Set Up a DMARC Policy That Is Safe to Roll Out

DMARC tells mailbox providers what to do when SPF and DKIM do not align with your From domain.

Minimum record

v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

  1. Start with p=none.
  2. Confirm SPF or DKIM alignment is consistently passing.
  3. Review aggregate reports.
  4. Move to quarantine only after legitimate traffic is clean.
  5. Move to reject only when you trust your sending inventory.

Tags worth understanding

  • p: policy
  • rua: aggregate reports
  • adkim: DKIM alignment strictness
  • aspf: SPF alignment strictness
  • pct: policy percentage during staged rollout

DMARC is most effective when it follows clean SPF and DKIM, not when it is used to compensate for weak sender setup.