Need help configuring postfix

[Raul Miller <moth@debian.org>]

Hi,

I'm probably just being stupid, but I can't figure out how to configure
postfix.

How do you configure postfix so that most of the time mail is delivered
directly, but some of the time it's delivered to a specific smtp server.
Also, it must deliver most mail in my primary mail domain remotely --
unless there's a local email username which corresponds to the local
part of the email address, those should be delivered locally.

So, raul@domain.org is delivered locally, and root@domain.org but
whoeverelse@domain.org is delivered remotely to the mx for domain.org.
[Also, I need to be able to run a script which toggles delivery of remote
messages between the usual mx rules and smarthost rules, but that's not
so urgent.]

I could probably figure this out if I sat down with the documentation for
a while and played with it, but at the moment I don't have an environment
where it's very safe to experiment.  [It's got some tools installed on
it which I need to address some other problems, but it's sending mail
to root which winds up going to a number of people.]

Thanks,

-- 
Raul