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

Bill Cole <asrg3@billmail.scconsult.com> Wed, 17 June 2009 03:27 UTC

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Date: Tue, 16 Jun 2009 23:27:27 -0400
From: Bill Cole <asrg3@billmail.scconsult.com>
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Subject: Re: [Asrg] What are the IPs that sends mail for a domain?
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Lyndon Nerenberg wrote, On 6/16/09 9:55 PM:
> On Tue, 2009-06-16 at 17:24 -0700, Douglas Otis wrote:
>> IMHO, all outbound MTAs should be required to return CVS records for
>> their EHLO name and offer MX records for their inbound.
>
> Doug, are you sure that's what you meant to say? The sentence is a bit
> ambiguous. Are you really saying any host that sends mail (is an SMTP
> client) MUST also host an listed SMTP server?

I can't testify to what he meant, but I think what he is actually saying is 
that if you have a machine that says "EHLO some.name" then there should be 
both a MX record for some.name and a SRV record for _client._smtp.some.name 
(i.e. a CSV/CSA record).

That doesn't mean requiring inbound SMTP on every outbound, it means 
requiring an affirmation in DNS that a name can be used in EHLO by a 
particular IP address and a way to get mail to the responsible party for the 
machine(s) using that name in EHLO. This is an admirable goal. A weaker goal 
would be to get people running non-spamming mail servers to follow the 
existing accepted standard of using a valid resolvable FQDN in EHLO.