After one-click unsubscribe web site may email the user last notification that unsubscribe was successful, and if the user wants to subscribe again - he can do so by clicking on that re-subscribe link (which can also be one-click).
Update: I just noticed that this goes against Amanda Peyton's last request (Do not send an unsubscribe confirmation email.).
But I guess she's wrong on that (because unsubscribe could be unintentional or malicious based on forwarded email).
OP here. I think the combo of one-click unsubscribe and not sending a confirmation is perhaps a bit aggressive, and maybe it should be one or the other. Though to be honest, I am thrilled if sites have any one of the 4 (and some do).
Update: I just noticed that this goes against Amanda Peyton's last request (Do not send an unsubscribe confirmation email.). But I guess she's wrong on that (because unsubscribe could be unintentional or malicious based on forwarded email).