Microsoft KB Archive/290497

= OL2002: You Cannot Open Attachments =

PSS ID Number: 290497

Article Last Modified on 10/1/2003

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The information in this article applies to:


 * Microsoft Outlook 2002

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This article was previously published under Q290497



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



SUMMARY
Outlook 2002 includes a new security feature that blocks attachments that are considered unsafe. If you receive an e-mail message that contains one of the blocked file types, you may receive the following warning message:

Outlook blocked access to the following potentially unsafe attachments: [...]

Although Outlook has blocked access to the attachment, the attachment still exists in the message. This article summarizes what to do if you have to open the attachment.

For additional information about the latest service pack for Microsoft Office XP, click the article number below to view the article in the Microsoft Knowledge Base:

307841 OFFXP: How to Obtain the Latest Office XP Service Pack



MORE INFORMATION
This security feature provides an additional level of protection against malicious e-mail messages. Updates are available for earlier versions of Outlook. By default, this security feature is implemented in Outlook 2002.

Use one of the following recommended methods to open the attached file:  Request that the sender post or save the attachment to a file share, and then send you the link to it. Request that the sender use a file compression utility that changes the file name extension. For a list of third-party compression products, click the following article number to view the Microsoft Knowledge Base article:

291637 OL2002: Attachments Are Not Compressed by Outlook

 Request that the sender rename the extension, and then resend you the file. After you receive the renamed attachment, you can rename the file with the original extension.

If the previously recommended methods do not meet your needs, use one of the following methods:
 * If you are in a Microsoft Exchange environment and your administrator has configured the Outlook Security settings, ask the administrator to modify the security settings for your mailbox.
 * If you are not in an Exchange environment, modify the registry to customize the attachment security settings (see the &quot;How to Customize Attachment Security Behavior&quot; section of this article for details).

How to Customize Attachment Security Behavior
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.

You can modify the attachment security behavior in Outlook 2002 if you are using Outlook in one of the following scenarios:
 * You are not using Outlook in an Exchange environment.
 * In an Exchange environment, the administrator has not configured the Outlook Security settings to disallow changes to the attachment security behavior.

In these scenarios, modify the attachment security behavior by making a modification to the registry. To do so:  Quit Outlook 2002, if it is running. Click Start, and then click Run.</li> In the Open box, type regedit, and then click OK.</li> See if the following registry key exists. If it does, skip to step 5.

HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Outlook\Security

If the registry key does not exist, create it. To create the registry key, locate and then click the following registry key:

HKEY_CURRENT_USER\Software\Microsoft

<ol style="list-style-type: lower-alpha;"> Click the Edit menu, click New, and then click Key.</li> Type Office, and then press ENTER.</li> Click the Edit menu, click New, and then click Key.</li> Type 10.0, and then press ENTER.</li> Click the Edit menu, click New, and then click Key.</li> Type Outlook, and then press ENTER.</li> Click the Edit menu, click New, and then click Key.</li> Type Security, and then press ENTER.</li></ol> </li> Click the Edit menu, click New, and then click String Value.</li> Type the following name for the new value:

Level1Remove

</li> Press ENTER.</li> Right-click the new string value name, and then click Modify.</li> Type the extension of the file type that you want to open in Outlook 2002. For example:

.exe

To specify multiple file types, use the following format:

.exe;.com

</li> Click OK.</li> <li>Quit Registry Editor.</li> <li>Restart your computer.</li></ol>

When you start Outlook 2002, you can open the file types that you specified in the registry.

NOTE: Microsoft recommends that you enable only the file types that you need. If you rarely receive a particular file type, Microsoft recommends that you give Outlook 2002 temporary access to the file type in question, and then reconfigure Outlook 2002 to block the file type by undoing the changes to registry.

Exchange Environment
If you run Outlook 2002 in an Exchange environment, your administrator can change the default attachment security behavior. For additional information, click the article number about how to configure Outlook 2002 in an Exchange environment below to view the article about how to configure Outlook 2002 in an Exchange environment in the Microsoft Knowledge Base:

290499 OL2002: Administrator Information About E-Mail Security Features

Attachment Behavior
Attachments are divided into three groups based on their file name extension, or type. Outlook handles each group in a specific way.

