This document discusses approaches for reengaging inactive email subscribers. It begins by explaining why companies should care about inactive subscribers and the typical ratio of active to inactive subscribers. Various strategies are then presented for reengaging inactive subscribers, including understanding the causes of inactivity, sending reengagement email campaigns, personalizing content, and making it easy for subscribers to update their preferences. Case studies are provided showing how specific companies implemented reengagement programs that resulted in cost savings and increased revenue by reactivating former subscribers.