Though I do the same as Adera meanwhile, trying to keep my inbox clean, I understand Tight's wishes. The best would be, if they had something like pm which you also receive when you're not in AChat. To avoid spam they can create a checkbox... like "NAME" is allowed to send you pm - yes/no.
Only prem members are able to post in forum and this after registration. You don't have to use same name as in game, this is the reason my name here in forum is different to game. Sometimes it's nice to have different names, like my little flirts here with Pse, Sexi and some more
Back to topic:)
I'm sure they changed something in this system, 2 or 3 weeks ago I received messages I had got one year ago and which I deleted after reading. Perhaps there is an issue in this system?