Domain-Based Message Authentication, Reporting and Conformance (DMARC) 

The DMARC product was created to call attention to an email authentication policy that protects against bad actors using fake email addresses disguised to look like legitimate emails from trusted sources. DMARC makes it easier for email senders and receivers to determine whether or not an email legitimately originated from the identified sender. Further, DMARC provides the user with instructions for handling the email if it is fraudulent.