17.5 Things to Try

• Where in this rule set 3 is the best place to check for DECnet addresses, that is, the best place to detect an address of the form host::user and convert it to the form user@host.DECNET?

• Most modern UUCP implementations allow domain style addressing. How can you determine whether your site needs to convert domain UUCP addresses back into the old host!user form?

• Think up the most bizarre but legitimate address that you can and give it to sendmail in rule-testing mode. Is it parsed as you expected? If not, why not?