Add Holidays to Zimbra Calendar

Rename the downloaded archive to match the included XML file (first part of file name).

Install and Configure (Admin Only)

Select Flush zimlet cache if updating a Zimlet.

Zimbra Admin → Configure → Zimlets → Gear Icon → Deploy

If you don't see the Holiday Calendars zimlet, refresh your browser page.

Zimbra Web Client → Zimlets (scroll down on left) → Holiday Calendars → Subscribe (US Holidays)

Zimbra Web Client → Calendar → Select the checkbox to display the holiday calendar