DMARC stands for Domain-based Message Authentication, Reporting, and Conformance. It is an email authentication protocol that helps prevent email spoofing, phishing, and domain impersonation. DMARC builds on two existing email authentication technologies: SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail).
Here’s how DMARC works:
- SPF (Sender Policy Framework): SPF allows domain owners to specify which mail servers are authorized to send emails on behalf of their domain. This prevents spammers from forging the “From” address in their emails.
- DKIM (DomainKeys Identified Mail): DKIM involves adding a digital signature to outgoing emails that can be verified by the recipient’s email server. This signature ensures that the email has not been altered in transit and that it originated from the claimed sender’s domain.
DMARC adds an extra layer of security by allowing domain owners to define a policy for how email recipients should handle emails that do not pass SPF or DKIM checks. There are three possible actions that can be taken for failed emails:
- None: The recipient’s email server takes no specific action, but the DMARC policy is still applied, and the owner receives reports about failed attempts.
- Quarantine: The email is treated as suspicious. It might be placed in the recipient’s spam or quarantine folder.
- Reject: The email is outright rejected and not delivered to the recipient’s inbox.
DMARC also enables domain owners to receive reports about how their domain’s email is being handled by various email providers. These reports can help domain owners identify unauthorized use of their domain, phishing attempts, and other email-related issues.
In summary, DMARC is an essential tool for enhancing email security and reducing the risk of phishing attacks by verifying the authenticity of the sender’s domain and allowing domain owners to specify how emails that fail authentication checks should be handled.