Re: Mail Essentials reveals identity of first BCC recipient

From: Jörgen Persson (jpnat_private)
Date: Wed Dec 12 2001 - 11:15:25 PST

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    On Wed, Dec 12, 2001 at 09:55:18AM +0000, Ronan Waide wrote:
    > Hi Bugtraqers,
    > 
    > I recently received a marketing mail from a supplier who uses an email
    > content filter called Mail Essentials from GFI Software (see
    > http://www.gfisoftware.com/me/mesfeatures.htm for more
    > information). The message had no destination address, having been sent
    > to a BCC list. On inspecting the Received: headers, I found one
    > inserted by Mail Essentials:
    > 
    > Received: From mail.server by other.server
    > 	Mail essentials (server 2.422) with SMTP id: <513at_private>
    > 	 for <bcc_person@address>; Wed, 29 Aug 2001 16:19:12 +0100
    > 	smtpmailfrom <originator@address> 
    > 
    > The 'bcc_person@address' was, presumably, the first person on the BCC
    > list - it certainly wasn't /my/ address. I brought this to the
    > attention of GFI software over a month ago, and the eventual response
    > was to the effect that 'BCC headers get stripped out' - evidently the
    > problem was misunderstood. Since I've not heard anything more from
    > them after clarifying the situation, I'm posting the problem here in
    > case anyone happens to use this software in-house.
    > 
    > Cheers,
    > Waider.
    
    True, the described behaviour is usually not desirable. ''GFI Software''
    ought to consider to change it.
    
    On the other hand, RFC 2821 and RFC 2822 clearly indicates that the Bcc:
    field is not to be trusted in general unless you know for certain how it
    will be handled.
    
    RFC 2821, section: 
    4.4 Trace Information
    7.2 ''Blind'' Copies
    7.5 Information Disclosure in Trace Fields
    
    RFC 2822, section:
    3.6.3. Destination address fields
    5 Security Considerations
    
    Sincerely,
    Jörgen
    



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