I installed both NS 6.2.3 and Netscape 7.0, with Mail & Newsgroups, and was successful in using this workaround. These are the steps to follow:
NOTE: Netscape Communicator 4.x must also be installed on the system.
Click on Start | Programs | Netscape Communicator | Utilities | Netscape Mail Notification
(You can make a shortcut for the feature on the QuickTray.)
Next: right click on the NSnotify icon in the System Tray, and select "Options".
Click on the "Launching Mail" tab.
Place a tick in the radio button next to "Path to Netscape.exe".
In the Target location select:
C:\Program Files\Netscape 6\netscp6.exe
OR... for Netscape 7.0
C:\Program Files\Netscape\Netscape\Netscp.exe
Next: send yourself an email to test the mail notification.
When I ran the test, in an interval of about 10 minutes the little red flag was waving, and Tom Hanks told me that "You've got Mail". I right-clicked the NSnotify icon in the System Tray, and selected "Run Mail", which took me to the Netscape 6.x and Netscape 7.0 Inbox.
NOTE: you will need to change the target setting to:
C:\Program Files\Netscape\Communicator\Program\netscape.exe
when, or if you want to use the Program in Communicator 4.x.
Ramona