this is my workaround
I do have tickets for internal tracking where I don't want to involve the client. The notification of replies by e-mail is one problem, the other problem is the existence of the tickets at the client dashboard.
I do have some domainnames that I rarely use. I use one of them for these problems. I create a client with the name of my client and the e-mailaddress nameclient@domain.com. Notifications will go to my own mailbox and the from within my SCP will have the name of the client.
It's a workaround. Probably not the best one, but it works for me.