IETF RFC 7489 PDF

Domain‐based Message Authentication, Reporting, and Conformance (DMARC) is a scalable mechanism by which a mail‐originating organization can express domain‐level policies and preferences for message validation, disposition, and reporting, that a mail‐receiving organization can use to improve mail handling.

Domain‐based Message Authentication, Reporting, and Conformance (DMARC) is a scalable mechanism by which a mail‐originating organization can express domain‐level policies and preferences for message validation, disposition, and reporting, that a mail‐receiving organization can use to improve mail handling.

DMARC does not produce or encourage elevated delivery privilege of authenticated email. DMARC is a mechanism for policy distribution that enables increasingly strict handling of messages that fail authentication checks, ranging from no action, through altered delivery, up to message rejection.