It's quite understandable that the email address can be mistaken for being public as it's listed in your own profile. There's no real feedback saying that the address is actually hidden from view, you simply have to trust that it is.
I find it very unorthodox that the X would actually put the application in sleep mode. The minimizing button should put the application in sleep mode, the X should close the application completely. It doesn't bother me too much since I just right click the icon in the system tray and force the application to close when I want to get rid of it, but there are GUI standards and I think it's a good thing to adhere to those.