Ebay are you watching?

Contacting losing bidders after the close of an auction is probably against eBay policy as you are using their site to gain the contacts. I have done this successfully myself a few times in the past as I don't have a great personal love for eBay and it is a great way to find a buyer.

The sending of promotional material to a winning bidder or losing bidder should be none of eBay's business after an auction has closed. Of course, they would not agree as they lose their cut from all directions. I am sure they are constantly trying to figure out a way to stop this practice and reap its financial benefits.