untagged messages

[hermit921]

I am still trying to figure out why some messages don't get tagged by
MailScanner 4-23, postfix 2.  Every email should get tagged with at least
one MailScanner header, but some don't.

I came up with an idea.  Is this feasible:
Spammer sets up his client to use our mail server as his smtp
gateway.  Should work for any message addressed to a user in our domain,
but he can't send mail outside.  So spammer addresses a message to
usera at mydomain, with CC or BCC to userb, userc, userd, etc.  Now I get
fuzzy....

One message appears here, postfix dumps it in the hold queue.  Postfix
splits it up at the same time, so only the original message gets the
MailScanner headers.  Since I can't track the original, I can't verify the
presence of headers.

Am I way off?