Weird. At least when I was on I wasn't getting any error messages (and it was working just fine). Your site is 502 again I guess it's down. Maybe send me a chat next time we're both online and we can try and figure out what's going on.
Oh, that's a little weird, perhaps it's a typo, and should read "proxy_http" instead of "proxy_html"?
As for the local emailer, perhaps you can install @psychobunny's fork?
npm install git+https://github.com/psychobunny/nodebb-plugin-emailer-local