I like the interface, modern and simple.
You can remove emails from admin dashboard opposite to the free version, which will move them to trash, it would be nice to also be removed from the email server.

Also, the premium version doesn't duplicate emails every time you hit the refresh button.
As a suggestion, it would be nice to have dedicated buttons for delete, mark as read, etc and live email view without needing to hit the refresh button, I am not an expert, I think Ajax can be used for that.
Least important, "From field" is in bold even the email is read, it is slightly confusing