Going Postal

GOING POSTAL....Suppose you have an ordinary piece of paper to mail. You don't want to fold it, so you put it in an ordinary 9"x12" envelope. It weighs less than an ounce.

Question: How much postage does it require?

To enter this contest, put two things in comments: (a) your guess, and (b) how long it took you to figure out the answer. This is an open book test and you may use any reference materials you like.

When we're done, I'll tell you what I think the answer is and what the post office thinks the answer is. Sadly, they don't seem to match.