Mail Client Concept

I think UI in the most mail clients needs a critical redesign. Here is a quick concept I did a few days ago on how to improve readability and reduce big mess.

This concept is generally for tech-savvy users. I exclude short introduction texts, as I think people know way more about certain message details from the subject line than from those introductions. Of course, if a sender didn't set a subject line, short intro should be shown.

What do you think about this design and presented concepts?