outis: Fight AI spam by generating and sending a fake "user unknown" bounce emails

Outis fights spam generating and sends a fake "user unknown" bounce for an email you received, so the sender believes your address does not exist. This isn't a new idea: I created a similar program back in 1998–1999, but I decided to revive it because it should work well with the recent trend of automated emails generated by AI, where the sender might expect a reply; it helps remove your email address from their list. Any idea on how to improve it? :)