The Buyer-Seller Messaging Service lets you communicate with buyers in the Amazon marketplace via Seller Central, or your personal or business email. You can contact a buyer directly from your seller account on Seller Central or by using your authorized email account (if you have the buyer's encrypted email address that was previously generated by Buyer-Seller Messaging). Either way, your correspondence will be visible on the Buyer-Seller Messages page.
If the buyer you are trying to contact has opted out of receiving messages, you can contact them based on the qualifications for sending a critical message. For more information, see Send a critical message to a buyer.
Buyer-Seller Messaging is the only approved method for communicating with buyers on Amazon.