§2024-10-01

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol designed to protect email senders and recipients from spoofing, phishing, and other email-based attacks. It builds on two existing authentication protocols, SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail), by adding a mechanism for domain owners to specify how email that fails these checks should be handled and providing a way to receive reports on email authentication activity.

• Key Components of DMARC:
  • SPF and DKIM Alignment: DMARC ensures that the "From" header in the email matches the domain authenticated by SPF and DKIM. If the email passes SPF and/or DKIM, it’s considered aligned.

Policy Specification: DMARC policies let domain owners dictate what happens to emails that fail authentication. They can set a policy to:

None: Take no action (only report failures). Quarantine: Send suspicious emails to the spam/junk folder. Reject: Completely block emails that fail DMARC checks. Reporting: DMARC provides reporting capabilities where domain owners can receive aggregate and forensic (failure) reports about messages claiming to be from their domain. These reports help monitor and improve email authentication.

Why is DMARC Important? Prevents Email Spoofing: By enforcing DMARC, organizations can prevent malicious actors from using their domain to send fraudulent emails, reducing the risk of phishing attacks. Improves Email Deliverability: Authenticating emails with DMARC can improve deliverability since many email service providers use DMARC policies to decide whether to accept, reject, or quarantine emails. DMARC is widely adopted by businesses and email service providers to enhance email security.