In Microsoft Windows XP, to help preserve the user's privacy and prevent virus attacks, Microsoft Outlook Express 6 blocks e-mail attachments that are considered unsafe and HTML content such as images. In Microsoft Windows XP Service Pack 2 (SP2), to prevent malicious scripts from running automatically, plain text mode is also turned on in Outlook Express.
This article describes plain text mode in Outlook Express and answers the following questions:
In Outlook Express, plain text mode lets users display incoming e-mail messages in plain text instead of in HTML. When Outlook Express runs in plain text mode, it uses the rich edit control instead of the MSHTML control. By using the rich edit control, you avoid any security issues that may result from using the MSHTML control.
The rich edit control provides an additional barrier to malicious code that is transmitted using e-mail. Computers that run earlier versions of Windows XP may be vulnerable to malicious code because Outlook Express processes HTML header scripts in the HTML content. The MSHTML control automatically runs these scripts. The rich edit control does not run HTML scripts. Because plain text e-mail messages do not require that HTML headers to be displayed correctly, there is typically almost no visible difference from this change. Parts of e-mail messages that do not appear to display correctly rely on HTML rendering and could present a danger to your computer.