How to accept sending mail only to some domains ?

[Maloupi]

I want to forbid sending mail to all domains except one. How can i do this ?
I see the "Email with domain" option but i did not understood how it works.
My idea was that if an account send a mail to user@baddomain.com it will be sent to user@gooddomain.com but i'm not even sure it works like this. It's not exactly what i need but if this is not possible to accept only a domain, it may be usable in my case.

[foxcpp]

You can use destination directives in submission block to define routing for each domain separately. In default config,, default_destination sends outbound messages via queue. You can change it to reject and then move queue use to destination gooddomain.com to allow such delivery for this destination domain. Like this:

submission tls://0.0.0.0:465 tcp://0.0.0.0:587 {
    ...
    source $(local_domains) {
        ...

        destination postmaster $(local_domains) {
            deliver_to &local_routing
        }
        destination gooddomain.com {
            modify {
                dkim $(primary_domain) $(local_domains) default
            }
            deliver_to &remote_queue
        }
        default_destination {
            reject 501 5.1.8 "Not allowed domains"
        }
    }
    ...
}

[Maloupi]

Thank you, i better understand how it works.
Great, it works very well.