I feel so stupid. I never thought there was a simple solution like this. I have to find out "why" it works. It is probably written somewhere here. It's late night I'm not going to do it now.
I read the answer in this page (and it is here I got the previous link). Thanks to Gomi to point me the solution. I would have linked the original post, but it unfortunately uses Archive: no and x-no-archive: yes, so no google groups.