Well that’s an incredibly good way to get fired. Where I work, I could read anyone’s emails anytime I want but I do not because, first, it’s not ethical and is, as mentioned, a good way to get canned. And it’s boring to read other people’s emails even apart from all that. I have far and away enough of my own.
And in some cases, you can get tossed in jail for doing so. Why do that?