[acronym for Domain-based Message Authentication, Reporting & Conformance] DMARC is an email authentication protocol that helps protect email domains from unauthorized use, including SPAM, spoofing, and phishing using policies of 'none', 'quarantine', or 'reject'. It builds upon two existing email authentication technologies, Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM), enabling email receivers to verify the legitimacy of incoming messages and guiding them on how to handle messages that fail authentication.
