WHAT IS EATING MY MAIL?!!!!!!!!!!

I have come to realize that something is deleting email from my inbox on a regular basis. I use KMail, and have used it for years. I am not aware of having made any changes to the configuration which would tell it to delete my email. I cannot find anything in the configuration suggesting that it is configured to do so. I have lost extremely valuable information because of this. I need to stop it NOW! How can I do this? Steve