[exim] How to point outgoing mail to hosting server

I have a exim box in my DMZ that forwards mails to the internet.
But I signed up with messagelabs.com and I need to point my exim box to
forward all mails to messagelabs.com server.

How can I do this?

Gareth Segree
Technical Support Analyst
The Gleaner Company Limited
Tel: 9223400 (Ext 6345)