Hi Tomasz, i brought up this discussion multiple times in the past.
As you said creating the X-HTML is the biggest problem. Another problem is that we allow only a small subset of tags and attributes. There are toolkits which you can use to create (X)HTML, but the output is not valid according to the XEP. Which means to have to modify the output again to get XHTML which is valid according to the XEP. I used IE on Windows and Gecko on Linux which are the most common toolkits to display and create (X)HTML.
I think we need another XEP which doesn't restrict the developers to only this small subset of tags. If we wanna move forward with xmpp-mail then we need it.
Alex
