SMTP Auth Setup for Eudora 5.0 and 5.1
Open Eudora. Select the "Tools" menu item and choose "Options". If you are on a Macintosh, select "Special" menu and choose "Settings".
Under Category, select "Getting Started".
Put a check in "Allow Authentication".
Press "OK".
If you are on Windows and using Eudora 5.1: Click on the "Checking Mail" icon, and under "Secure Sockets when Receiving", make sure "If available, STARTTLS" is selected.Now scroll down to "Sending Mail", and make sure there is a check beside "Allow Authentication".
Press "OK" to close out the dialogs. Quit Eudora, and start it up for the changes to take effect.