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Date: Fri, 23 Feb 2007 19:10:49 -0500
To: "SIMS Discussions" <SIMS@mail.stalker.com>
From: Bill Cole <listbill@scconsult.com>
Subject: Re: An elemental question.
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At 11:37 PM +0100 2/23/07, jorge  imposed structure on a stream of 
electrons, yielding:
>Hello,
>
>Let's say that the MX for my domain resolves to an IP address whose 
>inverse resolution points to another different host/domain.
>This is what happens when a mail server is run from a rented IP address.
>
>I believe that it's ok, but is it really ?

Mostly. It may raise a little suspicion.

The most important bit of resolution is that what you HELO and banner 
as (in SIMS, the "Main Domain Name" setting) should resolve forward 
to the IP others see you as. Reverse resolution is less important, 
but you should be concerned if it goes to a name that looks generic: 
derived from the IP address. Lack of any reverse DNS is even worse.

>What do you think ?
>Any url to learn more about this particular aspect ?
>Any comments would be greatly appreciated.

I don't have a specific deep URL, but you may find useful information 
behind http://www.sorbs.net in their description of their criteria 
for listing machines in their "dynamic" list. It gives a clue as to 
what some people are doing that is trusted by many others in a 
related area (i.e. stability and consistency of DNS.) What individual 
mail admins actually do in cross-checking can be a lot more severe, 
particularly with admins who have more understanding of how to tweak 
Sendmail than why...


-- 
Bill Cole                                  
bill@scconsult.com