Why am I seeing Yahoo email errors with DKIM failing even though SPF and DMARC pass?

Email marketer from StackOverflow user explains that intermittent DNS issues can cause temporary DKIM failures. They recommend checking DNS propagation and stability.

Email marketer from SparkPost explains ensuring the DKIM signing process is consistently applied to outgoing emails. SparkPost mentions issues with sporadic DKIM signing which means not every email is signed, it can cause deliverability problems.

Email marketer from Zerobounce shares that even with valid DKIM records, issues with domain reputation can result in deliverability failures, especially on services like Yahoo which may scrutinize senders with low reputation

Email marketer from Reddit user suggests that Yahoo's stricter DMARC policy implementation may cause issues even if DKIM technically passes. They recommend ensuring perfect alignment and monitoring sender reputation.

Email marketer from Email on Acid advises checking if the email content is being modified in transit by any intermediate servers, as this can invalidate the DKIM signature. Look for added footers or altered headers.

Email marketer from GlockApps highlights the importance of registering for Yahoo's feedback loop to receive reports on potential issues affecting deliverability, including DKIM failures.

Marketer from Email Geeks confirms they are experiencing pervasive Yahoo policy blocks for a client, with no luck getting it mitigated.

Email marketer from MXToolbox shares that using their DKIM record lookup tool can help identify if the published DKIM record is valid and reachable. They also recommend checking if the selector in use is the correct one.

Email marketer from Litmus recommends verifying that the DKIM record is correctly formatted and doesn't contain any syntax errors, which can prevent successful authentication.

Email marketer from Postmark indicates that insufficient DKIM key sizes (less than 1024 bits) can lead to failures. They suggest upgrading to a 2048-bit key for better security and compliance.

Email marketer from Mailhardener advises checking for DKIM alignment, which means ensuring the domain used to sign the email matches the domain displayed in the 'From' address. Mismatches can lead to DKIM failures even with valid signatures.

Expert from Email Geeks suggests temporarily changing the DMARC policy from p=reject to p=none to determine if the issue is DMARC-related.

Expert from Email Geeks explains that DKIM Perm fail can be caused by deleting the public DKIM key from DNS, misconfiguring the MTA, or a DNS server being down.

Expert from Email Geeks suggests that policy issues may not be DMARC related and asks if duplicate headers are present.

Expert from Word to the Wise (Laura Belsten) shares that if DKIM is failing despite SPF and DMARC passing, you should set up DMARC aggregate reports to identify which specific emails are failing DKIM and investigate potential alignment issues.

Expert from Email Geeks suggests that if the SPF string and 5322.from don’t align and DKIM is failing, the mail might be rejected due to DMARC failure.

Expert from Email Geeks mentions that online DKIM checkers typically only validate the DNS record and not the actual signature which means there may be a problem with the encoding of the message, leading to the DKIM failure on the email message.

Expert from Spam Resource (John Levine) explains that even if SPF and DMARC pass, a DKIM failure suggests Yahoo is specifically rejecting the message due to a detected invalid DKIM signature, and this could be caused by alterations to the message content in transit.

Documentation from ietf.org (RFC 6376) states that DKIM verification can fail (return PERMFAIL) if the signature is syntactically incorrect, the public key is unavailable, the signature does not verify, or the message has been altered since signing.

Documentation from Yahoo Help explains that a DKIM failure, even with passing SPF and DMARC, can occur if the DKIM signature is invalid due to modifications to the email content during transit or if the signing domain doesn't match the domain in the 'From' header.

Documentation from Google workspace shares information about ensuring your DNS records for DKIM, SPF and DMARC have propagated and are available on global DNS servers

Documentation from AuthSMTP explains that a DKIM selector is used to locate the correct public key in DNS. If the selector used to sign the email doesn't match the one configured in DNS, DKIM will fail.

Documentation from DKIM.org emphasizes that troubleshooting DKIM failures requires examining the email headers, DNS records, and mail server logs to identify the cause, such as incorrect key deployment or message modification.