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Exchange will not relay external of itself

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  • Exchange will not relay external of itself

    Hello all-

    I have no idea what the deal is here and I am getting a bit frustrated. I have installed a second Exchange 2003 server here in my organization and would like to eliminate the original. I have all of the mailboxes moved to the new server, as well as followed all of the steps to decommission the old server as per Microsoft's support doc.

    My issue is this, when I change my Connectors to reflect the new server as the local bridgehead, remove the original and change my router to point all SMTP traffic to the new server, I can no longer send or receive mail externally (this include to a server in the Org but off site).

    I am getting this bounced back when trying to send to an external address:
    Your message did not reach some or all of the intended recipients.

    Subject: test
    Sent: 11/18/2009 12:58 PM

    The following recipient(s) could not be reached:

    [email protected] on 11/18/2009 12:58 PM
    There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
    <server.domain.local #5.5.0 smtp;571 [email protected] prohibited. We do not relay>

    I am sure it is something going on with the new server since I can change everything back to the old server and mail starts flowing again immediately.

    Any ideas or suggestions?

    I know this is going o be something stupid that I overlooked...


  • #2
    Re: Exchange will not relay external of itself

    That is not an Exchange message that you have posted.
    The server the email is being delivered to is rejecting the email.

    Are you using a smart host? If so, check that there is no smart host and authentication details configured on the SMTP virtual server of the old machine. If there are, remove them and put them on to an SMTP Connector.

    Inbound email will be something else completely. You will need an NDR message from a failed inbound email to diagnose that. Exchange 2003 out of the box should accept email though.

    Simon Butler
    Exchange MVP

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    • #3
      Re: Exchange will not relay external of itself

      My apologies... I did not state that we do have an Internet Mail Connector and it is already configured using our smart host. I changed the local bridgehead server in the connector from the old to the new server and restarted the services.

      As for the external mail not coming through, I have not received an NDR for any of the test messages I have sent as I believe that our smart host holds that mail until the connection is restored.

      I have looked at the two servers side by side checking settings and so far I can't find anything that differs and it is just driving me up the wall! Thank you for the suggestion, I can't find any changes that may need made on our smart host's web site, but I think I will call them today and make sure.

      If anyone has any ideas or suggestions, I am happy to hear them.




      • #4
        Re: Exchange will not relay external of itself

        Just finished talking to support at the smart host. All they need is our external IP for the server, which isn't changing, so that isn't it.


        • #5
          Re: Exchange will not relay external of itself

          How does your routing from Exchange to the smart host and back is working?
          I don't think your Exchange servers are sending and recieving directly to and from the smart host, right?

          Is there some kind of port forwarding (Port 25 of course), server or service publishing?


          • #6
            Re: Exchange will not relay external of itself

            This may not be relevant, but have you checked the NAT settings at your firewall or router? Is the same public ip address being NAT'ed to both Exchange servers? If a different public ip address is being NAT'ed to the second server, it may be causing it to fail rDNS lookups.

            Also, what is the outgoing FQDN of the second server? This might also be causing it to fail rDNS and SPF lookups.


            • #7
              Re: Exchange will not relay external of itself

              In exchange it is specified that all outgoing email is to go to to via the Internet Mail Connector. All I have done is to change the local bridgehead server from the old to the new.
              DNS is working and correct on the new server. NAT had been changed on the firewall to point to the new server as well. The external and FQDN will not change, just the server.

              FWIW, I can also telnet out from the new server on port 25 just fine.