I also used Eudora from the year dot on my first mac, up until the end of last year. I too used to think that it was mission critical and I couldn't do without it. Over the Christmas break, I took the plunge and converted at least 15 years of accumulated Eudora over to Apple Mail, using the outstanding EudoraMailboxCleaner utility, which preserves all the flags. This also has a key advantage that it preserves all your original Eudora files, so you can always go back if you really want. I also purchased MailActOn which enhances the Rules available in Mail, and now I can do absolutely everything I used to do in Eudora, and believe me I was a power user, in Mail and now with the benefit of all the ease of use and additional integration with Mac OS X. It was one of the best decisions I ever made and now I do not miss Eudora at all.