DMARC is a proposed internet standard called Domain-based Message Authentication, Reporting & Conformance. Microsoft, Google, Facebook, PayPal, LinkedIn, Bank Of America and others behind it. DMARC doesnt replace SPF or DKIM, but it is predicated upon them, to the point that DMARCs official first step in its implementation guidelines is: Deploy DKIM & SPF. The problem is that few organisations have actually had the guts to use SPF to make a definitive statement about their email practices.”]
Source: https://nakedsecurity.sophos.com/2012/02/02/dmarc-microsoft-facebook-google-unite-to-fight-phishing/