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

Dotzero <> Wed, 01 July 2009 16:55 UTC

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Date: Wed, 1 Jul 2009 12:55:02 -0400
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From: Dotzero <>
To: Anti-Spam Research Group - IRTF <>
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Subject: Re: [Asrg] What are the IPs that sends mail for a domain?
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On Wed, Jul 1, 2009 at 11:28 AM, Alessandro Vesely<> wrote:
> Dotzero wrote:
>>> Thus, it turns out that if an MTA does mixed MSA and old fashioned port
>>> 25
>>> relaying for its clients, its IP cannot convey accountability.
>> The fact that it cannot (may not?) convey accountability does not mean
>> that it cannot or should not be held accountable for what it emits.
> I understand the 2nd "it" as referring to the MTA, not the IP address. It
> doesn't make much difference, since both of them are objects. AFAICS, the
> point is to hold _someone_ accountable, so that it might be theoretically
> possible to claim damage, in case. It is like an insurance, and postmasters
> tend to stipulate it with IP numbers rather than DNS names. Why?

IP Addresses are used rather than DNS names because it is
significantly easier to dump a domain name and use a new one than to
dump an IP address (range) and migrate to another unless there are
compromised hosts involved. IP Addresses tend to be more trackable and
ultimately tied to an ISP (even if that carrier is an upstream).

I tend to think less in terms of legal and claiming damage and more
along the lines of self help. Drop route (or the milder form of reject
SMTP connections) tends to have a significant impact on what one deals
with from abusive IP space. I don't necessarily recommend this as the
first response but if one does not get a response from an abuse