According to the following email notification from USPS Magento and OpenMage users should update USPS Endpoint to use HTTPS schema:
This message explains some security improvements planned for the USPS Web Tools services. Effective June 24th, 2021, Web Tools will remove support for all unsecure HTTP endpoints. After this change, all requests to an unsecure HTTP endpoint will fail when attempting to access the Web Tools APIs and integrators may see an error message. To continue using the Web Tools APIs, all requests must be made using the secure HTTPS endpoints listed below. Integrators currently using an unsecure HTTP endpoint should transition as soon as possible to the appropriate secure HTTPS endpoint below to prevent any loss of service. This change will impact only the API endpoints; the API request and response schemas will not change.
Support for the following unsecure HTTP endpoints will be discontinued in all Web Tools environments. In advance of the retirement date, please update your endpoints to the secure HTTPS endpoints listed below.
Web Tools Unsecure HTTP Endpoints Retirement Schedule
| Environment | Unsecure HTTP Endpoint | Retirement Date | New Secure HTTPS Endpoint |
| TEST | http://stg-production.shippingapis.com | 06/24/2021 | https://stg-production.shippingapis.com |
| PROD | http://production.shippingapis.com | 06/24/2021 | https://production.shippingapis.com |
To prepare your Magento or OpenMage store to the upcoming changes USPS endpoint be updated in Backend at System > Configuration > Sales > Shipping Methods > USPS > Gateway URL:
Posted in: Magento Maintenance