When sending Email messages from the system, you will be able to easily determine what has happened with the email. Each Email status is color coded.
When the Email message has a black circle, it means that the message has not been read.
** You may see that the status is undefined, generally that status is set for emails that go out via the legacy email campaigns. However when the email has been read, the circle color will change.
When the Email message has a blue circle, it means that the message has been delivered, but has not been read.