Again and again I just get "messages" that send me videos, links, pictures and such advertising for other sites and such. It's annoying, especially when you think you got a real message. An option to prevent anyone sending me any of those (even if they are legit) would be appreciated. Maybe even create a "permit picture, etc. once" feature inside Chats to allow a real Chatter to send you something, but only if you allow it yourself.