DMARC alignment and policy

What it is

DMARC binds the domain people see in From to an authenticated SPF or DKIM domain, then publishes handling and reporting preferences.

Why it matters

Alignment makes authentication meaningful to recipients and gives domain owners visibility into legitimate and abusive use.

How to implement

Start with p=none and aggregate reports, inventory every sender, fix alignment, then progress to quarantine or reject. Define subdomain policy and reporting destinations deliberately.

Common mistakes

• Treating p=none as finished protection.
• Enforcing before forgotten senders are aligned.
• Reading pass rates without separating legitimate sources from abuse.

Verification

Inspect Authentication-Results for dmarc=pass and confirm the passing identifier aligns with From. Review aggregate reports across at least one normal sending cycle.