I tried some plugins to manage the service of ‘Newsletter’ and at the end I chose your plugin.
I try to ask you two implementations:
1) it would be very useful to have a summary on the dashboard (registered users, pending subscribers, sent newsletters, pending newsletter, etc …)
2) pages with messages of entry, modification and cancellation data can not be closed and not allow you to return to the homepage. It would be nice to have the possibility to close them or take another action.