[otrs] Help needed in OTRS Notification

Hello, I have a question in OTRS Notification Event. Basically I have setup a Notification Event to send an email response to the customer when ever a ticket is completed and closed by the system. My company has about 4 domains which are setup with OTRS. Essentially, when any customer's ticket in these 4 domains is closed, it should send a notification to the customer and specify that particular domain to which the customer is associated with. So, my question here is how do I embed domain name in the notification event text so that the customer receives a response to contact that particular domain to which he is associated with. Can anybody of you help me here . Your help is greatly appreciated. Thanks Winter