The Thunderbird Beta channel just updated to version 126.0b1, and it brings major visual improvements to Cards View! 😍
(Shown here with all visible messages selected.)

A big round of applause to Micah and Sol from our UX team for their awesome work on this, and to our community for your valuable feedback here and on our #Thunderbird UX mailing list (https://thunderbird.topicbox.com/groups/ux).

Topicbox

@thunderbird COME ON! There is no improvement when — for the same pixel count — you go from 14 items to 10 items on display :(

@patpro @thunderbird

I believe Thunderbird is keeping the options to keep using the older "card view" in future releases. Also, in this case, it improves email readability significantly, with better separation, but if your only metric for improvements is the densest pixels per email, you could use the list view.

@fiberdrive Indeed, Table View is probably the option for you @patpro And you can also choose a more compact density.
@thunderbird @fiberdrive @patpro more options is always a good thing, especially customization!