Kostya,
If I understood the ultimate changes correctly (i.e. the way you had it implemented in the list view), - that's great, makes good sense!
Great! Thank you!
BTW, while looking at my messages on the phone today, I thought of one possible improvement:
In the "long" header view of the message, you have two lines allocated for the sender, - to the right of the square (that can be filled in with the photo if one exists in contacts, I guess).
If the sender information is taking only one line, then the second line is empty. Do you think that using it by the line "To: me" would be too confusing?
(In my case, - I am not using photos in contacts, and I switched off Gmail-like letters, so, it's an empty generic square on the left anyway, which by itself is taking up the space, but I understood, that many people use that feature. As for me, I'd eliminate that photo placeholder completely [and even more so, if the photos is empty].)
In any case, - this is not a big deal, - after all, it's only one line...