Workflows: handling inbound email on Fastmail with regular expressions (now featuring ChatGPT)

I've been using Fastmail for years now and have explored a number of different approaches to handling mail. I've approached it by creating rules targeting lists of top level domains, I've gone with no rules at all and a heavy-handed approach to unsubscribing from messages (operating under the idea that everything warrants being seen and triaged) and I've even used HEY.