What's the etiquette on looking at the other person's email when pair programming?

To me - if you're pair programming - then you don't open your email, or you decide you're cool with the other person looking at it.

I've worked with a person who looks away, and expects you not to look when they look at their email. I'm not familiar with this "code of practice".

My question is: What's the etiquette on looking at the other person's email when pair programming?