Php error in mb_send_mail

I have got:

mb_send_mail(): Unsupported transfer encoding "quoted-printable" - will be regarded as 8bit

What should I do?

Full headers:

Content-Transfer-Encoding: quoted-printable
Content-Type: text/html; charset=utf-8
MIME-Version: 1.0
Date: Thu, 17 Mar 2011 19:17:48 +0200
Message-ID: <1300382268.4d82423c6c409@mydomain.com>
From: noreply@mydomain.com
Subject开发者_JS百科: =?utf-8?Q?=D0=9D=D0=BE=D0=B2=D1=8B=D0=B9_=D0=BA=D0=BE?=
 =?utf-8?Q?=D0=BC=D0=BC=D0=B5=D0=BD=D1=82=D0=B0=D1=80?=
 =?utf-8?Q?=D0=B8=D0=B9_=D0=BA_=D0=B2=D0=B0=D1=88?=
 =?utf-8?Q?=D0=B5=D0=B9_=D1=84=D0=BE=D1=82=D0=BE=D0=B3?=
 =?utf-8?Q?=D1=80=D0=B0=D1=84=D0=B8=D0=B8?=
To: some@email.com

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Check this:

PEAR Bug #10146 - mbstring fails to recognize encodings.