Myself and a few other users in our deployment have a strange issue where not all messages display in the AJAX webclient. Interestingly enough, switching to HTML view allows the messages to display. Connecting from IMAP also allows the messages to display. We have tried multiple browsers and multiple machines. I have restarted zimbra, but have not yet restarted the server wondering if there is a specific log file I can look at to try and track down the issue.
It does not happen in the Inbox folder and a few other folders but it somewhat frustrating to not see all the messages in a folder.