SteamProphet attempts to collect as little identifying information as possible. When you log into SteamProphet, the authenticating service passes us a unique identifier. That's the only piece of information we store about you – we don't have your email address, account name, password, or anything else.
You choose what information to share with other users. By default, you are completely anonymous. You may waive your anonymity by changing your profile settings to include personally-identifying information such as a username or Twitter handle. Any information you choose to share this way is potentially visible to any other signed-in user.
SteamProphet will never send you unsolicited emails. We don't store your email address, so even if we wanted to, we couldn't.