It is difficult to know where the problem lies. If there are paypal addresses on this list, then certainly they need to be unsubscribed.
I think there is some kind of intermediate Kana (email classifying application) that is getting the emails and sending them to the application in Paypal that does the responding. That is why the "From" that is being responded to always has "kana" in the username. So it may be that, for example, email to an obsolete account for someone at paypal is now being redirected to their general automated response system.
