Open the Netscape mail application. Click on the "Edit" drop down menu and select "Properties...".
Enter a check mark in the box for "Use name and password", and enter your user name This email address is being protected from spambots. You need JavaScript enabled to view it. (replace account with the name or word that appears in front of the '@' symbol, and replace mydomain.com with your domain name).
Once all settings have been confirmed, click on the "OK" button in the bottom right hand corner of the window.