Very comfortable Rated 5 out of 5 stars
I've been using Thunderbird for years. But, this theme is so comfortable and close to what I use at work that out of habit I tried clicking on the "Send/Receive" button in the middle of the toolbar. I even tried.searching for it in "customize" before finally remembering Thunderbird calls it "Get Mail" and it's on the left of the toolbar.
Excellent job, Jarek.