[ALUG] Exim - deny rule ignored

Hi, I'm trying to change the behaviour of exim 4.50 such that as soon as a RCPT TO: foo@domain.com is received, it checks if that recipient exists and if not, denies service. deny !verify = recipient Should do it, at the top of the acl_check_rcpt rule. exim -bH shows the rule being loaded, but completely ignored. Indeed testing from my gmail account results in the standard mail rejection notice complete with spam index, instead of an SMTP-level deny. Any clues? Cheers, James