[TriLUG] Limiting postfix destinations

[Jeff Ellis]

I need to configure a postfix server to be able to send mail only to
certain domains. In other words, accept mail originating on localhost, but
only relay it if the recipient is in an "allowed" domain.  I've tried:

smtpd_recipient_restrictions = permit_auth_destination
relay_domains = alloweddomain.com

But sending a mail to some other domain still works too.  Anyone know what
I'm missing?

Thanks,
Jeff