Slightly late to the party reading this entry about how we should all switch to HTML email.
That’s so 90’s. HTML is a truly shocking format for email, capable of containing malicious code and tracking your actions (thus allowing spammers to know if your email address is still valid). Also, an HTML ‘document’ often isn’t the whole message. HTML often contains references to external content. Consider the <img> tag. I received an email the other day that consisted almost entirely of image tags pointing off to a site that the corporate proxy had tagged as inappropriate content. The message was completely broken and unreadable (probably just as well), and the proxy logs would show that I ‘attempted’ to browse to a blocked site, despite the fact that it was my email application acting entirely beyond my control. HTML? Its fine for web pages and that’s where it should stay.
What’s more, there at least 2 open standards far better suited to sending richly formatted emails. Rich Text Format (RTF) and Portable Document Format (PDF). Both do what they say on the tin, and both are viewable on pretty much every platform with a GUI. And neither will cause your machine to go trawling the web or turn into a zombie.