Level 1 (&quot;Unsafe&quot;)
The &quot;unsafe&quot; category represents any extension that may have script or code associated with it. You cannot open any attachment with an &quot;unsafe&quot; extension if you use a version of Outlook that has the security patch applied to it. The following list contains attachments that are considered unsafe:

<pre class="fixed_text">Extension      File type --- .ade           Microsoft Access project extension .adp           Microsoft Access project .asx           Windows Media Audio / Video .bas           Microsoft Visual Basic class module .bat           Batch file .chm           Compiled HTML Help file .cmd           Microsoft Windows NT Command script .com           Microsoft MS-DOS program .cpl           Control Panel extension .crt           Security certificate .exe           Program .hlp           Help file .hta           HTML program .inf           Setup Information .ins           Internet Naming Service .isp           Internet Communication settings .js            JScript file .jse           Jscript Encoded Script file .lnk           Shortcut .mda           Microsoft Access add-in program .mdb           Microsoft Access program .mde           Microsoft Access MDE database .mdt           Microsoft Access workgroup information .mdw           Microsoft Access workgroup information .mdz           Microsoft Access wizard program .msc           Microsoft Common Console document .msi           Microsoft Windows Installer package .msp           Microsoft Windows Installer patch .mst           Microsoft Windows Installer transform; Microsoft Visual                     Test source file .ops           Office XP settings .pcd           Photo CD image; Microsoft Visual compiled script .pif           Shortcut to MS-DOS program .prf           Microsoft Outlook profile settings .reg           Registration entries .scf           Windows Explorer command .scr           Screen saver .sct           Windows Script Component .shb           Shell Scrap object .shs           Shell Scrap object .url           Internet shortcut .vb            VBScript file .vbe           VBScript Encoded script file .vbs           VBScript file .wsc           Windows Script Component .wsf           Windows Script file .wsh           Windows Script Host Settings file

The following list describes how Outlook functions when you receive or send an &quot;unsafe&quot; file attachment: <ul> <li>Any &quot;unsafe&quot; attachment is not accessible. You cannot save, delete, open, print, or otherwise work with &quot;unsafe&quot; files. The top of the e-mail message indicates that Outlook has blocked access to the &quot;unsafe&quot; attachment. The attachment is not accessible from Outlook; however, the attachment is not actually removed from the e-mail message.</li> <li>If you forward an e-mail message with an &quot;unsafe&quot; attachment, the attachment is not included in the forwarded e-mail message.</li> <li>If you send an e-mail message that contains an &quot;unsafe&quot; attachment, you receive a warning message that says other Outlook recipients may not be able to access the attachment that you are trying to send. You can either ignore the warning message and send the e-mail message, or you can choose to not send the e-mail message.</li> <li>If you save or close an e-mail message that contains an &quot;unsafe&quot; attachment, you receive a warning message that says you will not be able to open the attachment in Outlook. You can override the warning message and save the e-mail message.</li> <li>You cannot open objects that are inserted into Microsoft Outlook Rich Text messages by using the Insert Object command. You do see a visual representation of the object, but you cannot open or activate the object in the e-mail message.</li> <li>You cannot open &quot;unsafe&quot; files that have been directly stored in an Outlook or Exchange folder. Although these files are not attached to an Outlook item, they are still considered &quot;unsafe.&quot; The following error message occurs in this situation:

Can't open the item. Outlook blocked access to this potentially unsafe item.

</li></ul>

Level 2
Level 2 files are not &quot;unsafe&quot; but they do require more security than other attachments. When you receive a Level 2 attachment, you are prompted to save the attachment to a disk; you cannot open the attachment in the e-mail message. By default, extensions are not associated with this group; however, you can add extensions to the Level 2 list.

NOTE: You can only change the list of files that are included in the Level 2 category if you are using Outlook in an Exchange environment and your mail is being delivered to an Exchange mailbox. An administrator must make these changes.

Other Attachments
When you try to open an attachment other than those in the &quot;unsafe&quot; or Level 2 lists, you are prompted to either open the file directly or to save it to a disk. You can turn off future prompts for that extension if you click to clear the Always ask before opening this type of file check box.

NOTE: If a program associates itself with a new extension, that extension is treated as an &quot;other&quot; attachment until you add the extension to the &quot;unsafe&quot; list. For example, if you install a program on your computer that uses files with an .xyz extension, whenever you open an attachment that has an .xyz extension, the new program opens and runs the attachment. By default, the .xyz extension is not on the &quot;unsafe&quot; or Level 2 list, so it is treated as an &quot;other&quot; extension. If you want attachments with the .xyz extension to be treated as &quot;unsafe,&quot; you must add the .xyz extension to the list of &quot;unsafe&quot; extensions.

<div class="references_section">

For additional information about the &quot;Level1Add&quot; registry key, click the following article number to view the article in the Microsoft Knowledge Base:

312834 OL2002: The &quot;Level1Add&quot; Registry Key Is Missing from Outlook 2002

Keywords: kbinfo KB290497

Technology: kbOutlook2002 kbOutlook2002Search kbOutlookSearch kbZNotKeyword3

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