Right. I think technically one could find out, with a bit of work on one's part by PMing someone and not getting an answer/get it "rejected" (don't know if it gets returned or one gets a message that it wasn't accepted or if it just gets "lost" in cyberspace :-) but since it's a feature for the person doing the ignoring not the one being ignored, I'd say the majority of time the one being ignored wouldn't know; there's no way to know who's reading one's posts anyway and they just don't "show up" for the person who has them on ignore so the person whose posts they were would have no idea?

I had set my posts so I only saw those which had been posted during the previous week and I got frustrated because I wanted to go back further in one forum and couldn't remember how I did it :-) Took awhile to get so I could "see" at least a month's worth of posts. I think it's kind of like that; the person's posts and/or PM's are "there" but don't show up because of an individual's settings.