Summary
Unexpected email blocks after setting up DMARC can be confusing, especially if your initial policy is set to 'p=none'. While 'p=none' is designed to be a monitoring-only policy that shouldn't impact deliverability, other factors can lead to blocks. These issues often stem from misconfigurations in SPF or DKIM, how recipient mail servers interpret authentication, or problems with email forwarding.
Key findings
- P=none policy: A DMARC policy of 'p=none' (monitor-only) should not directly cause email blocks, as its purpose is to collect reports without enforcing any action on failing emails.
- Indirect blocks: Blocks observed after DMARC setup might be due to underlying SPF or DKIM misconfigurations that DMARC highlights, or how receiving servers handle authentication. For more details, see our guide on emails failing DMARC checks.
- Bounce messages: The lack of specific DMARC-related bounce messages (despite DMARC being set up) suggests the blocks might be due to other factors or a misinterpretation of logs. Original bounce codes are crucial for diagnosis.
- IP address issues: Blocking an unexpected IP can indicate a bad forwarder breaking SPF or a recipient-side misconfiguration where incorrect IPs are checked against your messages.
- Troubleshooting: Effective troubleshooting requires examining raw email headers and bounce codes, not just summarized logs. Learn more about why legitimate email fails DMARC.
Key considerations
- Verify DMARC policy: Confirm that your DMARC policy is indeed 'p=none'. If it's 'quarantine' or 'reject', then blocks are expected for unauthenticated mail. For more information on policy types, refer to this eSecurity Planet article about DMARC setup.
- Review SPF and DKIM: Even with 'p=none', DMARC provides visibility. The blocks might indicate pre-existing SPF or DKIM failures that are now being reported, or that recipient servers are enforcing their own authentication rules more strictly.
- Analyze full headers: Request full email headers from recipients who experience blocks. This will reveal the complete authentication path and any failure reasons. Pay close attention to authentication results like SPF, DKIM, and DMARC alignment.
- Examine DMARC reports: Utilize your DMARC aggregate reports to identify sources of emails that are failing DMARC authentication. These reports are invaluable for understanding your email ecosystem.
What email marketers say
Email marketers often find themselves in a puzzling situation when email blocks occur unexpectedly after DMARC implementation, especially when they've initially adopted a 'p=none' policy. Their experiences highlight the need for clear understanding of bounce messages and the complex interplay between DMARC, SPF, DKIM, and recipient server behaviors. Many marketers seek clearer insights into why seemingly compliant emails are still encountering delivery issues.
Key opinions
- Unexpected blocks: Marketers frequently report seeing an increase in email blocks or rejections immediately after setting up DMARC, even when their intention was only to monitor.
- Log limitations: Accessing recipient logs is often possible, but the actual bounce messages within their interface may lack sufficient detail to diagnose the root cause of blocks.
- Misidentified IPs: A common concern is when an IP address that should not be involved in the sending process appears to be the reason for a block, indicating a deeper issue.
- Spam folder issues: Some marketers find emails landing in spam folders despite DMARC, SPF, and DKIM being configured, suggesting that authentication alone isn't always enough. Learn more about why emails go to spam.
Key considerations
- Request full bounces: Always strive to get the original, raw bounce codes and messages from the receiving server, as summarized logs often hide critical diagnostic information. This is key to troubleshooting DMARC failures.
- Monitor DMARC reports: Even with 'p=none', DMARC aggregate reports (RUA) provide valuable data on which IPs are sending mail on your behalf and whether it's passing authentication. This data can reveal unexpected sending sources.
- Check email headers: When troubleshooting, ask for the full email headers from a recipient who successfully received your email, then analyze the authentication results section to ensure SPF, DKIM, and DMARC are aligning correctly. Kinsta offers a detailed guide on how to fix DMARC fail errors.
Marketer view
Marketer from Email Geeks notes that since setting up DMARC, they have been observing blocks, and wonders if this behavior is expected.
Marketer view
Marketer from Email Geeks reports that while they can see recipient logs via their interface, the bounce messages themselves do not provide enough detail within the interface to pinpoint the issue.
