Took me long enough, but I finally found what I was searching for . In case someone else might have the same question, here's the mail box files location on Vista:

C:\Users\Username\AppData\Roaming\Qualcomm\Eudora

Where it states Username, replace with whatever account name is logged onto the 'puter and looking for the location. (Of course, I'm not going to post the name I use for mine .)

The easiest pathway to the location is entering it into a fresh browser where a URL is normally input. Doing so leads directly to the location opening.