If i look at a ticket, generatet from a mail the preview of: ä, ö, ü, ß look like this:

If i open the ticket in html-view everything is ok,
but if i try to forward the ticket as a mail,
or i try to answer inline the sendet mail looks like the preview...
thats what the locales of my server are:

is something else i can check? or is that a known issue?