If you merely deactivate your email address rather than closing your account or changing your notification settings or whatever, then the next time a legitimate service goes to send you a legitimate email that you asked for, it will bounce. In some sense this "shouldn't matter", as in a purely P2P system the only people who would notice are the sender and Apple -- and Apple knows what is going on, so should not penalize senders the way, say, Google would if they see you sending a ton of email to their domains and they all bounce -- but people tend to use services to help send email and centrally pool their reputation (such as mailchimp) and so these services themselves then watch the bounce rate of their individual customers and either charge them more or ban their access due to the bounce rate increase.