I've been using the preview of Panther for a little while now, and I would recommend holding out for its new version of Mail. The program is fast, stable, and sexy; I would never use anything else. Though the spam filtering doesn't seem to be working just yet, "Threaded View" is very nice for mailing lists---any list that uses the same subject line every time will be treated as a thread. Just stick with what you've got for a couple more months. I promise the wait will be worth it.