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Outlook Attachments Blocked 

The Outlook E-Mail Security Update (included in Office 2000 Service Pack 2 and later versions) blocks access to .exe, .com and other "dangerous" files. See bottom for a list of the affected file types. You cannot open these files from Outlook, nor can you use Outlook to save them to your system. If you try to forward a message containing an .exe file, Outlook does not include the attachment in the forwarded message.

With the rash of recent viruses using *.zip files to get past antivirus filters and bypass Outlook's attachment block, you may want to add the zip extension to the Level1Remove key to force users to save zips to their hard drive before opening or block access to zip files completely by adding zip to the Level1Add key.

So what do you do when you receive an .exe file and must find a way to open it? There are several methods, depending on your version of Outlook.

Outlook 2003, Outlook 2002 and Outlook 2000 SP3 (but not Outlook 98 or earlier Outlook 2000 versions) allow the user to use a registry key to open up access to blocked attachments. (Always make a backup before editing the registry.) To use this key:

  1. Run Regedit, and go to this key:

    HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Outlook\Security (change 10.0 to 9.0 for Outlook 2000 SP3 or to 11.0 for Outlook 2003)
  2. Under that key, add a new string value named Level1Remove.
  3. For the value for Level1Remove, enter a semicolon-delimited list of file extensions. For example, entering this:

    .mdb;.url

    would unblock Microsoft Access files and Internet shortcuts. Note that the use of a leading dot was not previously required, however, new security patches may require it. If you are using "mdb;url" format and extensions are blocked, add a dot to each extension. Note also that there is not a space between extensions.

If you are using this registry entry, a glance at Help | About Microsoft Outlook will show Security Mode: User Controlled above the license information.

To force users to save *.zip files to the hard drive before opening, add .zip to the extensions step 3. See How to configure Outlook to block additional attachment file name extensions for more information.

If you prefer not to edit the registry directly, you can use one of these tools to make the change; not all support both Outlook 2002 and 2000:

File extension File type
.ade Microsoft Access project extension
.adp Microsoft Access project
 app Microsoft Visual FoxPro application (blocked only in Outlook 2002 SP-2 and Outlook 2000 SP-3)
.asp Active server page. (Blocked in Outlook 2002 SP3 and higher)
.asx Windows Media Audio or Video shortcut (blocked only in Outlook 2002 builds earlier than 10.0.3005.x)
.bas Visual Basic class module
.bat Batch file
.cer (blocked only in Outlook 2003 and later)
.chm Compiled HTML Help file
.cmd Windows NT Command script
.com MS-DOS program
.cpl Control Panel extension
.crt Security certificate
.csh KornShell script file (blocked only in Outlook 2002 SP-2  and Outlook 2000 SP-3 and later)
.exe Program
 fxp Microsoft Visual FoxPro compiled program (blocked only in Outlook 2002 SP-2  and Outlook 2000 SP-3 and later)
.hlp Help file
.hta HTML program
.inf Setup  Information
.ins Internet Naming Service
.isp Internet Communication settings
.js JScript Script file
.jse Jscript Encoded Script file
.ksh KornShell script file (blocked only in Outlook 2002 SP-2  and Outlook 2000 SP-3 and later)
.lnk Shortcut
.mda Microsoft Access add-in program (blocked only in Outlook 2002 and a patched version of Outlook 2000)
.mdb Microsoft Access program
.mdt Microsoft Access workgroup information (blocked only in Outlook 2002 SP-1  and Outlook 2000 SP-3 and later)
.mdw Microsoft Access workgroup information (blocked only in Outlook 2002 SP-1  and Outlook 2000 SP-3 and later)
.mde Microsoft Access MDE database
.mdz Microsoft Access wizard program (blocked only in Outlook 2002 and a patched version of Outlook 2000)
.msc Microsoft Common Console document
.msi Windows Installer package
.msp Windows Installer patch
.mst Visual Test source files
.ops Office XP settings (blocked only in Outlook 2002 SP-1 and  and Outlook 2000 SP-3 later)
.pcd Photo CD image
.pif Shortcut to MS-DOS program
.prf Microsoft Outlook profile settings (blocked only in Outlook 2002)
.prg Microsoft Visual FoxPro program (blocked only in Outlook 2002 SP-2  and Outlook 2000 SP-3)
.pst Microsoft Outlook Personal Folders file (blocked only in Outlook 2000 SP-3)
.reg Registration entries
.scf Windows Explorer command (blocked only in Outlook 2002)
.scr Screen saver
.sct Windows Script Component
.shb Shell Scrap Object
.shs Shell Scrap Object
.tmp Temporary file. (Blocked in Outlook 2002 SP3 and higher)
.url Internet shortcut
.vb VBScript file
.vbe VBScript encoded script file
.vbs Visual Basic Script file
.vsmacros Visual Studio .NET macro project file. (Blocked in Outlook 2002 SP3 and higher)
.vss Visio shapes and Visio stencils (Blocked in Outlook 2002 SP3 and higher)
.vst Visio template (Blocked in Outlook 2002 SP3 and higher)
.vsw Visio workspace (Blocked in Outlook 2002 SP3 and higher)
.ws Windows script file (Blocked in Outlook 2002 SP3 and higher)
.wsc Windows Script Component
.wsf Windows Script file
.wsh Windows Script Host Settings file
 

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