There are many answers as to how to make email alerts, but I am not interested in those. Instead, I am interested in the kind of 'admin' notifications I get shown in the web interface - things like a node being out of space, or Graylog being an outdated version. Surely those can be sent via email instead of having someone manually check the web interface every day ?
Looks like we have an existing issue opened to address this. Also from that issue, someone has made a python script that can be put in a cron job to handle it. However, I can't vouch for if/how well it works. Hopefully it can work for you as a work around. It doesn't seem like that functionality would be too large of a task to build into Graylog, so I may check that out myself.