(DMARC) Domain-based Message Authentication, Reporting and Conformance
noun
An email authentication and reporting protocol that extends the Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM), allowing a domain owner to establish a policy in their DNS records to specify which mechanism (DKIM, SPF, or both) is used in sending email from that domain, how to check the "From" field end users see, how a recipient deals with failures, and how actions performed under the polices should be reported. Usually referred to by its acronym, DMARC.