There might be some cases when you know who you want to sell your ticket to. If you have already found a buyer, all you need to do is start the selling process. When you get to the step “promote your listing” you will be able to fill in the buyer’s email address, so that they will receive a private listing by email, which only they will have access to. Simples!
Please see below a print screen of that specific step within the sell flow: