Summary
Implementing a DMARC policy, particularly a strict 'reject' policy, can significantly impact email deliverability if not done carefully. A common pitfall is moving directly to p=reject without adequate monitoring and ensuring all legitimate sending sources are properly authenticated with SPF and DKIM alignment. When a DMARC record instructs receiving mail servers to reject emails that fail authentication, any legitimate emails not correctly set up can be blocked from reaching the inbox.
Key findings
- Immediate impact: Switching to a DMARC 'reject' policy without proper preparation often leads to an immediate and significant drop in email delivery rates.
- Authentication failure: Low delivery rates are typically caused by legitimate emails failing DMARC authentication, meaning they do not align with either SPF or DKIM records.
- Policy mismanagement: Implementing 'p=reject' prematurely, especially for root domains, without first verifying all sending sources, is a critical error.
- ESP limitations: Some ESPs (email service providers) might not inherently support DMARC alignment for all sending methods, necessitating custom configurations or subdomains.
- Misinformation: Advice to jump directly to 'p=reject' without a phased rollout and thorough monitoring is often misguided and can cause severe deliverability issues.
Key considerations
- Policy adjustment: The most crucial immediate step is to revert the DMARC policy to p=none to prevent further email rejection and allow legitimate emails to deliver.
- Authentication verification: Before enforcing a stricter policy, verify that all email sending sources are correctly authenticating with SPF and DKIM, and that DMARC alignment is achieved.
- DMARC reporting: Utilize DMARC aggregate reports to identify all legitimate sending sources and those failing authentication. This requires a dedicated DMARC monitoring platform. (See Understanding DMARC policies for more on this process.)
- Phased implementation: Transition gradually from 'p=none' to 'p=quarantine' and then to 'p=reject', using the 'pct' tag to slowly increase enforcement, ensuring no legitimate mail is affected.
- Expert consultation: Seek assistance from deliverability experts or DMARC specialists if internal resources or ESP support are insufficient for analyzing reports and configuring authentication.
What email marketers say
Email marketers often face significant challenges when implementing DMARC policies, particularly the transition to 'p=reject'. Many report experiencing immediate drops in email delivery rates or even complete cessation of email sending for certain properties. This typically stems from a lack of understanding regarding the stringent authentication requirements of DMARC and the proper phased approach to policy enforcement. Marketers emphasize the frustration of inadequate support from ESPs, highlighting the need for proactive troubleshooting and a deep dive into DMARC reporting.
Key opinions
- Accidental self-rejection: Marketers frequently find their own legitimate emails being rejected because the DMARC 'reject' policy was set up without ensuring all mail sources were correctly authenticated.
- Unprepared implementation: There's a strong consensus that going straight to 'p=reject' before verifying authentication for all sending domains is a common and damaging mistake.
- ESP limitations: Frustration is often expressed regarding ESPs that do not provide sufficient guidance or tools to manage DMARC implementation and troubleshoot deliverability issues effectively.
- Urgency for reversal: The immediate advice from many marketers is to revert to 'p=none' to restore delivery while proper authentication issues are resolved.
- Monitoring is key: Effective DMARC implementation relies heavily on continuous monitoring and analysis of DMARC reports, which many marketers find challenging without specialized tools.
Key considerations
- Immediate policy change: Marketers should immediately change their DMARC policy from 'p=reject' to 'p=none' if experiencing deliverability issues after implementation.
- Authentication checks: Verify SPF and DKIM configurations for all sending sources, including third-party ESPs, to ensure DMARC alignment.
- Leverage DMARC reports: Actively use DMARC aggregate reports to identify which email sources are failing authentication and adjust configurations accordingly. Tools for DMARC reporting are crucial (for example, refer to Switching to Reject: All About DMARC Policy for understanding percentage tags).
- Phased policy rollout: Adopt a gradual approach for transitioning DMARC policies from 'none' to 'quarantine' and then to 'reject', using the 'pct' tag to test the impact on a smaller percentage of emails first.
- Seek help: When facing persistent deliverability issues, it is advisable to seek help from email deliverability specialists or DMARC consultants.
Marketer view
Email marketer from Email Geeks describes experiencing very low delivery rates after implementing DMARC with a p=reject policy, observing rates as low as 11% and 28% for recent sends. They also noted being unable to send tests on another property, suspecting a related issue with the DMARC implementation.
Marketer view
Marketer from Spiceworks Community suggests that the safest way to begin with DMARC is to set the policy to 'p=none'. This initial setting enables logging of DMARC records and provides reporting capabilities without impacting email delivery, allowing for careful monitoring.
What the experts say
Experts in email deliverability consistently caution against the dangers of prematurely deploying a DMARC 'reject' policy. They emphasize that such a strict policy can immediately cause legitimate emails to fail delivery if all sending sources are not perfectly authenticated and aligned. The consensus among experts is to adopt a phased approach, starting with a monitoring-only policy ('p=none') to gather data and identify unauthenticated email streams before gradually moving to stricter enforcement. They also highlight the crucial role of DMARC reporting in this process, providing actionable insights into authentication failures.
