[exim] DB of allowed email addresses

Hi:

I'm using Exim as MTA's for a MailScanner clean and forward system.

I want to cut down on my backscatter load by having Exim lookup the to
address on any incoming email to decide if it should accept it at all.
I can write it in MailScanner but I don't want to let the junk get
that far down the chain.

I'm already looking up allowed domains using:

"domainlist local_domains = ${lookup mysql {SELECT DISTINCT domain
FROM domains WHERE Enabled = 1 and domain='${quote_mysql:$domain}'}} "

But is there a "local_addresses" sort of thing that will match
complete addresses instead of just domains?

Thanks in advance for your help