[otrs] Disable email-notification-ext from customer view

Hello all, In the customer view when I see the detail of a ticket, I will have a tree with the details of all the messages sent by the customer and by the agent. But it will have also all the notifications sent by email, so if an agent replies to a Ticket the tree will have the answer from the agent plus the notification sent by email (email-notification-ext) duplicating the answer and that becames confuse. I assume there is some way to turn this off with turning off email notifications, I've searched several times in the configurations but could find a option for this. Anyone know a way to turn the notification sent by email to appear in the history tree? Thanks for any help, Ricardo