Mozilla Thunderbird

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Mozilla Thunderbird

Mozilla Thunderbird logo
Mozilla Thunderbird 38.3.0 on Windows 10
Mozilla Thunderbird 38.3.0 on Windows 10
Basic data

developer Mozilla Foundation
Publishing year July 28, 2003
Current  version 78.1.1
( August 6, 2020 )
Current preliminary version 80.0beta5
(August 20, 2020)
operating system Windows, Linux, macOS, BSD, Solaris, eComStation and OS / 2
programming language C , C ++ , JavaScript , Rust
category Email client , Feed Reader , News Reader , instant messenger
License MPL / GPL / LGPL ( multiple licensing )
German speaking Yes

Mozilla Thunderbird ( German:  Donnervogel ) is a free e-mail program and at the same time a personal information manager (with CalDAV support), feedreader , newsreader as well as messaging and chat client ( XMPP and IRC ). The program is based on the source code of the Mozilla Suite and is available for a variety of operating systems.

Along with Microsoft Outlook, it is one of the most widely used user programs for e-mails.


Email client

Multiple identities

Mozilla Thunderbird supports the separate management of multiple POP3 and IMAP accounts. The accounts set up can be summarized in a global inbox . Several address books can also be kept. In addition to managing different identities within one profile, there is also the option of managing several separate profiles. While the identities use shared settings, address books and extensions, there is no connection between the different profiles. Each profile has completely separate accounts, address books and its own extensions and their configuration.

The use of different identities within the same profile is therefore primarily suitable for managing several mail accounts of one person, while the use of different profiles is particularly suitable when different people want to manage their own mail accounts independently within the same Thunderbird installation.

Secure communication, encryption

Mozilla Thunderbird supports security components such as electronic signature , message encryption and certificates according to the S / MIME standard. The GnuPG extension Enigmail made it possible to encrypt and sign emails with OpenPGP . In October 2019 it was announced that this add-on would be integrated directly into Thunderbird. It was unclear whether the Web of Trust would be supported as a feature for verifying PGP keys. In August 2020 the project announced that Thunderbird from version 80 onwards fully supports OpenPGP ("OpenPGP support is now feature complete").

HTML content

There are three modes available to the user for the HTML display of the e-mails . The first one shows the original HTML output . The second mode restricts the HTML output only to simple format instructions, abusive HTML elements are filtered out (see also Efail ). Finally, the third mode removes HTML tags completely and only displays the pure text of the respective message. For each of the sender accounts, you can determine whether the messages it sends should always be formatted with HTML or written as plain text . This default setting can be changed for each individual message if necessary.

Virtual folder and search function

Virtual folders show all messages that match previously defined search criteria (similar to the intelligent folders in applications under macOS or the labels of Gmail ). To z. For example, to get all messages from a certain sender from all currently available folders displayed, you create this search once and save it as a virtual folder. If this virtual folder is opened later, all corresponding messages are displayed even though they are in different folders.

By Homeowners are more options available to find out the main window specific emails.

Spam filter

Thunderbird offers an adaptive spam filter , which means that after a short learning phase the hit rate is already very high and usually increases with continuous use.

Compatibility and Portability

Thunderbird has good platform compatibility. It is possible to access the same profile data and e-mails from different operating systems , provided that the same Thunderbird program version is installed on both systems.

Thunderbird stores emails in several text files. Hash files are also created for faster access. Alternatively, the Maildir format is supported with restrictions.

Import functions are available for migrating from other e-mail programs to Thunderbird. This means that messages, including some settings, can be imported from Outlook or Outlook Express , for example . The entire data folder can be copied to back up the Thunderbird settings including account profiles and messages.

Contacts and appointments

Thunderbird offers an address book that enables comparison via LDAP , or via an extension via CardDAV . The Lightning extension integrated from version 38 for managing appointments and tasks in calendar form supports the CalDAV standard. This means that Thunderbird is also a personal information manager .

