In fact, yes, this has worked with me on several occasions... Got an email from international bidder, checked their feedback, and opened the bidding to them, though I do require international bidders to agree that proof of mailing ends my obligation to them if they are unwilling to pay the (sadly exorbitant) fees for delivery confirmation.
I feel bad charging someone more for shipping than an item is worth. (Though after one buyers pleas, I shipped an A800 to England, $40 for the system, $60 something shipping!)
Buyers CANNOT have bad feedback, so you saying you've checked to make sure it is good is laughable