Email security
How do I set up DMARC?
Short answer: Make sure SPF and DKIM are working, then add a TXT record at _dmarc.yourdomain.com starting with p=none, and tighten it to quarantine and reject over a few weeks.
The full answer
Step 1: Check that every service that sends email for you (your mailbox provider, newsletter tool, invoicing app) passes SPF or DKIM.
Step 2: Log in to wherever your domain's DNS is managed and add a TXT record with the name _dmarc and a value like v=DMARC1; p=none; rua=mailto:you@yourdomain.com.
Step 3: Read the reports for a couple of weeks. When only your real senders appear, change p=none to p=quarantine, and later to p=reject.
v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com
Want step-by-step help? Read What Is DMARC? A Beginner’s Guide to DMARC Policies.