Headers are not RFC compliant

I just got a automated quota mail back to a yahoo back
host mta6.am0.yahoodns.net[66.196.118.36] said: 554 Message not allowed - Headers are not RFC compliant[291] (in reply to end of DATA command)

Return-Path: <[email protected]>
Received: from localhost (unknown [127.0.0.1])
by 61.txxxxx.com (Postfix) with ESMTP id 05D95615450F
for <[email protected]>; Mon, 5 Jan 2015 23:33:50 +0000 (UTC)
X-Virus-Scanned: amavisd-new at 61.xxxxx.com
X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "Subject"
Received: from 61.xxxxx.com ([127.0.0.1])
by localhost (61.xxxxx.com [127.0.0.1]) (amavisd-new, port 10024)
with ESMTP id ltDWlbcWZcAw for <[email protected]>;
Tue, 6 Jan 2015 00:33:49 +0100 (CET)
Received: by 61.xxxxx.com (Postfix, from userid 0)
id 64BD7615450E; Tue, 6 Jan 2015 00:33:49 +0100 (CET)
To: [email protected]
Subject: Website quota notification
X-PHP-Originating-Script: 0:cron_daily.php
MIME-Version: 1.0
Content-type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
From: [email protected]
Reply-To: [email protected]
Subject: Website quota notification
Message-Id: <[email protected]>
Date: Tue, 6 Jan 2015 00:33:49 +0100 (CET)

The website xxxx.com is near or over quota.

Domain: xxxx.com
Used space: 499.99 MB
Soft limit: 500 MB
Hard limit: 501 MB
Usage ratio: 100.00%

 

if i look in the headers there is 2 times
Subject: Website quota notification
this is why yahoo bounced the messages

where can i fix this ?

 

i will do... and see what happends
i see this was reported to th ebugtracker in August

 

i removed the subject but then there is no subject anymore in the mail:
Subject:
X-PHP-Originating-Script: 0:cron_daily.php