I have a subfolder with emails from my grandson, all at least a year old, some older. All are unreadable and View Source shows me they're not email messages at all. Is this a known Thunderbird issue (I've had this once before, maybe five years ago) or should I be looking carefully at my Solid State drive? I deleted the messages and then looked at them in Trash. One of them had text from a completely unrelated email. Unfortunately I then deleted my Trash, so I can't find these again.