Executive's DNS Intelligence Brief

SPF (Sender Policy Framework) tells receiving mail servers which IP addresses are authorized to send email for your domain. Without SPF, any server can claim to send as your domain.

DMARC (Domain-based Message Authentication, Reporting & Conformance) tells receivers how to handle messages that fail SPF/DKIM checks. Without DMARC, failed authentication checks are ignored. Start with p=none and rua reporting to monitor, then escalate to p=quarantine and p=reject.

Publish an MTA-STS DNS record and host a policy file at https://mta-sts.evilhacker.com/.well-known/mta-sts.txt. This tells senders to require TLS when delivering mail to your domain.

DKIM selectors were not discoverable via common selector names. This does not confirm DKIM is absent — your provider may use custom or rotating selectors that cannot be enumerated through DNS (RFC 6376 §3.6.2.1). Check your email provider's DKIM settings to confirm signing is enabled.

Publish CAA DNS records to restrict which Certificate Authorities can issue TLS certificates for your domain. Specify your preferred CA (e.g., letsencrypt.org, digicert.com). CAA is advisory — CAs must check it before issuing, but absence means any CA can issue.

TLS-RPT (TLS Reporting) sends you reports about TLS connection failures when other servers try to deliver mail to your domain. Helps diagnose MTA-STS and STARTTLS issues.

DNSSEC (DNS Security Extensions) cryptographically signs DNS responses, preventing attackers from forging DNS answers. Contact your DNS hosting provider to enable DNSSEC signing.