I noticed the majority of people do not have this enabled in their profile. That means you can't receive private messages from staff, moderators, or members.
It's totally your choice but like myself I didn't even know it was there when I first joined up. Any member is welcome to send me a private message here especially if I screw something up on the trivia like forgetting to credit your points (I never do that though ;p).
But like once before awhile back if you don't have it enabled I might not be able to reply to your message.