Retailers are expected to increase their email volume by 19% this holiday season, and are investing in ROI-boosting technology allowing the delivery of more personalized and relevant messages. In contrast, the number of Black Friday and Cyber Monday shoppers who made a purchase after clicking through a link in a social network has declined 26% over the previous year, with socially-driven purchases comprising only 0.5% of online revenue during these two highly productive shopping days.