Solidify m4 files for domain structure and internal, external and nullclient machines. Reannounce to users that they should consult with the URL and conform their Eudora settings to the standards. On announced date, reconfigure DNS to point pop, popper, smtp and mail to mx1. Point ncsa.uiuc.edu and ncsa.edu to ex1. Change all MX records on hosts to point to ex1 and ex2.
Monitor log files and verify system is working properly.
The above does not apply to Eudora or other DNS unaware Mail User Agents. In the worst case scenario, any machine involved in the mail exchanging process can run any internal or external service if configured to do so. To remedy this, I had them use ex1 as their SMTP server, which would allow traffic from anywhere. And since they fit into the checkcompat rules, they were allowed them to use that machine. I could of simply have added their network to the authorized network file but that would defeat the whole purpose of the wrapper.