Add holidays to Zimbra-calendar

While Outlook users have the possibility to download holidays as a DSM package, other users have to set school and public holidays manually.
It is necessary to download the holidays and vacations as ICS packages from the Internet.
 
For example, you can find packages with holidays and vacations for the respective federal states in the correct format: 
 
https://www.ferienwiki.de/exports/de
 
https://www.schulferien.org/deutschland/ical/
 
http://feed.kleiner-kalender.de/ical/
 
https://www.feiertage-deutschland.de/kalender-download/
 
After downloading your packages, login to your Zimbra account on "mail.desy.de" and go to "Settings" > "Import/Export" > "Import" > "File" to "Browse" and select your previously downloaded package.

If you wish to be able to hide holidays, select a holidays calendar you have previously created under "Destination".
 
Alternatively, you can create a new calendar by pressing the "New" button.

Now press "Import". Your holidays have now been added to your chosen calendar.