Your problem is not really ISPConfig related as we have not written our own spamfilter, ISPConfig uses spamassassin. If spamassassin or in your case the sorbs and njabl lists score a message wrong, we can not change that.
Adding all email addresses or local domains to a whitelist will open up your server to spam too, as spam senders use faked email addresses to send emails which might belong to your server too.
If you want to add all domains to a whitelist automatically, you will have to write such a feature. ISPConfig 3 useses amavis + spamassassin where a global whitelist might be easier to implement.
I recommend you to see why you are listed on sorbs instead and to remove your server from the blacklists.
All 6 IP addresses of the server are listed clean.
But why is Sorbs and njabl reporting your mail as spam then? You should check the hostname of your mailserver too or the blacklisting of your server expired already.