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Re: Last Call: draft-klensin-rfc2821bis

2008-03-30 16:57:44

Ned Freed wrote:
Indeed, if you asked
a random sampling of those groups --remembering that there are a
huge number of SMTP servers in the world, only a tiny fraction
of which are professional operations and with an even smaller
fraction being large-scale, carefully-managed production ones,
you might discover that many of them had forgotten that there
was such a thing as an MX record and how to set it up.

And even if they know MX records exist they may not be able to use them. So
DNS provisioning arrangements allow users to set up MX records but there ar
others that do not.

This observation moves the proposed AAAA-only mode into one of high risk. 
Rather than the benefit of reducing complexity, it becomes the danger of 
threatening interoperability.

Let's note that the proposal is a change from a model that has worked solidly
for 20 years and has not been a source of problems.  While the proposal is fo
r a 
mode that is appealing, it is not necessary.

Methinks it is therefore time to respectfully retire the proposal.


        Anyone running a SMTP server on a truly dynamic address is
        asking for trouble.  This is independent of whether there
        is a MX record or not.  Invariably there will be SMTP
        connection attempts to the old address which are intercepted.

        Matching MX target against the greeting message would also
        address this.

        Also getting rid of implict MX records would "deal" with all
        those ISP's that insist that they need to re-write NXDOMAIN


   Dave Crocker
   Brandenburg InternetWorking
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