Occasionally I have listed with my old email address for Paypal payments, but the money still goes thru.

Go into your Paypal account & check whether the payments have gone into your account. Add your new email address as the primary to your Paypal account.

Then any future listings U submit now to eBay, make sure U put the correct email address to which the Paypal payments are to be paid.

Actually my old email address is the ID with which I sign in & a Paypal representative told me if I remove that address I won't be able to sign in.

I have several email addresses in my Paypal list, because I have more than one eBay ID.