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  • Internal MX record

    I know it is not required but, is it safe to do? I need it for some monitoring boxes that need to send email to our domain but do an MX lookup to send to the domain. Just wanted to make sure adding an internal MX record won't blow anything up.

    thanks,
    -d

  • #2
    Re: Internal MX record

    Whats wrong with allowing them access to external DNS to do this?

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    • #3
      Re: Internal MX record

      nothing..but it is an internal server... so the assumption was to create an internal MX record however, if I can just add our ISPs external DNS servers to the servers list of DNS servers then that should be fine. If Internet access is cut off we're going to know about it anyway.

      -d

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      • #4
        Re: Internal MX record

        Does the software specifically ask for your external mail address?

        I've personally never come across this for any software, SMTP servers yes.

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        • #5
          Re: Internal MX record

          If the software has its own SMTP engine, then this is a normal request. I think about half of the sites I am involved with have internal MX records.
          Although in most cases I will go looking in the application to see if it can use a smart host and then send the email to the smart host (Exchange server instead).

          Using an external DNS server wouldn't work because it will resolve to the external IP address which will be blocked by the firewall in most cases.

          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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          • #6
            Re: Internal MX record

            Originally posted by Sembee View Post
            If the software has its own SMTP engine, then this is a normal request. I think about half of the sites I am involved with have internal MX records.
            Although in most cases I will go looking in the application to see if it can use a smart host and then send the email to the smart host (Exchange server instead).

            Using an external DNS server wouldn't work because it will resolve to the external IP address which will be blocked by the firewall in most cases.

            Simon.
            Yeah, makes sense.. a bit more detail. this is a monitoring server and since I will be monitoring exchange, I can't have it send emails through in case it goes down. so I need to be able to send emails to a cell phone etc, from this thing. external seems fine but when I send it to the same domain hmail does an MX lookup and since there is no MX record it won't send it.

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            • #7
              Re: Internal MX record

              You should look to see if the software can use a specific SMTP host instead of MX records to send email. Then you could use your ISP's SMTP server.

              The other option would be to do an NSLOOKUP on the server, see what it comes back with for the MX record. If it does, then you could use a hosts file on that specific server to map the MX record host name to an external address.

              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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              • #8
                Re: Internal MX record

                Turns out the solution was to use something like a smart host. hMail has routes and those can be setup rather than doing an MX lookup for a given domain.

                no need for an MX record internally.

                and an NSLOOKUP just turned up all of our DCs when I did a "set type=mx".

                Thanks for making me think. =)
                -d

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                • #9
                  Re: Internal MX record

                  Originally posted by dsmythe View Post

                  no need for an MX record internally.

                  and an NSLOOKUP just turned up all of our DCs when I did a "set type=mx".

                  -d
                  If you didn't have an MX record then it would return the root of the domain, which in AD is your domain controllers.

                  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.

                  Comment

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