E-Mail Security Issues

File attachments in e-mail messages you receive can include different types of viruses, which may contain code that can damage data stored on your hard disk. To prevent the spread of viruses, Outlook checks the file type of each attachment against a list of file types that are known to be security risks. If an attachment is of a file type that can contain code that can run without warning, it is treated in one of two ways, depending on the file type level. If you use Microsoft Exchange Server, your administrator can add and remove file types for both levels of e-mail security.

Level 1 file types, such as .bat, .exe, .vbs, and .js, are blocked by Outlook, which means that you cannot see or access the attachment. Your Inbox will still display the paperclip icon in the Attachment column to let you know that the message has an attachment. Also, a list of the blocked attachment files will be displayed in the preview pane and at the top of an opened message.

If the file type is of level 2, you can see the icon for the attachment. When you double-click the icon, a message appears, warning you about the possibility of a computer virus. If the message is sent from a trusted source, you can then open the attachment immediately, or save it to your hard disk.

In addition to preventing potentially unsafe attachments from being opened, Outlook will warn you when you try to send a message containing attachments with file types known to be security risks. These attachments may not be able to be opened by any recipients using Microsoft Outlook.

To protect against viruses that might be contained in HTML messages you receive, scripts won't run and ActiveX controls will be deactivated regardless of your security zone setting. By default, the Microsoft Outlook security zone is set to Restricted Site.

To protect against any harmful macro viruses that might be contained in Office documents, your macro security level is set to High by default. You will be able to run only signed macros from trusted sources.