Bad Headers in incoming message

[liverpoolfcfan]

We have one customer whose email system is always duplicating the MIME-Version header in emails

MIME-Version: 1.0
From: **************
To: **************
X-Priority: 3 (Normal)
Importance: Normal
Date: Wed, 21 Apr 2010 15:27:43 +0100
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable

I thought if the user added the sender to their white list in their email preferences, it should allow those emails to come through - but it does not appear to be the case.

They still get caught and sent to the "bad header" quarantine.

Is there something I have configured incorrectly ?

Or, is there another way to handle this problem for this domain ?

Thanks in advance.

UPDATE:

It appears as though the emails are actually getting sent to the user - BUT ALSO getting left in the quarantine. Can that be right ?

The following headers have been added to the email

X-Quarantine-ID: <sFh93wkcdsLm>
X-Amavis-Alert: BAD HEADER SECTION Duplicate header field: "MIME-Version"
X-Spam-Flag: NO
X-Spam-Score: 0
X-Spam-Level: 
X-Spam-Status: No, score=x tag=-10 tag2=6.6 kill=15 WHITELISTED tests=[]
	autolearn=unavailable

[Klug]

We've encountered the same behaviour.

Some messages are quarantine for bad headers, especially accented chars in the subject.

But some of these messages are delivered (while being quarantined) and some other are not (quarantined only)...