CC destinations dropped

[brian]

A client of mine is complaining about not receiving certain messages. 
Her colleague is also being sent them and receives them just fine. She 
insists that they are not being sent to her junk folder and that she has 
no filters that might be moving them elsewhere.

I've had a look at the logs and can see that the latest msg appears to 
have been successfully sent to both mailboxes. However, I'm not sure how 
to correctly interpret the log entries. I'm including the entries below 
(removed date/time and indented for legibility) and hope that someone 
could be kind enough to clarify what's happening.

I believe the problem does not involve postfix, as pipe appears to be 
sending both. It looks to me as if lmtpunix is looking at just the one 
address and thinks there's a duplicate. Note the two duplicate_check 
lines, both of which reference the julia account. I've sent a test 
message and indeed the duplicate_check again referenced only the julia 
account again, and admin did not receive it.

The client cannot confirm whether this only happens when a message is 
addressed to both of them but thinks that may be the case.

But then pipe appears to send a copy to each mailbox after all. I'm 
quite confused.

The mailbox that is NOT receiving the msgs is admin, while julia does 
get them.

-- snip --
   postfix/smtpd[26599]: connect from 
mail-ob0-f171.google.com[209.85.214.171]
   postfix/smtpd[26599]: setting up TLS connection from 
mail-ob0-f171.google.com[209.85.214.171]
   postfix/smtpd[26599]: Anonymous TLS connection established from 
mail-ob0-f171.google.com[209.85.214.171]: TLSv1 with cipher RC4-SHA 
(128/128 bits)
   postfix/smtpd[26599]: E401F7A25EF: 
client=mail-ob0-f171.google.com[209.85.214.171]
   postfix/cleanup[26601]: E401F7A25EF: 
message-id=<CAACv9k3oJ8yZXwyRoGLVuKeCpUSiVEbbLWjPu5eQrTSXhbeweQ at mail.gmail.com>
   postfix/qmgr[27662]: E401F7A25EF: from=<SENDER at gmail.com>, size=2295, 
nrcpt=2 (queue active)
   postfix/pipe[26602]: E401F7A25EF: to=<admin at DOMAIN.ORG>, 
relay=spamassassin, delay=1.5, delays=0.23/0/0/1.3, dsn=2.0.0, 
status=sent (delivered via spamassassin service)
   postfix/pipe[26602]: E401F7A25EF: to=<julia at DOMAIN.ORG>, 
relay=spamassassin, delay=1.5, delays=0.23/0/0/1.3, dsn=2.0.0, 
status=sent (delivered via spamassassin service)
   postfix/qmgr[27662]: E401F7A25EF: removed
   postfix/pickup[26486]: 66E757A25FC: uid=5001 from=<SENDER at gmail.com>
   postfix/cleanup[26601]: 66E757A25FC: 
message-id=<CAACv9k3oJ8yZXwyRoGLVuKeCpUSiVEbbLWjPu5eQrTSXhbeweQ at mail.gmail.com>
   postfix/qmgr[27662]: 66E757A25FC: from=<SENDER at gmail.com>, size=2646, 
nrcpt=2 (queue active)
   cyrus/master[26609]: about to exec /usr/lib/cyrus/bin/lmtpd
   cyrus/lmtpunix[26609]: executed
   cyrus/lmtpunix[26609]: accepted connection
   cyrus/lmtpunix[26609]: lmtp connection preauth'd as postman
   cyrus/lmtpunix[26609]: duplicate_check: 
<CAACv9k3oJ8yZXwyRoGLVuKeCpUSiVEbbLWjPu5eQrTSXhbeweQ at mail.gmail.com> 
DOMAIN.ORG!user.julia   0
   cyrus/lmtpunix[26609]: duplicate_check: 
<CAACv9k3oJ8yZXwyRoGLVuKeCpUSiVEbbLWjPu5eQrTSXhbeweQ at mail.gmail.com> 
DOMAIN.ORG!user.julia   0
   cyrus/lmtpunix[26609]: mystore: starting txn 2147619229
   cyrus/lmtpunix[26609]: mystore: committing txn 2147619229
   cyrus/lmtpunix[26609]: duplicate_mark: 
<CAACv9k3oJ8yZXwyRoGLVuKeCpUSiVEbbLWjPu5eQrTSXhbeweQ at mail.gmail.com> 
DOMAIN.ORG!user.julia   1342580059 0
   cyrus/lmtpunix[26609]: Delivered: 
<CAACv9k3oJ8yZXwyRoGLVuKeCpUSiVEbbLWjPu5eQrTSXhbeweQ at mail.gmail.com> to 
mailbox: DOMAIN.ORG!user.julia
   postfix/pipe[26606]: 66E757A25FC: to=<admin at DOMAIN.ORG>, 
relay=procmail, delay=0.2, delays=0.16/0/0/0.04, dsn=2.0.0, status=sent 
(delivered via procmail service)
   postfix/pipe[26606]: 66E757A25FC: to=<julia at DOMAIN.ORG>, 
relay=procmail, delay=0.2, delays=0.16/0/0/0.04, dsn=2.0.0, status=sent 
(delivered via procmail service)
   postfix/qmgr[27662]: 66E757A25FC: removed
   postfix/smtpd[26599]: disconnect from 
mail-ob0-f171.google.com[209.85.214.171]
-- snip --