Email authentication check (SPF, DKIM, DMARC): Check a domain's email authentication and spoofing risk from public DNS: MX and mail provider, SPF (record, all-qualifier, DNS lookup count vs the 10 limit), DMARC policy/pct/rua, DKIM at 30 common selectors, MTA-STS, TLS-RPT, BIMI. Returns grade, spoof