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Multiple Exchange Servers Multiple MX records

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  • Multiple Exchange Servers Multiple MX records

    Hi everyone, I've been working in an organisation for the last year as the network administrator.

    To reduce network traffic the previous administrator setup an exchange server at each of our remote sites in the same domain that has it's own MX record and OWA..

    I'd like to install some sort of mail gateway software but can't due to there being 3 separate servers.

    How can I change things so that only one of these servers connects to the internet rather than all three ?

    Basically rather than each server sending and receiving email externally I want all email to be routed to/from the server at the main site.
    I'm assuming I need to setup routing groups but I'm unsure how to do this.

    Last edited by jimay3677; 27th April 2010, 03:59.

  • #2
    Re: Multiple Exchange Servers Multiple MX records

    uhm - does each site have it's own specific domain ?

    ie and ?
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    • #3
      Re: Multiple Exchange Servers Multiple MX records

      Originally posted by tehcamel View Post
      uhm - does each site have it's own specific domain ?

      ie and ?
      No, all in the same domain
      just in different subnets and OU's.
      servers are

      an mx record exists for each one and there is a permanent IP redirected to each through our firewall.
      I'd like to be able to just have one accessible to the outside world and route all the email to/from the other servers through it.

      They're all members of the the First routing Group in exchange
      Last edited by jimay3677; 27th April 2010, 23:14.


      • #4
        Re: Multiple Exchange Servers Multiple MX records

        You have to do two things:
        1. For outgoing mail just configure one SMTP connector with the bridgehead server of your choice and put the " * " in address space on it.

        2. For incoming mail choose one IP address for incoming and just delete the obsolete MX records.

        This configuration means that you don't have any automatic failover in case the chosen server goes down.

        Ok ok, there is a 3rd thing but this one is optional and depends on your bandwidth between the three locations and your needs. If you want to have more control over the network traffic and the mailflow you can configure two additional routing groups move the servers to the appropriate routing group and configure routing group connectors between them.
        Microsoft assumes high bandwidth with no firewall between servers within the same routing group, but it's up to you to follow this guidance.


        • #5
          Re: Multiple Exchange Servers Multiple MX records

          Hi, thanks for the help, I'm sure I did that before but it didn't work, oh well.
          Steps 1 and 2 followed, I turned off SMTP access for the remote site servers and all email appears to be sending/receiving from the master server with primary MX

          I tried step three but one of the routing group queues kept coming up with the unable to bind to server in DNS error, I compared all DNS settings etc and couldn't find the cause so went back to having all the servers in 1 routing group.

          I have one more question.
          I've allocated an external IP directed to our mail gateway (not yet setup)
          So once it's setup all I'd need to do is have our primary mx record changed to the gateway server and temporarily retain the MX for the current master but delete the other two servers?


          • #6
            Re: Multiple Exchange Servers Multiple MX records

            The first thing I would do is check that there is no smart host or external DNS server configured on the SMTP virtual server on each machine.
            Then ensure that you can telnet to port 25 of each server using IP address, netbios and FQDN. Any failures will result in Exchange being unable to communicate, as the servers need to see each other.

            If you are having all email going out through a single server, then a routing group isn't really required. A routing group is useful when you want to route email in different directions for a server or a group of servers. You may well be using routing groups in the state you are in now.

            Simon Butler
            Exchange MVP

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