qmail and mail relaying

I have installed qmail on a RH 6.1 system (tcpwrappers is installed). I can send and
recieve on that machine.

I would now like to selectively turn on relaying. Has anyone on this list done so.
If I follow the directions in the faq (and assume that everything for the wrappers is
installed, I get the folloing error message (netscape client) "the SMTP server
returned the following error '' "

Should I also install tcpserver?

Stephen