I like what I see so far! The most obvious change is the addition of a tab bar, which on first thought might seem like a pointless concept in a mail application. However, when thinking more about how e-mail works (and just about any other form of communication for that matter), you realize that it’s very much and constant exchange of information back and forth. Incidentally, tabs are about exactly that.

I often find myself switching between reading an old e-mail and composing a response, and having those as two tabs would be much more convenient than switching windows (which is always a hassle on the Mac if both windows belong to the same app). Right now it doesn’t look like it’s possible to get the compose window in a tab, but let’s hope that will come in the future.

I’m also hoping that a double click on an e-mail would open in a new tab rather than a window. Or how about dragging an e-mail to the tab strip!

There is some UI redundancy that I’m guessing is still being thought out. For example, when you select an e-mail you see two Reply buttons; one in the main toolbar with an easily recognizable icon, and another text-only button in the preview pane. The latter feels more contextual, but it makes the traditional icon feel redundant.

Shredder –- using the retro looking icon made by Jason Kersey.

The development builds of Thunderbird 3 go under the not exactly reassuring name “Shredder” and can be downloaded from mozilla.org — obviously at your own risk; be sure to back up your mail first. Overall, I’m really excited to see that things are moving forward with Thunderbird Shredder and I’ll definitely stay on the trunk from now on (or at least until it actually lives up to its temporary name).