Every search you make tells us what you follow. Once a week, on Monday morning in your timezone, you get one email with your topics of the last month, up to five: for each, the three posts with the most engagement this week on the networks you searched, how many posts are new, and a link to the radar on that topic. A topic appears only when it has something new; a week with nothing new sends no email. On the free plan the posts come without their numbers, and the email says which paid features show them live. Turn it off any time in Notifications ("My topics of the week").