RE: Dual homed Exchange 2003

  • From: "Michael B. Smith" <michael@xxxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 12 Aug 2004 14:42:59 -0400

You add manual routes for the private subnets.

It's exactly what I do on all my mail servers. 

-----Original Message-----
From: Art Henning [mailto:ahenning@xxxxxxxxxxx] 
Sent: Thursday, August 12, 2004 3:34 PM
To: [ExchangeList]
Subject: [exchangelist] Dual homed Exchange 2003

Exchange 2003 Enterprise installed on Server 2003. Latest SP's etc. Dual
homed. One nic (Nic1) on a DMZ ip mapped to the DNS MX record for our
public domain. The other nic (Nic2) on the private LAN (several subnets)
servicing our Windows 2000 Active Directory and providing our Exchange
Server services. Default SMTP Virtual Server configured for Nic2 ip and
Internet SMTP Virtual Server configure for Nic1 ip. Can properly service
incoming SMTP, POP3, OWA, IMAP requests thru the MX record ip. The
default gateway for the Exchange Server is the gateway for Nic2. This
allows other private subnets to connect to the Exchange Server services.
The Exchange Server sends all email from the default gateway nic (Nic2)
which is delivered thru the firewall ip address (not the MX record ip
address). The problem is some receiving email servers cannot resolve the
DNS entry for our Exchange Server because it is identified coming from
our firewall ip and not the MX record. The result is that some outgoing
email is rejected as either spam or relayed email. If I set the default
gateway to the Nic1 (the DMZ nic), all email is sent out with the MX
record ip address and the problem is no longer. But this introduces the
problem of not being able to route our Exchange Server services to the
other private subnets. Would like suggestions on how to crack this
catch-22 issue. Many thanks!

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