Still need proof that segmenting your e-mail house file and creating unique messages for each group can pay off? Consider the lift that American Greetings enjoyed from doing just that: Between October 2009 and April 2010, it increased customer engagement-opens, clicks, and transactions-13% for its AmericanGreetings.com and BlueMountain.com brands. For a membership fee, American Greetings subscribers can send e-cards or create and print cards from among the company’s vast library. As part of each campaign-and according to....