Check The Firewall For Norton Internet Security (as of Feb 2017) with Stamps.Com - or any other Program or App

This morning I checked the documentation on Stamps.com for how to configure the Norton Internet Security firewall and found it doesn't have the latest version. So here's how to do it (as it was I found it had already been configured when I eventually got to the right screen), but just in case you want to check too here are the screens.
First open Norton Internet Security. Then choose Settings at the top of the screen.

Next choose Firewall.

Then look at the tabs and choose Program Control.

You'll get a list of programs that are already penetrating the Firewall. It will tell you when you click on a program whether the Firewall is allowing one-way or two-way traffic and in which direction. Scroll down the window until you see the app. 

For Stamps.com the app is called ipostage.exe. Check that this file has supports two-way communications through the firewall.