This error message signifies that an email transmission failed because it didn’t comply with the sender’s Domain-based Message Authentication, Reporting & Conformance (DMARC) policy. Specifically, the recipient’s mail server evaluated the email against the sender’s DMARC record and determined that the message failed authentication checks. This could be due to a failure in either the Sender Policy Framework (SPF) or DomainKeys Identified Mail (DKIM) authentication mechanisms, as interpreted by the DMARC policy. As an example, if a sender’s DMARC policy is set to “reject” and an email fails SPF and DKIM checks, the recipient’s server will refuse to accept the message and generate this specific error code.
Understanding this rejection reason is crucial for maintaining email deliverability and ensuring the authenticity of messages. It highlights the importance of properly configuring SPF and DKIM records for a domain and aligning them with a clearly defined DMARC policy. Implementing these measures helps protect a domain’s reputation by preventing unauthorized use of its email addresses for phishing or spam campaigns. Historically, the rise of email spoofing and phishing led to the development and adoption of DMARC as a standardized method for email authentication and reporting.