split domain

Hello,

I am trying to setup a new domain in my cpanel that for e-mail would have some accounts locally and some accounts on a remote server. Unfortunately I don't have a list of e-mail addresses that need to be forwarded to the other server and I would like to to this "split domain" so that for any unknown local receipients it would forward the e-mail to the other server. I have to mention that the MX for the specific domain will be the cpanel server.
I am using exim and I have used google to search for a solution, but couldn't find anything useful..

 

I have succeeded in the end by doing this:
In exim advanced configuration editor in the editable box: PRENOALIASDISCARD
I have added a router with these rules:
==
whatever-name:
driver = manualroute
domains = "example.com"
transport = remote_smtp
route_list = example.com new.smtp.com
no_verify
==
At first it didn't work for me because I was putting this to ROUTEREND, however I searched the config until i found the virtual delivery router and I added this right after that one at the section mentioned above.