To configure ipchains to allow inbound mail to pass thru to an internal server and outbound mail from the internal server.

MY LINUX SERVER SERVERS AS PASS TRHU FOR INTERNET MAIL BETWEEN THE INTERNET AND INTERNAL NETWORK.  MY LINUX SERVER IS AN INTERMEDIARY BETWEEN THE INTERNET AND MY INTERNAL NETWORK.  IT USES A NIC TO CONNECT
TO THE INTERNET AND A SECOND NIC TO CONNECT TO THE INTERNAL NETWORK.  INBOUND MAIL COMES IN FROM THE
INTERNET TO THE LINUX SERVER WHICH IS THE DEFINED EMAIL SERVER ON THE INTERNIC.  THE LINUX SERVER THEN
ROUTES ALL MAIL WITH THE DOMAIN ADDRESS TO THE INTERNAL NETWORK TO A WINNT SERVER WHICH HAS MS EXCANGE
SERVER 5.5.  
OUTBOUND MAIL IS RECEIVED BY THE INTERNAL EXCHANGE SERVER AND ROUTED TO THE LINUX SERVER WHICH SENDS
IT OUT TO THE INTERNET.
THE ABOVE WORKS WELL EXCEPT WHEN I ENABLE THE IPCHAINS RULES to accept only smtp and then NO MAIL IS TRANSFERRED
IN EITHER DIRECTIONS.
IT SEEMS THAT THE RULES NEED TO CHANGE FOR THE SCENARIO DESCRIBED ABOVE.  I HAVE TRIED MANY COMBINATIONS
OF RULES TO CONFIGURE IT TO ACCEPT ONLY MAIL AND TO BLOCK ALL OTHER SERVICES BUT THE MAIL IS STILL ONLY
QUEUED AND NOT SENT.

THANKS