The filter that I'm looking for would work in quite simple way:
I would create a list of allowed e-mail adresses.
The filter would block e-mails from every adress that is not on this list and as it would block something, it would allso automatically send a reply to the sender of the blocked message.
The idea of this autoreply would be that of course the sender would know that his/her/their message newer reached me and possibly some instructions how he/she/they could ask me to add them to this list.
( This request method would be complicated enough so that someone would actually have to read the reply )

If anyone knows anything like this I would be realy interested...