS policy file, certificate validity, MX coverage, mode, max_age, and TLS-RPT record (RFC 8460)","exampleAgentPrompt":"Check whether acmecorp.com has a valid MTA-STS setup — I want to know if the DNS record is correct, the policy file is reachable over HTTPS without redirects, all MX hosts are covered, and whether TLS-RPT is configured too.","exampleUseCases":[{"title":"Debug sender MTA-STS failures","prompt":"Senders are reporting MTA-STS failures for payments.stripe.com — can you check the MTA-STS configuration and tell me exactly what's broken, whether it's the DNS record, the policy file, the certificate, or MX coverage?"},{"title":"Pre-deployment email security audit","prompt":"Before we go live, check if mailchimp.com has MTA-STS properly set up in enforce mode with a valid HTTPS policy file and all MX servers covered, and whether TLS-RPT is also in place."},{"title":"Verify inbound TLS downgrade protection","prompt":"Does fastmail.com protect inbound mail against TLS downgrade attacks? Check its MTA-STS policy — I want to know the mode, max_age, whether the certificate is trusted, and if every MX host is listed in the policy."}],"resultDescription":"Returns a structured report covering: presence and validity of the _mta-sts TXT DNS record, reachability of the HTTPS policy file (with certificate chain check and redirect detection), parsed policy fields (mode: none/testing/enforce, max_age), whether every MX host for the domain is listed in the policy, and status of the TLS-RPT record at _smtp._tls. Failures include per-check error messages explaining exactly what is misconfigured.","failureModes":["Domain does not exist or has no DNS records — returns not-found or DNS error","_mta-sts DNS record missing or malformed — reported as record absence or parse failure","Policy file at https://mta-sts.{domain}/.well-known/mta-sts.txt unreachable — HTTP error or timeout reported","Policy file served over redirect — flagged as non-compliant per RFC 8461","TLS certificate for mta-sts subdomain invalid or untrusted — cert check failure reported","MX hosts not fully covered by policy — lists uncovered hostnames","TLS-RPT record absent or malformed — reported separately in the TLS-RPT section","Invalid domain input (too long, bad format) — validation error returned"],"whenToPreferThis":"Use this endpoint when you need a complete, authoritative MTA-STS compliance check for a single domain — covering DNS record, HTTPS policy file integrity, certificate validity, MX host coverage, and TLS-RPT in one call. Prefer this over a generic full-domain mail security report when you specifically need to diagnose MTA-STS issues or confirm RFC 8461 compliance without the overhead of a broader SPF/DKIM/DMARC audit.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-31T18:40:53.650Z","isFirstParty":false,"canonicalSlug":"lookproof-mta-sts-checker-a66f4c17"}