This usually means that your email program settings just need to be updated to allow for “smtp authentication”. In your email program settings, first check that your outgoing/smtp email server is set to “mail.yourdomain.com” (If you have this set to use a different provider, such as sbcglobal, yahoo, aol, or roadrunner, you will need to contact that provider for assistance with your outgoing email problems.)
Next, check that the setting in your email program for “My outgoing server requires authentication” is selected. Usually, a setting beside this option allows you to choose “Use the same login as my incoming mail server”.
To see more detailed instructions on where to update these settings in Outlook, Eudora, and Netscape Mail, click here.