This document discusses how to use data to improve email engagement. It recommends using four key types of data - email interaction data, web interaction data, giving history, and demographics - to personalize email content. Personalized emails that send the right message to the right audience can increase unique open rates by 70%, click-through rates by 55%, revenue per email by 300%, and conversion rates by 225%. The document also discusses using data beyond emails, like on websites and donation forms, to continue personalizing the constituent experience.