If there's one thing that drives me absolutely mad it's when I sign up to a website or an app and they send me emails without my consent to either "remind" me to use their product more often or give me "fascinating" information about their product's features.
My question is, despite this practice being extremely annoying for people like me, is there evidence that shows that it's actually an effective way to get the average person to use new features, or to get him/her to return to the site or application more frequently? Do the benefits outweigh the costs?