So a box was telling me my inbox was almost full. I went to my inbox and deleted all of my unwanted messages. For a while, it was fine. Then when I started getting more PMs, the box was back, telling me my inbox was almost full again. I was irritated, so I just emptied the folder. But the "stored" messages were still there. I don't remember storing anything, I remember deleting a bunch of messages. How do I delete the stored ones permanently?