Re: proper dns listings for mail servers

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On 15 Aug 2005 15:28:00 -0700, shannon.hemmes@xxxxxxxxx wrote:

>Thanks Andy. But if the mail server has an internal IP address, what
>do you specify on the external DNS? Do you assign a new external IP
>ie. 200.xxx.xxx.x for the address? Or do you point it to the firewall
>IP address? If that's the case, it will create problems for folks
>using the VPN service that's built in on our firewall.
>
Did www.dnsreport.com show that you had a ptr for the sending ip of
your mailserver?


>
>Andy David - Exchange MVP wrote:
>> On Tue, 9 Aug 2005 17:36:36 -0700, "Shannon Hemmes"
>> <shannonela@xxxxxxxxxxx> wrote:
>>
>> >hi there,
>> >
>> >It's come to my attention recently that some sites are using rdns lookups
>> >and in some cases rejecting mail from our domain. I've inherited managing
>> >these systems & so am just learning the current setup.
>> >
>> >I figure we have something misconfigured in our external dns (hosted by an
>> >ISP). I'd like to know what the proper DNS configuration should be.
>> >
>> >Our setup:
>> >
>> >Firewall: firewall.domain.com (200.xxx.xxx.x)
>> >Spam filter: spam.domain.com (10.x.xx.x)
>> >Internal mail server (exch2k3): mail.domain.com (10.x.xx.x)
>> >
>> >Mail being sent out from our domain is routed thru the firewall:
>> >mail.domain.com>firewall.domain.com
>> >Incoming mail takes the following route: firewall>spam filter>internal mail
>> >
>> >Our ISP DNS has ptr record for our domain, that points to the firewall IP.
>> >They also have an mx record that points to our firewall.
>> >
>> >In looking at the message header from a message sent from our domain, shows
>> >the following received from path:
>> >Received: from mail.domain.com (firewall.domain.com [200.xxx.xxx.x])
>> >
>> >My guess is that we should have either an mx or a ptr record called
>> >mail.domain.com that points to the firewall IP? Would this be correct?
>> >Anyone care to do some explainin' to me?
>> >
>> >Thanks very much,
>> >
>> >Shannon
>> >
>>
>> You need a ptr record for the ip address of the host that is sending
>> the mail.
>> Check your domain at www.dnsreport.com
.

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