Keeping in mind the original question, the ignore system has for me a weak point.
if someone ignore you, can you know it but you cannot decide to ignore him.
You need to have an active pm to ignore someone that has ignored you.
I do not like this because I can "accept" that someone ignores me, but I do not like the idea that he can remove me from his ignore list, look my profile, my gift, that I see him popping and disappearing, come in a room that I open ... only based on his decision.
So my 2 cents :
1) Game should have the option to allow you to ignore someone that you know that has ignored you. (but it requires a game developpement so let's keep that for next century)
2) If you have the same thought that me : remember the right reflex that if someone has ignored you and that you still have a pm from him, use it before closing it to ignore him because this is the last chance you have to do so.