While talking to my sys admin, it dawned on me that our
firewall had not authenticated me from the account where
the perl scripts were written. See, when I was trying to
figure out why I could use my browser and not LWP, I was
surfing with IE on my local PC. So, from the Unix account where my perl scripts were, I fired up Netscape and typed www.usps.com. I supplied the firewall with my username and
password, ran the perl script again, and got the desired results. Thanks to everyone for your feedback.