I suggest that you load the configuration file /home/knoppix/.config/akonadi/akonadiserverrc in a texteditor and changeintoCode:[QMYSQL] StartServer=falseSave the file and exit the texteditor.Code:[QMYSQL] StartServer=true
Issue the commandin an LXTerminal and wait until kmail runs properly or exits with an error message.Code:kmail
Tell us if that resolved the issue.