@kirby
Or, was never configured probably.
It's a little miracle that mailer works on my instance, I had to jump through a lot of hoops to make mine work with ProtonMail. And it depends on other box to be up, runnning and connected — other than the one instance itself runs on, it should theoretically be up all the time as it's my VPN box, but in theory — a lot of things might go wrong.