Need Mercury to relay e-mail to another smtp server.

[mlamla]

Hi,
I am using Eudora Mail Server behind the firewall.
Mercury pc is on local LAN too.
I would like to use Mercury for filtering purposes only.
All preparations are made properly.
MX record of Mercury computer appears in our zone file on external DNS. And when I turn on pc with Mercury, mail traffic comming to Mercury.
I have issues with configuration.
In my scenario I need that Mercury will filter unwanted e-mail and then will relay all messages to my real Eudora server. (With relay denied to all other servers).
I installed MercuryS and E modules but cannot "say" to Mercury to relay all mail to 10.0.0.4
I am a bit confused with entering local domains in Mercury
Core Module Configuration.
I cannot "play" with relay/connection control in S module.

I will appreciate step by step configuration instructions.
There are not so many but I can not figure out what to do.

address of Eudora mail server - 10.0.0.4
name of eudora pc - nhcnet
alias in local DNS - mailhost.nhc.com

Thanks.
Michael.