Domain-based Message Authentication, Reporting & Conformance (DMARC) is an email authentication and authorization protocol designed to enhance email security by preventing email spoofing and phishing attacks. It provides a framework that allows senders to define policies regarding email authentication and instructs email servers on how to handle messages that fail authentication.

The DMARC protocol works by enabling domain owners to publish policies in their Domain Name System (DNS) records. These policies define what actions should be taken if an email fails authentication checks, providing a way to protect the domain from unauthorized or malicious use.

When an email is sent using a domain that has published a DMARC policy, the recipient's email server checks the message against the defined policy. The policy typically specifies whether the email should be delivered, quarantined, or rejected based on the authentication results.

DMARC enhances email authentication by leveraging two other key email authentication standards: SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail). SPF validates the sending mail server's identity, and DKIM verifies the integrity and authenticity of the email's content.

Understanding and implementing DMARC is critical for organizations aiming to bolster their email security measures. By adopting DMARC, businesses can reduce the risk of email-related threats, maintain the integrity of their brand, and establish trust with their email recipients.