If you use:
FEATURE(`blacklist_recipients')
then you can add entries to the map for local users, hosts in your domains, or addresses in your domain which should not receive mail:
badlocaluser@ ERROR:550 Mailbox disabled for this username
host.mydomain.com ERROR:550 That host does not accept mail
user@otherhost.mydomain.com ERROR:550 Mailbox disabled for this recipient
This would prevent a recipient of badlocaluser@mydomain.com, any user at host.mydomain.com, and the single address user@otherhost.mydomain.com from receiving mail