Email marketers struggle with subscriber attrition and declining response rates. Forrester data shows that 70% of US online adults have opted out of at least one marketing email in the past six months. However, the consumers who are turning away from email programs are the most valuable for marketers. They are heavier online spenders, and they rely on the Internet more for research. Preventing their defection stymies many marketers who opt to focus on list growth instead. Marketers need to examine subscriber behavior in a deep and extended manner and institute triggered reengagement programs or drop inactive subscribers from their lists.