It's even explained on that sticker that the PO apparently put on the mailer...

For a parcel to be sent 1st Class with Delivery Confirmation, it has to be AT LEAST 3/4" at its THICKEST POINT. Many times I don't even think the PO's care about this, but it seems that someone ACTUALLY did in this case. So since it was prolly less than the required thickness, to be able to send it with DC, it had to go Priority Mail at that point. And since it wasn't in any PM Flat Rate packaging, it got calculated at PM zone delivery. So my thinking is the $4.40 charge is the DIFFERENCE between the 1st Class shipping rate and PM zone delivery w/DC.

I've had MUCH experience with this before and its the main reason why I don't ship anything much anymore out of the PO in my own town. About 2-3 yrs ago I sent something small that also went 1st Class with DC. The clerk told me that it couldn't be sent 1st Class because it wasn't thick enough... I asked for the parcel back and told her that I'd go mail it in a town about 5 miles away. After that statement, she relented and mailed the parcel with no further questioning. So after that, I have basically sent ALL of my parcels there at this other P.O. Sure its a little bit of a drive, but there is actually MORE parking at this other P.O. and the clerk that is there (YES there is only 1 clerk there at any one time... its a smaller P.O.) has been there for quite awhile and is very nice.

Something to think about!

Jim