As an E-Bayer who has made nearly 200 purchases of stamps in recent years, I always follow up with a feedback comment after my purchase has arrived. Unfortunately some sellers (admittedly few) do not do so. Since I feel that feedback is so important a part of an E-Bay transaction, I have adopted the policy of "no feedback - no future purchase" from that seller! I believe sellers have a responsibility to their customers and that this point should be driven home the hard way - loss of additional sales.