No more than if the seller accepted your personal cheque.
When you pay directly by Paypal you can add the eBay transaction number to the PP form. Then both you and the seller mark the item as Paid.
If he were to try to claim that the transaction was unpaid, you can give the PP transaction number and win the case.
More to the point.
Why has the seller not corrected his email address with Paypal? It does take a day or so, but if he and you are patient, he would solve the larger problem not just the problem with your transaction. It's his lack of action that bothers me.
