Character encoding (out of office and redirect)?

Hi!
I have a problem where Out of office messages containing special characters gets replaced with a questionmark on the recieving end. Where to look for the reason? I guess there is some kind of encondingsetting I should look for?

I have also had reports on the same thing happening when a user sets up a inboxrule that forwards/redirects a incoming message.

Maybe this is the key?

https://technet.microsoft.com/en-us/library/aa997857(v=exchg.150).aspx

We have:

DomainName                           : *
ByteEncoderTypeFor7BitCharsets       : Undefined
CharacterSet                         : iso-8859-1
NonMimeCharacterSet                  : iso-8859-1
AllowedOOFType                       : ExternalLegacy
ContentType                          : MimeText