eMail: Capital offense?

I had our corporate attorneys look into this issue in a general way several years ago. I was told that in Missouri at least, a company may do anything they want to with an employees email, including but not limited to reading it. The catch is that the email must be delivered using company owned equipment. If the mail is received by or transits company gear, it actually belongs to them. That much I know. So, it seems fairly clear companies have a right to read your email. Then the question becomes what can they do about it? I would strongly suspect that if they have a clear company policy that demands no personal mail be sent or received, and they have no past incidents of enforcing it subjectively or failing to enforce it at all, and they can prove you were clearly aware of the policy, it would be very difficult to fight. Companies usually cover this by putting any regulations in the employee handbook or equivalent document, and when you start your employment they usually require you to sign a one-pager that says you have read and understand and agree to abide by all company policies. Not that I agree with any of the above, but that's what I've heard anyways. Jay West