[otrs] header-"references"&ticket status

I found the email-options I asked about...I must have been tired, I'm sorry,-I don't mean to spam :) This, I haven't really figured out:

Also....any possibility of having OTRS look at "References" in the mail-header? That way, when a user sends a request, we can answer the request by mail without having to wait for the ticket, as far as I can see the request and the answer now become two tickets.

And: is it possible to change the status of a ticket via email, specifically, can a ticket be closed via email? Margrete