Nasty KMail/Akonadi bug

Hi!

I've asked for help recently with the subject "KMail badly broken". I'd like 
to detail what I've learned about the cause of the problem, which has been 
solved.

I'm running my own, shiny, local Dovecot IMAP server.  I keep all mail in that 
server (except for the trash). It works really well.

The problem seems to occur, when I configure the trash folder to be on that 
server. It normally is in the "Local Folders". When I try to delete mail from 
the local trash folder, the problem occurs. 

Here is the problem description again, so you don't have to look in the other 
message ("KMail badly broken"):

-----snip-----
I'm getting a bad error from KMail:

"Im E-Mail-Programm ist ein schwerwiegender Fehler aufgetreten. Das Programm
wird beendet. Die Fehlermeldung lautet: Could not create collection trash,
resourceId: 2"

(Translation: "In the email program, a grave error occured. The program is now
being terminated. The error message is: Could not create collection trash,
resourceId: 2")
-----snip-----

Bye
Volker