Anybody have experience mailing cash in a flat-rate GPM envelope($5)? I was told that it had to be handed directly to a counter person at the post office to ensure delivery...If dropped in an outside box, it would be returned to sender with notification to bring the parcel to the post office to be delivered....However, the usps website states that it can be hand delivered to your mail courier or dropped in an express mail drop....Anyone have any experience with this?....Just trying to save myself a trip to the post office.....Thanks...Fumunda