Personalization — Choosing a tailoring depth, pricing it, and producing it at scale; the centerpiece is a four-school economics debate

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This module owns one decision: how much per-prospect tailoring a campaign buys, and how that tailoring gets produced. Line-by-line writing craft lives in Writing the email; campaign-level relevance and trigger selection live in Offer and messaging. Here you pick a depth, justify its cost, and choose a production method.

The pages:

Personalization levels — The four-rung ladder from mail merge to bespoke, and where replies actually move — researched one-liners roughly double rates, 17-18% against 7-9%.
Relevance vs personalization — Two schools that agree relevance persuades and fork on where the hours go — per-prospect hooks (Holland) or upstream segment design (Bay).
Research signals — The 3×3 time-box — three facts in three minutes, Steve Richard's and often misattributed — three signal families, and the hook test that filters trivia.
Personalization at scale — The three-stage pipeline — signal per row, LLM-written snippet, framework slot — and the guards against confidently wrong automated lines.
Economics of personalization — Four schools price the depth-versus-cost trade — hook-to-relevance, segment-level, volume-plus-offer, AI-scaled — converging on one per-tier spend frame.
Dynamic media — Personalized images, video and landing pages: practitioner-reported evidence only, never a first touch, and a steeper cost line per prospect.

Where practitioners genuinely disagree, pages present named approaches with Fits when / Avoid when criteria, Recognizable by cues, and a stated default — the economics page carries the module's central four-way debate.