How the heck did that happen?

I've been getting PORN emails in my SCHOOL email spam folder!!! I don't visit these types of sites on purpose and I sure wouldn't be using my SCHOOL email if I did!! Why the heck am I getting those emails? How do I stop them? At this point I don't know if the entire school system is getting them or not so it makes me nervous. If the whole system (or school) isn't getting them then it could possibly get me into trouble. Ugh!!!