saved_mail all gone

In kmail, you can save mail to a "saved_mail" file, which I created. Or I thought you could. After inputting about 50 or 60 messages, over the past several weeks, all but 3 are gone. (9.1) I have _not_ checked anything about expiring messages in the setup. Must I go back to MSWin and use Eudora? I sure wish there was a version of that for Linux! --doug