Remember those stalker-ish e-mails sent out by the Obama campaign all year? The oddly intimate subject lines and ugly formatting were all the result of extensive experimentation and data analysis.

“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.