I used a paid version of the Eudora email client about, hmm, 10 years ago maybe. Stayed with it for a couple of years. I use Mozilla Thunderbird for email these days. So, I was interested to learn about the first public beta release of...

Mozilla Project Penelope: Eudora 8.0.0b1 Open Source Version

...which is based on the Thunderbird email engine. I'm a very satisfied Thunderbird user. But, I may take a look at this beta release out of curiousity. Windows and Mac OS X binaries are available for download now.