After reading a bunch of negative comments here, let me add a little on the bright side. I've been using Thunderbird for many years, currently both at home and at work to manage gmail accounts, pop at home, imap in the office. It works great for me, with a few annoyances but nothing serious. As for the donations, Thunderbird seems to be somehow apart from Mozilla now, so I don't think much about specific org structur…
Source?
Thunderbird is owned by Mozilla ... if I donate, my money goes to Mozilla.