XADM: Unable to View Free-and-Busy Information Across Exchange Server Sites (270160)


The information in this article applies to:

  • Microsoft Exchange Server 5.5
This article was previously published under Q270160
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

When you try to view free-and-busy information for users in another site, when you click the Attendee Availability tab, only a string of hash marks (/) are displayed for those users, for example:

Username \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

You may also experience the following symptoms:
  • Directory replication issues
  • Issues sending or receiving e-mail messages
  • Public folder replication issues

CAUSE

This issue can occur if you have an anti-virus software package installed that is being used in virus scan Application Programming Interface (API) mode.

WORKAROUND

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To work around this issue, make sure that the BackgroundScanning value is enabled and increase the OpenRetryDelay value from the default setting.

NOTE: These procedures reduce but may not eliminate the number of error messages that are displayed during MAPI operations.

To enable the BackgroundScanning value:
  1. Start Registry Editor (Regedt32.exe).
  2. Locate the BackgroundScanning value under the following key in the registry:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\VirusScan

  3. If the value is set to 0, change the value to 1. To do so, click Binary on the Edit menu, type 1, and then click OK.
  4. Quit Registry Editor.
The Background Scanning process begins one minute after you change this key. After you enable the BackgroundScanning value, Microsoft recommends that you allow approximately one hour to pass for each gigabyte (GB) of attachments that are stored in your private information store before you perform a MAPI operation to ensure that all attachments have been scanned. After that amount of time, MAPI error messages are greatly reduced or may be eliminated.

To increase the OpenRetryDelay value:
  1. Start Registry Editor (Regedt32.exe).
  2. Locate the OpenRetryDelay value under the following key in the registry:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\VirusScan

  3. On the Edit menu, click DWORD, type 5000, and then click OK.
  4. Quit Registry Editor.
If the OpenRetryDelay value does not exist, you must create it. To do so:
  1. Start Registry Editor (Regedt32.exe).
  2. Locate the following key in the registry:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\VirusScan

  3. On the Edit menu, click Add Value, and then add the following registry value:

    Value Name: OpenRetryDelay
    Data Type: REG_DWORD
    Radix: Decimal
    Value: 5000

  4. Quit Registry Editor.

MORE INFORMATION

Attachments are scanned when they are sent or received by the Exchange Server computer if the anti-virus API is enabled. However, you need to rescan those attachments that are already present when an operation gains access to those attachments when you install the anti-virus software or update the virus signature file, unless the Background Scanning process has scanned those attachments. This procedure ensures that those attachments have been checked with the latest virus signature file. The Background Scanning process begins a full scan of all attachments in the information store if the virus signatures change or the vendor of the virus software changes.

The BackgroundScanning value is disabled by default on many types of third-party anti-virus software. In addition, the OpenRetryDelay value that the anti-virus software uses determines the time interval (in milliseconds) that the information store pauses before the information store attempts to reopen attachments that are being scanned when the client requests them. If the attachment is not scanned and made available to the MAPI request within this time interval, a timeout error message is displayed. By default, the information store uses a setting of 500 milliseconds (msec), or one-half of a second, unless otherwise specified in the registry.

Because all attachments are rescanned after virus signatures are updated before an operation can gain access to those attachments, it is important that you plan for signature update to occur during off-peak hours if possible. When you schedule the update for off-peak hours, you allow time for the attachments to be scanned and made available to any MAPI operations.
Modification Type:MinorLast Reviewed:4/25/2005
Keywords:kbprb KB270160
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