Email Header Authentication Checker

What this doesn't do: it does not cryptographically verify the DKIM signature — that requires the full raw message body to recompute the body hash, which a headers-only paste doesn't include. DNS records reflect the domain's current configuration, which may differ from when the email was actually sent. Authentication-Results verdicts are only as trustworthy as the mail provider that stamped them — this tool relays them, it doesn't re-check them.