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[Gregor Adamczyk]

Danke, Problem gerade behoben mit:

cp /kolab/etc/kolab/templates/webclient-config_nls.php.template 
/kolab/etc/kolab/templates/webclient-config_nls.php.template.or
vim /kolab/etc/kolab/templates/webclient-config_nls.php.template

unten einfügen:
$nls['defaults']['language'] = 'de_DE';
$nls['defaults']['charset'] = 'UTF-8';
$nls['charsets']['de_DE'] = 'UTF-8';

/kolab/sbin/kolabconf -n

-- 
Mit freundlichen Grüßen/With best regards
Gregor Adamczyk