Packages are also opened if there is no airbill attached to it. In my fedex career i've come across at least 10 packages, most of the envelopes though, that had no airbill on them. I take the pkg back to the station & we all have laugh. I guess people are just in such a hurry that they simply forget to attach the airbill onto the package. or if the package is damaged & snakes come crawling out