I have upgrade zimbra from zcs-5.0.18 on slackware 9 to centos 5.5 and zimbra zcs-5.0.18. Everything seemed fine. I then upgraded zimbra to zcs-6.0.6. All the mail is there and the users. The only problem picked up is now new emails do not show up with the subject line and the first line of the email in the webmail browser. Is there something I have not enabled. I did go through the options available and everything looked to be turned on that would enable the preview. The picture attached will clear up my explanation. The old mails from the previous version show up fine. It is just the new mails.
The link below shows this.
imgur: The Simple Image Sharer