How to set up DMARC
DMARC tells receivers what to do with mail that fails checks and sends you reports.
Why it matters
DMARC is what actually stops scammers emailing your customers from your domain. Gmail and Yahoo require it for bulk senders, and the reports show who is sending as you.
Steps
- Make sure SPF and DKIM are working first.
- Add a TXT record named _dmarc with a monitoring policy.
- Read the reports for a few weeks.
- Tighten the policy from none to quarantine, then reject.
For your developer
v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com
Check it worked
Rescan after the DNS change has spread. In Gmail's "Show original" view, DMARC should read PASS, and reports will start arriving at the address in rua.
Not sure if this affects your site?
Run a free scan to see exactly which of these your website needs.