To get subscribers to update their email settings, you need to show them how it helps *them* get better emails, not just how it helps you. You can send a short email explaining that by telling you what they like, they will stop getting the stuff they do not want and get more of what they enjoy. Frame it as a way for them to take control of their inbox and only see the most useful stuff from you. Maybe offer a small reward or a quick-read guide as a thank you for taking the time to fix their settings. Do you think making the preference page really easy to use is the biggest factor in getting people to actually update things?