Apologies to commenters! I have not been getting emails about comments posted to this site via Isso and Gmail. Previously, I didn't get the actual email, but I did get a security warning email from Google about Isso trying to send an email, and that's how I knew a comment is made.
Google stopped doing that, so I got nothing. But I learned about
App Passwords, which Google tells you about then tells you you shouldn't use them. But they do let third-parties send SMTP messages through Gmail, so I'm using them.
(If you're wondering why I use Gmail for this, it's that I'm not willing to create a throwaway email elsewhere because then I'd either have to pay for it, or it would be Yahoo or something, and I bet there are terrible obstacles preventing you from using their stuff to send mail from a comment system.)
tl;dr I will get notifications about comments now! And I'll go back and find your comments. Let me know if I miss any.