Spam/3rd Party Relay

[Hal <hal () mrj com>]

A fix is available for SMTP that shuts off the 3rd party relay function
preventing spam operators from using your site as a relay dump.  Mail hubs using
SMTP are commonly behind the firewall and the spam operator hits the fw mail 
proxy first.  Some current and older commercial FW products don't disable 3PR and spamming is possible off those sites. 
Which firewalls do block spamming?   I tested a small number of FW and found they are not anti-span. Am I correct to 
assume that commercial  FW vendors are upgrading their products to disable 3PR ?  Are there some relatively 
straightforward mods to sendmail.cf  to disable 3PR in older FWs?

Regards Hal
hal () mrj com