This document discusses how marketers can move from a segmented audience approach to email marketing to a more personalized approach using behavioral data across multiple channels. It advocates capturing customer behaviors from various sources, applying rules to generate personalized interactions, and measuring outcomes to continually improve personalization over time. The key questions addressed are what behaviors matter most, how to turn behavioral insights into actions, how to implement this approach at scale and across channels, and how to capture and learn from customer behaviors. Several examples are provided of companies that improved engagement metrics like open and click-through rates by taking a more personalized, behavior-driven approach to marketing.