I don't know the specific rules but the last time we sold the EA gave us good feedback on the profile of all viewers and bidders - eg, first time buyers & mortgage approved, cash buyers with proof of funds, in a chain, young couple, retired couple, etc. He also gave some background on any that showed serious interest, eg, where from, interest in or connection to the area, work background, etc. But he did not give names and addresses - whether this was to do with rules and regulations, I don't know. But nor did we seek such data because we weren't interested.