In order to use the USPS module, you need to have a USPS WebTools account, signed up to use their Rate Calculator API.

1. If you have a USPS account to use shipping assistance this is not the same as the WebTools User ID needed for Storez.
2. You must have a separate WebTools User ID for each web site - otherwise USPS will terminate your access.
3. You can register at this link » https://secure.shippingapis.com/registration/
4. You will soon (24-48 government hours) receive an e-mail from USPS with your user ID and some generic instructions.
   
5. In your Shipping Methods area, for the USPS shipping module, click Install, then fill out the various configuration information fields.
6. Call USPS 1-800-344-7779 (7:00AM to 11:00PM ET) and ask them to take your account out of Test mode ie: put it into production mode.