I have been using Thunderbird for some time. The reason I use it is because it came from Mozilla Mail which I have used before and I liked it. Thunderbird do have some more features than many other mail client. However its performance is bad. I put up with it for one or two months because I believe when final version of 1.5 is released it would be faster and better integration with Mac OS X. However it is not the case. It is slow: loading email, searching email, switch between different mailbox/account. And it doesn not really support Spotlight. It looks OS X application but not really one. Firefox and Thunderbird are the most bloat software of 2005. And now let’s say goodbye to then. Embrace Apple Mail 2, Safari, Shiira and maybe Opera 9 final. Really, Apple Mail 2 is elegant, enough feature for me, and at least 3 times faster and responsive than Thunderbird.