I can't seem to get a simple question about HTML email content and content filtering answered... so let me suggest instead that perhaps a scripting language interpreter could be embedded and/or accessible to the email processing "pipeline". I don't know if we call it a pipeline or not.

I wouldn't care about most of the tools, options and checkboxes related to content filtering if I could process messages through my own code. I don't much care what language it is just that we have a hook into the process that gives our code access "before" it finishes the routing/saving to an account folder.