Ishbel, out of interest how do you know when someone's PM box is full? Every now and then I try and send messages and get an "invalid message" message come back at me. I thought this was because I use a Mac with Safari and that maybe this was the problem.
I tried to reply to a message from Ayrton and the system said something along the lines of 'recipient has reached maximum number of messages allowed'... or words to that effect!