The tools to configure the emails exist within the dD Config tool. You can access that tool by navigating to http://xda-server:8989/ where
xda-server represents the hostname of the server where openXDA is installed. First, under
Settings > XDA Settings, you can configure the SMTP server used for sending emails. After that, you can go to
Emails > Email Groups to configure an email group which represents the collection of users, meters, templates, and criteria by which emails should be sent by the system.
Depending on the version of openXDA that you're running, you may encounter various issues with this process. Let us know if you get stuck.