Glossary · Email

DMARC (Domain-based Message Authentication, Reporting and Conformance)

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A policy layer on top of SPF and DKIM that tells receivers what to do with messages that fail authentication.

Diagram explaining DMARC (Domain-based Message Authentication, Reporting and Conformance)

SPF and DKIM individually tell a receiver if a message is authentic. DMARC is the policy that says what to do with the answer:

v=DMARC1; p=quarantine; rua=mailto:dmarc-reports@yourdomain.com; pct=100

Key tags:

p=none — monitor only; receivers send you reports but don't block anything. Good for the first 30 days.
p=quarantine — send failing messages to spam.
p=reject — bounce failing messages outright. The strongest setting; use only after SPF and DKIM are confirmed clean.
rua — the email address that receives aggregate reports (one daily summary per receiver).

DMARC also requires SPF or DKIM to be aligned with the From: header domain — meaning the authentication has to match the visible sender, not just any header.

DMARC (Domain-based Message Authentication, Reporting and Conformance)

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