Blocked sender list should only be applied to incomming mails
The email address block list is (since Firmware 18.3 / change ID NC-59396) also applied to mails from our internal mail server to external smtp servers. Adding the local domain to the block sender list is not possible. We cannot ensure that mails from external senders, using our domain as sender address (=email address fraud) will be rejected. The sender block list should be applied to mails from WAN sources.