A co-worker created a new group and department for a new ticket queue. A few events were set up also. Now we can't reply to him in the ticket. When we try, it gives us the message "One or more of the email addresses you are creating this ticket message for is reserved for department use". 

We looked at the department and email addresses, but nothing is tied to him. He is an agent. Does anyone know what to look at for this?

Thanks