Understanding DMARC Alignment and Policies to Protect your Emails

Email security is paramount, and DMARC (Domain-based Message Authentication, Reporting & Conformance) plays a critical role in safeguarding your communications. But what exactly is DMARC alignment, and how do quarantine and reject policies affect your email protection strategy?

DMARC Alignment: Your First Line of Defense

DMARC alignment ensures that the domain in the email's 'From' address matches the domain authenticated by SPF (Sender Policy Framework) or DKIM (DomainKeys Identified Mail). This alignment prevents attackers from using your domain to send fraudulent emails.

SPF and DKIM authenticate emails but don't inherently match the 'From' address domain, creating a potential loophole for malicious actors. DMARC closes this gap by requiring alignment, thus bolstering email security.

For DMARC verification to succeed, the domain in the From header must match the domains validated by SPF and DKIM checks. If they don't align, the email fails DMARC verification.

DMARC Policies: None, Quarantine, and Reject

After setting up DMARC with a policy of p=none, you monitor which emails pass or fail authentication. This phase helps you identify legitimate and illegitimate senders, paving the way for stricter policies.

DMARC None

Technical Viewpoint: The p=none policy doesn’t enforce any action on failing emails but provides reports to the domain owner.
Non-Technical Viewpoint: Think of it as a passive security camera that records incidents without taking action.

v=DMARC1; p=none; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=100;

DMARC Quarantine

Technical Viewpoint: Emails failing DMARC are marked for further scrutiny. They can be delivered to a quarantine mailbox, sent to the spam folder, or subjected to aggressive anti-spam filtering.
Non-Technical Viewpoint: Quarantining is like setting aside suspicious packages for inspection before they reach the recipient.

v=DMARC1; p=quarantine; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=100;

DMARC Reject

Technical Viewpoint: Emails that fail DMARC checks are outright rejected and not delivered to the recipient.
Non-Technical Viewpoint: The reject policy acts as a strict bouncer, denying entry to anyone without proper credentials.

v=DMARC1; p=reject; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=100;

Choosing Between Quarantine and Reject

Implementing DMARC Quarantine

Quarantine allows emails that fail DMARC checks to be accepted but treated with suspicion:

Delivery Options

Quarantine Mailbox: Admins decide the email's fate.
Spam Folder: Recipients can review and move the email.
Aggressive Filtering: Emails may be blocked due to high spam scores.

Benefits

Gradual transition to stricter policies.
Flexibility in handling potentially legitimate emails.

Risks

Misconfigured DMARC can lead to legitimate emails being quarantined, potentially harming your brand.

Implementing DMARC Reject

Reject ensures that emails failing DMARC checks are not delivered:

Benefits

Complete protection against malicious emails.
Recipients are shielded from potential threats.

Risks

Legitimate emails failing authentication are not delivered, possibly disrupting communication.

Making the Right Choice

The choice between quarantine and reject depends on your organization’s needs. Quarantine offers a cautious approach, while reject provides maximum security.

Example Scenarios

Scenario 1

None Policy: You notice several emails failing DMARC checks in your reports.
Quarantine Policy: You implement quarantine, and some legitimate emails end up in the spam folder. After adjusting configurations, you ensure only malicious emails are quarantined.
Reject Policy: Confident in your configurations, you switch to reject, ensuring all failing emails are blocked. This eliminates the risk of employees interacting with malicious content.

Scenario 2

None Policy: Your organization identifies legitimate third-party services sending emails on your behalf.
Quarantine Policy: You quarantine emails, fine-tuning DMARC settings. Third-party emails are monitored and allowed if legitimate.
Reject Policy: After ensuring all legitimate sources are authenticated, you move to reject, fully securing your email traffic.

Additional DMARC Examples for Enhanced Benefits

Example DMARC to Reject for subdomains and primary domain

v=DMARC1; p=reject; sp=reject; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=100;

DMARC with Subdomain Policy and Forensic Reporting
This record sets a reject policy for the main domain and quarantine for subdomains, including forensic reporting for failures.

v=DMARC1; p=reject; sp=quarantine; rua=mailto:[email protected]; ruf=mailto:[email protected]; fo=1; pct=100;

DMARC with Multiple Reporting Addresses
This record sends aggregate reports to multiple addresses and uses a quarantine policy for the main domain.

v=DMARC1; p=quarantine; rua=mailto:[email protected],mailto:[email protected]; ruf=mailto:[email protected]; pct=100;

DMARC with Percentage-Based Policy
This record enforces a reject policy on only 50% of the emails for testing purposes.

v=DMARC1; p=reject; sp=reject; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=50;

DMARC with Strict Alignment
This record requires strict alignment for both SPF and DKIM.

v=DMARC1; p=reject; sp=reject; adkim=s; aspf=s; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=100;

Further Notes

DMARC alignment and policy enforcement are essential for protecting your email domain. Starting with a p=none policy helps identify legitimate senders, while quarantine and reject policies provide increasing levels of security. Tailoring these policies to your organization's needs ensures robust protection against email fraud and impersonation.

Protect your business from email fraud today! Contact us to learn how DMARC can secure your communications and prevent impersonation. Reach out now!