Re: [Asrg] What are the IPs that sends mail for a domain?

Bill Cole <> Fri, 19 June 2009 02:43 UTC

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Subject: Re: [Asrg] What are the IPs that sends mail for a domain?
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Franck Martin wrote, On 6/17/09 1:27 AM:
> Sure, it is the the be strict in what you send, lenient in what you
> receive.

Yes, and with all due respect to Jon Postel, that principle is better suited 
to the Internet of the 1980's than it is to the Internet today. When there 
were a small number of ultimate authorities who put a de facto ceiling on 
leniency and the net was treated as a carefully watched experiment rather 
than as a production utility,

> If we don't specify some RFC/BCP to specify how SMTP over IPv6 should be
> negotiated, then no one will follow.
> We could say something like all emails on IPv6 must have a DKIM
> signature, have RDNS helo, etc... as there is not much of an
> implementation with IPv6, there is a chance for these practices to be
> adopted from day one...

As John pointed out, "Day One" is in the past and the IETF is hostile *as a 
matter of principle* to defining application layers differently for IPv6.

I don't think that principle is wrong. Also, I can't think of many examples 
of RFC's successfully performing the role you describe of leading a 
significant change in practice rather than describing what is already widely 
being done to good effect.

Put more directly: if you want something to end up as de facto mandatory and 
have a chance of ending up in an RFC, you have to start by getting it 
enforced by many working production systems.

> ----- Original Message -----
> From: "Bill Cole"<>
> To: "Anti-Spam Research Group - IRTF"<>
> Sent: Tuesday, 16 June, 2009 10:14:02 PM GMT +01:00
>    Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
> Subject: Re: [Asrg] What are the IPs that sends mail for a domain?
> Franck Martin wrote, On 6/16/09 11:33 PM:
>> Knowing that mail servers are not deployed on IPv6, what would it take
>> to make all these requirements mandatory for IPv6 and start with a
>> better infrastructure than on IPv4?
> How do you make anything mandatory on the net?
> RFC 821 is one of a handful of Internet Standards, and it is violated
> routinely by spammers and non-spammers for no better reason than that
> they never bothered to read it. That is possible because the major MTA's
> are functional when misconfigured (e.g. with a bogus name for EHLO/HELO
> use) and by default tolerate clients which violate standards.
> The only way anything can be functionally mandatory for email transport
> is if major MTA's will not work unless configured to comply and by
> default will not interoperate with clients that do not comply. RFC's are
> great, but they do not enforce themselves. If the big freemail providers
> and sites running Sendmail, Exchange, and Postfix generally accept mail
> from non-compliant clients, there will be a lot of non-compliant clients.
> To make good behavior mandatory, bad behavior has to break with enough
> frequency that it's easier to comply than negotiate exemptions.
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