I recently became educated in using measurements in the SYI for dimensions of large boxes. (hangs head in shame). I do not see on the Endicia form where to enter dimensions. I've always just plugged in the weight. Is there something obvious I am missing? Not once has a customer wrote to inform me that they were charged postage because I paid too little. And I have shipped tons of large boxes over the years (all Media Mail until just recently when I've had some large LEGO sets going Priority).
