This will prevent Sally from sending you messages, friend request or from viewing your profile. They will not be notified. Comments on discussion boards from them will be hidden by default.
“Cheaters often accuse you of cheating. Liars often accuse you of lying. Insecure people often crumble your security. Behavior speaks... How someone treats you may have nothing to do with you; but can be a reflection of who they are.”
―
Steve Maraboli