[exim] How to create a whitelist

I'm obviously new to mail management, and particularly to exim, so I
apologize for my ignorance.

I need to create a senders whitelist on my machine. I'm using the following:

WHM 9.9.8 cPanel 9.9.8-R89
exim 4.44
MailScanner w/ SpamAssassin

I would like to white list particular senders and not necessarilly their
host. Any assistance would be appreciated.

Thank you.

--
Ron Phillips