ZF 1.5 - Zend_Mail and long subject lines

[Ota]

When sending an email via Zend_Mail with a long subject (about 90 characters)
the whole emails gets garbled.

It seems that there is a problem with the encoding because the email body
then contains parts of the email headers.
Is this intended behaviour, i guess not? Maybe i am doing something wrong,
advice would be appreciated.

Thanks, ota!

Sending via Zend_Mail and stmp, utf8 encoded.

Enclosed are the first few lines without the content of the email i will
recieve:

------------------------------------------------------------------------

nistrator=20viazenetti?=
Date: Mon, 17 Mar 2008 18:19:00 +0100
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline

... encoded email content goes here ...

------------------------------------------------------------------------


The headers of the corresponding email, please note i replaced some parts
because of security issues:

------------------------------------

Microsoft Mail Internet Headers Version 2.0
Received: from SERVER ([192.168.21.4]) by SERVER with Microsoft
SMTPSVC(6.0.3790.3959);
Mon, 17 Mar 2008 18:04:52 +0100
Received: from localhost (localhost [127.0.0.1])
by SERVER (Postfix) with ESMTP id E996E8992E
for <VALID-o7pRwT2+n/***@public.gmane.org>; Mon, 17 Mar 2008 18:04:43 +0100 (CET)
Message-id: <***@SERVER>
date: Mon, 17 Mar 2008 18:04:43 +0100
Sender: VALID-fbqU/***@public.gmane.org
Errors-To: VALID-IfZyHHGB9+***@public.gmane.org
X-Mailer: viazenetti GmbH PHP Mailer
To: "TO NAME" <VALID-o7pRwT2+n/***@public.gmane.org>
From: "FROM NAME" <VALID-***@public.gmane.org>
Subject:
=?UTF-8?Q?EXAMPLE=20WEBSITE=20WEBSITE=20-=20SUBJECT=20SUBJECT=20=C3=84nderung=20der=20=20-=20Administrator=
Return-Path: VALID-mhO++***@public.gmane.org
X-OriginalArrivalTime: 17 Mar 2008 17:04:52.0437 (UTC)
FILETIME=[04350050:01C88851]