draft-ietf-dnsop-dontpublish-unreachable-03.txt (was: Re: Minneapolis - agenda items please.)

[Markus Stumpf <maex-lists-dns-ietf-dnsop@Space.Net>]

Sorry, to jump in the discussion at a late point. I'm rather new to this
list.

On Thu, Feb 21, 2002 at 09:40:22AM +0000, Philip Hazel wrote:
> Proposal is to reword the final paragraph to read as follows:
> 
>     If such a facility is required, it SHOULD instead be done by
>     arranging for the hosts listed in a domain's MX records to return
>     a 554 error response, either on initial connection, or following a
>     RCPT command for an address in a domain for which there is no
>     service.

Care should be taken IMHO to keep the wording RFC 2821 (SMTP) compliant.
    RFC 2821 Section 3.1 Session Initiation
already specifies a procedure just for that case (3rd paragraph):

    The SMTP protocol allows a server to formally reject a transaction
    while still allowing the initial connection as follows:
    [ ...]

Maybe a referral to the above mentioned Section would be a good idea?

Also:

    loopback address have been seen in the DNS. This seems to be a
    misguided attempt to specify "no SMTP service for this domain"
    more positively than just refusing connections to the SMTP port.

<SIDENOTE>
From my experience it's more likely that spammers don't have a valid
ip address to point the MX of their domain to. But they need a IP
to pass anti-spam checks, so they use 127.0.0.1 and have the advantage
not to get the bounces back. Btw. I have also seen the use of 0.0.0.0
instead of 127.0.0.1. The impact of 0.0.0.0 on some SMTP daemons is rather
terrible.
</SIDENOTE>

IMHO it would be a good idea to explicitely ban the use of "0.0.0.0"
(haven't found it mentioned in the draft at all) and it probably should
be a MUST NOT.

	\Maex

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