Dual homed Exchange 2003

  • From: "Art Henning" <ahenning@xxxxxxxxxxx>
  • To: exchangelist@xxxxxxxxxxxxx
  • Date: Thu, 12 Aug 2004 13:34:11 -0600

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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