[ulrikrasmussen]

But the things you mention are specifically the things that I think works better in the second one.

I can maybe agree that the first one looks more "polished" but at the same time I actually feel a but uneasy looking at it because my brain has to work harder to discern the UI elements due to the lack of colors and low contrast. Although the lines are heavier in the second one, I find it much easier to filter out the data that I am looking for.

Also the first one wastes screen real estate like crazy. I can only see 7 emails in that one, whereas the second one shows 14. I want all the emails that I receive within a single day to be able fit on a single screen so I don't have to scroll. Frankly, I think the first one sucks.

[nerdponx]

Fair enough, I suspect that there's no correct answer here short of doing extensive user studies and/or adding a lot of custom theme or UI configuration settings that the team certainly does not have time to work on. still, the UX/UI professionals are professionals for a reason, and it can't hurt to get their opinion specifically.