Re: sink.arpa question

[Jason Bertoch <jason () i6ix com>]

Ted Hardie wrote:
> But I think the key question is actually different.  Look at this
> text in RFC 2821:
>
>
>    If one or more MX RRs are found for a given
>    name, SMTP systems MUST NOT utilize any A RRs associated with that
>    name unless they are located using the MX RRs; the "implicit MX" rule
>    above applies only if there are no MX records present.  If MX records
>    are present, but none of them are usable, this situation MUST be
>    reported as an error.
>
> If I put in an MX record pointing to a guaranteed non-present 
> FQDN, someone complying with that text will throw an error rather than
> keep seeking for an A/AAAA.  Is *that* useful?  If so, then
> sink.arpa/1.0.0.257.in-addr.arpa as an MX record entry may be.

Yes, I understand the RFC.  That section is what allows this topic to be 
discussed in the first place.  sink.arpa may very well be the interim 
solution, too.  It definitely looks better than "0 .".  It just seems 
like an ugly, smelly hack when the fundamental problem lies with 
allowing the implicit MX.  It implies that I should, for the benefit of 
everyone, create a sink.arpa MX for every A record, where the effort 
could be better spent dropping the implicit MX rule and requiring an MX 
record for hosts that really do accept mail.

/Jason