There appears to be a problem with the message boards ability to send emails at the moment. For current members this means you won't get email notification when somebody sends you a private message. You should still get a pop-up message when you enter the site. Also remember to look at the top of the message board where it will tell you if you have any new messages.
I would like to add, to anyone who has been trying to join the site and been unsuccessful, that hopefully this technical hitch has now been solved and we look forward to welcoming you all here. I'm sorry if this has put you off in any way.