invoice email notification

Hello Gurus,

My client wants to update his new email id and delete the old one and restrict one of his colleague's email id.

SCENARIO: When the end-user creates an invoice his manager(internal) will receive a notification saying that the invoice is created. Now the manager has changed his email id and wanted to receive a notification to his new email id and delete the old one and also restrict to one of his colleague's mail id. How do I do this???

Note: It is for internal record email will not be received by the customer.