Recently I posted bug report
https://bugzilla.zimbra.com/show_bug.cgi?id=42251
"
When users try to view some emails content in Zimbra Advanced Web Client it
shows empty view field. After clicking on email on the list an error appears in
Firefox Error Console: 'G is null' in line 1494.
The same emails view in standard web client is correct.
"
Since all my exemplary e-mails are confidential I can't send them to developers. This bug reveals on two zimbra deployments i administer therefore I can't imagine that it concerns my users only.
It seems that all such emails are created in Outlook.
Do you have any e-mails causing such behaviour of extended web client?