Ship To is the name and address box that appears on-screen and on printouts and can be used to import text but it can also import Lookup values like an email for a Contact.
Import an Email Address to Ship To (Lookup) and BigBusiness will find the Customer or Contact, belonging to a Customer, to load their Shipping Name and Address details.
This function is extensible for custom lookups such as for large customers with Coded locations. Upload their locations as Contacts to use for automated purchasing import.