If you're a UPS Authorized Shipping Outlet or FedEx Authorized ShipCenter, you can log prepaid drop-off packages for compensation. PostalPoint doesn't currently have built-in support for doing this automatically.
The Custom Web Tools plugin adds any website to PostalPoint's Tools menu, so you can open it without leaving PostalPoint. You can also scan barcodes directly into the site by clicking any text box where the barcode should be "typed" into when you scan.
Download the plugin from the Plugins page, install it in Settings → Plugins, restart PostalPoint, then open the plugin's settings (the three-sliders icon under Settings → Plugins → Manage Plugins) and add the carrier portal's web address.