Authentication-Results is a header added by receiving servers that records SPF/DKIM/DMARC checks. Learn how to read it and troubleshoot deliverability.
Authentication-Results is an email header that receiving systems add to record the outcome of authentication checks like SPF, DKIM, and DMARC. It’s one of the fastest ways to see what the receiver concluded about a message.
This header typically includes pass/fail results and sometimes details like which domain was evaluated and which selector was used. Because it reflects the receiver’s view, it’s especially useful when diagnosing inconsistent inbox placement.
When troubleshooting, compare Authentication-Results with your DNS records and confirm alignment. Small differences like using a subdomain in DKIM or a different envelope-from domain can explain a DMARC fail even when SPF or DKIM shows pass.