Before revision:  We show that by offering a generous refund policy the seller can significantly reduce this type of uncertainty and regain market power. A simple mechanism that utilizes a generous refund policy and random discountsachieves the best guaranteed-profit among all possible mechanisms .
After revision:  We show that the seller may use a simple mechanism to best take advantage of the buyer's post-purchase learning to maximize his guaranteed-profit. We show that this mechanism combines a generous refund policy and random discountsachieves the best guaranteed-profit among all possible mechanisms .