Wednesday, January 26, 2011

MS Outlook 2003 clients disconnections with CAS Exchange 2010 Issue Solved!!

Hi everyone,
I'm glad to announce that we've facing the following issue:
"Outlook 2003 client disconnects every time from Exchange Server"
I have the following Exchange 2010 infrastructure:
Two CAS servers with Windows 2008 R2 Server over a VMware host
One DAG with two Mailbox server members.
As we had an exchange client environment with outlook 2003 SP3 running in On line mode, we started to have delay issues :
  • Outgoing e-mail messages stay in the Outbox for up to 1 minute.
  • New e-mail messages do not arrive in the Inbox for up to 1 minute.
  • Items that are deleted from folders do not disappear from the folder for up to 1 minute.
  • Items that are moved from one folder to another folder take up to 1 minute to disappear from the original folder.

This is caused by:
When Outlook opens an initial connection to an Exchange server, Outlook tries to register itself to receive new message notifications. If Outlook can register for User Datagram Protocol (UDP) notifications, an Exchange server sends a notification to Outlook by using UDP when a new message arrives in the mailbox. When Outlook receives this UDP notification, Outlook retrieves the message from the Exchange server and displays the message in the appropriate folder. If Outlook UDP, Outlook reverts to polling the Exchange server for changes. Although this polling behavior is initiated by Outlook, the Exchange server dictates the polling frequency. By default, Outlook performs polling every 60 seconds.
The problems occur because Exchange Server 2010 does not issue UDP notifications to Outlook. Therefore, Outlook cannot register to receive UDP notifications from Exchange Server 2010. Additionally, Outlook is not notified about changes that are made to a folder until Outlook polls the server for these changes. The default polling interval for Outlook is about 60 seconds. This is why you see delays that last approximately 1 minute in these folder actions. (see the art : )

Note This problem affects Outlook 2003 because it uses UDP as its primary method for receiving notifications from an Exchange server. Outlook 2007 is mostly unaffected by this problem because, by default, it uses an asynchronous notification process that does not rely on UDP notifications.

So we create a registry entry in both CAS servers as:

  • Start Registry Editor.
  • Locate and then click to select the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeRPC\ParametersSystem  Note Create the \ParametersSystem registry subkey if it does not exist.
  • Add the following registry data to the server:

    Value type: REG_DWORD
    Value name:
    Maximum Polling FrequencyValue data: any integer between 5000 and 120000 (decimal value)
  • Exit Registry Editor.
The decimal value 5000 has been set and this Outlook issue was fixed. Also we configured all Outlook clients 2003 to run in Cache Mode by GPO (see the link Using Group Policy to enforce Cached Exchange Mode settings at that section)

BUT BUT BUT, But as the mailboxes movement from Exchange 2003 to Exchange 2010 was progressing, we started getting connection problems that led me to create this POST.
After almost a month of troubleshooting with Microsoft, we deleted the registry entry in both CAS server and restarted the Exchange RPC service.

So PLEASE DO NOT CREATE THIS ENTRY  "Maximum Polling Frequency"  IN YOURS CAS servers this will open the Hell's doors!!
Be happy


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