DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM by adding a reporting function. It allows domain owners to publish policies related to email authentication and specify how receiving mail servers should handle messages that fail SPF or DKIM checks. To implement DMARC, you need to publish a DMARC record in your DNS settings. This record will include policies for handling failed checks and provide an email address for receiving reports about email activity.