Rated 5 out of 5 stars

Most of the dark Thunderbird themes look similar and, in my opinion, kind of ugly with the lines in between email messages. Dark Shadows XT removed the lines and favored a hover state to emphasize which email you're over. They also brightened up the interface enough to make it a dark theme, just not as dark-dark as the two ~dozen other themes I tried.

The one thing I don't like about it is the rounded corners. I prefer slight rounding at the edges if it needs to be done, but I'm less concerned with that than the colors so I'm still quite pleased.

Cheers