[otrs] Problem with followup

I'm using the forward facility to "forward" tickets to 3rd parties. I expect them to later on simply reply to the email sent with a "problem solved". Then I close the ticket. But instead of sending a email to the original customer (stating the change to closed), otrs sends a email to the 3rd partie. Is this the intended behavior ? Or am I misusing the forward/followup ? Thanks for your time, Duarte