When a tech closes a ticket an email get sent to the user to let them know the ticket is closed. Half the time the user replies to the ticket saying "thanks" which creates a new note on the ticket but then also changes the status of the ticket to "Open". Has anyone else encountered this or know of a fix?
Check Setup --> Tickets --> Status Types --> Click on the status you want to look at --> click the options tab and look at the option called Clients Can Reopen Closed Ticket. If checked, Clients will be able to add notes to closed Tickets. The Ticket status will automatically change to the Reopened Status Type (below).
Try unchecking that box and see if it changes the behavior into what you want it to do.