Domain-based Message Authentication, Reporting, and Conformance (DMARC): an email authentication policy that uses SPF/DKIM alignment and feedback reports to tell receivers how to handle messages claiming to be from your domain.
For information about DMARC, please view guidance on this topic from the following resources:
- the Cybersecurity and Infrastructure Security Agency (CISA);
- the National Institute of Standards and Technology (NIST).