While selling Xbox Live/Netfix/iTunes/PSN etc,you just have the code and giving it away via email,leaves you in the mercy of the buyer.If he complains that the code is invalid,you dont have any shipping proof or anything to safeguard yourself.eBay will also take the buyer's side as you don't have any proof.This is how you safeguard against those kind of people. The Precautions 1)Always have a No Returns Policy. 2)Take a screenshot of the validity of the code before sending it to buyer. 3)Don't sell to people with less than 10 Feedback(Optional) The Method Whenever you are selling a digital item.Write it down on a paper and ship that letter to the buyer.You can either email and also mail the code or just mail the code to him.This way you can have a proof of delivery that eBay so much wants. Get a tracking code and you are done. I am not from USA and I use services like Click2mail.com to do the work for me. This way I am safe and I can sell safely on eBay . Also don't mention in your listing that you will email the code.After the purchase ask the buyer if he wants it emailed or email it if the buyer requests it.Be safe with Paypal and eBay.They can hit you hard for no mistake of yours. Have Fun.