Douglas Otis wrote:
Providing an identifier for a machine is a different function than an
identifier for a mailbox-domain. Even mapping these identifiers from
the machine to the mailbox-domain is a challenge. AOL adds two
sub-domains to the root domain, as example. Finding the zone-cut
becomes a factor when even attempting to trace accountable entities.
One can not rely upon a wild-card SPF record, as these are intended to
provide a denial that the label is valid for a mailbox-domain. : (
so the problem is that in HELO web101.mail.yahoo.com, its
hard/impossible to determine that we should look up yahoo.com?