openHAB2, mail action

Hi community,
I’m using mail action, to send details to my account.
As I live in Germany I want to use some special charaters like “ä, ü” etc. in the subject. It should look like "Verbindung hat Verspätung …"
Subject of eMail I recive looks like "=?ANSI_X3.4-1968?Q?Ihre Verbindung hat Versp=3Ftung …"
Even if i use “\u00e4” for “ä” the result will be the same.

In the moment I use “ae” insteas of “ä” and the subject is fine.

Thansk for your support, Markus