The Postal Service has distributed its 2020 Web Tools API Release Notes, Version 1.5. They note that the May 21st release details are included. Updates for future releases will be distributed as details are finalized. Further information can be found at the USPS Web tools Portal – https://www.usps.com/business/web-tools-apis/welcome.htm.
Please contact webtools@usps.gov for additional information. A copy of the Release Notes is also available here –