How to interpret DMARC reports, including sender identification and failure types?

Key findings

• Comprehensive data: DMARC reports offer detailed information on email authentication, showing which emails pass or fail SPF and DKIM checks. This data is vital for ensuring your email infrastructure is correctly configured.
• Authentication failures: Failures can stem from various sources, including misconfigured SPF or DKIM records, email forwarding, or malicious spoofing attempts. Understanding the cause is key to resolution.
• Sender identification: Reports list senders, both legitimate and potentially unauthorized. It is critical to identify all services sending email on behalf of your domain, including ESPs, marketing platforms, and transactional email providers.
• Policy enforcement: Interpreting reports helps you move from a monitoring-only policy (p=none) to stronger enforcement (p=quarantine or p=reject), gradually improving your domain's security posture.
• Deliverability impact: Consistent DMARC failures can negatively impact your email deliverability, leading to emails being marked as spam or rejected by recipient servers.

Key considerations

• Data aggregation: DMARC aggregate reports (RUA) provide a high-level overview of all email traffic, while forensic reports (RUF) offer detailed insights into individual failures, though these are less commonly provided due to privacy concerns.
• Alignment requirement: For DMARC to pass, the domain in the 'From' header (RFC5322.From) must align with the domain used for SPF (RFC5321.MailFrom) or DKIM (d= domain in the signature). Lack of proper identifier alignment is a common cause of failures.
• Third-party senders: Ensure all legitimate third-party senders (e.g., ESPs, CRM systems, accounting software) are correctly authorized via SPF and DKIM. Unrecognized senders in your reports could indicate legitimate, but unconfigured, services or potential spoofing.
• Troubleshooting methodology: When encountering DMARC failures, investigate volume spikes from unknown sources, check your SPF and DKIM records for errors, and consider the impact of email forwarding. For a more detailed guide, see how to troubleshoot DMARC failures.
• Report tools: While raw XML DMARC reports are complex, various tools can parse them into human-readable formats, making interpretation much easier. GoDMARC provides a useful resource on understanding DMARC reports and their parameters.

Key opinions

• Initial confusion: Many marketers find DMARC reports complex and overwhelming at first, often needing assistance to decipher the data, particularly when seeing high DKIM failure rates while DMARC overall pass rates appear good.
• Sender relevance: Distinguishing between legitimate email sending platforms (like ESPs or CRM systems) and unknown or suspicious senders is a common task. Marketers focus on ensuring their primary email service providers (ESPs) are correctly configured.
• Deliverability focus: The main goal for marketers is to optimize inbox placement. DMARC reports are a tool to identify and fix issues that could lead to emails being marked as spam or rejected, thus impacting campaign performance.
• Identifying all senders: It can be surprising to discover unknown services sending email on behalf of their domain (e.g., HR platforms, ticketing systems, internal IT services), necessitating a full audit.

Key considerations

• Impact on campaigns: Marketers must understand how DMARC failures directly translate to missed opportunities and reduced ROI from their email marketing efforts.
• Third-party authorization: Ensure that every service sending emails using your domain is properly configured with SPF and DKIM, as a single misconfiguration can lead to significant DMARC failures and affect your sender reputation. If you need help, setting up DMARC records is a good starting point.
• Identifying unauthorized senders: A high volume of DMARC failures from unrecognized senders often points to brand impersonation or phishing attempts, which require immediate attention to protect your brand and recipients.
• Gradual policy enforcement: Marketers should advocate for a gradual transition of DMARC policies from p=none to p=quarantine, then p=reject, to avoid disrupting legitimate email flows while enhancing security.
• Reviewing data regularly: Regularly reviewing DMARC reports helps marketers stay ahead of potential deliverability issues and identify new sending sources that need to be authorized.

Key opinions

• Failure complexity: Experts note that DMARC failures can occur even when one authentication method (SPF or DKIM) passes, and they can result from networking problems, not just spoofing. These distinctions are crucial for accurate troubleshooting.
• Judgment calls: Tracking down the root cause of DMARC failures can be challenging, requiring experts to make judgment calls on the severity of issues based on volume and origin.
• Mixed senders: DMARC reports often show a mix of legitimate and questionable senders, including email service providers, ticketing platforms, IT services, and sometimes spoofing attempts or failures due to email forwarding.
• Volume is key: Experts advise focusing on senders showing significant mail volume in DMARC reports, as these are typically legitimate services (even if previously unrecognized) or clear indicators of malicious activity.

Key considerations

• Distinguishing failure types: It is important to understand why DMARC fails, differentiating between issues like SPF or DKIM misconfiguration, email forwarding complexities, and genuine spoofing attempts. For more details on why authentication might fail, check out why DMARC authentication fails.
• Email forwarding impact: Email forwarding often breaks SPF authentication (due to changes in the Mail From path), leading to DMARC failures. Understanding how email forwarding affects DMARC is critical.
• Identifying unknown legitimate sources: Beyond obvious ESPs, various other services might send emails on your domain's behalf (e.g., cloud hosting, HR platforms, internal systems). DMARC reports are essential for discovering these unrecognized sending sources.
• Proactive monitoring: Consistent monitoring of DMARC reports allows for proactive identification and mitigation of issues, improving overall email security and preventing your domain from appearing on a blocklist or blacklist.
• Prioritizing issues: Not all failures are equally severe. Prioritize investigation into significant volumes of unexplained failures, especially those that could indicate active spoofing or major misconfigurations.

Key findings

• Report types: DMARC produces two main types of reports: aggregate reports (RUA), which summarize authentication results, and forensic reports (RUF), which provide detailed information on individual failures. GoDMARC explains the different purposes of these reports.
• Authentication standards: DMARC relies on the successful authentication of SPF and DKIM. Reports detail the results for each protocol for incoming emails purporting to be from your domain.
• Identifier alignment: A key concept in DMARC is identifier alignment, where the domain in the RFC5322.From header (visible to the user) must match the domain used for SPF or DKIM authentication. Failures often occur when this alignment is broken.
• Policy application: DMARC reports indicate whether the DMARC policy (p=none, p=quarantine, or p=reject) was applied to non-compliant emails and the outcome.
• Source identification: Reports list the IP addresses and hostnames of servers sending mail using your domain, allowing you to identify all sources, both authorized and unauthorized.

Key considerations

• Data structure: DMARC aggregate reports are typically sent in XML format. Understanding this structure is crucial for manual parsing or for selecting a tool that can effectively interpret it.
• Monitoring unauthorized sources: The information contained in RUA and RUF reports is vital for identifying and addressing any unauthorized senders using your domain for malicious activities like phishing.
• Policy progression: Documentation supports a phased approach to DMARC policy enforcement, starting with monitoring (`p=none`) to gather data before moving to `p=quarantine` or `p=reject`.
• Report analysis: While reports can be dense, the core purpose is to provide visibility into email streams, helping you secure your domain. DuoCircle details what a DMARC aggregate report provides.
• Troubleshooting issues: DMARC reports are the primary source for debugging authentication failures, helping to refine SPF and DKIM configurations for legitimate sending services.