Is DMARC essential for email deliverability and what to do when Return Path reports spam issues with good open rates?

Key findings

• DMARC function: DMARC acts as a policy layer, instructing recipient servers on how to handle emails that fail SPF or DKIM authentication and alignment checks.
• Delivery impact: Unlike SPF and DKIM, a missing DMARC record will not directly cause email bounces, but its absence leaves your domain vulnerable to impersonation and phishing.
• Insightful reporting: DMARC generates aggregate and forensic reports, offering valuable visibility into authentication problems and potential fraudulent use of your domain. You can learn more about interpreting these reports in our guide how to interpret DMARC reports.
• Seed list limitations: Return Path's 100% spam reports for seeds do not necessarily reflect the deliverability of all your emails to actual subscribers, as seed lists can behave differently than real user inboxes.
• Open rate reliability: While open rates are a key metric for marketers, internet service providers (ISPs) often use a broader set of internal data and engagement signals to determine inbox placement, making your reported open rates a partial picture.

Key considerations

• Phased DMARC implementation: Begin with a 'p=none' DMARC policy to gather data without impacting delivery, then gradually move to 'quarantine' or 'reject' after thorough analysis.
• Consistent monitoring: Regularly review your DMARC reports (RUA and RUF) to identify all legitimate sending sources and any unauthorized use of your domain. This ensures that only authorized senders are emailing on your behalf.
• Reputation safeguarding: Even with current good open rates, consistent spam placements (especially observed through seed lists) can cumulatively damage sender reputation over time, potentially impacting future deliverability.
• Audience alignment: While focusing on engaged subscribers is beneficial, ensure that volume changes align with ISP expectations, particularly during processes like IP warming. This helps maintain a stable sender reputation.
• Comprehensive analysis: Avoid relying solely on a single metric or tool. Combine data from your email service provider (ESP), Google Postmaster Tools, and other testing tools for a complete and accurate view of your deliverability. For more on Google Postmaster Tools, see this guide from Mailgun.

Key opinions

• DMARC for protection: Many marketers primarily see DMARC's value in protecting their domain from spoofing and phishing, which indirectly protects their sender reputation.
• Deliverability perceptions: Some marketers believe DMARC is not a strict requirement for email delivery, differentiating it from core protocols like SPF and DKIM.
• BIMI prerequisite: It is widely recognized that DMARC, particularly at an enforcement policy, is a necessary step for implementing BIMI (Brand Indicators for Message Identification).
• Conflicting data: Marketers frequently express confusion when deliverability monitoring tools, such as Return Path, report high spam rates while their own campaign open rates remain strong, leading to questions about data accuracy.
• IP warming expectations: During IP warming, marketers generally expect that some emails may initially land in the bulk or spam folder, anticipating improvement in inbox placement over time.

Key considerations

• Clarify DMARC's purpose: Marketers should understand that DMARC's primary role is in authentication and reporting, which supports deliverability by enhancing trust, rather than directly controlling inbox placement. For more, see our guide on DMARC, SPF, and DKIM.
• Prioritize authentication: Ensure SPF and DKIM are correctly configured first, as their failures can lead to immediate bounces. DMARC builds upon these foundations.
• Investigate discrepancies: When monitoring tools show unfavorable results that conflict with internal metrics, it is crucial to investigate the underlying reasons for the discrepancy. This might involve looking into different data points or how the monitoring tool collects its data.
• Monitor reputation trends: Focus on long-term trends in inbox placement, bounce rates, and spam complaints across major ISPs rather than isolated data points. This provides a more accurate view of your sender reputation.
• Optimize audience engagement: Continually refine audience segmentation to target highly engaged users. This practice positively impacts sender reputation and overall deliverability, as engaged recipients send positive signals to ISPs. For more on improving engagement, check out this guide on email deliverability audits.

Key opinions

• Core function: Experts agree that DMARC's primary function is to prevent unauthorized entities from sending emails using your domain, providing a policy framework for how receiving servers should handle unauthenticated messages.
• Indirect deliverability impact: While not a direct inbox placement tool, DMARC is crucial for fostering trust and protecting brand reputation, which indirectly supports deliverability.
• Reporting value: The reporting capabilities of DMARC are highlighted as critical for gaining comprehensive visibility into email flows and quickly identifying any authentication issues or abuse.
• Seed list nuances: Experts explain that seed lists from providers like Return Path might not perfectly reflect real-world inbox placement, as they are a specific set of addresses used for testing, not live user inboxes.
• Early warnings: Discrepancies between seed list performance and strong open rates are often considered potential early warning signs of underlying reputation issues that warrant proactive investigation and attention.

Key considerations

• Proactive DMARC deployment: It is crucial to implement DMARC to prevent spoofing and gain visibility into email authentication practices, ideally progressing to an enforcement policy (quarantine or reject) over time. Find out how to implement DMARC p=reject safely.
• Holistic data analysis: Experts advise looking beyond just open rates and Return Path data. It's important to consider trends in raw open numbers, Google Postmaster Tools data, and other engagement metrics for a comprehensive and accurate picture.
• Address underlying reputation: If seed list data suggests issues, even when coupled with good open rates, investigate potential problems with subscriber acquisition, engagement, or content that might be quietly impacting your sender reputation.
• Understand ISP metrics: Recognize that ISPs calculate engagement and reputation using proprietary algorithms and a broader range of signals than what marketers typically track through their platforms. This nuance is critical for effective deliverability management.
• Long-term strategy: Deliverability is a continuous effort. Small, consistent issues, such as some mail going to the bulk folder, can accumulate over time and lead to significant problems if not addressed proactively. This is highlighted in Mailgun's blog on DMARC and email deliverability.

Key findings

• Complementary protocols: DMARC (Domain-based Message Authentication, Reporting & Conformance) is explicitly designed to work in conjunction with existing SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) authentication standards.
• Policy enforcement: Documentation specifies that DMARC allows domain owners to publish a policy in their DNS, instructing receiving mail servers on how to handle emails that fail both SPF or DKIM authentication and alignment checks.
• Reporting capabilities: DMARC enables senders to receive comprehensive aggregate (RUA) and forensic (RUF) reports. These reports provide crucial visibility into who is sending email on behalf of their domain, both authorized and unauthorized.
• Enhanced security: By defining a clear policy for unauthenticated mail, DMARC significantly helps in preventing phishing, email spoofing, and other forms of email abuse, thereby protecting the sender's brand and their recipients.
• Identity alignment: For an email to pass DMARC, either SPF or DKIM must pass and, crucially, the domain used for that authentication must align with the domain in the From: header (RFC 5322.From). This alignment is a stronger requirement than SPF or DKIM alone.

Key considerations

• Incremental deployment: Official documentation frequently advises a gradual DMARC rollout, starting with a 'p=none' policy to monitor email flows without affecting deliverability, before transitioning to more stringent 'quarantine' or 'reject' policies.
• Accurate DNS records: Proper and accurate configuration of DMARC, SPF, and DKIM records in DNS is absolutely paramount for successful email authentication and optimal deliverability.
• Active report analysis: Senders are encouraged to actively analyze DMARC reports to identify all legitimate sending sources and quickly detect any unauthorized senders, allowing for timely policy adjustments and mitigation.
• Sender reputation impact: Implementing DMARC (especially with an enforcement policy) can significantly improve sender reputation by clearly demonstrating the domain owner's commitment to email security and integrity. Mailgun's blog states that DMARC helps improve email delivery rate.
• ISP compliance: Major ISPs increasingly rely on DMARC, alongside SPF and DKIM, as a strong signal for legitimate email traffic. This compliance directly influences inbox placement and overall deliverability.