Even with seemingly correct DNS records, Google Postmaster Tools (GPT) can display DKIM/DMARC authentication failures due to a multitude of factors. These include Google's analysis of received emails beyond just DNS records, potential spoofing or signature failures, limitations in SPF records from platforms like Hubspot, issues in DMARC policy enforcement due to alignment failures, incorrect DKIM key rotations, problems arising from email forwarding or subdomain delegation, differences in regional DNS resolutions, exceeding SPF lookup limits, having multiple SPF records, impacts from shared hosting environments, the necessity to test configurations, the impact of organizational domain compliancy being set to organizational when it should be set to subdomain, incorrect domain record set ups, DMARC key sizes being below 1024 bits and DNS propogation delays. This emphasizes the need for detailed investigations beyond basic DNS record checks.
9 marketer opinions
GPT might report DKIM/DMARC authentication failures despite seemingly correct DNS records due to various reasons. These include: propagation delays after DNS changes, typos in DNS records, DMARC policy enforcement issues, incorrect DKIM key rotation, email forwarding problems, incorrect subdomain delegation, regional DNS differences, exceeding SPF lookup limits, multiple SPF records, shared hosting issues impacting reputation, and the necessity for third-party testing to confirm configurations.
Marketer view
Marketer from Email Geeks suggests that GPT reports on both authorized and unauthorized use of a domain and recommends checking the IP address screen in GPT to identify unfamiliar IPs.
4 Apr 2024 - Email Geeks
Marketer view
Email marketer from Reddit shares that when emails are forwarded, the SPF record of the original sender might not match the forwarding server, causing SPF to fail. While DKIM could still pass if set up correctly, DMARC may fail due to SPF misalignment.
29 Apr 2025 - Reddit
5 expert opinions
Even with correct DNS records, Google Postmaster Tools (GPT) can show DKIM/DMARC authentication failures due to several factors. These include the fact that Google evaluates emails received and not just DNS records, potential issues of signature failures, spoofing, or reliance on SPF results which may not reflect the entire email stream if using third party platforms like Hubspot. Failures can also stem from discrepancies between organizational domain configurations and subdomain records, and needing to use third-party tools to correctly setup a DMARC record.
Expert view
Expert from Email Geeks explains that Google looks at the email it's receiving, not just the DNS records. Even if DNS records are fine, authentication can still be broken, and suggests that something may have broken or spoofing may be occurring.
26 May 2022 - Email Geeks
Expert view
Expert from Spamresource.com suggests that there are several reasons for failure, but to check common misconfigurations such as incorrect record syntax, propagation delays after updates, and alignment issues where the domain in the 'From' address doesn't match the domain used for DKIM signing or SPF authorization. They recommend using third party tools to confirm configurations work.
2 May 2023 - Spamresource.com
5 technical articles
Even when DNS records appear correct, Google Postmaster Tools (GPT) may show DKIM/DMARC authentication failures for several technical reasons. These include DMARC policy enforcement when alignment fails despite passing SPF/DKIM, issues related to DKIM key rotation, incomplete SPF records that do not include IPv6 addresses, exceeding SPF lookup limits, or using a DKIM key size below 1024 bits.
Technical article
Documentation from Microsoft explains that SPF records need to include IPv6 addresses if you are sending mail from IPv6 addresses. An incomplete SPF record that only lists IPv4 addresses will cause SPF to fail for IPv6 mail streams.
7 Jul 2023 - Microsoft Documentation
Technical article
Documentation from DMARC.org explains that if your DMARC policy is set to 'p=quarantine' or 'p=reject', email receivers will enforce the policy even if SPF and DKIM pass, but alignment fails. Alignment refers to the domain used in the 'From' address matching the DKIM signing domain or SPF authorized domain.
30 Dec 2023 - DMARC.org
How do I troubleshoot and fix SPF and DMARC settings for email deliverability issues?
How to diagnose DMARC failures using DMARC reports?
How to deal with a failing DMARC email authentication protocol?
How do I properly set up DMARC records and reporting for email authentication?
How can I troubleshoot DMARC failures and identify the cause of authentication issues?
How do I troubleshoot DMARC failures and potential DKIM replay attacks affecting email deliverability?
© 2025 Suped Pty Ltd