Endicia is the PC postage provider for USPS labels printed from our Shopify store. We are billed by Shopify and Shopify pays Endicia, so when USPS asks for the Account ID to do an Automated Package Verification (APV) dispute, where would I find this information? It is not given in the information shown on our Shopify bill or in the information on the adjustment shown in the customer's order.
According to this press release, Endicia was integrated into Shopify (we are not using an app).
The responses from the Shopify Support Advisor have not helped with this problem.