the first error is the cause of the others.
The first error:
Warning: set_time_limit() [function.set-time-limit]: Cannot set time limit in safe mode in /var/www/vhosts/fcbruettisellen-dietlikon.ch/httpdocs/kontakt/index.php on line 62
is occurring because the host server is set to use safe mode. Universal Email cannot be used on a server that has safe mod turned on. With Safe mode turned on, some php functions that are used by universal email will be disabled. safe mode must be turned off when using universal email.