As of June 4, Let’s Encrypt stopped sending email notifications about failing renewals, which was the only reason to have that ENV variable set.
I just ran discourse-setup-ruby and didn’t get a email address for LETSENCRYPT_ACCOUNT_EMAIL and now Discourse won’t work because the clever logic refuses to request a certification if there’s no email address. It’s been almost a year since including an email address in that variable did anything.
So this if needs to be deleted:
i noticed this on rebuild yesterday, i had to run .\launcher rebuild app after a seemingly successful .\discourse-setup. Looking forward to the fix you’ve mentioned 
Well, the easiest thing to do in the short term is just include an email address–any email address–in LETSENCRYPT_ACCOUNT_EMAIL.
what made us support renewal emails, when renewal happens automatically via the acme.sh cron job ?
The renewal emails were for a service, that was once provided by let’s encrypt, to notify you if your certificate was about to expire (see link above). There was really no reason for that test for LETSENCRYPT_ACCOUNT_EMAIL to be included when it was added 6 months ago.
I think that originally (8 years ago or so) Let’s Encrypt required an email address, which is why the test for it ever existed. For a long time, if you didn’t supply an email address, they’d not give you a cert.
There were some issues having to do with the nginx config that were breaking the renewals, even though the cron job was running (at least, I think that’s what it was; I didn’t pay careful attention to those updates, or I’d have brought this up then)