Gmail and Yahoo now expect bulk senders to publish a DMARC record. It tells mailbox providers what to do with mail that claims to be from your domain but fails SPF and DKIM. Here is how to add one safely.
1. Make sure SPF and DKIM pass first
Add your domain in Delivrie and publish the DKIM and SPF records it shows you. Wait until the domain says Verified. DMARC only helps once these pass.
2. Start in monitoring mode
_dmarc.yourdomain.com TXT "v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com"With p=none nothing is blocked. You receive daily reports showing who sends as your domain, so you can find tools you forgot about, like your invoicing app or CRM.
3. Tighten the policy
After a week or two of clean reports, change p=none to p=quarantine, then later to p=reject. Mail that fails authentication then goes to spam or is refused, which protects your customers from phishing.
Where to add the record
In your DNS provider, create a TXT record with the host _dmarc (some providers want _dmarc.yourdomain.com) and paste the value. Changes usually appear within minutes but can take a few hours. Read more in the DMARC docs.
