If you don't need email notifications, then it's not a problem.

One nice feature from gmail/yahoo/outlook/etc.: temporary email addresses that forward to your email. This would solve the problem.

Or, maybe alternative notification methods are preferred? If they wanted, a user can input an email address with a plus (if they're using gmail) and then receive notifications only on that. If the user wanted, then they could block all incoming messages that match that generated email.