Every now and then, I get e-mail about rejection for files, that were already rejected, sometimes month or more ago. But maybe, that they are rejected for free section, because I have "yes" checked.

yes if the image is declined, then they go into free section for acceptance or rejection.  If you do not want t give away images, make sure the default does not change on you because it does.  The only way hen is to delete them unless hey remove it for you once.  It has chaned on my from No to yes on free section in he middle of an upload session so double check.