Domain-based Message Authentication, Reporting & Conformance (DMARC) is an email authentication protocol that helps protect against email spoofing and phishing. It allows domain owners to specify how their emails should be handled if they fail authentication checks, which can improve email deliverability and security. DMARC works in conjunction with two other protocols: Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM). By implementing DMARC, organizations can receive reports on email authentication issues, enabling them to monitor and improve their email practices while ensuring that only legitimate emails are sent from their domains.