DMARC stands for Domain-Based Message Authentication, Reporting and Conformance. It has been designed to reduce email abuse. This technology is based on the specifications for DKIM (Domain Keys Identified Mail) and SPF (Sender Policy Framework). A DMARC policy lets you indicate that your emails are protected using the SPF (Sender Policy Framework) and DKIM (Domain Keys Identified Mail) procedures. This policy also lets you specify how the recipient handles emails based on the results of the DKIM and SPF check and notifies you, as the domain owner, of any abuse.
DMARC policies are added in the form of a TXT record. This record is called the DMARC record. It is created with the subdomain name _dmarc (e.g. _dmarc.example.com). The TXT record consists of tags that are separated by semicolons.