Subject: draft-danisch-dns-rr-smtp-02.txt

From: Robert Elz <[email-masked]>
Date: Tue, 03 Jun 2003 20:11:07 +0700

DNS people may want to take a look at

	draft-danisch-dns-rr-smtp-02.txt

and make some comments.   In particular...

      +---+---+---+---+---+---+---+---+
      | N |    Entry Type Code  (4)   |
      +---+---+---+---+---+---+---+---+
      |  Encoded and Compressed DNS   |
      /  Name as described in RFC1035 /
      +---+---+---+---+---+---+---+---+

is going to be worthy of some comment I suspect (and from a quick
glance, probably more).

I gave up on careful reading at ...

   The suggested method is to let the DNS server for the sender domain
   provide informations about which IP addresses are authorized to use
   the domain within a sender's address.

which I cannot find any possible way to implement.   That is, I have no idea
at all how I'd specify which IP addresses are authorised to send e-mail
claiming to be from munnari.oz.au - as that set is more or less, the
IP address where I happen to be this week, and can be anything.

What's more, usually, wherever I am, I use whatever is the local mail
relay (check this message, you don't find it coming from anywhere near
munnari.oz.au - but it is also not forged, I promise...).   If there is
none, I will send directly from my laptop, but using the local relay allows
for it to queue and retry sending mail, while not requiring my laptop
to remain active.

I simply will not, ever, relay all my mail back to Australia to be sent
back (quite often, to wherever I happen to be).   That's the only way I
can imagine making the scheme in this doc work.

What's more, to assist in reducing, as the claim is that this will do,
everyone has to do it - it is no good just some small fraction of sites
saying "I know where email from my domain name must come from" even allowing
for the small chance that they're correct in that assessment.
If there aren't enough people implementing this, no-one is going to
waste time attempting to verify it.   If verification is attempted,
it is useful only if mail is permitted only on success - which means
everyone has to install RMX records and keep them up to date somehow.

Forget it.

kre

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