Virtualmin autoresponder utf8

The autoresponder is using iso-8859-1, yet it does a lot of crap with French and German special characters. How can one change that to utf8?

email:

[…]
Subject: Autoreply to test
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=iso-8859-1
Date: Fri, 22 May 2015 20:45:34 +0000 (UTC)

You email has been delivered, but the email address you have used will be obsolete soon. Please use @XXXX.net instead of @XXXX.de.

Remarque:
Votre email a =C3=A9t=C3=A9 livr=C3=A9, mais l’adresse e-mail que vous avez utilis=C3=A9 ne sera pas valide tr=C3=A8s bient=C3=B4t. Par cons=C3=A9quent, utiliser @XXXX.net =C3=A0 la place de @XXXX.de s’il vous pla=C3=AEt.

Hinweis:
Ihre E-Mail wurde zugestellt, jedoch wird die von Ihnen verwendete E-mail Adresse bald ung=C3=BCltig sein. Bitte benutzen Sie daher @XXXX.net anstelle von @XXXX.de

anyone?