You could even get one of those plugs with an analogue timer in that case.
But if you already have some kind of home automation set up, a lot of smart plugs can measure current going through it, so you could just set up a rule to turn it off at 10pm, or combine with a motion detector to turn off if the room has been empty for 10 minutes.
Isn’t Spamhaus basically a protection racket, like Yelp and the BBB? Either way, email is messed up, I do everything to avoid having to deal with it myself after having to deal with running a mail server for a while, and things have only gotten worse.