Why is GPT showing DKIM/DMARC authentication failures despite correct DNS records?

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.

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.

Email marketer from AuthSMTP answers that on shared hosting, other users may be sending spam which will effect your domain reputation causing failure.

Email marketer from Mailjet explains that even if you've correctly configured your DNS records, it can take some time for these changes to propagate across the internet. During this propagation period, some servers might still be using outdated information, leading to authentication failures. It is also important to verify the records with a DNS lookup tool.

Email marketer from Email on Acid Support shares that in rare cases, DNS records might resolve differently in different geographic regions. This means that your records might be correct in one region but not in another, causing intermittent authentication failures. Using a global DNS checker can help identify these issues.

Email marketer from SparkPost explains that even a minor typo in your DKIM or DMARC records can cause authentication failures. Double-check your records for any errors, such as incorrect syntax, missing semicolons, or extra spaces.

Email marketer from MXToolbox answers that having multiple SPF records can invalidate your authentication. You should have a single SPF record that includes all authorized sending sources.

Email marketer from GlockApps that DNS records can be set up correctly but not work in a test environment, testing your DNS configuration records with a 3rd party testing tool is advisable.

Email marketer from StackOverflow responds that if you are sending email from a subdomain, ensure that the DKIM and DMARC records are set up correctly for the subdomain and not just the main domain. Subdomain delegation can sometimes cause authentication issues if not properly configured.

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.

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.

Expert from Word to the Wise explains that DMARC failures can occur if there are changes to the organizational domain which are not reflected in the subdomain DNS records. It can also arise if compliancy dashboard in GPT is set to organisational domain when looking at a subdomain.

Expert from Email Geeks shares that DKIM failing indicates a signature failure and that SPF success rate from Hubspot won't reflect SPF for Hubspot mail, rather 1:1 mail for the domain.

Expert from Email Geeks suggests using a third-party DMARC reporting tool as DMARC reports are not human-readable and need to be processed by a system.

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.

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.

Documentation from Google Workspace Admin Help explains that if you've recently rotated your DKIM keys, ensure that both the old and new keys are valid and published in your DNS records during the transition period. If the receiving server uses the old key while it's being phased out, authentication will fail.

Email marketer from DKIM standard answers that DKIM standard may not be met if key size is below 1024 bits which can cause failure.

Documentation from RFC 7208 details that SPF specifications limit the number of DNS lookups that can be performed during SPF evaluation. If your SPF record requires too many lookups (e.g., through multiple 'include:' mechanisms), the SPF check may return a 'permerror' or 'temperror', leading to authentication failure.