On Apr 14, 2009, at 12:40 PM, SM wrote:
I don't think you can override a Draft Standard with a BCP. There was a discussion about the fallback to A/AAAA RRs (implicit MX) last year during a Last Call. The consensus was to keep it in the SMTP standard.
The RFC 282x update effort was to ensure compliance with dependency changes since their completion. This basis excluded consideration of protocol changes. The update did not close the book on changes to SMTP that would make it better behaved. The Internet, and DNS in particular, will become unworkable whenever some protocol becomes a vector for undesired traffic then requires global changes to unrelated systems. Defensive wildcard records targeting roots should not be published by all networks and systems not intended to handle the protocol becoming an undesired traffic vector.
One issue raised was to ensure SMTP independence of DNS when there is an MX record mandate. For example, when hostname addresses are placed into host tables, MTAs should still exchange messages. Most SMTP servers are doing extensive rule checking based upon several list types. A rule that requires MX RRs MUST also include exceptions based upon information from other sources.
To help SMTP make a transition to an MX RR requirement, a new RFC related to DNS failure detection may thereby enable DNS related rule exceptions. ADSP, about to be published, might include some of the needed language.
-Doug _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
