The conflicting uses of X.7.8 are in response to two different SMTP commands.
As a result, there is no interoperability problem in practice. The "auth
invalid" only occurs in response to the "AUTH" command, and the "trust
relationship required" only occurs in response to the "BURL" command.
As there is no interoperability problem to fix, the goals are to document the
meaning clearly and minimize changes to deployed code. We have to create 1 new
code to make the meaning clear, but we don't have to create 2 codes and
shouldn't if we want to minimize changes in deployed code. As X.7.8 appears to
have more AUTH deployment than BURL deployment, I suggest deleting X.7.15 from
this draft and changing X.7.8 and X.7.14 to say:
X.7.8 Authentication credentials invalid
Authentication failed due to invalid or insufficient
authentication credentials. When this code is seen in response to the
Submit BURL command [RFC4468], it is synonymous with code X.7.14.
Defined by RFC XXXX. Registered by IESG.
X.7.14 Trust relationship required
The submission server requires a configured trust relationship
with a third-party server in order to access the message content.
This value replaces the prior use of X.7.8 for this error
condition, thereby updating [RFC4468].
Defined by RFC XXXX. Registered by IESG.
This approach does not alter:
<http://www.ietf.org/internet-drafts/draft-siemborski-rfc2554bis-09.txt>
which is in the RFC editor queue.
One other question: do we want to list one or more non-extended SMTP codes that
are typically used with an extended code in the registry?
- Chris