What is an email spoofing policy (DMARC)?
DMARC stands for “Domain-based Message Authentication, Reporting and Conformance”. It’s an email validation system designed to protect your company’s email domain from being used for email spoofing, phishing scams and other cyber-crimes.
DMARC empowers SPF by stating a clear policy which should be applied and allows to set an email address which can be used to send the statistics reports regarding a specific domain. Both methods use DNS (Domain Name Service). This gives you, as an email sender, the ability to specify which email servers are permitted to send email on behalf of your domain.
See full article here, including how to implement SPF and DMARC for sending and parked domains.