[exim] Slowing Blacklisted Authenticated Users

I have something like this to help stop users that have had there
email password compromised.

# : block authenticated senders on zen.spamhaus.org and bl.spamcop.net
deny
dnslists = bl.blacklist1001.org
dnslists = bl.blacklist1002.org
        authenticated = *
        verify=recipient
        message = SPAM: rejected sender $sender_host_address is on
multiple black lists.

Is there a way instead of totally blocking rather limit these IP's to
say 10 recipients an hour? Or what's a good number to limit at?