I think you need to look at some websites. Wikipedia, for example, on the E-mail Spam article:But you can send email from over 1000 accounts via 1 computer. So while yes their are botnets to spam email, many people would rather steal your password and you not know your infected so they can keep steeling your password, then use it on a different computer to actually send out the emails. When your computer is botted its virtually useless. People would realize they were infected when they couldn't do anything on it anymore. So as for the NFL one they were better off just planting the virus and stealing your pass, then using a different bot to actually send out the emails.