UPDATE: Problems are surfacing with Outlook users. If you use Outlook to read your email, you are probably getting an error message that the Global Address List cannot update due to a busy server. This issue is being looked at by the Zimbra Administrators.
Friday, January 30, 2015, problems with the settings in Zimbra were preventing customers from accessing the Global Address List.
The problems have been rectified and the Global Address list is not functioning properly.