“Asking people to reply to your emails is a tactic that doesn’t scale, but you can learn a ton in the process.”
Unlike radio, television or print marketing, email is an open line of communication that works in both directions. Moreover, readers of your emails are already used to responding to emails—all you have to do is ask them to respond. Whether it be a survey, or an answer to a riddle, ask your readers to reply and see where the conversation takes you.