What is DMARC?
DMARC (Domain-based Message Authentication, Reporting and Conformance) is a DNS record that tells receiving mail servers what to do with email that claims to be from your domain but fails SPF and DKIM checks.
Why businesses care
Without an enforcing DMARC policy, criminals can send convincing email that appears to come from your domain to your customers and staff. Large mailbox providers also expect it from domains that send email at volume.
Example
v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com; pct=100How to check
Look up the TXT record at _dmarc.yourdomain.com, or run the DMARC checker.
How to fix
Publish a record at _dmarc. Start with p=none and a rua reporting address, review reports, then move to p=quarantine and p=reject.
Common mistakes
- Staying on p=none indefinitely
- Publishing two DMARC records
- Moving to reject before every legitimate sender passes SPF or DKIM
- Omitting a reporting address
Sources
Check it with DMARC Checker
Look up and validate your DMARC record, see whether it is enforcing, and get a safe starter record to publish. Free tool.
Open DMARC Checker