The USPS shipping module provides an interface to retrieve realtime shipping quotes from USPS.
You need an to register an account at USPS and obtain the USPS API credentials before you can use this shipping gateway.
The USPS gateway tab:

The following fields are available:
| Field | Description |
|---|---|
| USPS Web Tools User ID | The USPS web tools user ID you received when registering at USPS |
| Server URL for USPS Rating Tool | The server URL for the USPS rating tool |
| Server URL for UPS Tracking Tool | The server URL for the USPS tracking tool |
| Server URL for USPS Labeling Tool | The server URL for the USPS labeling tool |
| Packaging Size for USPS | Your packaging size. Available options are: |