Eudora6
A new screen titled "Options" will open up, on the "Getting Started" ensure the "Allow authentication" option has a check mark.
Select the "Checking Mail" option from the side menu, ensure the user name option is setup as account@mydomain.com. This should be the similar to your email address, but with a period in place of the '@' symbol. You can check the option "Save password" if you do not wish to re-type your password each time you send.
Select the "Sending Mail" option from the side menu. Ensure the "SMTP Relay Personality" is set to None. Place a check in the box for "Allow authentication".
The first time that you try to sendmail, Eudora should ask for a user name and password. Enter your the same information as was entered into your configuration information, account@mydomain.com and your password.