Exchange 2013 OWA replaces Swedish characters (ÅÄÖ) with question marks (?)

Hi

I have a problem with Exchange 2013 OWA.

The problem is that Swedish characters (ÅÄÖ) is replaced by question marks (?) when sending an email from OWA.

The behavior is has the following scenario:

1) If you have an Swedish character (åäö) in the subject field, the mail will have all content correctly. That's means the character å ä ö is in the message body. 

2) If you don't have any Swedish characters (åäö) in the subject field, the content will be incorrect, all the Swedish characters are replaced with question marks (?). 

Does anyone else had this odd behavior, and do anyone have a solution for it?

Best Regards
Lars