Hi everyone,
USPS having issues with their API.
USPS (shipping service provider) is having problems with their API which X-Cart uses to get automatic ⌠USPS■ shipping rates.
The issue affects those merchants who use carrier-calculated shipping rates from USPS: USPS servers may fail to return shipping rates and your customers may receive an error ▒We do not ship to this location▓, or USPS shipping method will not be offered on checkout.
While this problem exist, you can consider to disable USPS method temporarily and create custom a shipping method to ensure your customers will receive proper shipping rates.
We have contacted USPS and will try to find out more details. We will keep you posted.
UPDATE June 20, 2013 11:05 AM (UTC):
USPS services are still down. Although USPS company hasn▓t provided any information on the issue yet, people are
reporting that USPS site, postage tracking and APIs are down. So, if you use USPS carrier-calculated shipping rates in your stores, they may not work at the moment due to the USPS outage. We highly recommend adding alternative shipping options in your store as described above in order to overcome the problem.