File Types Impacted by the Outlook E-mail Security Update

When you install the Outlook 98/2000 E-mail Security Update, Outlook checks the file type of each attachment received in your Inbox. Outlook compares the file type against two different lists of file types — Level 1 security file types and Level 2 security file types. Access to Level 1 security file types is restricted since they can execute programs or code, or contain links to programs that could execute. Access to Level 2 security file types is not restricted, however you can only save them to your hard disk drive. Access to files that are not on these lists is not restricted.

Caution  The procedure below requires editing your registry. It should only be performed by advanced users and only after making copies of your registry files, System.dat and User.dat — both hidden files in the Windows® folder. Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

1. On the Windows taskbar, click Start, and then click Run.
2. In the Open box, type regedit, and then click OK.
3. Do one of the following:

   Level 1

   1. Click the HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Security.
   2. On the Edit menu, point to New, and then click the Level1AttachmentAdd Type key.
   3. Click Type and then enter a text string for the file extension you want to add. You can separate multiple types with semi-colons ( ; ).

   Key: Level1AttachmentAdd
   Type: <string>

   Level 2

   1. In HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Security
   2. On the Edit menu, point to New, and then click the Level2AttachmentAdd Type key.
   3. Click Type and then enter a text string for  the file extension you want to add. You can separate multiple types with semi-colons ( ; ).

   Key: Level2AttachmentAdd
   Type: <string>