Just wanted to +1 this.

I have the same problem, no obvious solution.

I'll be sure to stop back in if I figure anything out.

As of 4/4/18, The one click install has bugs, and from what I can tell this bug has existed for nearly a year now and probably pretty abandoned application because no one has every gotten it to work or figured out what their issue truly was.. Thru all the weed picking I did, its a internal DNS issue where the server can't get the ip for the domain to send the initial admin confirm email .

All the past users have mostly thought it was a SMTP connection issue, or a external direct firewall issue.. But its definately presetup screwup application / server configuration error, that could be a routing, firewall, misconfiguration and probably all of above...

cd /var/discourse
tail -f shared/standalone/log/rails/production.log

and you will find this after trying to send a smtp email
Job exception: getaddrinfo: Name or service not known

DNS...

i think its something to do with the network internal ip setup because the server is responding fine on lookups with the provided defaults, and that when I initially setup using a SMTP on the server itself (failed and went to google smtp) that 587 was getting blocked, but not on the internet ip, but on the internal 172.17.0.ip, i didnt understand the internal ip to begin with, so i initially yelled at DO for oddly blocking my servers port 587.. but that was not the case.. simply some screwup on the applications set on their part