Do Away With HTML Based E-mail: Most e-mail software comes configured to relay messages both in text-only mode and HTML format, which allows for the rendering of graphics and other Web-based content. But blindly accepting HTML content from third parties is a bad idea on a number of levels. The most dangerous threat is HTML content that enables the silent downloading of malicious software. In addition, even if you've never replied to a single piece of junk e-mail, spammers can tell if they've got a working e-mail address if you merely view one of their HTML-based e-mail ads. [...]
Likewise, sending e-mail in HTML mode is just a bad idea all around, and these days, it's a recipe for making sure the messages you send get caught in the recipient's junk mail folders. That's because in an effort to bypass anti-spam technologies that look for spammy words in the body of the e-mail, a huge percentage of spam now arrives embedded in HTML code and in images.
