DMARC (Domain-based Message Authentication, Reporting & Conformance) is an email authentication protocol that uses SPF and DKIM to verify email senders and prevent spoofing, ensuring that emails are legitimate and from the claimed domain
What DMARC Does:
DMARC builds on SPF and DKIM by adding a policy component to instruct receiving email servers how to handle emails that fail authentication checks.
How it Works:
- Authentication: DMARC verifies the authenticity of an email by checking if the domain in the “From” address matches the domain used in SPF or DKIM authentication.
- Alignment: It ensures that the domain in the email’s “From” header aligns with the domain used in the SPF or DKIM signature.
- Policy: DMARC allows domain owners to publish policies in their DNS records that specify how receiving servers should handle emails that fail authentication.
- Reporting: DMARC also enables reporting, allowing domain owners to monitor email authentication results and identify potential issues.
Why it’s Important:
- Prevents Spoofing: DMARC helps prevent email spoofing, where attackers forge emails to appear as if they are from a legitimate domain.
- Reduces Phishing: By verifying the authenticity of emails, DMARC helps reduce the risk of phishing attacks.
- Improves Email Deliverability: Implementing DMARC can improve email deliverability by helping email providers identify and block fraudulent emails.
DMARC Alignment:
- Strict Alignment: The domain in the “From” header must exactly match the domain used in SPF or DKIM authentication.
- Relaxed Alignment: The domain in the “From” header must be a subdomain of the domain used in SPF or DKIM authentication.
DMARC Policy Options:
- p=none (Monitoring): DMARC checks are performed, but no action is taken on failed emails.
- p=quarantine (Quarantine): Failed emails are marked as spam.
- p=reject (Reject): Failed emails are rejected
