XML Formatted Email

XML can do a very cool trick.

If you include the name of an XSL file in the XML file, you can produce what looks just like a formatted HTML file when you load the XML file into a browser.

The question I have is this. How would you actually produce an actual HTML file that can be sent as a formated email by using this XML and XSL combo?

Let me put it another way.

First of all, consider this. Email has the capacity to send HTML formated text.

Second of all, consider this. XML along with a stated XSL style sheet can be loaded into a browser to produce an HTML document (right?).

So can the same be said for an email message? If email is sophisticated to send and html file properly formatted and presented as if it was being viewed in a browser, can it also to the same with an xml file?

I imagine not. I would imagine that it could not pull off this trick. I imagine that the first order of business would be to use the xml and xsl files to produce the html file and then use that generated html file as the email.

So what code or tools can be used to produce this html file?