The owner of the company would like to forward an e-mail received from a
specific customer's e-mail address to his external e-mail -

This is the process - Our customer ) sends and e-mail to the
owner of the company ). Whenever the owner of the company
receives e-mail from our customer , the e-mail should
automatically be forward to the owner's external e-mail )

How do I do this? I tried a forwarding rule and it didn't work. Do you
have any other suggestions on how to accomplish this?

Thank you in advance for your help and quick response!