This was "ages" ago, pre 1.0 so ~2 years ago. TBH, I can't recall which model we used. We ran it in production for several months on a proprietary training dataset of 30k emails, re-training it once a week.

I regret not following through more on that project, but hey, you've only got so much political capital to burn when people ask you "and how does it make us money?"