[ale] postfix + amavis + spamassassin - Reject based on to address

[ale1 at cybertechcafe.net (Nathan J. Underwood)]

I'm still googling for this (albeit poorly), but wanted to see if anyone 
out there had an answer.  Is there a way using the setup below that I 
can have the postfix box reject email based on the To: address (before 
it gets to the exchange box)?

+----------+    +----------+   +-----------------------+    +----------+
| Internet | -> | Firewall | ->| Postfix + SA + Amavis | -> | Exchange |
+----------+    +----------+   +-----------------------+    +----------+
-- 
--
registered linux user # 73046