Notify outside sender with message, Rules

Thank you for the anwser. I´m sorry for not had replied until now.
The email that I want to redirect to, is external and sub domain of may primary Email domain.
Simple the client´s, although tould to send to other email, they keep sending to a team email, that should be cloused for the outside of the organization, but isn´t.
I made a redirect rool for all email´s from outside the orgazition domain to the correct email, that was what I intended to do. But Workers have to continue teeling the client to not do that. The idea was to configure the notification with rules or somenting like that. If it was a normal account it would by a lot more easier.