So that other day I noticed that all friend confirmation E-mails from Four Square reveal their real E-mails. This instantly raised a red flag in my mind. Not only is it a privacy issue, but also a security one since users use their E-mails to login into the service. Upon further inspection, and a couple more tweets later, Zane Aveton @Zaneology) brought to my attention that under Four Square settings you can disable the option of friends seeing your E-mail, which she has done. So I dug up the Four Square e-mail notifying Zane’s acceptance of my friend request, and sure enough, her E-mail was there!