I have a postfix mail server running on a CentOS distb. The problem is that emails sent to local domains should actually be sent to another server using the same domain.
Let me explain:
My Local Domain: mydomain.com
My External Domain: mydomain.com
My local sender: firstname.lastname@example.org (local) -> My recipient: email@example.com (external)
So it means that any email sent to the same domain should be send to an external domain with the same name.