Implementing the right DMARC policy is crucial for email security, preventing identity theft, and improving email deliverability. However, many organizations are unsure which policy to apply or how this authentication standard works.
What is DMARC and Why is It Important?
Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a global email authentication standard designed to prevent phishing, spoofing, and other cyberattacks. It ensures that emails sent from a domain are properly authenticated using SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail).
DMARC allows businesses to monitor who is sending emails on their behalf, generate reports on suspicious activity, and define what happens to messages that fail authentication checks.
DMARC Policies: p=none, p=quarantine, and p=reject
When setting up DMARC, organizations can choose from three policies depending on their desired level of protection.
1. p=none (Monitoring and Reporting)
This is the most flexible policy and is typically used during the early stages of DMARC implementation.
✅ Purpose: Allows organizations to monitor email traffic without affecting message delivery.
✅ How It Works: DMARC reports provide insights into who is sending emails on behalf of the organization, helping identify both threats and legitimate sources that need proper authentication.
✅ Best for: Businesses starting with DMARC who want visibility before enforcing restrictions.
⚠ Limitation: Does not prevent fraudulent emails from reaching recipients.
2. p=quarantine (Suspicious Emails Sent to Spam)
With this policy, emails that fail authentication are not blocked, but they are marked as suspicious.
✅ Purpose: Prevent unauthenticated emails from landing in the primary inbox.
✅ How It Works: Recipient mail servers redirect unauthenticated emails to the spam or junk folder instead of delivering them directly.
✅ Best for: Organizations that have identified their legitimate email sources and want stronger protection without immediately blocking emails.
⚠ Limitation: Some legitimate emails may end up in spam if SPF and DKIM are not correctly configured.
3. p=reject (Full Blocking of Fraudulent Emails)
This is the strictest and most secure policy for preventing phishing and unauthorized emails.
✅ Purpose: Ensure that unauthenticated emails never reach recipients.
✅ How It Works: Email servers automatically reject any messages that fail DMARC checks, preventing them from even reaching spam folders.
✅ Best for: Businesses that have verified all legitimate email sources and want maximum protection against fraud.
⚠ Limitation: If SPF and DKIM are not properly configured, some legitimate emails could be blocked.
How to Implement the Right DMARC Policy
For an effective DMARC strategy, organizations should follow a step-by-step approach:
1️⃣ Start with p=none: Monitor email activity and detect unauthorized senders.
2️⃣ Adjust SPF and DKIM settings: Ensure all legitimate sources are properly authenticated.
3️⃣ Switch to p=quarantine: Gradually protect against unauthenticated emails without full rejection.
4️⃣ Implement p=reject: Apply maximum protection once all authentication issues have been resolved.
Conclusion
Implementing DMARC correctly is essential for protecting domain reputation and preventing email-based attacks. A gradual approach—starting with p=none, moving to p=quarantine, and finally enforcing p=reject—ensures a smooth transition without disrupting legitimate email delivery.
Organizations looking for enhanced protection can consult email security experts or use specialized DMARC monitoring tools to ensure their implementation is effective.
