I selfhost my own mail server (my primary mail in fact).
My LE certs expired on Christmas eve, when I was also getting sick. I didn’t realize my mail server was down for a week until about NYE. Luckily Postfix queued all my emails and there was nothing important lost, but I am reevaluating self hosting my mail server. That being said, this was also the worst issue I’ve faced in over a year of self hosting mail. And it only arose because my dumbass still hasn’t automated my certificate rotation.
I have the renewal process itself automated, just not the replacement process.