In OTRS events are the elements that starts the notification sending.
There are ticket related events, article related events and so on, but for a simple Trouble ticketing Management System the events that we approaching are: TicketCreation, ChangeTicketOwner, Change Ticket Status, Article Create
Ticket Creation: When a new ticket is inserted in OTRS a notification is sended to agents
Change Ticket Owner: When a ticket is created there isn’t an owner, when a ticket is “In process”, the ownership changes and a notification to the customer is sended.
article Create: When a note(external or internal) is writed about the ticket, a notification to the customer is sended. In some cases it’s better that an internal note remain accessible by the agents and not customers.
We must take in account that the event “Ticket Closed” is an internal note, then the message cannot be sent if we’ve disabled the notification with internal note(or, better, we can specify other deep filters).
Change Ticket Status: When a ticket changes status, a notification can be sent to inform customers.
Well, the configuration for notification can be made by the toolbox EVENT in admin section.