On Wed, 21 Oct 1998, The IESG wrote:
The IESG has received a request to consider LDAP Schema Definitions for
Intranet Mail Routing - The mailRecipient Object Class
<draft-lachman-ldap-mail-routing-03.txt> as a Informational. This has
been reviewed in the IETF but is not the product of an IETF Working
Group.
I believe this document needs an IESG warning.
Any interpretation of the local-part of the address, including LDAP
lookups, is entirely inappropriate until it has been determined that the
right-hand-side belongs to the host processing the message (section 5.2.16
of RFC 1123). It would be quite dangerous to permit an architecture where
an incautious entry in an LDAP directory could alter mail-routing for a
user or host outside the local domain.
Therefore, it must be clear that this is a convention for local routing of
email only by a host which is listed in an MX or A record for the domain
on the right-hand-side of the address.
- Chris