How to add IOSS number using Automation Rules
If you choose to upload CSV files from your store into your Stallion Express account, you will need to set up an IOSS Automation Rule to avoid your recipients paying twice for imported fees.
You can use this instructional to set up an IOSS Automation Rule on your Stallion Express account:
https://scribehow.com/shared/How_to_Setup_an_IOSS_Automation_Rule__4Ya5qao_QgOw0O-dOrjtug