I'm in the same situation. AFAIK Priority Mail boxes/envelopes are only
shipped with Priority postage and anything else will charge extra to the
seller (?), so to be safe and avoid any more hassle I just put it in a
plain envelope I have lying around...
What about for Ground Advantage Returns? The seller sent me the item in
a priority mail envelope, but the return postage is Ground Advantage
Return (no weight or zone listed). I would guess you can't use the
Priority Mail
envelope.https://community.e...
