RE: RES: source mail server IP differs from MX IP

  • From: "John Tolmachoff \(Lists\)" <johnlist@xxxxxxxxxxxxxxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Tue, 29 Mar 2005 08:36:27 -0800

Yes and no. ;)

That is called IPNOTINMX. While some systems may take an aggressive
approach, it is meant to be used in a weighting system only, and if fact no
weight is given to failing the test, but in fact a very small negative
weight is applied towards passing it.

The reason that it can not be used as a spam test is that most newsletters,
auto notices, sales receipts and so forth never come from an IP that would
be in the MX records for the sending domain. Additionally, there are many
domains using 3rd party services as their gateway but send outbound direct.

You should be fine.

John T
eServices For You

> -----Original Message-----
> From: Dan Klobnak [mailto:dan.klobnak@xxxxxxxxxxxxxxxxxxxxxxx]
> Sent: Tuesday, March 29, 2005 5:57 AM
> To: [ExchangeList]
> Subject: [exchangelist] RES: source mail server IP differs from MX IP
> Tiago, I am not 100% sure that I will have that option, but I appreciate
> the suggestion.
> Going back to my original scenario: is it a potential source of issue?
> Thanks! D
> Subject: RES: source mail server IP differs from MX IP: potential
> blacklist ramifications?
> From: "Tiago de Aviz" <Tiago@xxxxxxxxxxxxxxx>
> Date: Mon, 28 Mar 2005 17:20:53 -0300
> X-Message-Number: 12
> Why not relay mail through the UNIX box too?
> Tiago de Aviz
> SoftSell - Curitiba
> Subject: source mail server IP differs from MX IP: potential blacklist
> ramifications?
> From: "Dan Klobnak" <dan.klobnak@xxxxxxxxxxxxxxxxxxxxxxx>
> Date: Mon, 28 Mar 2005 06:37:17 -0600
> X-Message-Number: 4
> Hi there,=20
> My eyes have been swimming from all the reading I did this weekend, and
> =
> this last issue was when I was a couple short of a six-pack...both =
> literally and figuratively.=20
> We are dealing with SPAM (who isn't). But have no real solution in place
> =
> right now. One particularly attractive option: not making it my problem.
> =
> My company recently merged with another company, which has an IT staff =
> of 12 to my one with apprentice. They have Saphos Puremessage for Unix =
> in place, and offered to help.=20
> The idea seems simple enough.
> I modify my MX to their perimeter X.X.X.X server.
> They filter and forward to our server based on a table entry similar to
> =
> DNS.
> However, all my sent messages will originate from my Y.Y.Y.Y ip (I'd =
> rather not have it go back through their system)
> So, does this pose a potential issue regarding blacklists. I *believe* =
> one method of determining SPAM sources is a comparison of source IP to =
> public record (MX)? Or am I really way off on the idea of Reverse DNS?
> Thanks for the insights! Dan
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