[exim] Exim-Gateway

Hi everybody,

I want to replace my sendmail mail relay server with Exim server. So please, How can I configure the Exim server to just handle all the incoming mails for my.domain.com domain to specific server say; mail.my.edu which holds all my users. and how can I configure the Exim server to receive, and send to the world all our outgoing mail from the same server.
Thanks in advance
Bond