The email preview pane in Outlook Express and other email clients allows you to quickly review a lot of messages just by moving through them in the inbox. This is certainly convenient, but it can make your PC vulnerable to infection by worms or viruses. In order to preview a message, the mail client has to open the message and interpret any web code, images, etc. that may be embedded in it. If there is anything malicious in the email, it can execute.
The preview pane in Outlook Express uses Internet Explorer to render images and web code. Many PCs running IE have been infected by malicious web sites just by visiting them; an HTML email message is no different than a web page–the same malicious programs can be put in HTML email messages. It’s a serious security risk but there are three things you can do to keep yourself safe:
1. Turn off message preview completely. In Outlook Express, click View–>Layout and remove the checkmark beside Show Preview Pane.
2. Click Tools–>Options and click on the Read Tab. Check the box that says Read all messages in plain text.
3. Click the Security tab. Under Download Images, click the checkbox that says Block images and other external content in HTML e-mail.
Other email clients allow you apply various similar settings; a web search or review of the program documentation will get you pointed in the right direction.
Until next time, I leave you with another Security Maxim:
Always disable any message preview or auto-open features in your e-mail client, including the blocking of external images, or view messages as text-only until you know they are safe.