Vacation plugin - setting charset

[Sedrla]

Hi,
I have installed vacation plug-in to RoundCube and running excellent except one.

My .vacantion.msg contain auto-respond text(set in Rounube) with our national chars (Czech) - coding in utf-8.

When everybody receive this auto-respond email using this text (I tested in my mail client Thunderbird), so subject and body of this mail is unreadable - contain bad chars.

What can be wrong?

Thanks for any answer.

Ruda