[Exim] What goes where?

Hi

can someone point me in the right direction .. I am sending out automated emails and have just moved from a couple of servers (one Postfix and one Qmail) which seemed to be working ok to a new server running Exim .. and I'm now seeing different behaviour happening

When an email goes out there are three addresses involved
- the recipient, e.g. to@???
- the 'visible' sender, e.g. from@???
- a background handler, e.g. bounce@???

I want the recipient to see the email as if it had come from from@??? and to be able to reply to from@???

I want any auto-generated responses (particularly bounces, failures etc, but ideally also out-of-office and vacation) to go to bounce@???

In the previous installation this mostly worked by using sendmail -f to set the bounce address and the headers
    from = from@???
    reply-to = from@???
    return-path = bounce@???
      bounce-to = bounce@???

Is there a standard way of achieving this or does it break down because of badly behaved clients?? Am I backing a loser here? Like I say, I seemd to get ok behaviour under previous mailers .. and yes I am using untrusted_set_from

Kind Regards

Robert