Or in general for exporting mails from KMail - make a folder, make it an mbox folder, copy the required mails to it. If the folder is made in the top level, it is seen directly in ~/.Mail
Eudora can open the mbox file directly as it is its native format - just copy it to Eudora's Mail folder.
Or use MHonArc to convert to html first.
Just an aside - tho these posts only talk about the exciting stuff, most of the time is spent in audio processing, making playlists etc...