Glossary of terms

Plain-English definitions of the key terms.

Published 28 Jun 2026 0

A quick reference for the terms you will see across DMARCER.

  • SPF - lists who may send email for your domain.
  • DKIM - a signature proving a message was not tampered with.
  • DMARC - ties SPF and DKIM together and sets what to do with failures.
  • MTA-STS - requires encrypted email delivery.
  • TLS-RPT - reports on encrypted-delivery problems.
  • DNSSEC - protects your DNS records from tampering.
  • RUA - aggregate DMARC reports (summaries).
  • RUF - forensic DMARC reports (individual failures).

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