DMARC ties SPF and DKIM together and tells providers what to do when authentication fails. Learn DMARC policies, alignment, and rollout strategy.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol that helps prevent domain spoofing. DMARC builds on SPF and DKIM and lets domain owners publish a policy describing how receivers should handle emails that fail authentication.
DMARC also enables reporting so you can see who is sending mail on behalf of your domain. This visibility is crucial for identifying legitimate senders, misconfigurations, and malicious impersonation attempts.
Most teams roll out DMARC in stages: start with monitoring (p=none) and reporting, then move to quarantine and finally reject once legitimate sources are aligned. Proper alignment settings (aspf/adkim) help ensure only trusted mail passes.