Primer
MTA-STS, TLS-RPT, and why most domains skip them
Everybody talks about DMARC. Nobody talks about whether the mail in transit is encrypted. MTA-STS (RFC 8461) and TLS-RPT (RFC 8460) are the answers, and they take about an afternoon each to stand up once you know what you're doing.
Field guide · being rewritten
This article is being upgraded to the new voice.
We're rewriting our primers alongside the new site so they match the tone of our field reports (like our Proofpoint teardown) — practical, no fluff, with real records and real fixes.