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  • Random bouncebacks from known good addresses

    Ive got a user who is receiving bouncebacks from known good addresses, example: sending an email to 15 recipients will sometimes generate a "user doesnt exist" error message for 2 or 3, yet other 12 will go through with no problem. The address is definitely good, and it doesnt happen all the time. Any ideas where to check? Thanks in advance
    Exchange 2003 sp2, outlook 2003 client

  • #2
    Re: Random bouncebacks from known good addresses

    Are the bounces coming back for internal or external recipients? If they are external, I often find that domains like Yahoo, etc. that maintain multiple incoming email servers will have a problem with one or more of them at various times which causes a bounce to occur. You can check this by performing an email test at www.dnsstuff.com for the affected email address to see if all mail servers respond with 250 status codes.

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    • #3
      Re: Random bouncebacks from known good addresses

      To echo what has already been said, I find this is the case with the large providers with multiple mail servers/gateways. The problem is getting them to fix the issue - it would have to be something that the recipient needs to complain about.

      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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      • #4
        Re: Random bouncebacks from known good addresses

        Thank you for the replies. The bouncebacks are not from the large providers like Yahoo, etc. They are from various organizations, sometimes its even an internal address. Strangely, he can then find the original in his sent folder, forward it to all the same recipients, and it will then go through.
        Any ideas are welcome

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        • #5
          Re: Random bouncebacks from known good addresses

          It is very important that you differentiate between internal and external recipients, because they are handled in different ways.

          Of course that is presuming that the user is connecting to Exchange as a MAPI client and not POP3/IMAP/SMTP client.

          For internal users you shouldn't be seeing SMTP rejects. Message tracking should show the message going through Exchange and what Exchange did with it.

          Does the user have multiple accounts in Outlook?

          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: Random bouncebacks from known good addresses

            Thanks for the quick response. The user is using Outlook 2003 here in the office, so I guess he is connecting SMTP. Im sorry but Im not knowledgeable enough to answer. I set up Outlook with the defaults, and specify the exchange server name and user name,if that helps.

            In the case of the rejected message being forwarded and then being sent successfully, that message is sent to an internal distribution list.
            As for the external bounceback, that is going out to a user at another organization. The bounceback is almost immediate in both cases

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            • #7
              Re: Random bouncebacks from known good addresses

              Your understanding of Exchange and Outlook is wrong.
              Outlook when connected to Exchange (ie you selected Exchange in the config wizard) doesn't use SMTP. SMTP is only used to send the email between servers or to external recipients.

              If this is only happening for one user then the problem is either a profile issue or finger trouble by the user (ie they are making an error entering the email address). A new Outlook profile may resolve the issue.

              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


              • #8
                Re: Random bouncebacks from known good addresses

                This problem seems to be getting worse, as I am now hearing about it from 2 other users. Here is the error message:

                <<The e-mail address could not be found. Perhaps the recipient moved to a different e-mail organization, or there was a mistake in the address. Check the address and try again.
                <mail.vital-signs.com #5.1.0>>

                The users are internal and external known good addresses. On a second try, often the message will go through. Could it be caused by my server being overloaded?

                Any ideas are welcome.

                Comment


                • #9
                  Re: Random bouncebacks from known good addresses

                  Its really important that you are sure what messages are being received for INTERNAL and EXTERNAL email. They should not be the same.
                  Furthermore it is important that you know whether the message is mixed internal/external recipients, or pure internal or external only.

                  The message you have posted below is an SMTP message, which would not occur with internal email as internal email does not use SMTP.
                  The message means what it says - the user is not recognised at that server. What it does NOT mean is that the message was delivered to the correct server.

                  As for the server being overloaded as the cause - that I doubt. It wouldn't generate that type of message. You haven't said how many users you have, but if it is less than 500 then there is no way the server is overloaded no matter what the specification of it is.

                  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


                  • #10
                    Re: Random bouncebacks from known good addresses

                    Thank you Simon for the quick response. These messages are being sent to mixed internal and external recipients.

                    On the particular message I reference there were 2 recipient non-deliveries, the error I posted was for the internal recipient, there was another line for an external recipient with the exact same message .

                    Thanks for clarifying the overload possibility, I have 250 or so users, some in-house, some remote/VPN. I am hearing form both that this has been happening.

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                    • #11
                      Re: Random bouncebacks from known good addresses

                      Have you got message tracking turned on?
                      If so that will show you what the server is doing with the message.
                      You should not be getting SMTP errors with internal email. Do any of the users involved have delegates on their accounts? That is about the only thing that will generate user unknown NDRs with internal email.

                      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


                      • #12
                        Re: Random bouncebacks from known good addresses

                        Yes, I do have message tracking turned on. I do not know about delegates,but isnt it strange that it will often go through on the second attempt?

                        Also, how do you tell it is an SMTP error message?

                        Comment


                        • #13
                          Re: Random bouncebacks from known good addresses

                          The fact that you have message at all is an SMTP error.

                          SMTP errors are always

                          code server message

                          4.5.1 mail.example.net "the message here"

                          You need to track the message through message tracking and see what Exchange did with the message.

                          If your clients are connecting via MAPI and not SMTP then you shouldn't see any SMTP messages internally, so either something isn't correct internally or the message is trying to go outside the network for some reason.

                          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


                          • #14
                            Re: Random bouncebacks from known good addresses

                            Simon, thank you. I have asked to be alerted to the next instance so I can track the message. But what would cause a client to connect via MAPI or SMTP?
                            Some of the users that have this problem do have laptops that they dock in the office but connect by VPN when out of the office.

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                            • #15
                              Re: Random bouncebacks from known good addresses

                              Without knowing what Exchange is doing with the message, whether they are connecting via SMTP or MAPI, it is impossible to know. There are simply too many variables.

                              You simply do not have enough information - or have provided enough information to be able to pinpoint the issue.

                              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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