Lost emails

One of our users has lost the body of her emails (the files with the extension .001. She can see the email but can't see the message. I have no idea how this has happened as I don't think it is a Tobit problem. Have any forum members encountered this problem? I need to find out so that I can try to prevent it from happening again. Sorry its in English but I don't know German

It would be important to know if she has lost ALL message files (also extensions 0tx, $00 etc) or if she has lost specifically files with 001 extension.
I had a similiar experience when an archive.dat file went corrupt. It wasn´t appearent during daytime when everything seemed to be normal. But during nightly cleanup service all the files got deleted. As the archive.dat holds all the messages information it seems that when it is not accessible or present, the cleanup service takes it as invitation do cleanout an entire directory.

Maybe your problem is related to that.