What is DMARC?
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol that builds on SPF and DKIM. It tells receiving email servers how to handle messages that fail authentication checks and provides reporting on authentication results.
DMARC Policy Options:
| Policy | What Happens | When to Use |
|---|---|---|
| p=none | Monitor only, deliver everything | Initial setup |
| p=quarantine | Send failed auth to spam | Testing enforcement |
| p=reject | Reject failed auth entirely | Full enforcement |
DMARC Requirements:
- SPF and/or DKIM must be implemented first
- SPF or DKIM must align with the From header domain
- DMARC record published in DNS
Why DMARC Matters
DMARC is mandatory for email senders in 2024. Gmail and Yahoo's 2024 requirements specifically call for DMARC implementation.
Benefits of DMARC:
- Prevents Phishing: Blocks spoofed emails using your domain
- Improved Deliverability: Authenticated domains get better inbox placement
- Visibility: Reporting shows who's sending email on your behalf
- Control: Decide what happens to unauthenticated messages
- Brand Protection: Stops attackers from impersonating your company
Benchmarks
| Policy Stage | Implementation | Typical Duration |
|---|---|---|
| Monitoring (p=none) | Start here | 2-4 weeks |
| Quarantine (p=quarantine) | Gradual enforcement | 2-4 weeks |
| Reject (p=reject) | Full protection | Ongoing |
Industry Standards:
- Organizations with p=reject see 15-20% better deliverability
- 90%+ of Fortune 500 companies have DMARC at reject
- DMARC adoption accelerated in 2024 due to Gmail/Yahoo requirements
Best Practices
- Start with p=none: Monitor before enforcing
- Review Reports Regularly: Analyze DMARC reports weekly at first
- Gradual Escalation: Move to quarantine, then reject
- Fix SPF/DKIM First: DMARC depends on proper implementation of both
- Set Subdomain Policy: Use sp=none or sp=reject for subdomains
- Monitor Percentage Tags: Use pct=100 for full enforcement
- Request Reports: Include rua (aggregate) and ruf (forensic) tags
- Document Changes: Keep track of policy changes and dates
Common Mistakes
- Jumping straight to p=reject without monitoring (can break email)
- Implementing DMARC before fixing SPF/DKIM issues
- Never reviewing DMARC reports
- Not setting up report receiving (rua/ruf tags)
- Forgetting about DMARC after initial setup
- Ignoring subdomains in policy
- Using pct<100 (partial enforcement creates confusion)
- Not having a process to handle legitimate failures
Key Takeaways
- DMARC tells receiving servers how to handle unauthenticated emails
- It builds on SPF and DKIM—both must be implemented first
- Start with p=none (monitoring), then move to quarantine, then reject
- Gmail and Yahoo require DMARC for bulk senders as of 2024
- DMARC reports provide visibility into who's sending for your domain
- Full enforcement (p=reject) prevents phishing and improves deliverability
- Review reports regularly during implementation
- DMARC at reject is the gold standard for email security
Sources:
Related Terms
Dark Funnel
Buyer research happening outside tracked channels. LinkedIn, podcasts, communities.
Data Enrichment
Adding firmographic and contact data to leads. Improves targeting and personalization.
Data Validation
Verifying email addresses are valid before sending. Reduces bounce rates.
Deal Velocity
Speed at which deals move through pipeline. Faster indicates better fit.
