The email from ebay after an item is sold has an address, it may be their registered address, it may be their primary delivery address or it may be the last address they used.

That address will disappear if the buyer goes through checkout and changes to a different address, the address that is in checkout is the only address that will be exported to Paypal and is the only address you should post to.

The only time you would send to the pre checkout address is if the buyer pays by bank deposit without completing checkout.