The submission service still exists, so I should:
1 - get rid of the 127.0.0.1:10026 but from master.cf.
2 - in master.cf change the submission line "-o content_filter=smtp-amavis:[127.0.0.1]:10024" to "-o
content_filter=smtp-amavis:[127.0.0.1]:10028" (just to avoid 10026 for now)
3 - in amavis 50-user add:
$inet_socket_port = [10024,10028]; # listen on two ports
$interface_policy{'10028'} = 'ORIGINATING';
And that should do it?
Yes. You should see "ORIGINATING" as part of the "Passed CLEAN" log line, and no more
"...OpenRelay".