[Mailman-Users] Disappearing message

[Anne Ramey]

Have a new and different one.  One of my users that has two lists, let's 
call them list1 and list2.  If he sends a message to list1 and cc's 
list2, list1 never receives the message.  If he sends the same message 
only to list1, it goes through fine.  According to my exim logs, it is 
delivering both messages to list1:

ex.

2007-10-22 08:28:48 1IjwOm-0002t6-2J <= lists.owner at addre.ss H=myhost 
P=esmtp S=288168 id=46C8249D004309AE at myinternalrelay T="[List1] Agenda 
Change Advisory Board - Oct 23,2007 3:00pm"
2007-10-22 08:28:48 1IjwOm-0002t6-2J => list1 <List1 at lists.mydomain.com> 
R=mailman_router T=mailman_transport
2007-10-22 08:28:48 1IjwOm-0002t6-2J => list2 <List2 at lists.mydomain.com> 
R=mailman_router T=mailman_transport
2007-10-22 08:28:48 1IjwOm-0002t6-2J Completed

2007-10-22 08:52:31 1Ijwli-0003WN-LD <=  lists.owner at addre.ss H=myhost 
P=esmtp S=288873 id=46C8251F004335C3 at myinternalrelay T="FW: [List2] 
[List1] Agenda Change Advisory Board -Oct 23, 2007 3:00pm"
2007-10-22 08:52:31 1Ijwli-0003WN-LD => list1 <List1 at lists.mydomain.com> 
R=mailman_router T=mailman_transport
2007-10-22 08:52:31 1Ijwli-0003WN-LD Completed

The first message is successfully posted to list2, the second message is 
successfully posted to list1.  The first message has absolutely no MM 
longs relative to list1.  Nothing in the vette, smtp, post, error, 
bounce, etc.  Nothing at all related to message one for List1.  This is 
a weekly message and this has happened for the last 4+ weeks.  Before 
that it appears to have worked fine.  I haven't made any system changes 
in that time.  What could cause something like this.  Is is possible a 
list setting could do this?  I checked the sender filters on both lists 
but saw nothing that looked wrong.

Any assistance would be appreciated.

Anne