DMARC (Domain-based Message Authentication)
A protocol that tells receiving servers what to do when SPF or DKIM checks fail for your domain.
DMARC builds on SPF and DKIM by adding a policy layer. It tells receiving mail servers what to do when an email fails authentication — and provides reporting so you can monitor your domain's email traffic.
DMARC policies:
p=none: Monitor only (take no action on failures)p=quarantine: Send failing emails to spamp=reject: Block failing emails entirely
Example DMARC record:
v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com; pct=100
Best practice implementation path:
1. Start with p=none to monitor
2. Review DMARC reports for legitimate senders
3. Add those senders to your SPF record
4. Move to p=quarantine, then p=reject
Google and Yahoo now require DMARC for bulk senders (5,000+ emails/day).
Related Terms
SPF (Sender Policy Framework)
A DNS record that specifies which mail servers are authorized to send email on behalf of your domain.
DKIM (DomainKeys Identified Mail)
A cryptographic email authentication method that verifies an email was sent by an authorized server and wasn't altered in transit.
Sender Reputation
A score assigned by ISPs to your email sending domain/IP that determines whether your emails reach the inbox.
Related Blog Posts
Want to learn more?
Read our in-depth blog posts on email verification and deliverability.