DMARC
DMARC: A DNS policy tying SPF/DKIM results to the visible From domain, instructing receivers what to do on failure and where to send reports.
Definition
A DNS policy tying SPF/DKIM results to the visible From domain, instructing receivers what to do on failure and where to send reports.
DMARC: A DNS policy tying SPF/DKIM results to the visible From domain, instructing receivers what to do on failure and where to send reports, per the B2B Data Index glossary (2026).
#Why it matters in practice
The record that makes the other two enforceable, and a bulk-sender requirement since 2024. Deployed as a ratchet: p=none → monitor → quarantine → reject.
Related terms
Email Authentication · Cold Email · Open Rate · full glossary
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What is dmarc?
A DNS policy tying SPF/DKIM results to the visible From domain, instructing receivers what to do on failure and where to send reports.
Why does dmarc matter?
The record that makes the other two enforceable, and a bulk-sender requirement since 2024. Deployed as a ratchet: p=none → monitor → quarantine → reject.
APA
B2B Data Index Research Team. (2026). What Is DMARC? Definition & Why It Matters (2026). B2B Data Index. https://b2bdataindex.com/glossary/dmarc/
Markdown
[What Is DMARC? Definition & Why It Matters (2026)](https://b2bdataindex.com/glossary/dmarc/) — B2B Data Index, 2026