kmail has messed up the email accounts

Hi,

somehow kmail has messed up the email accounts in that I can not pick a sender 
from the list of my email addresses when creating a new message, and emails 
I'm sending are being put into the wrong Sent folders despite the correct 
folders are configured in the settings.  "Wrong Sent folders" means that a 
message from account A is being into the Sent folder of account B instead of 
into the Sent folder of account A when I'm sending it.

How can I fix this?