Set up a brand new user. 
Start kontact and begin to configure kmail. Select: create a new imap account
from the wizard. As encryption method choose "gpg wallet encryption". 
Search for the settings (verified for freenet.de) and then accept the values
offered (which are right by the way). 
Now at the end, after putting password and everything select join the account.
Then O.K. 
You will now be where you have been. Nothing as been created. 
If you set up the very same email account manually, everything will work as
expected. 

What the software should do: 
the wizard should save the account set up correctly and save the account. 
What the software does:
runs through the process correctly but at the end the account is not saved.
Manual procedure instead works.