DMARC, SPF, and DKIM are email authentication protocols designed to protect against email spoofing and phishing. SPF (Sender Policy Framework) lets domain owners specify which mail servers are allowed to send emails on their behalf. DKIM (DomainKeys Identified Mail) adds a digital signature to each message, allowing recipients to verify that the email was not altered and truly comes from the stated domain. DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM, enabling domain owners to set policies for handling unauthenticated emails and receive reports about suspicious activity. Together, these protocols help ensure that email messages are legitimate and reduce the risk of impersonation attacks.