Forensic email analysis isn’t a hunch, it’s a discipline — and Chapter 12 builds that discipline as an actual workflow. Preserve the message as a raw .eml file first. Triage with Authentication-Results. Trace the Received chain from the bottom up, since the first server to touch a message is the hardest for an attacker to forge.
The chapter’s sharpest section is the From/Return-Path/Reply-To triangle — three fields that should broadly agree in legitimate mail and frequently don’t in an attack. A CEO-fraud attempt might show a perfectly normal-looking From display name with a Reply-To pointed at a completely unrelated domain.
From there it applies the workflow to realistic case patterns: lookalike domains, forged Received chains, and the header inconsistencies that expose business email compromise.