Thunderbird calendar client setup at DTU

Thunderbird mail and calendar client

This page explains several methods for using calendars with the Thunderbird mail client. You must be using Thunderbird version 3.1 or higher.

Thunderbird Lightning add-on

The Thunderbird add-on named Lightning can be used to enable calendar messages within Thunderbird.

See also

There is a Danish website for Mozilla calendars at, and some instructions on the page You can also look at

Installation of Thunderbird Lightning Add-on

Open the Thunderbird Add-on manager (the Tools->Add-ons menu):

  • In this window use the Get Add-ons pane and search for Lightning.

  • Click Add to Thunderbird.

After restarting, Thunderbird will have the Lightning calendar extension in the menu bar item Events and Tasks:

  • Select Events and Tasks->Calendar (Control+Shift+C) to view the calendar tab.

Using a CalDAV calendar service gateway

E-mail and calendar clients which do not use Microsoft’s proprietary Exchange protocol must use Calendaring Extensions to WebDAV, or CalDAV, which is an Internet standard allowing a client to access scheduling information on a remote server. At DTU Fysik we have set up a DavMail gateway service for use by non-Microsoft calendar clients at the address Several ways of accessing this calendar are described in the sections below.

Configuring Thunderbird Lightning for a DavMail calendar

Set up a standard IMAP mail account as described at How to set up Email at DTU Fysik. and then follow the Thunderbird calendar setup (in French).

Summary of the setup of DavMail in Thunderbird Lightning:

  • In Thunderbird enter the Calendar tab, right-click to get a menu and choose New calendar…

  • Select: On the Network -> CalDAV

    At DTU Fysik, set the following network CalDAV server address:

    changing the USERNAME. You must be a mailbox user on the Exchange server in order for this to work.

Exchange Calendar and Tasks Add-on for Lightning (Thunderbird/Seamonkey)

The Exchange server offers an Exchange Web Services (EWS) interface to calendars etc.

Installation of Exchange EWS Calendar and Tasks Add-on

You can install the Ericsson exchangecalendar extension to Lightning described as:

  • The only add-on for Thunderbird and Seamonkey which will add access to you Exchange calendars, contacts and Global Address List [GAL]. It is an add-on for the Lightning. Calendering Add-on and will allow you to communicate with an Exchange 2007, 2010 and 2013 server using the Exchange Web Service [EWS] interface. You can access any Calendar, Task or Contacts folder on the EWS server in an easy way. And also manage your [Out of Office] settings.

Adding a DTU Exchange calendar

In the Thunderbird calendar pane (Events and Tasks->Calendar):

  1. Right-click on a calendar and select New Calendar….

  2. In the Create a New Calendar window choose On the network.

  3. Then choose the format Microsoft Exchange 2007/2010 (as provided by this new add-on).

  4. Assign a calendar name, color etc. in the next window. Use your own address in the E-mail: field.

  5. In the next window Exchange/Windows AD settings enter the following EWS server URL (see the how to add a calendar FAQ):

    You should not use the autodiscovery checkbox since this function is not implemented in the FYS network.

  6. The Mailboxname is either your E-mail address (the usual case): (or any E-mail alias)

    but for shared calendars you may also enter another user’s E-mail (only if the mailbox owner has chosen to share his/her calendar with you).

  7. The Username is your DTU initials, and the Domain is:
  8. Now press the button Check server and mailbox. You will be asked for your login name and password.

  9. Press Next and Finish to complete the setup.

  10. Wait a minute or two while the new calendar gets loaded into Thunderbird. You may also right-click on the calendar and choose Reload remote calendars.

Using the Exchange calendar

Right-click on the new calendar to check:

  • Exchange (EWS) Properties such as AD, Meetings and Folders.

  • Out of Office settings such as auto-reply and dates.

External network calendars

Independently of which calendar client software you use, there are some network based calendars which you may want to consider subscribing to:

  • National holiday calendars: If you wish to import your national holiday calendar into your personal calendar, there is a list of calendars here Calendar - Holiday Files. For example the Danish Holidays are available at DanishHolidays.

  • Campusnet_Calendar at DTU: You can subscribe to your personal Campusnet_Calendar as described in the iCalendar-udgivelse page. In this case you must select the iCal calendar type (in stead of CalDAV).

    Note that your personal Campusnet_Calendar` is accessible from calendar clients like thunderbird, ect. as read-only.

Configuring Thunderbird Lightning for an ICS calendar

  • In Thunderbird enter the Calendar tab, right-click to get a menu and choose New calendar…

  • Select: On the Network -> Icalendar (ICS), and provide url location of the *.ics file.

Additional technical details

Below are some technical details which are mainly of interest to system administrators.

Autodiscover DNS name

The Exchange Calendar and Tasks Add-on for Lightning described above may use the DNS address See the FAQ item

We have tried to make a DNS CNAME alias for pointing to This indeed makes mailbox autodiscovery work as expected.

Unfortunately, since the central Exchange server’s SSL certificate doesn’t belong to the domain, error messages were experienced with Outlook clients. Therefore we no longer use the autodiscover DNS alias.

Thunderbird LDAP directory setup

DavMail Directory support is now available to access Exchange address book through LDAP. See Thunderbird directory setup. This still needs testing.

Building DavMail RPM

Search for ready RPMS at davmail at

To build using rpmbuild use the DavMail source with the davmail.spec file, and relevant source files from SOURCES. Configure the rpmbuild environment as described at configure rpmbuild.

To build an RPM on a CentOS5 configure the following external repositories:

Set enabled=0 in the /etc/yum.repos.d/*.repo file of those repositories, then install the required packages:

yum install ant ant-antlr --enablerepo=c5-testing,blackop