it seems the router is using a bit too fuzzy logic trying to send mail to its destination:
we’ve had several occasions where mail destined for internet address ab@domain.com was sent to ab.xx@AnotherInternetDomainInOurDirCat, apparently because the router couldn’t find the original address in the DD and searched through all the attached directories and sent the msg to a ‘close enough’ matching, but totally different email account.
this is worrying as the user who has sent the msg is unaware that the msg was actually sent to another account (it could have been an internal memo, sent to a client 
what if a user has been deleted from the DD?
dircat allows a msg to be routed to the nearest ‘lookalike’
is there a way to stop these fuzzy lookups and to send/recieve msgs to the intended recipient only?