By the way, from an email angle, I find it hard to comprehend using any email client which follows the "one window divided up" philosophy that seems prevelent on Windows. I find it clunky and I'm all the time resizing windows etc to try and get the view I want. I really can't understand why people stick to that layout :-<
However, there are things that one *can* learn from programs like Thunderbird. It seems to me that the key is to enhance areas of the existing good software. Learn from what else is out there, improve on ideas, and deliver the best possible program.