NethServer Version: 6.9
Hello everyone, we are using nethserver as mail server, recently we had some spam issues due to hacked password from an external user.
The strange thing is that this external user was capable of sending mail from a fake domain not present in our nethserver. how is it possible? how can i disable my server sending mail from unknown domains?
(Obviously i changed the password of the hacked user and we have no more spam)