Um... I can see that being OK for the one who is trying to send more messages while already having his inbox/outbox full.
But what about when someone is trying to send someone with a full inbox a new PM? What notification does the sender get then? Because I see only one notice in the script there, where there should be two, one for someone trying to send OUT of a full inbox/outbox and one for someone trying to send TO a full inbox/outbox. Or did I get something wrong?