This isn't possible yet. The only solution is to code your own email script and redirect the user to this script at the end of the survey.
Using cronjobs would be another alternative for automated email sending, but you'd also have to code that script.
Best regards/Beste Grüße,
Dr. Marcel Minke
(Limesurvey Head of Support) Need Help? We offer
professional Limesurvey support Contact: marcel.minke(at)survey-consulting.com'"