Can a virus infect my PC when opening email in the preview pane?

Helpline Q&A Directory

Perhaps I am behind the times or misunderstanding something, but I always thought the only way a computer could be infected with a virus via Outlook Express was by opening an attachment to an email. Is viewing an email in the preview pane without opening the attachment also unsafe?

Most viruses infect files and documents and can only be spread by email when they are sent as message attachments. With this virus, your PC is only at risk of infection when you open the attachment.

However, there are some types of virus (for example, Bubbleboy or KakWorm) that spread in messages without attachments.

They do this by including executable script code within the body - or text - of the mail message. This code is executed as soon as the message text is displayed, even when it is displayed in the Outlook Express preview pane.

This occurs because Outlook Express uses Internet Explorer to display the text of messages. Internet Explorer will execute script code if it appears in a mail message, just as it would if it appeared in a web page.

To prevent the code being executed, don't display the message text. And the only way to avoid that is to disable the message preview so that you can select and delete the infected message without displaying its contents. This is a bit of a sledgehammer/nut scenario, because the preview pane is very useful and you might never receive one of these script viruses.

Microsoft has released a security update that solves this problem. It is incorporated in Internet Explorer 5.01 and later releases, so the issue should really only be of concern to readers using older versions of the software.

However, antivirus companies are reporting that this type of virus is now the most common, which strongly suggests that many people either aren't aware of the problem or haven't bothered to do anything to prevent it.

Microsoft also has a patch available for Internet Explorer users who don't want to upgrade the version they are currently using. You can obtain this using Windows Update. (See also tips, How to avoid internet worms and Vanquish viruses.)