My kid, my car, my cell phone, my computer. Bet your fanny I have the right to check on what my kids are doing. I used the History key on the computer to check before they figured out how to hit delete. Then I went to Spector Pro and told them about it. I've also been known to record telephone calls when the mom antenna goes up, and they know about that as well. They'll be driving soon and I'm planning on putting a device on the car, too. They also know that it's not that I don't trust them, it's that I don't trust what might be on the other end of the emails.
Better be careful with. Depending on the circumstances that might be a felony.