KMAIL SMTP sending mails does not work under 11.0

I took a backup of the file home/XXXX/.kde/share/aps/kmail generated under 10.2 and performed a complete new installation of 11.0. In order not to loose the old messages I copied the complete aforementioned folder to 11.0 prior to installing KMail. As a result smtp sending mails does not work “no connection to computer smtp.web.de

I included an other user and configured kmail, wrote a message and smtp worked.
Question: How can I delete the configuration of KMail for a specific user? Which files should I copy after the configuration in order to have access to my old messages?

Werner

Have a look at /home/the_user/.kde/share/apps/kmail/

even after deleting any files and folders kmail shows me the configuration entered previously - this indicates that the configuration of kmail is kept elsewhere - who knows file name and folder?

Werner