That happened to me a couple of times. I had to report them to the Mgt. and they were time-out after they kept sending me messages.
How do you do that? Not ignoring, but just blocking someone from sending you PM?
I ignored my troll for a few days but I decided it wasn't the right approach. Now I quote him when he gets mad before he has time to apologize.
I've heard I'm currently ignored by one poster. Fine with me, he talked about my: "extreme liberal ideas" and he has several semiautomatic guns at his place getting ready for the next LA riot to defend his life and property.