Topic Last Modified: 2006-09-05

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine the value for TempFileThreshold:

HKEY_LOCAL_MACHINE\Software\TrendMicro\ScanMail for Exchange\RealTimeScan\ScanOption

The TempFileThreshold registry value is applicable for message body and attachment scanning. If the size of the message body or attachment is greater than the value specified in the TempFileThreshold key, the temp file will be created on disk. Otherwise, it will be created in memory. The default value for TempFileThreshold is 3,072 kilobytes (3 MB).

The Exchange Server Analyzer also queries the Win32_ComputerSystem Microsoft Windows® Management Instrumentation (WMI) class to determine the value set for the TotalPhysicalMemory key. This value represents the amount of random access memory (RAM) installed on the computer.

The Exchange Server Analyzer also queries the Active Directory® directory service to determine the value for the global settings delivContLength attribute located at:

CN=Configuration, CN=Services, CN=Microsoft Exchange, CN= OrganizationName , CN=Global Settings, CN=Message Delivery

This attribute represents the maximum size of incoming SMTP messages.

If the Exchange Server Analyzer finds that the value for TempFileThreshold is less than 70 percent of the maximum incoming message size on an Exchange Server computer with 1 GB or more of RAM, a warning is displayed.

This warning indicates that the TempFileThreshold registry value may not be optimized for your environment. This value should be set to be at least equal to the attachment size limit you have set on your Exchange servers.

This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

To correct this warning

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\Software\TrendMicro\ScanMail for Exchange\RealTimeScan\ScanOption

  3. In the right-hand pane, double-click TempFileThreshold.

  4. Enter a value, in kilobytes, that is equal to the average message size in your orginization. For example, if your average message size is 10 MB, you would enter 10240.

Additional system memory may be required if you increase this value. For example, if the 'ScanningThreads' value is set to 8, and the 'TempFileThreshold' value is set to 10240, the minimum memory required for virus scanning will be 80 MB (ScanningThreads * TempFileThreshold).
  1. Close the registry editor, and then restart the ScanMail_RealTimeScan service and the Microsoft Exchange Information Store service for the change to take effect.

Before you edit the registry, and for information about how to edit the registry, read the Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (