HI there!

I am trying to setup Postfix for the first time (have used Sendmail
only in the past) and I am running into a slight problem. Mainly, I
need to have this server, foobar.A.com, (which it is the MX record for
A.com domain) to "only" receive email for the A.com domain and 'pass
it' to the final server (running Exchange, exchange.A.com). At the same
time, I want it to "only" accept outbound from the Exchange
(exchange.A.com) server as well.

How should my main.cf look? Thank you in advance.