Definition

DMARC

Also known as: Domain-based Message Authentication, Reporting & Conformance

A policy standard that builds on SPF and DKIM to tell receivers what to do with mail that fails authentication.

DMARC ties SPF and DKIM together and adds two things: alignment (the authenticated domain must match the visible "From" address) and a policy telling receivers what to do with mail that fails — do nothing, quarantine it to spam, or reject it outright.

DMARC also provides reporting: receivers send back aggregate reports showing who is sending mail using your domain, which surfaces both configuration problems and outright spoofing attempts against your brand.

Major mailbox providers now effectively require DMARC for bulk senders. A published DMARC policy, with aligned SPF and DKIM, is a baseline expectation for reaching the inbox at scale.

Related terms

See it in action

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