“The subject lines that worked best were things you might see in your in-box from other people,” campaign e-mail director Tony Fallsgraff told Bloomberg BusinessWeek. “‘Hey’ was probably the best one we had over the duration.” The magazine got a peek inside the system, where hundreds of subject lines and e-mail formats were tested on small groups before hitting millions of in-boxes. (The campaign used similar experiments on its Web site, testing various messages to get visitors to submit their e-mail addresses.)
Mild profanity was also surprisingly popular, and ugly basic text beat out nicely-designed buttons. Most supporters would not unsubscribe no matter how many e-mails they got -- an insight future campaigns are sure to keep in mind.