On Wednesday 02 July 2008 22:40, Douglas Otis wrote:
4.3. ADSP Lookup Procedure
,--
|If a query results in a "SERVFAIL" error response, the algorithm
|terminates without returning a result; possible actions include
|queuing the message or returning an SMTP error indicating a
|temporary failure.
'--
The term "queuing" is rather vague. In addition SERVFAIL may not be
visible behind a caching resolver. In this section it likely to imply
a message is to be held (as in requeued) pending restoration of DNS
services, and not that the message is to be queued for delivery to
individual recipient email-addresses. This section also imposes a new
interoperability requirement for SMTP that previously did not exist.
Prior to the imposition of this requirement, crucial systems with
addresses assigned within a host address entry could sustain
communications even in the event of DNS becoming inoperable.
Perhaps the following sentence could be added:
---
To ensure message reception remains viable for crucial systems when
DNS fails, the IP addresses of crucial SMTP clients should be white-
listed. This will allow ADSP and DKIM to be selectively bypassed
during such events.
Since the cited paragraph doesn't require any particular behavior, I don't see
the value in this.
I do wonder if it would be useful to return an error state as a result rather
than requiring one to infer a protocol related error from no result.
Scott K
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