My c'list was hacked recently and the new operators of my account ran scam ads all over the USA. So if you send money to a PO box, you have no recourse at all, not through the c'list account , not through the PO box, Nada.
I inadvertantly put my email address in an ad instead of my usual phone number with spelled numbers (86 seven five 30 ni-ee-eyen). That put my email on a similar ad with another with my phone number and the scammers started bombarding me with foul images, obscure phone messages, random weird emails, all to set me up for the idea that something weird was happening. When I got an email from c'list saying my account had been hacked and that I should follow this link and change my password immediately, I followed the link and did, but it was a link to a phony c'list password change page and when I thought I was changing my password I was really giving the scammers my password-and away we went.
Some of the ads they ran were for camera gear, but mostly expensive rv's and sporting goods and riding lawnmowers, all 2-3 grand items for 1 to 1.5K. Of course I deleted them all and really did change my password after that. An interesting weekend. Never trust anyone except for a face to face, cash in hand, public place, time to inspect and nothing weird.