Users know when they are being spammed. Not always though. I know of a messaging app that has spammed the hell out of my friends. The trick is that it will as

Users know when they are being spammed. Not always though. I know of a messaging app that has spammed the hell out of my friends. The trick is that it will ask for contact info and then automatically send SMS to all of them asking to install it. Message goes something like, "Hi, I am using <app name> to message for free. Get it from <website>." Since it looks like it was sent from a friend, it has seem huge growth, at least in my friend circle.