I’m not sure that I like Thunderbird 3.0. I was a big fan of TB up until 2.x, but with the 3.x version released, I’m not sure. Double click on a message, and look at the (default) buttonbar. Why is there a “write” button, and and “address book” button? Where are reply (all) and forward? Oh, they are in the message-header-block, but why can’t I remove them there? Why don’t the previous/next buttons work properly (not even with add-ons)? What’s the fuss about tabbed reading? Why would I want tabbed email-reading? There is a smart-folders reading mode, but where can I see/setup how smart I want TB to be? Why is the “new” button renamed to “write”? Write an event? And what’s with the hint texts: Write event hints “create a new message”, write task hints “create a new message”? Why can’t I see my calender AND my email in one view, why can’t I disable the tabs?
Adding features is never really a bad thing, but don’t touch thing that work. And have worked for decades. Don’t reinvent the wheel. A round one is just fine on our planet.