How can DMARC reports be enriched with user-level data for better domain enforcement?
Michael Ko
Co-founder & CEO, Suped
Published 22 May 2025
Updated 16 Aug 2025
6 min read
DMARC (Domain-based Message Authentication, Reporting, and Conformance) has become an indispensable standard for email security. It provides domain owners with crucial visibility into their email streams, allowing them to monitor authentication results for SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) and detect unauthorized use of their domain. The DMARC reports, specifically RUA (Aggregate) and RUF (Forensic) reports, are the backbone of this visibility.
However, while incredibly valuable, these standard DMARC reports have a significant limitation: they are designed to report on domains and IP addresses, not individual users or specific sending applications. This means that while you can see which IP addresses are sending mail on behalf of your domain and whether it passes or fails DMARC authentication, you typically cannot see who initiated the email. This lack of granular, user-level insight can hinder efforts to achieve full DMARC enforcement.
The challenge then becomes, how can we enrich these DMARC reports with user-level data? This enrichment allows for more precise identification of legitimate versus fraudulent sending sources, enabling stronger domain enforcement and a more secure email ecosystem. Let's explore why this is essential and how it can be achieved.
DMARC reports are essential for email security, providing visibility into email streams. They help identify unauthorized use of a domain and are foundational for improving deliverability. These XML-based reports detail authentication results for SPF and DKIM, offering a broad overview of your domain's email traffic. You can learn more about what information is contained in DMARC RUA and RUF reports to get a clearer picture.
While valuable, raw DMARC reports primarily show IP addresses and aggregate statistics. They don't inherently reveal the individual user or specific sending application responsible for sending an email. This lack of granular data can hinder precise remediation efforts. For instance, if an IP shows failures, it's hard to know which internal team or external vendor is causing the issue. This is why reading and analyzing DMARC reports can be complex without additional context.
This limitation is particularly challenging for organizations with multiple email sending services or large internal user bases. Without user-level context, moving to a stricter DMARC policy, such as p=reject, can be risky, potentially blocking legitimate emails. While tools can analyze DMARC reports into an easy-to-read format, they often leave many questions unanswered about specific senders.
The quest for user-level insights
Enriching DMARC data means adding a layer of detail that traditional DMARC reports lack. This additional context typically involves linking IP addresses and authentication results back to specific users, departments, or applications within an organization. For many organizations, the ability to pinpoint the exact source of an email, especially one that fails DMARC, is critical for rapid incident response and effective policy adjustments.
The core challenge is that DMARC was designed to validate domains, not individual users. This user-level data often resides in internal logs, email service provider (ESP) records, or other systems that aren't directly linked to the DMARC reporting mechanism. Bridging this gap requires creative solutions and data correlation. Without this, organizations might struggle with issues like emails going to spam due to unidentified sending sources.
Map internal IPs: Correlate internal IP addresses used for email sending with employee directories or application logs to identify specific senders.
Leverage ESP data: Work with your Mailchimp or other ESPs to access detailed sending logs, which often include user identifiers or campaign names.
Custom headers: Implement custom email headers to embed user or application IDs, which can then be parsed and correlated with DMARC reports.
Centralized logging: Consolidate email logs from all sending sources to a central system for easier analysis and correlation.
Obtaining this granular visibility is not always straightforward, but its value for precise enforcement and threat identification is immense. Knowing which user or system initiated a problematic email provides actionable intelligence far beyond just an IP address. It truly helps in maximizing DMARC reporting.
Strategies for data enrichment
There are several strategies to enhance DMARC reports with user-level data. One common approach involves integrating DMARC reporting solutions with internal IT systems, such as directory services or network logs. This allows mapping reported IP addresses to specific internal users or applications.
Another strategy is to work closely with your email service providers. Many ESPs offer detailed sending logs that can often be cross-referenced with DMARC reports. This is especially useful for external bulk senders or marketing platforms, where the IP addresses in DMARC reports belong to the ESP, not your direct infrastructure. Identifying email sending vendors is a key part of this process.
Raw DMARC reports
Type of data: Aggregated authentication results, source IP addresses, mail server identities.
Visibility: Shows if emails are passing or failing SPF/DKIM alignment, identifies sending IPs.
Actionability: Good for identifying broad patterns of abuse or misconfiguration. Requires further investigation to pinpoint internal source.
Enforcement potential: Difficult to move to p=quarantine or p=reject without risking legitimate traffic.
Enriched DMARC data
Type of data: Includes user IDs, department names, campaign tags, sending application names, in addition to standard DMARC data.
Visibility: Reveals the specific user or system responsible for sending, providing full traceability.
Actionability: Enables precise remediation, allows direct intervention with a user or immediate adjustment of a misconfigured application.
While this enrichment can be complex, especially for high-volume or diverse email ecosystems, the payoff in terms of improved security posture and streamlined incident response is significant. The benefits of implementing DMARC are truly maximized when coupled with such insights.
Elevating domain enforcement
With enriched DMARC reports, domain enforcement shifts from a reactive, IP-centric approach to a proactive, user-centric one. This allows for targeted actions against unauthorized sending, whether it's an internal misconfiguration or an external phishing attempt. This granular data enables a much more precise understanding of your email domain reputation.
For instance, if a DMARC failure is traced back to a specific user account, you can quickly identify if it's a compromised account, a misconfigured application, or simply an employee using an unauthorized sending method. This level of detail empowers administrators to implement p=quarantine or p=reject policies with much greater confidence, knowing they can accurately distinguish between legitimate and illegitimate traffic. This helps in safely transitioning your DMARC policy.
Ultimately, enriching DMARC data helps create a more robust email security posture. It not only protects your brand from impersonation but also ensures higher email deliverability by allowing legitimate emails to pass through unimpeded, while blocking or quarantining harmful ones. This detailed insight into email traffic makes DMARC a far more powerful tool for domain protection.
The path to deeper insights
Enriching DMARC reports with user-level data transforms them from basic authentication logs into powerful forensic tools. This enhanced visibility is crucial for truly robust email security and deliverability. By understanding not just that an email failed, but who or what caused the failure, organizations can achieve a level of domain enforcement that standard DMARC alone cannot provide.
Views from the trenches
Best practices
Regularly review aggregated DMARC reports to identify common failure patterns and potential sending issues.
Work with your Email Service Providers (ESPs) to ensure they support DMARC and provide detailed sending logs.
Implement a phased approach to DMARC enforcement, starting with p=none and gradually moving to p=quarantine or p=reject.
Common pitfalls
Misinterpreting DMARC reports without adequate user context can lead to accidentally blocking legitimate emails.
Not correlating DMARC data with internal user activity logs from your directory services or network monitoring.
Relying solely on DMARC forensic reports (RUF), which can be unreliable and raise privacy concerns.
Expert tips
Consider implementing custom email headers to embed user or system identifiers for easier correlation with DMARC reports.
Prioritize aligning all legitimate sending sources with SPF and DKIM before moving your DMARC policy to enforcement.
Utilize DMARC reporting services that offer advanced analytics and integration capabilities to simplify data enrichment.
Expert view
Expert from Email Geeks says that the "layer 2" terminology for DMARC extensions should be avoided, as it has a very specific and widely understood meaning in networking that differs from what is being discussed.
2021-03-25 - Email Geeks
Marketer view
Marketer from Email Geeks says they do not understand how user-level data is captured since DMARC inherently does not include it.
Mailchimp or other ESPs to access detailed sending logs, which often include user identifiers or campaign names.
Salesforce)
