As the emails you send out of the system are sent from a noreply@smartr365.com email, any replies the customer sends will be stored in the history section but I'm afraid there's currently no notification that comes up when someone has replied - it is more so reliant on you checking the case periodically to see if a reply is there.

I appreciate this is not an ideal outcome, so if you did want an alert/notification to be sent when you get an email reply back in future, I'd suggest raising this as a feature request on our UserVoice platform