Was surprised I could not find a search for your forum, so my apologies if this has been answered…
A feature that I believe would be of great value would be synchronizing the users list to the newsletter.
Example: as it is today, a person subscribes to the newsletter but needs to subscribe separately as a WordPress users if other features are offered (such as a My Library page we use to help our WordPress users consolidate their favorite articles and videos).
Am I overlooking something? Is this something already available? or perhaps it is something that can be considered for future versions?
Other than this one feature, your Newsletter plugin is excellent, and even better since we bought the Pro version! 
Keep up the great work Stefano!
Garrett