This Documentation is currently under construction (01.02.2021, UCO)

Here you can find an overview over the Calendaring tool which is included in the Zimbra Mail Service.

You can access and synchronize your calendars via the following tools:


Define Start of the Week

If the calendar week in Zimbra starts e.g. with a Sunday but the desired day should be a Monday, then it can be changed in the calendar settings: Settings → Calendar → General → Week start


Previously accepted calendars are always hidden via the leading Zimbra mail system.

Log in to the Zimbra web client at https://mail.desy.de.
In the Calendar tab, the calendar to be hidden is deleted by right-clicking on Calendar.

Status (Free/Busy)

The possibility of free / busy visibility can be adjusted in the calendar settings.

Go to: Preferences → Calendar → Permissions → Free/Busy

The standard setting here is "Allow both internal and external users to see my free / busy information".
However, this can be adapted to your own needs.

Furthermore, you can use "Invites" to regulate who is authorized to invite you to appointments.


The synchronization of Zimbra with other, external calendars, e.g. the Google calendar is not possible, so that the entries are shown in both calendars at the same time.


Shared Calendars (Find/Add)

Shared calendars can be searched and integrated as follows:

1. Click on the wheel to the right of the calendar

2. Click on Find Shares

3. Search for the calendar in the upper search field

Shared calendars are deleted as follows:

Right click on the calendar and then delete

Known Problems

Error Message "... could not be updated"

Error Message: "... could not be updated"

This is a bug for which there is the following workaround:
Just click forward a week and then back again.
The calendar will then update and display the Free / Busy information.

Is the display still empty?
Then the authorizations for the free / busy information should be checked and, if necessary, changed:

  1. Log in to https://mail.desy.de with your DESY data.
  2. Go to the "Settings" tab.
  3. Go to "Calendar" in the navigation bar on the left.
  4. Then scroll down until you come to the "Permissions" block.
  5. Here you can select something like "Anyone can see my free / busy" information "or" Nobody can see my free / busy information view ". It is also possible to define a specific group of people who may view this information.
Entries don't show up or disappear

When creating a calendar entry, the appointment is entered in the personal calendar "Calendar" by default.
If the entry is to be made in another calendar, this must be selected beforehand (see screenshot)

Please check whether the appointment was accidentally made in your personal calendar (or possibly in another calendar) and that the calendar is also checked/activated in your view.


The phenomenon was observed that registered appointments simply disappear after 1-2 minutes.
In a similar case, the problem could be resolved as follows:

  • Zimbra's network traffic was scanned with the Firefox developer tool. It was found that a created calendar entry always disappeared after a "BatchRequest", but not with a "CancelAppointmentRequest", as it is otherwise sent by triggering the user. The trash folder was full but the calendar entries that had disappeared were not displayed.
  • First of all, the delegation for iCal CalDAV was deactivated, because it is assumed that there is interference here: Preferences -> Calender -> Apple iCal -> Enable delegation for Apple iCal CalDAV client
  • After clicking "Save" a message similar to the one on the attached screenshot appeared, which was answered with "Yes".
  • Then, Zimbra started to reload the missing data. They were in the trash folder. Zimbra did not report that the data was successfully or completely loaded.
  • Der Trash bin has been emptied manually.
  • Finally, new calendar entries were created and remained visible.
Embedded Calendars cannot be viewed

If embedded calendars can no longer be viewed or edited despite having the reading or writing rights, it is recommended to remove these calendars and re-integrate them again.

Please find the documentation how to proceed in this case:

General Information (click)

Outlook (click)


User Authorization

Group calendars are based on functional accounts for which the calendars and, if necessary, the e-mail function must be enabled by the mailmasters.
The responsible group administrators will authorize the group members for the respective group calendar.
The release is to be done as follows: Right click on the desired calendar → Edit Properties
→ Entry of the e-mail addresses → Control of the role: "View" is entered by default → OK.



Integration into Outlook

If calendars, existing in Zimbra, are not or no longer available in Outlook, please proceed as follows:

  1. Open Outlook.
  2. Select the "Zimbra" tab in the menu bar.
  3. Select "Share Status".
  4. Activate the desired calendars by ticking the control box and confirm with OK 
  5. Close Outlook and wait for synchronization after restarting.
External Usage

There is a possibility to set up a Zimbra group calendar, which can be read by external employees without a DESY account.

For this purpose, the web office would have to set up an extra website for such purposes.
Example: https://www.desy.de/room/occupancy/@@siteview

Access with DESY account is possible.
Access with DESY-IP is possible if the website on which this calendar was integrated is only accessible with DESY-IP.
Access for external parties is possible by setting up a functional account with reading access and sharing the corresponding account data. 

Visibility exists for everyone.

Group Calendars

Group calendars are made available for functional accounts.
Since functional accounts do not have e-mail and calendar functionality by default, these must first be made available by the mail masters.