Cybersecurity glossary
What is DMARC?
Also known as: Domain-based Message Authentication, Reporting and Conformance
Definition
DMARC is a DNS policy that tells receiving mail servers what to do with email that fails SPF and DKIM alignment for your domain, and where to send reports about it.
Why it matters
Policies are p=none (monitor only), p=quarantine (treat as suspicious) and p=reject (block). Start with none, use the aggregate reports to find every legitimate sender, then tighten. DMARC prevents exact-domain spoofing but not look-alike domains.
Common questions about DMARC
See also
Sources
Related Guides
GuideGRC
How to Run a Security Awareness Training Program That Changes Behaviour
Build a security awareness and training program that changes behaviour: role-based content, phishing simulations done fairly, policy acknowledgement, metrics that matter and reporting to leadership.
Read more GuidePersonal Security
Binance Hacked: $6.3 Billion Stolen — What Happened and How to Protect Your Crypto
Binance suffered a massive cryptocurrency theft on October 29, 2026. Here's what we know about the breach, what remains unclear, and how to protect your crypto from hackers and increasingly convincing scams.
Read more GuidePersonal Security
10 Ways to Keep Your Funds Safe on a Crypto Exchange After the Binance Hack Reports
Binance is investigating a suspected hot wallet hack. Here are 10 practical steps to protect crypto held on any exchange: account security, withdrawal limits, self-custody and scam awareness.
Read more GuidePersonal Security
How to Turn On MFA for Your Most Important Accounts
Learn how to turn on MFA across your email, financial, and business accounts. Follow practical steps to configure authenticator apps and passkeys securely.
Read more