Note that if you include bad links (causing the email to bounce on someone's spam filter) or reply to someone's pm over e-mail, then yes, I see that. I may take action cracking down on the former a bit - I like to keep Elliquiy's address off of blacklists and it's frustrating to have to deal with them.
Otherwise, I generally view pms when another member has reported their private messages (I have seen people forge complaints or skip on the story - annoying), or when we otherwise receive reports of harassing behavior. If you're overly paranoid about it, consider that between all the sites I run there are three thousand private messages a day. I could not hope to read a fraction of them.