Proper SMTP server setup - was Anti-Spam ideas for usenet/list harvested email addresses

["Daniel L. Miller" <dmiller@amfes.com>]

Jacob Anawalt wrote:
> Doesn't some spam come directly from an individual running SMTP from
> their box to yours? I'm pretty sure this is the case for the
> W32/Swen@MM's email spreading methods.

I have exactly this configuration.  Our e-mail is hosted off-site on 
another server, but I have configured an Postfix server to send all our 
outgoing mail.  Is there a "proper" way I should configure our internal 
server and/or domain registration so we don't appear to be a spammer - 
since a reverse lookup would fail and my internal SMTP server does not 
accept mail at this time?

Daniel