You got the email first and dense fucker that you are, you had no idea what I was talking about.
Once I got through to you and you fixed the problem you were able to read the PM's I sent you. Full disclosure, I made the same mistake once and that's why I know how to fix it.
What does that mean? Is that something I can control by my settings somewhere? Is it something that has been set up by TER against a user?
If you have another member on ignore, his posts will not be visible to you and his PM's to you will be rejected. I personally think it's one of TER more crappy features, but some people seem to like it.
I am assuming you did not intend to place this person on ignore and are looking for how to unignore him. It's pretty simple, but like most things on the internet you need to know where to start. Simply click on your "mail" tab at the top of the page, the third option from the left is your "ignore list" click on it and all the members you have on ignore will be displayed, simply click "remove" on any member you no longer wish to ignore.
Personally I don't need an "app" to ignore someone, but it appears that some people need help in order to ignore someone. The thing about the feature I don't like is that it does not give you the option to block someone from blowing up your PM inbox without also ignoring that members board posts. Now it's all or nothing when you ignore someone.
Oddly I had hit the wrong thing on my phone and I was on my own ignore list. How's that for creating a personal crisis...
Well.....add me to the idiots list. I put a certain someone who has posted in this thread on ignore last week and he sent me a very vague pm:
"Hey asshole, do you know you have me on ignore?" LOL
True story, with witness available if needed.
You can't get a PM from someone you ignored. 
You could have pm'd that bit of info. Lol
You're not on ignore. YET.
He emailed me. Ok you petty, picky fkker? :
You got the email first and dense fucker that you are, you had no idea what I was talking about.
Once I got through to you and you fixed the problem you were able to read the PM's I sent you.
Full disclosure, I made the same mistake once and that's why I know how to fix it.
Of course I always have a 78% chance of being right if I accuse you of PUI so I'll roll with that! Lol
I've accidentally ignored a bunch of people because of that, and several times it has been myself! 