Return-Path: Received: from bigsky.scconsult.com ([66.73.230.187] verified) by mail.stalker.com (CommuniGate Pro SMTP 5.1.7i) with ESMTP id 38784204 for SIMS@mail.stalker.com; Fri, 23 Feb 2007 16:11:16 -0800 Received-SPF: pass receiver=mail.stalker.com; client-ip=66.73.230.187; envelope-from=listbill@scconsult.com Received: from bigsky.scconsult.com (localhost [127.0.0.1]) by bigsky.scconsult.com (Postfix) with ESMTP id 5ECFC43F911 for ; Fri, 23 Feb 2007 19:10:53 -0500 (EST) Mime-Version: 1.0 Message-Id: In-Reply-To: References: X-Message-Flag: Use of Microsoft mail clients is the primary cause of cracked systems. Please switch! Date: Fri, 23 Feb 2007 19:10:49 -0500 To: "SIMS Discussions" From: Bill Cole Subject: Re: An elemental question. Content-Type: text/plain; charset="us-ascii" ; format="flowed" 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