Mail Programs: Basic Configurations

Here you will find an overview of the basic configuration of various mail programs.

Microsoft Outlook

Microsoft Outlook is limited to use on DESY Windows Devices. In addition to Microsoft Outlook itself, the so-called Zimbra Connector for Outlook (ZCO for short) is required for use. Like Microsoft Office, this must also be installed via the Software Shop. The use of Microsoft Outlook is necessary if you need to make your calendars (and e-mails) accessible offline. For example, to be able to access your data while on the road.

However, some of the required settings or approvals cannot be made in Outlook itself, but must be made beforehand via the Zimbra web interface (see above). Outlook also copies your data from the central service to your local device (creating a local image of your data available on the central service). The required copying process (synchronization) requires a corresponding amount of time especially in case of large inboxes and/or many appointments in calendars, on the one hand during the very first synchronization to your device, and on the other hand after longer periods of absence like e.g. vacations.

The fact that the data is stored locally on the device's hard drive also weakens the protection of the data somewhat compared to using the web interface, as this can create an additional point of attack.

Outlook can offer a clearer view of the calendars, especially for people who are confronted with managing many calendars in everyday life. Outlook can also provide integration into Word or Excel, e.g. for serial letters.


Thunderbird is offered for installation at DESY both under Windows in the Software Manager DSM and under Ubutu in the software repositories.

Like Outlook, Thunderbird synchronizes the data available in your mail account locally to your device and creates a corresponding profile there. The use of Thunderbird is necessary if, for example, you need to make your e-mails accessible offline. For example, to be able to access your data while on the road.

Please note that the use of Thunderbird as a calendar tool must be discouraged due to various problems. See:

Smartphones / Tablets

Smartphones and tablets also usually come with their own calendar programs and allow many different calendar programs to be installed via the app stores. These also only provide an image of your data locally on the device. DESY-IT does not yet have a basic recommendation for certain applications.

In principle, however, the use of ActiveSync (which includes the synchronization of mails, calendars and contacts) should be primarily used as a synchronization type. Only if synchronization via Active Sync is not possible or desired, mails (with an IMAP account), calendars (with a CalDAV account) and contacts (with a CardDAV account) should be transferred from/to the central service to your device. Due to the wide variety of programs, different devices, etc., DESY-IT can only provide limited support in these cases.

Brief overview

Please note that only the Zimbra web interface provides a direct view of your email/calendar account data. All other applications only provide a local image of the data, which means that it has to be copied from/to the calendar/mail service.

Therefore: Please prefer to use the Zimbra web interface ( Then use a locally installed e-mail/calendar program (e.g. Outlook) if

  • the Zimbra web interface cannot be used efficiently (e.g. on smartphones or tablets)
  • you need your data offline (e.g. on business trips)
  • you need extended functions or a link to other programs (such as Word or
    enterprise resource planning)

Email program availability

  Zimbra Web Outlook Thunderbird Apple Mail
Windows yes yes yes no
Linux yes no yes no
macOS yes no yes yes
iOS yes no no no
Android yes no no no


Relevant aspects of the email programs

  Zimbra Web Outlook Thunderbird Others (e.g. Apple Mail)

Supported by DESY-IT

yes yes only mail limited

Cross-operating system

yes no yes no

Local image (synchronization)

no yes yes yes

Offline availability of data

no yes yes yes

Integration in office-programs

no yes no no

Configuration required on each device

no yes yes yes

Synchronization-problems possible

no yes yes yes