email problem
One user is randomly not receiving emails. Just had an email addressed to him with copy to another user which they received but he did not. Server 10.7.5
Look through /var/log/system.log, do you show the message delivered to dovecot ?
The end of the log line would have: (delivered via dovecot service)
If you suspect a mail filter (client or server), you can enable logging of all imap transactions (including move, delete, etc)
I can post directions if needed.