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  • SMTP Queues Performance

    Hi,
    I am having a problem regarding exchange 2003 SMTP queues; I have an exchange 2003 server running sp1. The exchange is sending many thousands of e-mails a day to externals servers.
    When the SMTP queues become full (more than 1000 e-mails), There is degradation on the server performance to 2/3 then the performance it has before (the sending speed to other external destination is reducing by 1/3).I didnít find any Hardware problem regarding Memory, CPU or I/O.

    1.Did anyone notice this kind of problem?
    2.I search the internet and I found that the maximum value of SMTP Server\Remote Queue Length should be should be less than 1,000, I think itís related to this issue, and I wonder if anyone knows why it should be less ?

    Thanks

  • #2
    Re: SMTP Queues Performance

    Any reason the server isn't on Exchange 2003 SP2?
    Is the Windows server up to date as well?
    Why are you seeing queue length of 1000 messages? If I see any messages in the queues for more than about ten minutes I investigate why? Are you doing mass mailing through Exchange?

    You need to explain a lot more about the topology of the network, but the first recommendation I would make is to get the server fully up to date.
    Exchange 2003 SP1 is over three years old - in the current security climate not having servers up to date is not a good idea.

    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: SMTP Queues Performance

      The topology is very simple: an exchange server that getting an email from another application (on another server) and send it outside to the internet, nothing special in the topology.
      The exchange is running on SBS 2003, no specific reason why the exchange is not running sp1, but i didnít see any update in the service pack documentation regarding this problem.
      I guess we can call it a mass mailing because we are talking about many thousands and when you send so much e-mails sometimes the destination is unreachable and the queue is getting full.
      The funny thing is that this beaver doesnít happen on regular IIS when I am using its SMTP(on windows 2003), only on the exchange.

      Comment


      • #4
        Re: SMTP Queues Performance

        The fact that there is nothing in the readme file about the service pack that deals with this issue does not mean that either you shouldn't install the service pack or that the problem may not be resolved. As far as I am concerned Service Packs are not optional. Exchange 2003 SP2 has been available for well over two years and is rock solid. I would suggest that you get the server up to date with Service Packs for both Windows and Exchange, then run Microsoft Update to ensure that the server is up to date with everything that is post those service packs.

        However Exchange is very poor at bulk emailing. If you are using another application to generate thousands of email messages then ideally those messages shouldn't go through Exchange but out directly if the application has its own SMTP server. Exchange isn't really designed to bulk emailing.

        If the destination isn't available then I would expect the messages to queue. There is nothing that you can do about that.
        If everything is on a single hard disk or array then that will cause performance issues, because the hard disks are being thrashed. If you have tried it with a plain IIS machine then that machine was probably doing nothing else, so Windows was able to use more resources to process the email messages. Depending on the specification of the hardware of your SBS server (Which is probably quite old if you are still on SP1) the bottleneck could be there.

        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: SMTP Queues Performance

          I installed SP2 on the exchange server and the problem is still exists. The server is running on two separate disks (SATA 2) and the SMTP queue is on different disk then the operating system, Exchange is the only application running on the server, I disabled all other services.
          The strange thing is that the performance problem only happen when the queues are full (more than 1000 e-mails) and it doesnít happen when no e-mails are in the queues.
          I am wondering whatís happen to exchange when the queues are full and why Microsoft doesnít recommend that exchange will have more than 1000 e-mail in the queues ?

          I am starting to understand that exchange is not good for bulk emailing but I still donít understand why?

          Comment


          • #6
            Re: SMTP Queues Performance

            Exchange is not designed for bulk emailing. It is designed for large numbers of users sending messages throughout the day, but not having many thousands of messages dumped on it at once. If you send 20,000 messages then Exchange will try and send each message individually. If you use a tool designed to bulk email then it will use more efficient techniques for sending the email - for example by sending all email for aol.com as one message, rather than lots of individual messages.

            As this is SBS, you cannot run it as Exchange only. Whatever you have disabled you need to enable again, as the server will fall over at some point, or at very least fill up the logs.

            Two SATA disks is not really going to be enough. If I was building a system for high email volumes it needs to have multiple RAID arrays, SAS/SCSI, not SATA. The database and transaction logs need to be on different arrays.

            You also need to look at why you are sending email to addresses where the email ends up in the queues and is not delivered. Are you doing some form of mass marketing using lists that are not clean? Is your connection to the internet throttled?

            To put it simply - the machine you have
            - is running an application that is not designed to bulk email
            - does not have the required hardware to process large volumes of email.

            I would compare it with taking a Ferrari shopping for the weekly groceries. Yes it will do the job, but you will struggle.

            There are tools and applications that are so much better at doing this job - Exchange is not one of them. You would probably be better of using a server located in a data centre, and getting your application to send the email to that server. The server in the data centre would not be running SBS, but some kind of bulk email tool.

            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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