Put stamped letter in metered mailbox?

Question

I wasn't paying attention today, and I accidentally dropped a stamped letter in a mailbox I later realized said "metered." The letter is very important, so I'm wondering if anyone knows will it a) get to its destination or b) at least get sent back to me if they won't deliver it? Do they sort the letters later to make sure they're really metered? Thanks for your help!

Answer 1

It will get to it's destination. Things like that keep the USPS employees on there toes.

Answer 2

I have had letters get to me that were a few cents short of acceptable postage (I tossed some money in the mailbox in some special postal service envelope).  If the weight goes over the price of the stamp you put on it, it will probably be returned back to you (with the stamp canceled out :p).