GetUserContactDetails returns all available contact information except street address and email address. Sellers who wish to send an email to bidders should use AddMemberMessagesAAQToBidder.
хотя когда-то
eBay® only stores the buyer email address in their system for 15 days. If you download shipments from their system that are older than 15 days, you will see "Invalid Request".
проверьте на недавнем заказе, если не второе - тогда первое
