What is DMARC and how it works

What is Domain-Based Message Authentication Reporting & Conformance (DMARC)?

DMARC verifies whether or not an email genuinely comes from the domain it claims to be from. It does this by building upon two existing authentication mechanisms: the Sender Policy Framework (SPF) and Domain Keys Identified Mail (DKIM). SPF checks that the sender’s IP address is authorized to send mail for the domain, based on the domain’s SPF DNS record, while DKIM confirms the message has not been tampered with in transit by validating its cryptographic signature. If a message fails either of these checks, the mailbox that receives the potentially spoofed email will follow any DMARC policies outlined by the administrators. 

DMARC helps organizations protect the legitimacy of their domains, preventing third parties from spoofing company emails for phishing campaigns and impersonation attacks. By creating strict DMARC policies that either quarantine or reject a potentially dangerous email altogether, domain owners can prevent unauthorized senders from tricking their customers. 

Another core function of DMARC is to produce authentication reports that give admins insight into how a domain is being used across the email ecosystem. If a company uses third-party services to send out marketing emails, for example, this report will help flag any unauthorized systems or misconfigured senders. 

When DMARC technologies align with comprehensive policy-building, they come together to give organizations more control over their email domain. 

How DMARC Works

The DMARC protocol adds another layer of authentication on top of SPF and DKIM. Whenever a receiving server gets an email, it follows this process:

1. Authenticate the Sender’s Domain: Perform a basic check to test whether the email comes from an authorized sending IP (as per SPF) and has a valid cryptographic signature (DKIM).
2. Validate Domain Header Alignment: This step checks that the domain authenticated by SPF or DKIM matches the one visible in the “From” header of the email. Validating this matching ensures that a hacker couldn’t simply bypass SPF and DKIM by using an unrelated domain.
3. Apply Domain’s DMARC Policy: Administrators will publish their custom DMARC policy as a DNS TXT record under the domain. This policy will dictate what happens when an email receiver gets a message that fails authentication checks. Typically, this is either to reject (block outright), quarantine (send to spam or freeze for admin’s verification), or do nothing (allow through).
4. Generate DMARC Reports: Finally, DMARC will produce XML-based reports that trace where mail comes from, which services are failing verification and alignment in steps 1 and 2, and whether these failures are suspicious or accidental. These reports give admins full visibility over activity within their email domain. 

Although DMARC, SPF, and DKIM do help to prevent 이메일 스푸핑, more modern attacks are using advanced tactics like display name spoofing and clone phishing to bypass them. Organizations should pair DMARC with other threat detection strategies to better identify potential threats and mitigate them before they cause damage in a system.

Why Implement DMARC: Key Benefits

DMARC is a fundamental tool for protecting a company’s domain and ensuring only authorized systems can send email on its behalf. Considering how vital email sending systems are, DMARC helps to ensure these systems remain compliant and within the scope of a company’s intention. 

에 따르면 Check Point State of Cybersecurity 2025 Report, phishing remains one of the top cyberthreats, often being used as a main vector to deliver malware and ransomware. Due to this, the ability to impersonate a legitimate company’s email domain is invaluable to attackers, making DMARC verification essential.

Here are some of the benefits of using DMARC:

• Reputation: A company’s reputation is one of their most valuable assets, being the driving force for brand loyalty and prolonged customer success. If a cyberattacker is able to spoof a company’s domain and send malicious files from it, the event can damage a company’s reputation significantly. If customers lose faith in a business, they may defect to competitor brands. DMARC prevents unauthorized systems from sending email messages with an organization’s domain, protecting its overall reputation. 
• Cybersecurity Protection: An email that fails the authentication steps laid out by DMARC is often one that comes from an unverified source. By blocking these emails or placing them in quarantine, DMARC reduces the chances of a phishing or impersonation email arriving in an employee’s inbox. 

Domain Visibility: Another core aspect of DMARC that is often overlooked is its ability to give administrators more visibility into the connected services that send emails on their behalf. From marketing tools to HR systems and billing platforms, keeping track of all these automated services is difficult without help from DMARC systems. They will flag any misconfigured services, helping security teams maintain full control over their outgoing communications.

DMARC Records and Policies: Everything You Need to Know

DMARC records are the TXT files that domain admins publish in their DNS. It aims to outline the security team’s preferred policy, detailing how any messages that fail any step of the authentication process should be handled.

There are three main DMARC policies, each of which causes a different action after authentication failure:

• Reject (p=reject): Reject completely blocks all unauthorized messages. Any message that could potentially be a spoof is instantly prevented from reaching its intended recipient. As the strongest policy, this is only used once admins have verified that all third-party providers have been validated.
• Quarantine (p=quarantine): Any failing messages are instead routed to a spam folder or a holding zone. Admins can look through the emails within the holding zone to diagnose why they failed. This option is a useful point, as it provides admins with extra information that they can use to further configure their policies.
• None (p=none): None is an option that lets through absolutely all traffic. Much like Reject, this is an extreme policy that is only used in specific circumstances. Most of the time, None is best for organizations that still need to configure their domains and identify legitimate sending sources, using the extra data as a guide.

What Is a DMARC Report?

A DMARC report is a feedback mechanism that details information collected by mail servers. It reveals how emails claiming to use your company’s domain acted during the authentication process. For example, it could indicate that the emails passed DKIM but failed SPF, flag which sending sources are using your domain without permission, and outline suspicious activity. Reports are useful in giving admins additional context about which external sources may be impersonating your brand. Over time, reports guide admin toward stronger DMARC policies, highlighting which senders need more adjustments.

DMARC Management

Centralized DMARC management systems allow admins to better adjust their policies and achieve visibility over external sending services. By centralizing reporting and identifying any problematic sources, admins have a better idea of how to adjust to mitigate potential failures. 

Using a DMARC management system heavily reduces the amount of time that admins need to spend reading through XML reports or troubleshooting services one-by-one.

DMARC and Compliance

Alongside being a useful security and visibility tool for administrators, DMARC is also a recommended part of several compliance frameworks. Several countries outline email management services configuration requirements for government agencies, which include using the Sender Policy Framework, Domain Keys Identified Mail, and DMARC for validation.

Some industry-specific compliance frameworks, like the PCI DSS also include wording that points toward a DMARC solution. The PCI DSS asks for automated mechanisms to protect against phishing attacks through verification. While this doesn’t precisely outline DMARC, it describes the exact function of DMARC and its partner protocols. 

The use of DMARC is even a central part of the EU’s email communication security standards, demonstrating how commonplace the protocol is in regulatory compliance.

Protect Enterprise Email & Collaboration with Check Point

Implementing DMARC is one of the most effective ways to stop domain spoofing, impersonation attempts, and phishing. But managing it successfully across dozens of sending sources can quickly create a managerial burden. Check Point Harmony Email & Collaboration removes that burden, giving organizations real-time visibility into DMARC activity and clear, actionable guidance for every misconfigured sender. 

Harmony automatically analyzes DMARC failures from all third-party services that send email on your behalf, providing actionable recommendations for remediation. Instead of manually digging through XML reports or testing SPF and DKIM alignment, security teams can use a centralized dashboard to find errors and what to do to fix them.

DMARC management arrives as part of Harmony’s wider email security support, which provides NLP-driven threat detection, account takeover protection, automated reporting, and zero-day malware prevention. Harmony gives your business everything it needs to manage its email security and collaboration platforms without adding operational overhead.

To strengthen your email security posture and improve your authentication posture, request a demo of Harmony Email & Collaboration 오늘.