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Exchange 2007 error 550 5.7.1 Unable to relay

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  • Exchange 2007 error 550 5.7.1 Unable to relay

    My setup:
    Single 2003 domain, two exchange 2007 SP1 servers, one is HUB/CAS another HUB/MAIL. Clients – Outlook 2003 SP2

    Some of our users will get this error as they try sending an email to multiple external recipients.
    Detailed NDR is below:

    #550 5.7.1 Unable to relay - reinject host refused rcpt to: - psmtp ##

    “Your message wasn't delivered because of security policies. Microsoft Exchange will not try to redeliver this message for you. Please provide the following diagnostic text to your system administrator”.

    I have no email policies setup other then the default one. We also use a smarthost for outbound mailings and no filtering is done. Checked my domain for blacklisting – OK, checked for Open relay – OK.

    Any suggestions?
    Regards,
    John

  • #2
    Re: Exchange 2007 error 550 5.7.1 Unable to relay

    Whose smart host do you use? The error looks like one generated by Postini. It isn't an Exchange message so is happening from outside the server.

    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: Exchange 2007 error 550 5.7.1 Unable to relay

      You are right - it is Postini. I have talked to them and they were saying that this has to be something on my exchange server. Not sure what could it be...
      Any ideas?
      Regards,
      John

      Comment


      • #4
        Re: Exchange 2007 error 550 5.7.1 Unable to relay

        Do you route inbound email through another host or anything like that? Scan email using an appliance?

        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: Exchange 2007 error 550 5.7.1 Unable to relay

          No, I do not route inbound email thru another host nor using an appliance to scan it.
          Could it be because my outgoing and incomming IP's are different, because of the use of smart host?

          Does it make any sense? have not had this issue while were on 2003 exchange.
          Regards,
          John

          Comment


          • #6
            Re: Exchange 2007 error 550 5.7.1 Unable to relay

            If your IP addresses are different then that could be causing a problem. One antispam technique is to call back to the IP address connecting to confirm that it is an SMTP server. A bot wouldn't respond. Therefore if you have incoming SMTP traffic coming in another way then that test would fail.

            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


            • #7
              Re: Exchange 2007 error 550 5.7.1 Unable to relay

              Thanks Sembee. I will have to look into this more further, and see if there is anything that could be done to correct this.
              Also found some documentation on Postini's site in regards of message reinjection. See below...

              The reinjection host must be configured to allow the message security service IP
              addresses to relay for external recipients. You may have already set up your mail
              server and firewall to accept messages from the message security service, but
              reinjection requires further access. Your reinjection server must accept mail from
              the message security service and send it out again. This is called a private relay.

              Do you think I should consider configuring my exchange as a reinjection server also?
              Regards,
              John

              Comment


              • #8
                Re: Exchange 2007 error 550 5.7.1 Unable to relay

                I haven't had anything to do with Postini, so cannot comment on their requirements for their service.

                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


                • #9
                  Re: Exchange 2007 error 550 5.7.1 Unable to relay

                  fair enough...
                  Regards,
                  John

                  Comment

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