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Cant send email to users on isp domain. but others ok

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  • Cant send email to users on isp domain. but others ok

    Hi All
    First time here.
    Have exchange 2000 running for small company.
    Server gets to the internet via our router/adsl modem.
    Our ISP provider is a company called TPG.

    I can send email to everyone in the world (and have been able perfectly for the past 2 years), EXCEPT for people whos email address is [email protected]

    Now, this ONLY started happening 2 months ago.

    The ISP instigated a null check thingy to supposidly stop spam (ref below).

    What do i need to do, to fix this particular problem

    -Cheers
    Craig



    ====================
    message from TPG help desk
    ===============
    In the last few months, we enabled sender address verification so that we will only accept mail from verified e-mail addresses. By verification, we mean e-mail addresses which does exist and will accept mail in return. This is to help reduce the amount of unsolicited bulk and/or commercial e-mails (or more commonly known as spam) and viruses from being sent to our users.

    The way it works is that before accepting a message, we perform an SMTP callback to one of the Mail eXchanges (MX) listed for the sender's domain. We then use the delivery status notification address, which is the null envelope sender address (<>) used for error reporting, to verify the existence of the e-mail address used by the sender and check to ensure that it will accept mail in return.

    If the callback is successful, that is - the selected MX for this domain replies saying that the sender's e-mail address does exist and will accept mail for this address, then we will accept the message and deliver it accordingly.

    If the selected MX for this domain refuses to accept mail for the sender's e-mail address, then the message is rejected by our mail servers with the appropriate error as provided by the selected MX.

  • #2
    Re: Cant send email to users on isp domain. but others ok

    Are you using a smart host? See if the ISP has an outbound SMTP server that you can use. That should get round the problem. Then configure an SMTP Connector for their domain to us that smart host.

    While I applaud the ISPs motives, that tactic must cause performance issues. Try that on any server I manage and there will be a 10 second delay before the server responds. Multiply that by 100s of messages and you have a lot of servers waiting around.

    My only other thought is whether the ISP has issues resolving your MX records. Can other users of that ISP send email to you correctly?
    I am presuming that email comes in directly on SMTP, and not via a POP3 connector or other connection.

    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


    • #3
      Re: Cant send email to users on isp domain. but others ok

      Nope.
      Not using a smart host

      Comment


      • #4
        Re: Cant send email to users on isp domain. but others ok

        The ISP needs to be challenged further on this. Their message seems like a canned response. If the ISP will not assist, then as you are a customer of theirs, vote with your feet - go elsewhere.

        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


        • #5
          Re: Cant send email to users on isp domain. but others ok

          If you vote with your feet, http://bc.whirlpool.net.au/ will give you the best options for what you want. I have used aaNet (Residential) for the past 2 years and they have given me no problems. Have a look in Whirlpool Forums (TPG) and see if you can find some assistance to your problem there.
          1 1 was a racehorse.
          2 2 was 1 2.
          1 1 1 1 race 1 day,
          2 2 1 1 2

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