Do not ship using USPS boxes!

[myfavorite4]

I am a buyer and I have been charged postage due for sellers using USPS Flat rate and priority mail boxes but printing their own labels.

You can't do that! You may have gotten away with it for awhile but the postal service is cracking down.  It's a big headache to explain to the seller and get refunded the postage due.  You really are not allowed to tape 2 of their boxes together.

ebay does address  this on their site but I doubt anyone is reading it thoroughly.

 

[inceptions]

Sellers can use Flat and Priority Mail boxes and print their own labels. But they have to choose the correct options when they create the label. This is not related to PO Boxes - it's the same requirement no matter where the package is shipped.

Sellers can tape two boxes together (assuming they are the same size) as long as they aren't using the Flat or Regional rate cartons.

[myfavorite4]

My postmaster said you may not change the appearance of their USPS boxes in any way.  Taping 2 USPS boxes together is not allowed because it changes the predetermined size of a single box.
This all  has something to do with the shipping contracts they have with other carriers.

[inceptions]

You may not change the appearance of USPS Flat Rate and Regional Rate cartons or tape them together for the reason you were given.

There is no such restriction on Priority Mail cartons that ship based on size and weight.