You can email all (or selected individuals) registered through the manage website part of the application (not otherwise readily visible).
Also, all entries posted through the Noticeboard or Blog (part of the content management options) end up being emailed to registered members. That way, people can go into the private part of the system and review the entry in case they have deleted the email).
Also, as a general point of information, system does not retain (because of GDPR issues) details of emails that are sent out. And the system doesn't have facilities for recepients to respond (the emails go in one direction only).