I'm sure it takes a lot of time and dedication to developing the plugin, and I enjoyed reading the article, but this is not what I was expecting to see.
What would be useful to me though is a list of the top X e-mail contacts I received e-mail from and sent e-mail to the last Y days. I regularly have contact with several people from the same company/brand, and I always are using the search bar on top like: "John Doe something I remembered from the specific e-mail I'm looking for".
So basically I'm not that interested in mails I received from a brand, but I'm more interested in e-mails I received from a specific person.
Gamification would be awesome candy: statistics and graphs on how fast I'm responding to e-mails I receive, etc.