We currently send out email with an attached PDF invoice to customers when an invoice is created in our system.  Our customers want the ability to specify a second email address that should receive this email as well.  We do not want to have a contact created for this to happen.  Is there any way for a CRM workflow to use an email address in the TO or CC that is not an actual record in the system?  Note: Our system is set to send unresolved email addresses and the invoice entity option to create an email is greyed out and we can not select it.