I don't have technical people on the inside. I don't
think it's a dumb way either. Using the firewall is
impossible. Most IM clients have a default port, a
secondary port, and if those fail, they pick random
ports. How would I go about stopping that at the
firewall without completely shutting down the internet
connection? Using DNS to stop IM should work very
well. Unless the client is hardcoded to use IP, it
will make a DNS request to find the login server. If
the DNS request returns a bogus IP, it never goes out,
no matter what port it connects on.