mail redirection (mime_header_check)

Dear Mailinglist!

I am filtering mails with certain attachments (.pif, .scr, etc.) on my
postfix system (2.0.14).

----------my /etc/postfix/mime_header_checks-------------
/filename=\"?(.*)\.(scr|pif|lnk|vbs|vbe|vb)\"?$/ FILTER filterredirect:
---------------------------------------------------------

----------my /etc/postfix/master.cf----------------------
....
filterredirect unix - n n - - pipe
flags=R user=spam argv=/bin/mail spamaccount@domain.at
---------------------------------------------------------

With the configuration above all emails with these attachments get
redirected to my spam-account (spamaccount@domain.at).
It is working flawless, but I can see the attachments only as text (see
below).

---------------test-email------------
....
[email-header]
....
Content-Type: application/octet-stream; name="test.scr"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="test.scr"

ZGFzIGlzdCBlaW5lIHRlc3RkYXRlaSAgISEhIQ0KdGhhdLRzIG EgdGVzdCBmaWxlICEhIQ0KZGFz
IGlzdCBlaW5lIHRlc3RkYXRlaSAgISEhIQ0KdGhhdLRzIGEgdG VzdCBmaWxlICEhIQ0KZGFzIGlz
dCBlaW5lIHRlc3RkYXRlaSAgISEhIQ0KdGhhdLRzIGEgdGVzdC BmaWxlICEhIQ==
--------------------------------------

I think the "Content-Transfer-Encoding: base64" is the problem. ("not
filtered" emails have "Content-Transfer-Encoding: quoted-printable").
Do I have to decode it before ? Does anybody know how ?

I've tested this with a few email-clients (lotus notes client, evoulution,
outlook 2000;)

thank you for your help
richard brunner