Open Eudora 4.3.2. Select the "Tools" menu item and choose "Options". If you are on a Macintosh, select "Special" menu and
choose "Settings". 
Under "Category", select "Sending Mail".
Put a check in "Allow Authentication".
Press "OK".
Scroll down to "Ports" (if you are on a Macintosh, it is called "Ports and Protocols") in the "Options" window.
Press OK and you are done. * If
you do not find an Icon called Ports (or Ports and Protocols),
your Eudora installation is missing a required plug-in, called "Esoteric
Settings". Just follow these instructions below to install the plug-in:
Windows Make sure the Eudora application is not open. Look in your
Eudora directory for a directory called "extrastuff". In this directory, there
is a file called "esoteric.epi". Just drag and drop this file into the top
level of your main Eudora directory. Restart Eudora, and when you go to
Tools Menu - Options, you'll see the Ports icon appear in the
list.
Macintosh Quit Eudora and look in the Eudora Application folder for
a folder called "Extras". In this folder is a file called "Esoteric Settings".
Drag this file into the "Eudora Stuff" folder, and restart Eudora. Now when
you go to Special Menu - Settings, you'll see the Ports and
Protocols icon in the list.