Extracted from debian-list
Tip provided by Roberto Ripio

Is it possible (and how :) to convert Windows Eudora Folders, and
Adresses to Linux?

I will reference to my actual setup,
using Kmail (from KDE).

First of all, some terminology: what is called 'folder' under kmail-linux was
called 'mailbox' in Eudora-win, being 'folder' used to name subdirectories
for hierarchical archiving.

If mailboxes was what you meant, then no conversion is necessary. Eudora
mailboxes are in UNIX mail format. I simply copied the .mbx files to my
mail subdirectory, /home//Mail, opened kmail, and voila, they were
ready to browse.

Different mail setups may have differences in the details, but the important
thing in that your Eudora mailboxes are actually UNIX mail folders.

Eudora addresses are not much complicated. Wherever you have your Eudora mail
you will find a file called nndbase.txt. Simply erase the first two entries
in each record: The first is the word 'alias', and the second the actual
value of alias. What will remain in each record will be somethig like
"Roberto Ripio" . In my setup, I had to copy the edited file
to "/home//.kde/share/apps/kmail/addressbook".