The above was an explanation of the legitimate
practice. The abuse is where
 a third party pretends to be the seller, contacts the second etc. bidders
 and requests payment be sent to a blind PO Box, then skips with the funds
 never sending any goods.
 BTW I just sent an inquiry to eBay to see if this is rumor, hoax, or fact.
  
I always check the email address of the person requesting payment. If it is not the same
as listed in Ebay, I would get really suspicious.
Steve Robertson - <steverob(a)hotoffice.com>