Two Exchange 2003 servers on same subnet unable to send emails to each other

Posted on 2008-11-06
Last Modified: 2012-05-05
I have two Exchange 2003 SP2 servers. One is on Windows 2003 server and the other on a Windows 2000 server.  

We moved the Windows 2000 server from a remote location that is in the process of moving to a new building.

We placed the new Exchange 2003 on our existing subnet. Our internal Exchange 2003/Windows 2003 server was already operational on this LAN.

I have taken care of all the port forwarding, etc. and to the outside world the Exchange server works fine.  However, it will not send email to my existing domain and I can't send email to the new domain.

Exhange 2003 SP2 on Windows 2003

Exchange 2003 SP2 on Windows 2000

If I attempt to email, the SMTP connector doesn't send to the Exchange server handling

I watched my firewall traffic and realized I had missed the fact it was still resolving to our public IP.
On the two Exchange servers I created DNS Forward Lookup Zones for the other Exchange servers domain and created an A record and an MX record using the INTERNAL IP of the machine.

When I use NSLOOKUP | set q=mx and query for the domain (e.g., I get the INTERNAL IP address. However, when I try to force the connection from the SMTP server Queues list, my firewall logs shows the Exchange server trying to connect to the EXTERNAL IP on port 25. This happens on both servers.

I have flushed the DNS cache, rebooted the servers etc. with no change.  This is causing issues because we send lots of email between the domains.

Any help will be greatly appreciated!!
Question by:robertbranch
    LVL 32

    Accepted Solution

    Let us try to do one thing at a time....
    One the Server follow these:
    • Goto the Default SMTP Connector -> Properties -> Address Space. I assume you would be seeing sth like this
      • Type: SMTP
      • Address: *
      • Cost: XYZ....well make this cost 25
    • Now Create a New SMTP Connector populate these
      • Under Address Space:
        • Type : SMTP
        • Address:
        • Cost: 1
      • Under General
        • Forward all mails to......
    • Save and restart SMTP Service
    Now send a mail from Existing domain to NewDomain, let me know if this succeeds
    LVL 32

    Expert Comment

    Above solution  assume that both server are in Different Forest and differnt Exchange ORg.
    If they are in same Forest and Exchange Organization then let me know

    Author Closing Comment

    Worked like a charm, I di the exact same thing on the other server pointed back at the other domain.  One note: if you use an IP address in the Forward To field it must be enclosed in brackets example [].

    LVL 32

    Expert Comment

    Glad to be of help....I overlooked that part ;-)

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