The basic flow is as follows:
Your email field Category field (determines recipient) Subject Message
First, the Message field is a <textarea> currently. Would it be possible to replace this with the built-in WYSIWYG editor so senders can send (safed) HTML emails?
Secondly, would I be able to hook in with Xenforo's built-in email system or will I need to write my own php portion to handle passing off the form information to my Microsoft Exchange server?