Alerts can be set up under Tools > Alerts > Add another!
From the 'Create An Alert' page, you will be able to configure when you would like alerts to be sent out.
Send an alert when - This is where you will select who the alert should be triggered for. I.e. My company would be any of the mailboxes on timetoreply, whereas if you were to select an individual mailbox specifically, the alert would only fire if that mailbox is a part of the conversation. If you were to select a group mailbox, then the group mailbox would need to be a part of the conversation in order for the alert to be triggered.