I dunno - one of my dialup users just got spam with these headers:

Received: from mx20b.rmci.net (mx20b.rmci.net [205.162.184.38])
 by mail.angel.net (Postfix) with SMTP id D574625142
 for <xxxxxxx@angel.net>; Thu, 5 Sep 2002 15:49:59 -0400 (EDT)
Received: (qmail 2771 invoked from network); 5 Sep 2002 19:50:45 -0000
Received: from wireless-216-222-100-96.boi.rmci.net (HELO SMTP) (216.222.100.96)
  by mx20.rmci.net with SMTP; 5 Sep 2002 19:50:45 -0000
Subject: Brutal Rape galleries! Dweiss, it's your personal invitation!