You've never run into this before? I can't think of a single instance of business email sent to a business address being considered private and only to one person unless it's a small company and there's already a track record of it being okay. It makes me nuts too - I'm currently tangling with a lower employee at a small company, and she ended up reading and replying to mail sent to a higher employee because they were on vacation - but I'm surprised you consider it a violation. I mean, if you send a snailmail letter to, say, the VP of an airline's refund department, do you think they'll really read it - or is it the staff under them?