DMARC is a validation system designed to prevent email spoofing, where one sender pretends to be another.
The solution also provides good mitigation against sending spam from authority domains.
When you setup Xink re-routing (server-side), your DMARC policy will continue to work - No worries!
To use DMARC you will need to set up SPF and DKIM for your domain (and verify both are correct), before adding the DMARC TXT record to DNS.
Your choices for the policy are none, quarantine or reject. It’s recommended that you start with “none” so you can gauge the impact, especially if you are using third-party mailers to send mail from this domain, before moving to quarantine, or reject.
Value: "v=DMARC1; p=none"
To check the results, send a test message and check the header or use this service:
Domain Health Checker.
Use DKIM to validate outbound email sent from your custom domain in Microsoft 365
Use DMARC to validate email in Microsoft 365
Turn on DMARC for G Suite