The "P" at the end should give it away. All the bills I've ever seen have begun with "HR" or "SB" for 'House of Representatives' or 'Senate Bill' respectively (or something along those lines).
Also... wouldn't the amount of internet sales help out the post office or at least make up any difference from lost snail mail (no pun intended

)? I've been to the USPS
more often since the internet boom... and the lines seem longer and longer as time goes on. They're doing just fine

.
my .02