Version:           1.5.3 (using KDE 3.1.3)
Installed from:    compiled sources
Compiler:          gcc version 3.3
OS:          Linux (i686) release 2.4.22

i use kmail for really long for my emails ... in the version that comes with kde 3.1.3 there are some special happening

the problem is that it is not really good reproducable ... sometimes it happens, sometimes not

try:
1) open kmail
2) write email
3) save email in draft
4) send email 
5) close email
6) start email again : you can see a unread email in draft ... but all fields of it are empty and the subject is "No Subject" ... when you click on it, it sometimes disapears and sometimes stays where it is

or try:
1 - 3
4) close kmail
5) open email 
6) send email
7) close kmail
8) open kmail: the same "ghost" email in Inbox or drafts or in both