RT not setting return email address

Greetings all,

I have rt installed (3.0.11) and working but it doesn’t set the reply-to
address properly. The address is set in the queue properties but when I
click reply it replies to the email address located on the individual
server.

eg: rt@host.domain.com instead of rt@domain.com

I have read that the you can change the headers via the templates but I
cannot for the life of me figure out what module/routine to use.

TIA.

David.