Comment by Mike-Kelner

I know an old-school Linux admin who has been successfully running his own email servers for 30+ years - from small private ones to larger corporate setups. For spam detection he uses his own system, and it works surprisingly well even without any LLM (though an LLM could surely make it even better). So the "you can't self-host email" meme was never quite true - it is about willingness and ability to configure everything right.