The use of Netscape for reading mail is not supported. You should be using Outlook, Outlook Web Access or Apple Mail to access Cornell's Exchange server, not Thunderbird, Eudora or other mail client.
Here are quick instructions for setting up Netscape Mail.
Start Netscape Communicator
On the Menu bar, choose Edit, Preferences... The Preferences Window will appear.
In the left side window, click on Identity under Mail and Newsgroups
In the right window, fill in your Name and Email Address
In the left window, click on Mail Servers
In the right window, in the Incomming Mail Servers window click the Add button.
In the Mail Server window that appears, Enter your mail server name. Enter lns61.lns.cornell.edu for your mail server name, and your LEPP UserID for User Name. Do not enter your Cornell NetID.
Do Not check Remember Password. Leave this box Unchecked
If you wish, check the box next to Check for mail every __ minutes and enter a number you desire. Click Okay
In the Outgoing Mail (SMTP) Server window, enter lns61.lns.cornell.edu
In the Outgoing Mail Server User Name, enter your LEPP UserID