[Exim] Whitelist of users for LARTed domains

Greetings,

I have the following director in my configuration which blocks hosts from
certain domains:
bounce_spam_master:
driver = smartuser
require_files = /etc/exim/spammers
senders = /etc/exim/spammers
new_address = :fail: "unknown local-part \"$local_part\" in domain
\"$domain\""

My ultimate goal is to have hotmail senders blocked except for a specific
set of $sender_address in a file.

Can anyone think of a good way to do this by adding a conditon?

Thanks,
scott
--
Scott Nolde
GPG Key 0xD869AB48