DMARC

DMARC (Domain-based Message Authentication, Reporting and Conformance) is a standard that improves the security of your emails through sender authenticity verification by using SPF and DKIM mechanisms. DMARC allows the senders to specify which actions must be taken with the emails that do not pass verification and provides reports about fraud attempts.

First, you must decide whether to implement either restrictive (reject or quarantine) or neutral (none) DMARC policy. It tells the recipient servers how to proceed with unvalidated messages.