These directions work for Windows 95/98/2000/XP.
STEP 1
When you open Eudora at first time, you will see "New Acount Wizard"
as below. Please select "Skip directly to advanced account setup",
then click on "Finish".
If you change existing account setting, go to "Tools" and move down
to "Personalities". Click on personalities.

Move to account which you wish to change setting, then right click to choose "Properties".
STEP 2
Select "Generic Properties" at "Account Settings for <...>".
STEP 3
Select "Incoming Mail" tab.

Click OK.
STEP 4
Go to "Tools" and move down to "Options...". Click on options.
STEP 5
We recommend to select "Send plain text only" at "When sending mail with styled
(HTML):". HTML format sometimes can not be readable of some mail client application.
Click on "Styled Text" at left menu.
That's all for the basic seting. Click on "OK".