prefixkit RU

DNS, SSL & email

Email header analyzer

Paste the message headers to see which servers it passed and where it was delayed, whether SPF, DKIM and DMARC passed, whether domains align, and what spam filters said.

Gmail: ⋮ → “Show original”. Outlook: File → Properties → Internet headers. Apple Mail: View → Message → All Headers. Everything runs in your browser.

How to read the result

Every mail server adds a Received line on top, so the real path runs bottom-up. We reverse it and compute the delay at each step. SPF, DKIM and DMARC results come from the Authentication-Results header written by the receiving server.

Why a message went to spam

  • SPF fails: the sending server is not in the domain record. SPF and DMARC generator.
  • DKIM is missing or does not verify. Check the domain DNS.
  • The sender IP is blacklisted. Blacklist check.
  • No reverse DNS (PTR) for the server IP, an internal host in the Message-ID, no List-Unsubscribe on bulk mail.

Domain-wide statistics

Headers show one message. To see everyone sending mail as your domain and how much fails, load DMARC reports into the DMARC report analyzer.

More tools: dns, ssl & email

DNS lookupAll records plus SPF, DKIM, DMARC and DNSSEC.DNS propagationIs a new record visible in 20 countries yet.WHOISRegistrar, dates and status of a domain or IP.SSL certificate check newExpiry, issuer, names, HTTPS redirect and HSTS.CSR generator newCSR and private key in the browser, RSA or ECDSA.SPF & DMARC generator newRecords for Google, Microsoft, Yandex and more.Blacklist checkAn IP or domain against 29 spam lists, plus PTR.HTTP security headers newHSTS, CSP, cookies, redirects and a grade.DMARC report analyzer newWho sends as your domain; when to set p=reject.