DMARC Policy Configuration
Summary
DMARC policy determines what happens when email authentication fails. The three policy levels are p=none (monitor only), p=quarantine (spam folder), and p=reject (block delivery). Policy should be implemented gradually using the pct= parameter.
What Is DMARC Policy Configuration?
DMARC policy is specified in the p= tag of your DMARC DNS record. It controls enforcement when SPF or DKIM authentication fails. The policy applies to the percentage of emails specified by pct= (default 100%). Example: v=DMARC1; p=quarantine; pct=25; rua=mailto:[email protected]
Why DMARC Policy Configuration Matters for Email & DNS Security
DMARC policy is the enforcement layer of email authentication. p=none provides visibility but no protection. p=quarantine reduces phishing impact. p=reject completely blocks spoofing attempts. According to IntoDNS analysis, only 23% of domains with DMARC records have moved beyond p=none to enforcement policies. Gmail and Yahoo require p=quarantine minimum for bulk senders as of 2024.
How DMARC Policy Configuration Works (Technical)
- 1.Email fails SPF or DKIM authentication
- 2.Receiving server checks DMARC alignment
- 3.If alignment fails, apply DMARC policy
- 4.p=none: deliver normally, send report
- 5.p=quarantine: deliver to spam folder, send report
- 6.p=reject: block delivery entirely, send report
- 7.pct= controls percentage of emails policy applies to (gradual rollout)
Common Misconfigurations
❌ p=reject without testing
Consequence: Blocks legitimate emails from misconfigured senders
How IntoDNS detects this: IntoDNS recommends p=none → p=quarantine → p=reject progression
❌ No subdomain policy (sp=)
Consequence: Subdomains inherit policy, may block legitimate email
How IntoDNS detects this: IntoDNS checks if sp= is explicitly set for subdomain control
❌ pct=100 on first deployment
Consequence: All authentication failures enforced immediately, high risk
How IntoDNS detects this: IntoDNS recommends starting with pct=25 and gradually increasing
How IntoDNS.ai Detects & Scores This
IntoDNS validates DMARC policy syntax, checks policy strength (flags p=none as weak), validates pct= parameter, checks subdomain policy (sp=), and provides migration recommendations from none → quarantine → reject.
How To Fix DMARC Policy Configuration Issues
- 1.Start with p=none for monitoring: v=DMARC1; p=none; rua=mailto:[email protected]
- 2.Wait 2-4 weeks and analyze aggregate reports
- 3.Fix any legitimate senders failing authentication
- 4.Upgrade to gradual quarantine: p=quarantine; pct=25
- 5.Increase pct= by 25% every 2 weeks
- 6.At pct=100, monitor for 1 month
- 7.Final enforcement: p=reject; pct=100
References
Source: IntoDNS.ai – DNS & email security diagnostics
Last updated: 2026-01-14
Category: email