Only one of the identifiers is needed if you're specifying a customer, however remember that email may not be a unique identifier on your site if you're allowing duplicate email addresses.
If GetAll is set to true, all data for all customers (including addresses) will be returned.
Warnings:
This can return a huge amount of data, if GetAll is true.
Example(s):
Return the data for the specified customer.
<AspDotNetStorefrontImport Version="7.1">
<GetCustomer EMail="admin@aspdotnetstorefront.com"/>
</AspDotNetStorefrontImport>