trying to understand 8bit emails

[Fraser Campbell <fraser@wehave.net>]

Hi,

I'm trying to understand 8bit emails.  Using mutt I send an email with a jpeg 
attached, for the jpeg I specify 8bit encoding.  I send the email off and 
although it's viewable on the other end and appears to be intact (i.e. I can 
view it) doing a diff between the emailed jpeg and the original shows that 
there are differences.

All servers along the way are postfix.  I've tried sending 8bit email with 
kmail as well and with kmail the files are different as well, so different 
that the emailed copy doesn't resemble the original in any way when viewed.

I always use base64 encoding personally (well occasionally uuencoding) I am 
asking this because a customer of mine seems convinced of the need for 8bit 
encoding.  According to what I see in postfix docs and 
http://www.faqs.org/rfcs/rfc1652.html things should work.

Does anyone have some pointers on where things might be going wrong?  Is there 
an 8bit email FAQ somewhere (doesn't have to be postfix specific).  Here the 
smtp session captured with sniffing session on the remote server:

    EHLO mail.customer.com
    MAIL FROM:<fraser@wehave.net> SIZE=27501 BODY=8BITMIME
    RCPT TO:<fraser@customer.com>
    DATA
    Received: by mail.customer.com (Postfix, from userid 500)
        id 49B193FF2; Mon, 23 Jun 2003 14:04:59 -0400 (EDT)
    Date: Mon, 23 Jun 2003 14:04:59 -0400
    From: Fraser Campbell <fraser@wehave.net>
    To: fraser@custoemr.com
    Subject: test
    Message-ID: <20030623140459.A18472@mail.wehave.net>
    Mime-Version: 1.0
    Content-Type: multipart/mixed; boundary="tThc/1wpZn/ma/RB"
    Content-Disposition: inline
    Content-Transfer-Encoding: 8bit
    User-Agent: Mutt/1.2.5.1i


    --tThc/1wpZn/ma/RB
    Content-Type: text/plain; charset=us-ascii
    Content-Disposition: inline

    asdf

    --tThc/1wpZn/ma/RB
    Content-Type: image/jpeg
    Content-Disposition: attachment; filename="self_service.jpg"
    Content-Transfer-Encoding: 8bit

    8bit garbage starts here ...

-- 
Fraser Campbell <fraser@wehave.net>                 http://www.wehave.net/
Halton Hills, Ontario, Canada                              Debian GNU/Linux