What is your email client?
From:
http://support.microsoft.com/kb/817878
When you open file attachments that are considered safe, Outlook 2003
or Outlook 2007 puts these attachments in a subdirectory under the
Temporary Internet Files directory as an additional precaution. When
Outlook 2003 or Outlook 2007 first tries to use a temporary file, it
examines the registry to determine whether the following value exists,
depending on your version of Outlook.
Outlook 2003
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Security
Value Name: OutlookSecureTempFolder
Data Type: REG_SZ
Outlook 2007
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Security
Value Name: OutlookSecureTempFolder
Data Type: REG_SZ
If the value exists, and if the value contains a valid path, Outlook
2003 or Outlook 2007 uses that location for its temporary files.
If the registry value does not exist, or if it points to an invalid
location, Outlook 2003 or Outlook 2007 creates a new subdirectory
under the Temporary Internet Files directory and puts the temporary
file in the new subdirectory. The name of the new subdirectory is
unknown, is randomly generated, and takes on the following form,
depending on your version of Outlook.
Outlook 2003
C:\Documents and Settings\username\Local Settings\Temporary Internet
Files\OLKxxx
In this example, username is the user name that is used by the person
who is currently logged on to the computer, and xxx is a randomly
generated sequence of letters and numbers.
Outlook 2007
C:\Documents and Settings\username\Local Settings\Temporary Internet
Files\xxxxxxxx
Note In Windows Vista, the temporary file resides in the following
location:
C:\Users\username\AppData\Local\Microsoft\Windows\Temporary Internet
Files\Content.Outlook\xxxxxxxx
DDW