Domain-based Message Authentication, Reporting, and Conformance (DMARC) is an email authentication protocol that prevents domain spoofing. Attackers often use illegitimate means to send malicious emails using domain names associated with trusted brands or individuals. These emails may ask recipients to click on unsafe links or enter their login information. Unfortunately, recipients often struggle to distinguish between genuine and fake emails, putting sensitive company data at significant risk.

More at https://support.powerdmarc.com/support/solutions/articles/60000676275-what-is-dmarc-