From: Jonas Eckerman <jonas_li...@frukt.org>
   Date: Thu, 23 Jul 2009 15:37:11 +0200
   
   Michael Hutchinson wrote:
   
   >> I saw a test
   >> message with just the word test in the subject hit DCC once.
   
   > That's really strange, I don't see how DCC would fire on the subject..
   > the checksum of the message must have somehow matched some Spam.. 
   
   That's perfectly normal. DCC doen't just match spam, it matches things 
   that has been seen before. That means it matches bulk, but also anything 
   that happens to be very common for other reasons.

yep.
   
   I imagine that an empty message with the subject "test" is pretty 
   common, so it's perfectly reasonable for DCC to have seen such messages 
   many times before.
   
   I don't know if DCC cares about the subject att all. If it doesn't, it's 
   even more liekey that it would hit on an empty test message.
   
   /Jonas

DCC does hit on empty messages.   The empty messages can be
whitelisted.   The DCC distribution includes a fetch-testmsg-whitelist
script:

% head /usr/src/dcc-1.3.111/misc/fetch-testmsg-whitelist
#!/bin/sh

# Fetch a list of "empty" mail messages for whitelisting.  Many free mail
#   service providers add HTML or other text to mail.  That causes empty
#   and nearly empty mail messages to have valid DCC checksums and not be
#   ignored by DCC clients.

# The fetched file can be included in whiteclnt files.  For example, the
#   following line in /var/dccwhiteclnt would whitelist many common
#   empty messages

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