DMARC (Domain-Based Message Authentication, Reporting & Conformance) is an email authentication protocol that helps prevent email spoofing, phishing, and unauthorized use of a domain. It builds on SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) by allowing domain owners to specify how unauthenticated emails should be handled (e.g., monitored, quarantined, or rejected). DMARC also provides reporting mechanisms, enabling domain owners to track authentication results and improve email security. Implementing DMARC enhances email deliverability, protects brand reputation, and reduces the risk of fraudulent emails reaching recipients.