Darryl, I like your research and have done it myself. Many years ago when I was young and didn't know better or do my research I did the mailbox thing and got a call and warning from the postmaster and have played by the book ever since.
Something else to consider is the Post Office is in dire straights like many cities/towns so fines are being handed out left and right....
5 over used to be a normal thing while driving and rarely pulled over and then just a warning. Now it is a ticket and FINE. just my .02