I had the same battle today. I had an #10 envelope that was padded to be over 1/4" thich but less than 3/4" thick. I even pointed out to the post office employee on his own form where it says that if any of the 3 dimensions exceed the max the the next mor expensive rate is used. He was going to charge me for a parcel but I told him it should be a large envelope. Even after I showed him his own form he said " I don't care = ther is no way that envelope is a large envelope." Fortunately I have a still open complaint with the service department and I called them again today. Still waiting for a call back.