OL98: Information About the Outlook E-mail Security Update

This article provides general information about the Microsoft Outlook E-mail Security Update that released on June 7, 2000.

The Outlook E-mail Security Update provides additional levels of protection against malicious e-mail messages. The update changes the way that attachments are handled by Outlook, and the way that Outlook can be controlled programmatically.

For more information about the update and how it may affect the functionality of Outlook, this article includes links to a known issues list, information for developers, information for administrators, and other information to consider before you apply the update.

History of the Outlook Security Updates

This Outlook E-mail Security Update is the second attachment-handling update for Outlook.

The first security attachment update, the Outlook E-mail Attachment Security Update, requires that you save certain file types to a disk. For additional information about the first security attachment update, click the article number below to view the article in the Microsoft Knowledge Base: The Microsoft Outlook E-mail Security Update changes and extends attachment handling. For general information about this update, and to download the update, please see the following Microsoft Web site:

Customizing the Behavior of the Security Update

If you are not running Outlook in an Exchange Server environment, or your mail is delivered to a local Personal Folders file (.pst), you cannot configure the settings for the update and you must use the full feature set of the update.

If you run Outlook in a Microsoft Exchange Server environment and your e-mail messages are delivered to a server-based mailbox, your administrator can control specific features that are included with the update. However, if your mail is delivered to a Personal Folders file (.pst), then you cannot configure the settings for the update.

New Attachment Behavior

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

Level 1 ("Unsafe")

The "unsafe" category represents any extension that may have script or code associated with it. Any attachment with an "unsafe" file extension is inaccessible if you use a version of Outlook that has the security patch applied to it. The following list contains attachments that are considered unsafe. NOTE: The list of files that are included in the Level 1 category can only be changed if you are using Outlook in a Microsoft Exchange Server environment and your mail is being delivered to an Exchange Server mailbox. These changes must be made by an administrator.

The following list describes how Outlook functions when you receive an "unsafe" file attachment:

• Any "unsafe" attachment is not accessible after you install the update. You cannot save, delete, open, print, or otherwise manipulate "unsafe" files. The top of the e-mail message indicates that Outlook has blocked access to the "unsafe" attachment; the attachment is not accessible from Outlook, however, the attachment is not actually removed from the e-mail message.
• If you forward an e-mail message with an "unsafe" attachment, the attachment is not included in the forwarded e-mail message.
• If you send an e-mail message that contains an "unsafe" attachment, you receive a warning message that says other Outlook recipients will not be able to access the attachment that you are trying to send. You can either disregard the warning message and send the e-mail message, or you can choose to not send the e-mail message.
• If you save an e-mail message that contains an "unsafe" attachment, you receive a warning message that says you will not be able to access the attachment from Outlook. You can override the warning message and save the e-mail message.
• You cannot open objects that are inserted into 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.
• You cannot open "unsafe" files that have been directly stored in an Outlook or Exchange Server folder. Although these files are not attached to an Outlook item, they are still considered "unsafe."

Level 2

Level 2 files are not "unsafe" 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 from within the message. By default, no file extensions are associated with this group.

NOTE: The list of files that are included in the Level 2 category can only be changed if you are using Outlook in a Microsoft Exchange Server environment and your mail is being delivered to an Exchange Server mailbox. These changes must be made by an administrator.

Other Attachments

When you try to open an attachment other than those in the "unsafe" 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 file extension, that file extension is treated as an "other" attachment until you add the file extension to the "unsafe" list. For example, if you install a program on your computer that uses files with an .xyz file extension, whenever you open an attachment that has an .xyz file extension, the new program opens and runs the attachment. By default, the .xyz file extension is not on the "unsafe" or Level 2 list, so it is treated as an "other" file extension. If you want attachments with the .xyz file extension to be treated as "unsafe," you must add the .xyz file extension to the list of "unsafe" file extensions.

New Programmability Behavior

When you install the update, programmatic access to Outlook is restricted. If other applications try to use Outlook on your behalf, you receive a warning message and you are prompted to confirm what the other application is doing. You receive warning messages when another application tries to do anything in the following list:

• Send mail on your behalf
• Access your address book
• Access e-mail names from your messages
• Access e-mail information from your contacts or other types of items
• Save your messages to the file system
• Search your messages for content
• Use Simple Messaging Application Programming Interface, Simple MAPI, to send messages without your consent

The update may affect how other applications interact with Outlook by changing the default security zone settings from "Internet" to "restricted," and by automatically disabling script in Hypertext Markup Language (HTML) e-mail messages and unpublished custom Outlook forms.

For additional information about developer-related updates and how they may impact third-party products and custom Outlook solutions, click the article number below to view the article in the Microsoft Knowledge Base:

Known Issues

A Microsoft Knowledge Base article that summarizes known issues with the E-mail Security Update will be added to this section when it is available.

Installation Considerations

Before you install the Outlook E-mail Security Update, Microsoft recommends that you understand how the update will affect the way that Outlook handles attachments and other applications:

• Several Outlook features no longer work. For a detailed list of issues, refer to the "Known Issues" section in this article.
• Any process or program that you use to automate Outlook may function differently and the process or program may not work. This includes synchronization utilities for handheld devices and any program that has mail-based features or features based on attachments.
• If you use Outlook in Internet Mail Only mode, or if your e-mail messages are delivered to a Personal Folders file (.pst), you cannot disable any of the features that are included with this update. If you decide to install the update, you will receive all of the new features.
• If you have "unsafe" attachments with file extensions that are on the "unsafe" list in any of your existing Outlook items (e-mail messages, contact, tasks, and so on), the items are not accessible. Before you install the update, Microsoft recommends that you save all of the items with file names that are on the "unsafe" list to ensure that you can access the files after you install the update.
• The original attachment security update, the Outlook E-mail Attachment Security Update, is available. For more information about obtaining a previous version of the attachment security update, see the "History of the Outlook Security Updates" section in this article.

For additional information about the Outlook E-mail Security Update, click the following article numbers to view the articles in the Microsoft Knowledge Base: