You will need to change the email column in the Bulk Upload template (you can also use the Bulk Update template to update existing users) to notification_email, and add a new column labelled username.

In the notification_email column, you will enter the email that you want the user's emails to be sent to, and the username column will be what the user logs in with (instead of an email).

In summary:

Once they've been uploaded, you can navigate to their profile to edit their Notification Email, if needed.

If the user has a Notification Email set, you will see the Notification Email field in the form.