MailPoet is an awesome newsletter plugin. Currently, it doesn’t have a way to synchronize lists by user roles, it only creates on ‘WordPress Users’ list with all your users.
This plugin extends the functionality of MailPoet by creating additional automatically synced lists, one for each WordPress User Role on your site.
When changing the role of a user, the lists should be automatically updated.
You can edit and delete any of these lists (although you can’t remove subscribers, as with the ‘WordPress Users’ list). You can recreate them by clicking the ‘Re-Sync Role Lists’ button on the edit lists page.