This report provides a forecast for the US population of email users, marketing email volume, and email marketing spending for the years 2015 to 2020. It estimates the total number of online users and active email users segmented by age group, as well as mobile email users. It provides a forecast for total email volume and marketing email volume by retention email, acquisition email, and transaction email. It also segments total email marketing spending into strategy, data, analytics, creative, delivery, and integration. We provide an estimate of email marketing spending for 12 industries including financial services, retail, travel, and consumer products. The report provides historical data going back to 2005 and a five-year forecast.