Whitelist for dnsbl recipients

[User Ernie]

I am using the sendmail FEATURE(`dnsbl', on my mail gateway server which feeds
several other mail server, to do lookups from an aggregated black list t1.dnsbl.net.au
It works too well!

Because t1.dnsbl.net.au a comprehensive, aggregated black list, a lot of mail 
from poorly configured senders gets rejected. Every now and then I have a request from a
user to turn of the black list feature for their mail box. I thought I could do it 
with a rule in the /etc/mail/access file, using a syntax like:

To:user at some.domain.name.com	OK


That didn't seem to work, I still got lots of reject messages in the mail
log.

Can anyone suggest a way of solving the problem?

I have no problem white listing source addresses, but there are too many
source addresses to solve this problem, it really needs to be an exempted
recipient address.

- Ernie.