I was on my yahoo messager a few weeks back when I've been getting requests from people over messanger asking to add me as their friend.
So how the scam works. You will get a request from a bot who will send you a friend request on the in messager that Yahoo has built into their email system. When you click the add as friend it adds the bots email to your system. So what does this mean? No matter if you hit the spam button it will still go to your inbox folder because you have that bots email in your safe email folder.
So if your wondering why you keep getting the same message from a spam even after hitting spam block thats what is happening.