Can anyone think why somebody would legitimately send a message containing '<img="http' to me? Bear in mind that any companies doing business with me won't be sending mail to the address being filtered i.e. my personal address.
I can't think of a reason for someone outside your organization to do so.
I believe you can do this in Exchange, though, so that one can put bulky images for a newsletter on the company server and email just the HTML to internal recipients. In that narrow context the feature has some utility. (Although I'd just put up a PDF and send a link to that.)
