Actually, Eudora was developed in 1988--when e-mail was not a
household name--by someone in the
University Of Illinois. It was bought by
Qualcomm in 1992, who continued to develop it, and does so today.
It is available in three versions. A "pro" version, which costs about $50, a "sponsored" version, which is the same except it's free and you have to view a small, static banner ad whenever you use it, and "light" version, which is free and bannerless, but you don't get the all of the fantastic features of the other two versions.