[exim] Check SA whitelist

hey guys,

I was curious, what would be the conditional statement to lookup an
e-mail within a whitelist file in the format of:
whitelist_from email@???

The reason I ask is that I'm looking at wildlsearch and nwildlsearch,
but I've notified the overhead is more than I'd like.

Any ideas?

--
Thank you,
Greg Borbonus
*Nix Server administrator