Random issue with Outlook 2003 accessing Exchange 2010.

Possible Symptom

  • Slow or hangs when accessing shared calendar or public folder information from outlook 2003
  • Delay in email
  • Errors
    • “Unable to open your default e-mail folders. The Microsoft Exchange Server computer is not available. Either there are network problems or the Microsoft Exchange Server computer is down for maintenance.”
    • “Unable to expand the folder. The set of folders could not be opened.”


3 Possible causes

  1. RPC Throttling
    • Here is a very good article on it
    • In a nutshell you need to set a policy that will increase “RCAMaxConcurrency”
      • As a testing step run this:
        Get-ThrottlingPolicy | set-ThrottlingPolicy –RCAMaxConcurrency $null
      • If it does resolve the issue follow the article above to set a new policy correctly and revert the test setting
        Get-ThrottlingPolicy | set-ThrottlingPolicy -RCAMaxConcurrency 20
  2. UDP notification
    • Solution is to put the 2003 Outlook client in cached mode.
  3. Genuine network issues (here are some general tips)
    1. Check cabling
    2. Check Switch Logs
    3. Try to isolate client to server to eliminate network issues as a cause.
    4. Disable TOE and RSS on NICS
    5. Check that the NIC and the switches are running the same speed and duplex
    6. Use a sniffer to inspect traffic.

5 thoughts on “Random issue with Outlook 2003 accessing Exchange 2010.

  1. I recently experienced this issue with a customer migration from Exchange 2003 to Exchange 2010, into a mixed Outlook 2003/2010 client environment.

    Most staff did not have any issues however opening 3 to 4 additional mailboxes; however some had a requirement of up to 8, which is where the issues began to appear. At first it seemed intermittent, until I came across this post, which I ultimately implemented, and then this blog article by Henrik Walther that completed the picture.

    The exact resolution I used was as follow:

    Create the following registry key:
    “Maximum Allowed Sessions Per User”=dword:00000064

    Start the Exchange Management Shell and run the following command:
    Set-ThrottlingPolicy –RCAMaxConncurrency 100

    Bounce the applicable Exchange Services:
    NET STOP MSExchangeIS
    NET START MSExchangeIS
    NET STOP MSExchangeRPC

    Restarting the Exchange RPC Client Access service will mean that the Throttling Policy update will apply immediately, instead of having to wait for AD to replicate.

    I hope this helps someone.

  2. Pingback: Outlook 2003 Error Exchange 2010 - ORG.org

  3. Pingback: Outlook Problems Accessing Email - ORG.org

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