How to get email address where notification was sent

In iSupplier, I can only set up a supplier user with one email address.  However, when I open the supplier user account in the Security > Users window, I can edit the email address there to add more email addresses separated by commas.  I need to know if this will work -- if the notifications for the supplier will be sent to all the email addreses I set up in the Users window.  I cannot test it by turning on the workflow mailer because it will trigger sending of a large volume of test notifications as we do a lot of testing in the