I snooped in my boyfriends email and found some dirty pictures, what should I do?

I saw that in my boyfriends in box he had some emails from flickr of naked women. The emails are all stamped with times during the middle of the day, when I know for a fact he is at work. I was just wondering, how flickr works. do you sign up and they automatically email you pictures. Is this something like spam? Or did he request those pictures? Also if he is doing dirt how do I confront him without giving away the fact that I looked through his email?
I snooped in my boyfriends email and found some dirty pictures, what should I do?
maybe he has a subscription of the said naked pics. but then i think it's better than him having another girl isn't it? but i think it's best if you feign-act that you'll browse his email,. if he won't agree, then ask him if he's been hiding something from you..