Fonts and formatting in Office Communicator?

Question

I have a bot which generates html messages and most of the IM clietns support HTML tags. But office communicator doesn't seem to understand HTML tags and needs fonts and formatting information in RTF format.

I thought of using HTML to RTF converter and passing that RTF information to Office Communicator. But instead of displaying fonts and formatting information, it shows actual RTF data (syntax). Any idea of how OC handles fonts and formatting information?