Domain based Message Authentication, Reporting and Conformance (DMARC) was conceived to allow email senders to specify policy on how their mail should be handled, the types of reports that receivers can send back, and the frequency those reports should be sent. Standardized handling of SPF and DKIM removes guesswork about whether a given message is authentic, benefitting receivers by allowing more certainty in quarantining and rejecting inauthentic mail.
In particular, receivers compare the "From" address in the message to the SPF and DKIM results, if present, and the DMARC policy in the DNS. The results are used to determine how the mail should be handled. The receiver sends reports to the domain owner about mail claiming to originate from their domain. These reports should illuminate the extent to which unauthorized users are using the domain, and the proportion of mail received that is "good."
- NIST Special Publication 800-177, at vi.