vtra,
As far as I know, Avast should work with Netscape being that Netscape (basically now AOL) still uses Pop and SMTP protocols.
Try the Mail Protection Wizard as Shgoh suggested or go into the Avast Help file. If you open up the Avast AV screen and click the button in the upper left corner, the Setup page will open. Find Help and then search for Manual Configuration. It is really easy.
Techie