Acquisition of new subscribers is a daily task for the commerce marketer, who may lose as many as 30 percent of subscribers yearly through the natural processes of attrition — i.e., unsubscribes, bouncebacks, bad addresses, even spam complaints. Since buying outside lists to supplement an in-house list is a poor substitute for organic list building, it falls to the marketer to find new ways to appeal to prospects and customers. One simple tip is to sell the sign-up. Make it a compelling, engaging and personal invitation to join the brand conversation. The key word here is "invitation."