When sending a message with multiple users in CC: field, only the first user receives a message with contents. All additional users listed in CC: field receive notification that a message has arrived with the subject - but when they open the message, it is blank…

I am using
Outlook 2010
Zarafa-client 7.2.4-52167
Kopano 8.5.5.5.0
postfix 3.1.0-3ubuntu0.3

When I open the user’s mailbox in the web-app, the message does not appear to exist
I have reviewed logs, and have not found anything obvious. Any help would be appreciated.