The US Post Office has an unusual room at each location

Have you ever had a customer promise to send a payment on their past due bill with you, say in the amount of $500 and when it arrives in the mail it is $100?
Unfortunately for you, the envelope went thru the "incredible shrinking room" that exists in each post office. Any form of payment that enters comes out denominated in a smaller dollar amount than when it went in. Fortunately, it didn't go into the "lost in the mail" room where the payments never seem to make it out to you in spite of the customer's assertions that it was mailed and now it is your problem.