In suse the kmail folder is situated in /home/user/.kde/share/apps/kmail.
If you have reinstalled your system and opening kmail and clikkin on mails they magically disappears ... well I think it is a kmail bug!!!
Anyway just stop clikkin on mails, close kmail, go in emails folder (the folder above) and delete all indexes (*index*)
hope to have been clear and helpfull as usual.
happy suse, happy people.
Antonio
