Learn DMARC
DMARC passes when at least one validated SPF or DKIM identifier aligns with the RFC5322.From domain. It also publishes handling preferences and reporting destinations.
Read each short explanation, work through the example, then answer a pop quiz. Every answer explains the reasoning. Incorrect answers unlock a fresh question on the same idea; the full lesson contains ten questions.
01Understand the basics
Ready to learnDomain-based Message Authentication, Reporting, and Conformance (DMARC) connects the visible RFC5322.From domain with validated SPF and DKIM identifiers. DMARC passes when at least one authenticated identifier aligns. A DNS policy also requests handling for failures and can request reports.
02Understand alignment
Ready to learnStrict alignment requires identical domains. Relaxed alignment requires the same organisational domain, which current DMARC determines through DNS tree walking rather than a bundled public-suffix guess. SPF alignment uses the authenticated MAIL FROM domain; DKIM alignment uses a validated d= domain.
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03Deploy from evidence
Ready to learnBegin by collecting aggregate reports and finding every legitimate sender. Correct authentication and alignment before asking receivers to quarantine or reject failures. RFC 9989 replaced percentage rollout with t=y testing mode, which requests one policy level below the stated policy.
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