Subject: you must fill your zones with TXT records

From: Tony Finch <[email-masked]>
Date: Tue, 10 Aug 2004 20:18:40 +0100

Traditional remote domain verification involves checking that the domain
stated in an email address has a valid MX or A record published in the
DNS. This implies that a spammer could send email "from" any old machine
with an A record and expect it to be accepted. Sender-ID does not solve
this problem unless you publish a -all record for EVERY HOST on your
network, since in the absence of a Sender-ID record the recipient will
fall back to the current behaviour.

With CSV the problem is slightly worse, because traditionally no checking
is done on the HELO domain. To prevent a spammer from making up names in
your zone, you must publish a wildcard -all record to ensure that the
recipient knows that you are aware of CSV and wish to ban the use of
nonexistent naes.

Tony.
-- 
f.a.n.finch  <[email-masked]>  http://dotat.at/
BERWICK ON TWEED TO WHITBY: WEST OR SOUTHWEST 2 OR 3 INCREASING 3 OR 4. FAIR.
GOOD. SLIGHT OR SMOOTH.

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From: Meng Weng Wong <[email-masked]>
Date: Tue, 10 Aug 2004 22:38:30 -0400

On Tue, Aug 10, 2004 at 08:18:40PM +0100, Tony Finch wrote:
| 
| Traditional remote domain verification involves checking that the domain
| stated in an email address has a valid MX or A record published in the
| DNS. This implies that a spammer could send email "from" any old machine
| with an A record and expect it to be accepted. Sender-ID does not solve
| this problem unless you publish a -all record for EVERY HOST on your
| network, since in the absence of a Sender-ID record the recipient will
| fall back to the current behaviour.
| 

I wonder how feasible it would be to deprecate the implicit
MX rule.

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From: "Murray S. Kucherawy" <[email-masked]>
Date: Tue, 10 Aug 2004 20:04:58 -0700 (PDT)

On Tue, 10 Aug 2004, Meng Weng Wong wrote:
> I wonder how feasible it would be to deprecate the implicit MX rule.

You mean RFC974?

I imagine such a notion would face a great deal of opposition.