What the experts say
Experts in email deliverability emphasize that a DMARC 'p=none' policy should indeed have no impact on email delivery, as its role is purely for monitoring. When unexpected blocks occur, the focus shifts to deeper diagnostic issues such as misconfigured forwarders, recipient-side validation errors, or subtle SPF/DKIM alignment problems. They consistently advise reviewing raw bounce data and email headers for accurate troubleshooting.
Key opinions
- Raw bounce data is key: Without access to the original bounce codes and messages, it is extremely difficult to diagnose the actual issue causing blocks. Summarized reports are often insufficient.
- P=none should not block: If a DMARC record is correctly configured with 'p=none', there should be no change to email delivery or blocks as a direct result of DMARC enforcement.
- Forwarders or recipient configuration: Unexpected blocks might stem from a bad forwarder that breaks SPF authentication or a misconfiguration on the recipient's side, leading them to check incorrect IPs against incoming messages. For more on this, see demystifying SPF TempError.
- Header analysis: Offering to examine email headers for a test email is a crucial step in pinpointing the exact cause of deliverability issues. This is often the first step in troubleshooting DMARC failure reports.
Key considerations
- Isolate the issue: Determine if the blocks are truly DMARC-related or a symptom of broader authentication issues (SPF, DKIM) that DMARC is now reporting. Sometimes, a DMARC record check may activate an action if misalignment is detected.
- Check for SPF failures: Email forwarding is a common culprit for SPF failures, as the original sender's IP changes. Ensure your SPF record accounts for all legitimate sending sources.
- DKIM verification: Ensure your DKIM signatures are correctly applied and validated, as DMARC relies on either SPF or DKIM (or both) to pass alignment.
- Engage recipients: When possible, communicate with recipient postmasters to understand their specific filtering rules and receive detailed bounce logs or header analyses.
Expert view
Expert from Email Geeks suggests that the reported issue of unexpected IP blocks is likely due to either a problematic email forwarder that is breaking the SPF authentication, or a misconfiguration on the recipient's mail server that incorrectly checks IPs against the incoming messages.
Expert view
Expert from Email Geeks states that the user's DMARC record appears to be correctly configured, emphasizing that a 'p=none' policy should not cause any changes to email delivery or result in blocks.
What the documentation says
Official documentation and technical guides generally outline DMARC as an authentication protocol that allows domain owners to protect their domain from unauthorized use. When set to 'p=none', DMARC is designed purely for reporting, providing visibility into email streams without dictating enforcement actions. Blocks occurring at this stage usually point to issues with underlying SPF or DKIM mechanisms, or specific recipient server policies.
Key findings
- DMARC's function: DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol that uses SPF and DKIM to prevent email spoofing and phishing.
- Policy types: The 'p=none' policy (also known as 'monitoring mode') instructs receiving servers to report on DMARC failures without taking any action against the email, such as quarantining or rejecting it. This is explained in our guide to simple DMARC examples.
- Alignment requirement: DMARC requires either SPF or DKIM to align with the 'From' domain in the email header. If both fail alignment, DMARC will fail.
- Reporting mechanisms: DMARC reports provide aggregate data (RUA) on email authentication results and can optionally send forensic reports (RUF) detailing specific failures. These are vital for understanding DMARC reports.
Key considerations
- Underlying failures: Blocks observed after implementing 'p=none' often point to pre-existing SPF or DKIM failures that are now being reported, rather than DMARC itself causing the block.
- Third-party senders: Ensure all legitimate third-party email senders (like marketing platforms or transactional email services) are correctly authorized in your SPF record and are signing emails with DKIM that aligns with your domain. Rackspace's documentation explains how DMARC enforces SPF and DKIM.
- Sender reputation: Even with perfect DMARC alignment, poor sender reputation (e.g., due to spam complaints or hitting spam traps) can lead to blocks or spam folder placement by receiving mail servers.
- Review DMARC reports: Regularly review aggregate DMARC reports to identify all sending IPs for your domain and verify their authentication status. Unexpected IPs or consistent failures indicate sources that need to be addressed.
Technical article
Documentation from Kinsta states that the DMARC fail error means an email did not pass the DMARC authentication process, and can often be fixed by configuring SPF, DKIM, and DMARC correctly.
Technical article
Documentation from Cisco explains that DMARC activates an action when it detects a misalignment between the email sender and the address as perceived by the recipient, which can lead to emails being blocked or quarantined.
Related resources
12 resources
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