To ensure your messages pass the DMARC check with flying colors, you'll need to make certain the domains listed in the From, Sender, and Mail-From headers match each other exactly. That is, the domain listed in the From header is the exact actual sending domain.

For example, if your sending domain is ABCdomain.com, but your From field shows 123domain.com instead, you will almost certainly run into DMARC issues. Sometimes, even the difference between mail.ABCdomain.com and ABCdomain.com is sufficient for a server to place your message in a spam folder. We make sure that our Email Best Practices are clear that the domain listed in the From header and the actual sending domain should match for exactly this reason.