Authentication is too late now, if you have already sold the sneakers. So make sure you ship the item promptly after you receive the payment. You might consider insuring it and requiring a signature upon delivery.
If you do decide to require a signature, make sure you TELL your buyer that you are doing that so they can be prepared for it. Don't ever surprise them with a signature required. That is a good way to make a buyer mad.
mam98031 • Volunteer Community Member • Buyer/Seller since 1999
"I can explain it to you, but I can't understand it for you." Quote from Edward I Koch