From: Andrew Newton [mailto:andy(_at_)hxr(_dot_)us]
Why do you need a list of valid users to do a Sender-ID check?
Without a valid list of users, a mail gateway
cannot simply reject a message to domains it is
responsible for. For example:
fleeblebur.org, let's say, has 3 MX hosts,
ralph.fleeblebur.org with a priority of 0, fred.fleeblebur.org and
bob.fleeblebur.org both with a priority of 10. ralph
may have a valid user list, being the primary MX host
which will handle the majority of mail. fred and bob
may not, being simply configured to spool mail until
ralph is back online.
In this scenario, now that a given message is
coming from trusted hosts, will Sender-ID be effective?
Sr. Unix Systems Administrator