Zimbra lacks a calendar feature commonly used by serious Outlook and Entourage users, the ability to configure reminders for individual calendar entries. The workaround is to create a 'reminder' calendar entry, which does not work well as it requires manually changing the reminder if the original appointment changes. If you are a current or prospective Zimbra user and would like to have this feature added, please
vote for this bug. On a related note, the Zimbra Toaster (which provides popup notification of new mail) does not support calendar reminders, which is documented in
this bug.