Umlauts -> X in subjects?

[Thorsten Schnebeck]

Hi,

so finally we start using Kolab so far as our email server but my 
boss moans about subjects that have an X in place for an Umlaut.
I know that the true mail RFC doctrine only allows 7bit subjects 
but this is real world. 

So, how can I config the system to get rid of stuff like

X-Amavis-Alert: BAD HEADER Non-encoded 8-bit data (char E4 hex) in 
message header 'Subject': Subject: Reservierungsbest\344tigung\n
Subject: ReservierungsbestXtigung

Bye

  Thorsten