Does DCC skip attachments?

Gary Mills mills@cc.UManitoba.CA
Tue Sep 9 16:30:03 UTC 2003

On Tue, Sep 09, 2003 at 10:05:37AM -0600, Vernon Schryver wrote:
> > From: Gary Mills [] 
> > I had a complaint today from a professor who was e-mailing documents
> > from his home address to his work address.  The mail was rejected by
> > DCC.  When I looked at the DCC log, I discovered that the mail was
> > multipart/alternative with an attachment.  The plain text part was
> > empty.  The HTML part was also empty, except for all the font and style
> > definitions inserted by his MUA.  These two parts certainly could be
> > identical to thousands of other messages, which would cause DCC to
> > consider the mail as bulk mail.
> >
> > However, the attachment was his own PDF file, and should have been
> > unique.  Did DCC skip this part when it was calculating checksums?
> Some image types are ignored by some DCC checksums.  That description
> of the message implies that it should not have had a Fuz2 checksum,
> but the other checksums should have been computed and distinct.  Where
> they?  The checksums of a message can be computed by feeding it to
> `dccproc -QC`

Here they are from the DCC log:

     Body: 91fa0b7f ae66cd83 0a3416c2 4e48320d       0      
     Fuz1: 9896a514 ae3431f6 7c0cfa58 b4eabc5d       0      
     Fuz2: e49f6eba 1055a720 6a9afb79 9a2ede52    4077      

By the way, people often do send empty messages for good reasons,
although I'm sure they don't realize how much MIME and HTML goo is
in the empty message.  Sometimes they do it with a message in the
Subject header that is meaningful to the recipient.  Sometimes they
do it to send somebody a file attachment, again relying on the Subject
header to convey some information to the recipient.  They expect all
this to work, of course, and are surprised when DCC rejects the mail.

-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-

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