I've just had an email melt-down today and have lost everything, that is 'every thing', in my In box (the other created folders are OK).
So, if anyone has sent me mail recently and was expecting a reply or needs me to know something important, you'll have to send it to me again. Because it's all gorn.
I've rummaged around in the System, especially the Library mail folders, but to no avail. I still think it's all 'there' somewhere, as my computer's hard disk seems about the same size (there was a lot of mail, let me tell you), but I can't extract it.
Oh, well, move on. And hope nothing truly important has flown.