No, I wouldn't. And I wouldn't use it, even if it were free. The current system of labelling via filters gives me fine-grained control from the very first e-m

No, I wouldn't. And I wouldn't use it, even if it were free. The current system of labelling via filters gives me fine-grained control from the very first e-mail. Machine learning will require a (possibly long) training period, and may still then be prone to false positives and negatives.