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  • MX records and CNAMES

    hi,

    I am looking at an exchange 2000 server which is named "mailsrv" but for which the public MX record is published by the ISP as mail.domain.com.

    While the server sends a receives messages without mayor problems, the tests in dnsstuff.com inidcate this situation as a concern (greeting name mismatch), also, emails are tagged as possible spam more often that what I consider normal.

    - Should I request the ISP to change it's MX record to match the computer name of the Exchange server?...
    - Or can I correct this using a CNAME to create an alias with the published name?
    - If so, should the CNAME be created at ISP or at local-domain level?

    Notes: SPF record is published and the IP is not listed in any blacklist that I am aware of.

    Thanks in advance.
    Siko.

  • #2
    Re: MX records and CNAMES

    Siko, can you tell the exact url of that test? so I can test it on my system.

    In Exchange System Manager go to the Server / Protocol / SMTP
    rightclick on your 'SMTP virtual server' and open the Properties
    Go to tab Delivery, and click on the button Advanced
    - What says the 'Fully quallified domainname'? and what is the result when on clicking on 'check DNS'?

    \Rem

    This posting is provided "AS IS" with no warranties, and confers no rights.

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    • #3
      Re: MX records and CNAMES

      Simply make the change in the FQDN field as outlined above.
      Unless you are using multiple Exchange server, ignore the Check DNS button.

      You should also ensure that you have a reverse DNS address on your IP address. Ideally that should match your host and the SMTP banner.

      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


      • #4
        Re: MX records and CNAMES

        ignore the Check DNS button
        You sure? Because a few years ago after I installed exchange server 2003 on my system, I discovered that the exchange server showing the FQDN of that server in NDR's. I dit not liked that idea so on that tab 'Advanced Delivery' instead of typing the FQDN I now typed a shorter fake-name, clicked OK, done.
        But from that moment several contact starts complaining that our company email was marked by the spamfilter on their network.
        What I then dit was registring that fake-name in the internal DNS server as a Cname for the exchange server. The complainings stopped. But I have to tell that that in time I did a lot of other tuning on Exchange Server the same time.

        In fact there are two possible solutions, one of them solved my problem;
        1. use the 'Check DNS' button, to check the name matches.
        or
        2. use the ISP's smtp server as a smarthost (by forwading the email that comes thoug the Internet mail SMTP connector )

        That is why I asked siko for the link, to do a quick test.

        \Rem

        This posting is provided "AS IS" with no warranties, and confers no rights.

        __________________

        ** Remember to give credit where credit's due **
        and leave Reputation Points for meaningful posts

        Comment


        • #5
          Re: MX records and CNAMES

          Check DNS does nothing to help.
          All it does is use the local DNS servers to see if the name that you have put in the FQDN resolves correctly. Unless you have setup a split DNS system, it will probably fail. The result of Check DNS has no factor on whether the information you have put in there is valid or not.

          If you put fake information in to that field, then you will have problems. That field needs to contain valid information. However it needs to resolve correctly for EXTERNAL hosts, to an external IP address. Check DNS cannot test that. Only an external DNS resolution can check that, using the tests at dnsstuff.com for example.

          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


          • #6
            Re: MX records and CNAMES

            thanks Simon for updating me on this.

            Originally posted by Siko
            also, emails are tagged as possible spam more often that what I consider normal.
            That counts for outbound I think, or do you mean tagged by your own spamfilters? Read the header information maybe you can found out a reason for the tagging.

            \Rem

            This posting is provided "AS IS" with no warranties, and confers no rights.

            __________________

            ** Remember to give credit where credit's due **
            and leave Reputation Points for meaningful posts

            Comment


            • #7
              Re: MX records and CNAMES

              Originally posted by Rems View Post
              Siko, can you tell the exact url of that test? so I can test it on my system.

              In Exchange System Manager go to the Server / Protocol / SMTP
              rightclick on your 'SMTP virtual server' and open the Properties
              Go to tab Delivery, and click on the button Advanced
              - What says the 'Fully quallified domainname'? and what is the result when on clicking on 'check DNS'?

              \Rem
              First of all, thanks for the help, and please accept my apologies for the delay, health issues in the family had me away from normal life for a while.

              I changed the name as suggested and now the external test (at dnsstuff actually) gives me an "OK/passed" so it seems solved. We'll see if the false spam tagging is reduced now.

              @Rem,
              yes, I meant outbound messages. No problem with the internal one.

              About the "Check DNS"... it fails under both configurations, concurring with Sembee's explanation

              Thanks again to you all.
              Cheers.

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