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  • Exhange send on multiple IP's

    Our exchange 2003 server is behind our firewall. It sends mail through the firewall on one of our public IP addresses.We have two mail domains. [email protected] and [email protected]hich ever domain mail is being sent from, it uses the same public IP address.We want it to send mail from domain1 using public IP address1 and send mail from domain2 using public IP address2. Is this possible? If so then how do you go about it. Thanks for any help on this.Mike

  • #2
    Re: Exchange send on multiple IP's

    Not possible.
    Exchange will only send email out on the main IP address of the server. Multiple IP addresses are close to pointless with Exchange.

    If you are hosting two domains then set them up identically, using the same host names for the MX records etc.

    Simon.
    --
    Simon Butler
    Exchange MVP

    Blog: http://blog.sembee.co.uk/
    More Exchange Content: http://exchange.sembee.info/
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    Sembee is a registered trademark, used here with permission.

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    • #3
      Re: Exhange send on multiple IP's

      I too am in a similar situation. We have several companies within our organization. Currently we have our exch server able to send mail but not receive as we have our ISP handling that (pop3 accts set up in outlook 2k3). We are in the process of moving away from the pop accts and in discussion with our ISP rep - we can have each of our domain names point to 1 mail record (along with setting up various A records for accessing mail via OWA) for incoming email. I wasnt sure if you can have multiple domains point to 1 mail record and thought you needed multiple records for this but apparently that is not the case


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      • #4
        Re: Exchange send on multiple IP's

        You can have as many domains point at a single MX record as you like.
        I personally know of a server with in excess of 100,000 domains all pointing at the same MX record. MX records are just a DNS entry, and as long as it resolves, it can be anything you like.

        The mx record for domain1.com and be host.domain2.co.uk if you like. It doesn't matter.

        Simon.
        --
        Simon Butler
        Exchange MVP

        Blog: http://blog.sembee.co.uk/
        More Exchange Content: http://exchange.sembee.info/
        Exchange Resources List: http://exbpa.com/
        In the UK? Hire me: http://www.sembee.co.uk/

        Sembee is a registered trademark, used here with permission.

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        • #5
          Re: Exchange send on multiple IP's

          Originally posted by Sembee View Post
          I personally know of a server with in excess of 100,000 domains all pointing at the same MX record.
          I have three things to say:

          1.

          2. That better be some serious ROI to justify renewing those.

          3. Who is it? C'mon, you can tell us. We won't tell anyone.


          EDIT: thanks for the answer Sembee, I completely overlooked that possibility.
          Last edited by Nonapeptide; 7th November 2008, 16:42.
          Wesley David
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          • #6
            Re: Exchange send on multiple IP's

            I didn't say it was an Exchange server.
            It belongs to a rather large domain name registrar. So they don't renew their domains, their clients do.

            Simon.
            --
            Simon Butler
            Exchange MVP

            Blog: http://blog.sembee.co.uk/
            More Exchange Content: http://exchange.sembee.info/
            Exchange Resources List: http://exbpa.com/
            In the UK? Hire me: http://www.sembee.co.uk/

            Sembee is a registered trademark, used here with permission.

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            • #7
              Re: Exhange send on multiple IP's

              Alright, if it can't be done then how does one handle reverse lookups?

              If the exchange server is sending mail for all domains through a single IP address, and you have your reverse lookup set to the 1st domain, then when mail is sent from domain1 a reverse lookup shows domain1. When mail is sent from domain2, reverse lookup shows domain1 and fails.

              With the amount of spam out there, reverse lookup to identify the sender is becoming more important.

              This is what we are trying to accomplish. Each domain with it's own IP so a reverse lookup shows the right domain.

              So, out there in the real world, how does one handle this?

              Mike

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              • #8
                Re: Exchange send on multiple IP's

                Reverse lookups simply need to match the server's identity. They have nothing to do with the domain the email message is coming from.

                So as long as the server has an A Record of mail.example.net, it announces itself as mail.example.net and the reverse DNS is mail.example.net then the message will pass reverse lookups, whether the email is coming from joe.smith @ example.net, joe.smith @ example.com or joe.smith @ example.org.

                There are simply not enough IP addresses in the world for every domain to have its own IP address.

                Reverse lookup is checking the server that is sending the message, not the specific sender. If someone is trying to ensure that the domain on the email matches the domain on the reverse DNS lookup then they will be dropping a lot of email - email from hotmail (who use other domains than hotmail.com), anyone routing their email through their ISP (Which is what you have to do if you cannot get a reverse DNS lookup set).

                Simon.
                --
                Simon Butler
                Exchange MVP

                Blog: http://blog.sembee.co.uk/
                More Exchange Content: http://exchange.sembee.info/
                Exchange Resources List: http://exbpa.com/
                In the UK? Hire me: http://www.sembee.co.uk/

                Sembee is a registered trademark, used here with permission.

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