Think of HTML e-mails as potentially dangerous web sites
@zcochran88
HTML e-mails function like mini web pages, so turning them on is akin to visiting a malicious web site. The javascript is exploited to download the virus to your computer. I found some instructions from SecurityNewsDaily on how Apple users can prevent getting infected:
"Apple Mail users can block loading of images hosted on remote Web servers by going to Preferences > Viewing > uncheck Display remote images in HTML messages, which would theoretically block a remote JavaScript-directed download. (The malicious message that Eleven found affects Windows PCs only.)"