I did a quick google search and it looks like it is ok for the employer to open any and all mail it gets, regardless of who it is addressed to.
Taking what ever is in the package is another matter, and not giviing it to the person is just plain crappy.
"There is a common misconception that it is illegal to open mail addressed to someone else that has been delivered to you. There is no federal statute that prevents you from opening mail not addressed to you once it has been delivered by the Postal Service. If you take something that was in the mail you might violate a state law against stealing. If you use information contained in the mail for a wrongful purpose like identity theft, you are breaking state and federal law, but opening the mail is not illegal in itself.
Read more: What Is the Federal Law for Opening Mail Not Addressed to You? | eHow.com http://www.ehow.com/about_6293417_…l#ixzz18hUBdECq