ShipStation utilizes Stamps.com's address verification service for address validation within the United States. This service verifies US mailing addresses, providing address standardization, ZIP+4 and carrier route information, residential /business delivery flag, and the latest USPS Delivery Point Validation service which indicates if a given address is indeed "deliverable" as determined by the USPS.
All imported US addresses are verified to provide warnings and errors where applicable. These related warnings and errors can be ignored, as they do not prevent you from shipping an order. However, many carriers will return errors if you attempt to ship orders that are missing critical address information. By default, ShipStation will also utilize Stamps.com's address correction features to modify addresses that appear to be incorrect.
It is important to note that while this auto-correction is very helpful in most cases, it does have the potential to incorrectly alter an address. If you would rather not have addresses automatically corrected, you can change the settings for each store individually.
Head to your Account Settings (the gear icon in the upper right).
Next, select Selling Channels and then Store Setup from the sidebar on the left.
Uncheck the Automatically standardize and correct bad addresses when validated? checkbox.
After changing the settings for the store, any new orders will still be verified, but not automatically corrected.