To set up DMARC, you need to publish a DMARC record in your DNS settings. This record specifies your preferences for how receiving mail servers should handle emails that fail SPF or DKIM checks. Here is an example of a DMARC record: v=DMARC1; p=none; rua=mailto:dmarc-reports@example.com In this example, the "p" tag indicates the policy (none, quarantine, or reject), and the "rua" tag specifies the email address where reports should be sent.