Mac Forum / Applications / Eudora / April 2008

Now that's really weird!  If you have no mailboxes, Eudora normally will
create new empty In, Out, and Trash boxes.  I'd suspect a corrupted
settings file. You can rebuild the Settings by holding down all the
modifier keys (command-option-shift-control) while you select Settings
from the Special menu.  This will retain your server info, but most of
your other customizations will be lost.  Before rebuilding the Settings,
put a copy somewhere outside the Eudora Folder so you can easily get it
back if it turns out the problem is not solved by rebuilding the
Settings.

You can make it a little easier to restore your customizations if you
have Eudora create a list of them for you before you rebuild the
Settings.  Do this by opening a new message composition window and then
choose "Insert system configuration" from the Help menu.