You mean I can put a check in my mailbox, and they'll leave me stamps???
If you go to USPS.com and put a book of stamps in your cart, you'll see the $1 "shipping and handling" charge.
The thing is, I didn't leave the package in my mailbox -- I gave it to the shipping department at my company (like I always have). I'm not sure how it gets from the shipping department to the post office, but I'm assuming someone actually comes by and picks it up (we're a large company).
CW