One more thing to keep in mind. When used with mynetworks, as I already explained the RHS of the table entries is ignored.
Therefore, your attempt at a reject rule: 10.147.11.11 reject is completely ineffective. If you want to use CIDR rules with exceptions to define trusted clients, you need an access(5) table. Therefore, you'd need to replace all instances of: permit_mynetworks with check_client_access ${cidr}trusted-clients.cidr and then the RHS values are as documented in access(5). http://www.postfix.org/access.5.html Keep in mind that CIDR table matching is order dependent, first match wins regardless of specificity. Therefore, list more specific patterns above less specific ones: 10.147.11.11 REJECT November 11 is an unwelcome enemy 10.147.11.0/24 OK All other days in November are good or: 10.147.11.11 DUNNO November 11 is a stranger in a strange land 10.147.11.0/24 OK All other days in November are fine -- Viktor.