Hi Scott,
The changes you have done so far are one half of the solution.
Next what you need to do is, create a new target mapping (Administration>Campaign management>Target mappings) defined on schema nms:recipient, but instead of default @email attribute, this time you will configure @email2 as the column to be used for email sending.
You can then define this mapping to make use of default delivery log and tracking log schema or they can have a different schema to track these.
For more information on it please refer to official documentation link.
Hope this helps.
Regards,
Vipul