EmpowerID retrieves attribute values for each user account in a connected account store and maps them value for value to the corresponding Person attributes stored in the EmpowerID Identity Warehouse. In this way, if the value of "State" for an AD user account is "Massachusetts" then the value of "State" for that account's Person object in EmpowerID is "Massachusetts." However, EmpowerID allows you to create your own Attribute Flow Handlers to customize these values. You do this by creating a class library in Workflow Studio that inherits from the DefaultAttributeflowHandler class and by overriding the method specific to the account store (external or EmpowerID) you wish to effect. For more information on customizing Attribute Flow, see Creating Custom Attribute Flow Handlers in the Developer's Guide.
The Mail attribute should always flow from Exchange to EmpowerID.