i've found that i'm getting notification emails even though i am not subscribed to any comments - this is tested as a non-registered, not logged on user
upon clicking the 'manage subscriptions' link, there are no subscriptions to manage, which is expected, yet i'm still getting the notification mails
how to reproduce this is another matter - this may have been the result of setting 'Advanced subscription', then subscribing, then disabling the option, then unsubscribing (just a guess)
could also be a potential problem with subscribing as logged on user, then logging off and subscribing as a non-registered user with the same mail maybe?
just throwing things out here