Config Question

["Kevin Traas" <KTraas@uniserve.com>]

I'm new to ZMailer and have a question.  If it's something covered in docs
somewhere, just kindly point me in the right direction.  Thanks.

I've successfully compiled and installed zmailer-2.99.48p2 on my Debian
GNU/Linux 1.2.x system.  Mail is entering and leaving the system via SMTP
normally.

My question is:  I've just reconfigured my LAN and DNS.  The system that
used to receive e-mail to my domain is being replaced by this Linux system
running ZMailer.  The problem I've run into is that for any mail coming to
username@DN, errors occur if username doesn't exist on the Linux system.

For ease, I'll call the Linux system A and the old system B.

I now have DNS configured so that any mail addressed to username@DN is
delivered to system A.  I'd like to configure ZMailer to automatically
forward any mail for which it can't resolve the username to system B.  The
reason for this is that I want to phase out system B.

In reading somewhere, I came across "smarthost".  Is this what I need to
configure?  If so, how?  If not, then what?

TIA for your help,

Kevin Traas
Systems Analyst
Edmondson Roper CA
http://www.eroper.bc.ca