[exim] how to allow a domain to send/receive email only loca…

Hello

I want allow a local domain (domain.com) to send email ONLY locally,
and I don't allow domain.com to send email to remote email (externally) .
Also I want to block all email from external senders sent to domain.com .
(In other words domain.com should send and receive email only locally in the server).

How to configure exim to do this ?

(I have cPanel/exim running in Centos)

Thank you
Graziano