Most of my sales now are small letter. Only 2 have been 'forced' into Simple Delivery, where the buyer pays more for 'delivery' than the item cost, so most of my profit taken by Ebay. So anyway I stick the £2.70 label on to a small envelope, expecting a Recipt from PO showing tracking number. My PO says that a glitch (on Ebay or Horizon) prevents printing of the tracking number on the receipt for a small letter, but it does work on a Large letter.