Key opinions
- Phased DMARC deployment: Experts strongly advise against directly setting a DMARC policy to 'p=reject' from the outset; instead, a gradual approach beginning with 'p=none' is essential.
- Authentication prerequisites: All sending sources, including those from third-party ESPs, must be fully authenticated and aligned with SPF and DKIM before contemplating a 'reject' policy.
- DMARC reports are critical: Regularly reviewing and understanding DMARC aggregate reports is paramount for identifying and fixing authentication issues.
- Misleading advice: Any recommendation to jump directly to 'p=reject' without comprehensive monitoring and authentication checks is considered irresponsible by experts.
- Value of reject policy: For some organizations, a 'reject' policy might offer minimal additional value compared to 'quarantine' if the primary goal is deliverability, rather than strict anti-spoofing enforcement.
Key considerations
- Revert to monitoring: If experiencing delivery issues due to DMARC, immediately change the policy to 'p=none' to allow mail flow while troubleshooting.
- Monitor and fix: Utilize DMARC reporting to identify unauthenticated mail streams and rectify SPF and DKIM configurations. This phase can take weeks to months.
- Gradual progression: Once authentication is clean, gradually transition to 'p=quarantine' and then 'p=reject', using the 'pct' tag to increment enforcement safely. This systematic approach is covered in DMARC Explained: Five Steps to Email Authentication.
- Understand DMARC alignment: Deeply understand how DMARC requires mail to be authenticated in a specific and aligned way beyond basic SPF and DKIM setup.
- Utilize analytics tools: Leverage tools that analyze email headers and DMARC reports to diagnose authentication issues precisely.
Expert view
Email deliverability expert from Email Geeks strongly advises against immediate p=reject implementation without prior authentication checks, recommending an immediate switch to p=none. They suggest that failure to check authentication beforehand is a critical error.
Expert view
Deliverability consultant from SpamResource highlights that transitioning to a DMARC reject policy should be approached with caution. They advocate for extensive testing and monitoring at 'p=none' and 'p=quarantine' before considering a full 'p=reject' deployment.
What the documentation says
Official DMARC documentation and related technical guides emphasize a cautious and data-driven approach to DMARC policy implementation. They clearly state that the 'reject' policy is the strictest and should only be applied after thorough monitoring and ensuring all legitimate email streams pass DMARC authentication. The documentation often highlights the importance of starting with 'p=none' to gather comprehensive reports, which are crucial for identifying and correcting any authentication gaps. It also outlines the role of the 'pct' (percentage) tag in enabling a gradual rollout of stricter policies.
Key findings
- Phased approach: Documentation consistently recommends a phased DMARC rollout, starting with 'p=none' for monitoring, then 'p=quarantine', and finally 'p=reject'.
- Pre-requisites: Successful DMARC implementation relies on correctly configured SPF and DKIM records and their alignment with the domain in the 'From' header.
- Reporting is crucial: DMARC aggregate reports provide essential data on email authentication results, which are necessary to identify legitimate email sources and fix issues.
- Percentage tag (pct): The 'pct' tag allows for a gradual enforcement of DMARC policies, enabling administrators to apply 'quarantine' or 'reject' to a subset of emails before full deployment.
- Reject policy risk: Implementing 'p=reject' too early can lead to legitimate emails being blocked or sent to spam folders, causing significant deliverability problems.
Key considerations
- Start with 'p=none': Begin with a 'p=none' policy to monitor DMARC compliance without affecting email delivery, gathering data to understand all email streams. More information can be found on use cases for DMARC policies.
- Ensure SPF and DKIM alignment: Confirm that all legitimate email sending sources are properly configured for SPF and DKIM and achieve DMARC alignment. This is critical before moving to stricter policies, as highlighted in Outlook's New Requirements for High‐Volume Senders.
- Analyze reports diligently: Spend ample time (weeks to months) analyzing aggregate DMARC reports to identify all valid sending sources and correct authentication failures.
- Iterative policy progression: Gradually increase the DMARC policy from 'p=none' to 'p=quarantine' and then to 'p=reject', using the 'pct' tag to mitigate risks during the transition.
- Monitor continuously: DMARC implementation is not a one-time setup; ongoing monitoring is essential to adapt to changes in sending infrastructure or third-party senders.
Technical article
Mailjet's documentation outlines that DMARC authentication involves a step-by-step process. This process begins with setting up SPF and DKIM, followed by configuring the DMARC record and email address to receive reports.
Technical article
Fortinet's cyberglossary defines DMARC as an email security protocol. It clarifies that DMARC verifies email senders by building upon existing standards such as the Domain Name System (DNS), DomainKeys Identified Mail (DKIM), and Sender Policy Framework (SPF).
Related resources
12 resources
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