Mastering DMARC: Boost Your Email Security IQ

In 2023, over 3.4 billion phishing emails were sent daily, contributing to a surge in cybercrime and financial losses. According to a recent notice from the FBI’s Internet Crime Complaint Center (IC3), business email compromise (BEC) attacks have cost organizations in the US and worldwide nearly $55.5 billion. Basic email authentication methods like SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) offer some protection, but they can be bypassed.

That’s where DMARC (Domain-based Message Authentication, Reporting & Conformance) steps in. By implementing DMARC, organizations can effectively protect their domains from phishing and spoofing, improve email deliverability, and enhance overall security.

In this blog, we'll explore how to master DMARC, its benefits, and best practices to ensure your domain remains secure.

What is DMARC and Why is it Important?

DMARC is an email authentication protocol that helps organizations protect their domains from email spoofing and phishing. It builds on SPF and DKIM to ensure that only legitimate emails are delivered. With DMARC, domain owners can:

• Block fraudulent emails sent on their behalf.
• Gain visibility into who is sending emails using their domain.
• Improve deliverability by ensuring legitimate emails reach inboxes.

Case Study: In 2019, Toyota Boshoku Corporation, a subsidiary of Toyota, suffered a $37 million loss due to a Business Email Compromise (BEC) attack. Cybercriminals impersonated a company executive's email address, instructing an employee to transfer funds to a fraudulent account. Implementing robust email authentication protocols like DMARC could have added an extra layer of security to prevent such impersonation attacks.

How Does DMARC Work?

DMARC protects your domain by adding an extra layer of verification to emails. It works through three key steps:

1. Authentication:

The receiving server checks if the email matches your SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) records to confirm it’s from a trusted source.

2. Policy Enforcement:

You set a DMARC policy to tell the server how to handle emails that fail authentication:

• None: Deliver the email and report its status.
• Quarantine: Send the email to the spam folder.
• Reject: Block the email completely.

3. Reporting:

DMARC generates reports showing which emails pass or fail authentication. These insights help you spot spoofing attempts and improve your email security.

Steps to Master DMARC Implementation

1. Start with a “None” Policy

Set your DMARC policy to “none” to begin collecting reports without blocking any emails. This allows you to monitor email traffic and spot issues without affecting email delivery.

Example Policy:

2. Analyze DMARC Reports

Review DMARC reports regularly to detect unauthorized senders and potential issues. Tools like the Phishing Simulator and Threat Intelligence can help analyze these reports effectively.

3. Move to “Quarantine” or “Reject” Policies

Once you’re confident in your email authentication, tighten your policy:

• Quarantine: Suspicious emails are sent to the spam/junk folder.
• Reject: Unauthorized emails are blocked entirely.

Example Policy:

4. Ensure SPF and DKIM Alignment

Make sure SPF and DKIM are correctly configured and aligned with your domain. Misalignment can lead to legitimate emails failing DMARC checks.

5. Monitor and Refine Continuously

DMARC isn’t a “set it and forget it” solution. Continuously monitor your reports, refine your policies, and stay updated on new threats.

Benefits of DMARC Implementation

Implementing DMARC offers significant advantages for your organization's email security, deliverability, and reputation. By authenticating your emails and preventing misuse of your domain, DMARC helps protect your business from costly phishing attacks and enhances your overall security posture. Let’s explore the key benefits.

1. Protection Against Email Spoofing

DMARC stops cybercriminals from impersonating your domain, making it harder for them to send phishing emails that deceive your customers or employees.

2. Improved Email Deliverability

With DMARC in place, authenticated emails are less likely to be flagged as spam, ensuring they reach recipients' inboxes and improving your email communication effectiveness.

3. Brand and Reputation Protection

By preventing spoofed emails, DMARC safeguards your brand’s integrity and maintains trust with your customers, partners, and employees.

4. Valuable Insights Through Reporting

DMARC generates detailed reports on email activity, helping you identify unauthorized senders, detect vulnerabilities, and take proactive steps to strengthen your email security.

Common Challenges and Solutions

Even with its benefits, DMARC implementation can present specific challenges that require careful planning and ongoing management.

1. Complex Setup Process

Setting up DMARC can seem overwhelming, especially for first-time users. To simplify the process, start with a “none” policy to collect data without disrupting email delivery. Gradually move to stricter settings like “quarantine” or “reject.” Use tools like the Phishing Simulator to test your configurations and identify potential issues.

2. Misconfigured SPF and DKIM

Incorrect SPF or DKIM records can cause legitimate emails to fail authentication checks. Ensure both records are properly set up and aligned with your sending domains. Regularly verify your settings and update them when changes are made to your email infrastructure.

3. Handling Legitimate Email Failures

Sometimes, legitimate emails may fail DMARC checks due to misconfigurations or third-party services. Regularly review your DMARC reports to identify legitimate senders that are being blocked. Update your SPF and DKIM records or adjust your DMARC policy to include these trusted senders.

4. Managing Ongoing Maintenance

DMARC is not a one-time setup — it requires ongoing attention. Continuously monitor your reports, update your configurations, and stay informed about new threats. Establish a routine to review your email security posture and refine your policies as needed.

Key Takeaways for IT Leaders

Mastering DMARC is essential for protecting your domain and improving email security. By implementing DMARC policies, analyzing reports, and refining configurations, you can:

• Block email spoofing and phishing attacks.
• Improve email deliverability rates.
• Protect your brand’s reputation.

Start your DMARC journey today and strengthen your organization’s email security posture.

Boosting Your Email Security Beyond DMARC with Keepnet

While DMARC is critical, it should be part of a broader email security strategy. Keepnet provides comprehensive solutions to enhance your organization's defenses, including:

• Phishing Simulations: Train employees to recognize phishing attacks with real-world simulations.
• Security Awareness Training: Reduce human error by educating your workforce on security best practices.
• Incident Response Tools: Quickly identify and respond to email threats before they escalate.

Explore the Keepnet Human Risk Management Platform for an all-in-one approach to email security and human risk management.