In the days of spam-riddled inboxes, everyone has an opinion on how to raise the average conversion, the average sale, average open rate or the average click-through rate. Years of data from some of the best, and worst, companies who specialize in online marketing have been analyzed and published to help construct best practices for e-mail marketers. For that, I say, "Congratulations. You're on course to bring e-mail marketing, a gateway of infinite marketing possibilities and unlimited return-on-investment potential, to an average level.