What is DMARC?

DMARC is an email-authentication DNS record that tells receiving mail servers what to do with messages that fail SPF or DKIM checks for your domain, and where to send reports.

A DMARC record lives at _dmarc.yourdomain.com, for example v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com. The policy p=none only monitors, p=quarantine sends failing mail to spam, and p=reject blocks it.

Without an enforced DMARC policy, attackers can send phishing email that appears to come from your exact domain. Gmail and Yahoo require DMARC from bulk senders.