Qualcomm has posted the first beta of Eudora 8.0, a now open source e-mail program based on the Thunderbird back end. However the front end should be much more familiar to Eudora 6 users than the Thunderbird frontend.
Eudora was my primary e-mail program for about a decade, and my wife still uses it as hers. I switched to Thunderbird a couple of years ago shortly after I switched to Mac OS X. Eudora had fallen behind the curve, and could no longer reasonably display a lot of the messages I was receiving. The transition was painful. I never did get all my archived messages into Thunderbird, and still have to open up Eudora when I want to review a message more than a couple of years old.
Eudora used to be free-as-in-beer, and then eventually Qualcomm bought it from the University of Illinois and took it commercial. I never could figure out why Qualcomm of all companies did that. I guess they were a different company back then. In any case, they apparently noticed that Eudora wasn’t really part of their core business, and they’ve decided to spin it out to the open source community.
To me, Eudora 8 looks like a mixture of both Thunderbird and Eudora. I can clearly see the heritage of both. Indeed you can’t run Thunderbird and Eudora at the same time, because Thunderbird recognizes Eudora as another instance of itself, and apparently they share some preference and data files. However, the menu structure is very definitely Eudora. In particular it has an improved filing system (though I’m more focused on labels these days than folders).