[cobalt-users] Receiving mail only from SpamFirewall & allow SMTP Verify to send mail?

[Bill Gunning <bgunning@xxxxxxxxxxxxxxx>]

Is their a way to setup sendmail to only accept mail from a spam firewall 
i.e., (http://www.barracudanetworks.com), and
also allow my clients to send mail using SMTP verify?

I am planning on purchasing a Barracuda Spam Firewall, and they recommend 
using your firewall to block access to the email servers behind
the Barracuda, but if I do that then my clients will not be able to send 
mail from outside my network using SMTP verify,. if they can-not get to
the box, and if people from the outside can get to the box then they can 
by-pass the SpamFirewall and sendmail directly to the Cobalt
box ignoring the MX record and jumping directly to the box!!!

Any ideas? Can I edit sendmail.cf to only accept mail from one source and 
allow SMTP verified clients to send mail?

Bill