[Exim] Whitelist

I want to set up exim to check a user defined whitelist of email addresses
before rejecting an email because of various criteria such as the sender
could not be verified, or they are on a RBL. How exactly could I set this
up in the configuration file?

accept local_parts = some_user_list ?
the list would be in the users home directory and I would like exim to
check the lists of all users for all emails scanned. If this is not
possible, then I can have a single list with all of the email addresses in
it.

Also should the list contain the full address:
user@???

I still want to do all of the standard exim checks on any other emails that
come from that domain, I just want to let user@??? through no
matter what.
I am also using SA-exim, so it would be nice if this bypassed this also.

thanks for any advice.
Torin