Tried that, didn't work.
This email still came through and it was well after I made the change so the system had time to update:
X-Greylist: delayed 623 seconds by postgrey-1.31 at dns.domain.com; Thu, 30 Sep 2010 09:08:17 PDT
Received: from aju112.onlyoffer.info (unknown [184.108.40.206])
by dns.domain.com(Postfix) with ESMTP id DC7CB10B42C0
for <email@example.com>; Thu, 30 Sep 2010 09:08:17 -0700 (PDT)
From: "SwipeBids" <firstname.lastname@example.org>
Date: Thu, 30 Sep 2010 11:30:06 -0400
Subject: WHAT?? iPhones for under 20?? Itís true!