Exim as relay server

Hi I have exim running on port 8900 and another mail server running on port 25. This mail server will be used to relay outgoing emails to exim. But somehow I am getting this error from exim 550, 'relay not permitted' when relaying email to exim. Is there any way I can configure exim to permit relaying?

All iedas are highly appreciated.

From serverfault jpartogi

• Add this to your config:

  hostlist   relay_from_hosts = 127.0.0.1 : 10.0.0.1/24
  

  This will allow relaying from localhost and 10.0.0.1/24. Change 10.0.0.1/24 to whatever host/mask combination suits your network.

  jpartogi : Is `10.0.0.1/24` the local interface ip?

  ErikA : The list following the equals sign is a colon-delimited list of networks (in CIDR notation) that you want to allow relaying from.
  From ErikA