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 [email protected]?
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?