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. -Doug _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
