If there is no e-mail server configured, don't display the 'Send message to participants' functionality

The 'Send message' functionality is not working by default. You need to have the e-mail configurations.

Clicking on 'Send an invitation email to these users' will result in having 'An error occurred while sending the notification emails.' message displayed.
There is no additional information on how to fix the problem and this is also not covered by the application's documentation.