If full support, set up rdist using gnu rdist. Local changes to motd can be put here, and only here. Remove any other aliases. Also telnet to port 25. Test the sendmail by 'expn your.name', 'expn diary', and any other alias that might cause sendmail to choke.
Machine has operator login with correct operator password.
Use a similar machine to create the correct format. Get someone else to verify them if you don't know how. Ask customer before installing any of these. Extra-Cost Optional software packages. If customer has net support, or is a one-time only localization, let them know about the charges marked beside the packages.