Netflix series mark as seen?

I've been new to Netflix, but I've been watching series and movies for a long time, meaning I'm being offered a lot of series that I've already seen.

Can I mark them somehow as seen so that they will not be proposed anymore?

You can rate them (with a thumbs up or down), which signals Netflix that you already know the movie. He is then much less often suggested, but if you have him with a thumbs up rated, but it does not quite stop.