This indicator shows the amount of participants that have never received an email from the project.

Both manual and automated Communications count.

Depending on your process, this may or may not be a problem. If participants are meant to access the course through an invitation email, the indicator will remind that necessary precondition has not been met yet.

Notice that the indicator cannot interpret the content of the email sent from the project, so it will consider any email, regardless if it is a invitation email or not.