On Sat, Jun 09, 2007 at 07:51:51AM -0700, Douglas Otis wrote:
The discovery process itself might provide a solution. For a message
to contain a valid email-address, the domain of this address MUST
locate either an MX or A record. The DKIM WG could strongly
recommend A record discovery be deprecated, and that only MX records
be used for discovery. Within a few years, it should be possible to
obsolete use of A record discovery. An email-address would not be
valid without an MX record. This would mean that policy placement
adjacent to the MX record would be the only location any policy
record would need to exist. In this case, the discovery process
itself indicates whether or not the sub-domain is USED/UNUSED.
Are you referring to the process that some MTAs follow? For example, if
a MTA needs to deliver a message, it is suppose to find a MX for the
right hand side of the email address and deliver it to the eventual A
record (Hector's claim that some MX records return IPs confused me).
Some MTAs, when they don't find an MX record, just lookup an A record
instead and deliver to the resulting IP.
If that's the case, shouldn't the deprecating of A lookups when a MX
lookup fails be brought to the SMTP group?
--
:: Jeff Macdonald | Principal Engineer, Messaging Technologies
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