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Re: [ietf-smtp] IETF Policy on dogfood consumption or avoidance - SMTP version

2019-12-20 08:11:34
On 2019-12-19 17:52:53 -0500, Hector Santos wrote:
On 12/19/2019 1:32 PM, Viktor Dukhovni wrote:
This includes RBL checks, presence of PTR, PTR name regexp checks, ...
Rejecting address literal in EHLO is a filter in this class, that can
be justified entirely on its efficacy.  If the reported one complaint
in 10 years is about right, then it is working well enough in practice.

I don't agree this is a justification to bring break a base SMTP protocol

The fact is, there is a SMTP protocol rule of using a HELO/EHLO [ip-literal]
that MUST match the connection IP.  If not, it is a strong reason for
rejection.  I have wcSAP stats for that.

You are aware that you are directly violating a MUST NOT constraint in
the RFC by doing this, while there is no such constraint against
rejecting all IP literals (or just IP addresses equal to 7 modulo 13,
FWIW). I don't think you can argue with protocol compliance on this.

The difference with the SDO is a flat rejection of ip-literal based on some
subjective notion that ALL senders using ip literals are bad.

If it rejected on the rDNS detection that a FQDN was available and enforces
its usage, that may be a easier argument to sell because it is a
deterministic rule.

I am very unclear on what you understand to be "deterministic". 

You seem to be making assumptions on what a "good operator" should do,
use statistics to verify that applying these assumptions as rules have a
sufficiently high true positive and false negative rate and then call
them "deterministic".

If other people do the same (but with assumptions that don't match
yours) you call it "subjective".

By far, CBV is the highest payoff filter right now, today,
bar none, than any other known method.

There are some people (not me) who consider CBV abuse.


   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp(_at_)hjp(_dot_)at         |    -- Charles Stross, "Creative writing
__/   | |       challenge!"

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