Instant messaging client

Thunderbird supports instant messaging and chat with the following protocols: Internet Relay Chat (IRC), XMPP and Twitter (Direct Messages). Google Talk , which is no longer available , is also supported (Google Talk is based on XMPP).


An integrated newsreader for RSS feeds is available

Further functionalities

Screenshot of Thunderbird 3 with an alternative theme and extensions Lightning , FoxClocks and Compact Menu 2 under Ubuntu 9.04

With the help of extensions ( add-ons ) further functionalities can be added.

The user interface of Thunderbird can be adapted to your own needs with themes .

Future aspirations

At FOSDEM 2020, Thunderbird unveiled future endeavors. For example, the address book for Thunderbird 78 or later should be renewed and support CardDAV , the calendar should be better integrated, the chat should also speak the Matrix protocol, the handling of mailing lists should be improved and the interface language should be changed from XUL to HTML; the JMAP protocol should also be supported.


Compared to Microsoft Outlook

Mozilla Thunderbird includes all functions for e-mail and message receipt of since Microsoft Windows 98 supplied default e-mail program, Outlook Express , which in Vista by Windows Mail and Windows 7 through Windows Live Mail was replaced, and offers an alternative to competitive commercial programs.

Compared to Microsoft Outlook , a client to the Microsoft Exchange Server , Thunderbird currently has less support for synchronization with external devices such as smartphones or PDAs . In addition, a connection to an Exchange server with Thunderbird is not possible. The reason is the proprietary RPC protocol MAPI of the Exchange server.


There is an offshoot of Thunderbird for the Windows operating system, which can run without installation and can therefore be used as portable software across computers , e.g. B. on an exchangeable USB mass storage device .

In the name dispute between Debian and Mozilla , the Linux distribution Debian 2006 renamed the associated version of the e-mail program Icedove (English for ice pigeon ). The name dispute was settled in 2016 and Icedove was replaced by Thunderbird in Debian.

Postbox is a modification that was started commercially in 2007 by the developer Scott MacGregor, who previously also played a key role in Thunderbird.

History of the Thunderbird Project

The relationship between the Thunderbird project and the Mozilla Foundation has been widely discussed.

On July 7, 2012, it was announced that Mozilla wanted to limit work on Thunderbird to stability and security updates. For this purpose, since November 20, 2012 - the release date of version 17, which appeared as ESR ( Extended Support Release ) - only updates that no longer contained new functions have been added every six weeks. Mozilla justified this step with the increasing shift of e-mail services from desktop to web-based environments. As a further reason, Mozilla stated that it wanted to use its resources for other projects such as Firefox OS , Mozilla Firefox Mobile or the iPad Junior browser based on WebKit ; accordingly, the Thunderbird development team was disbanded and the staff turned to other work. In the run-up to the decision, most Thunderbird users were already satisfied with its range of functions, so Mozilla no longer had to add any new functions. However, new functions could still be implemented by independent developers; Mozilla wants to provide the necessary infrastructure. With the appearance of the ESR generation 31 of Firefox, Thunderbird was also updated to the same version number.

At the end of November 2015, Mozilla CEO Mitchell Baker wrote in a "long e-mail" that it would be better if Thunderbird would be spun off from Mozilla, otherwise the Firefox programmers would have to take the mail client into consideration again and again, which is what the development of Firefox would hinder. Conversely, the same applies to the work of the Thunderbird developers in relation to changes in Firefox. The announcement sparked outrage among users who were concerned about the existence of the e-mail program, which is used in particular across platforms for the use of encryption services. The p≡p Foundation and Digitalcourage wanted to continue the development of Thunderbird, but the Thunderbird Council withdrew from the negotiations because it "apparently feared the dominance of the crypto community", according to Heise online .

In May 2017 it was announced that the Mozilla Foundation and the Thunderbird Council had agreed on the legal and fiscal whereabouts of the Thunderbird project under the umbrella of the foundation. A collaboration was initially only considered with the Document Foundation and the Freedom Conservancy software ; in addition, a complete independence of the Thunderbird project was discussed - a possibility that cannot be ruled out for the future. Thunderbird has been technically independent from Mozilla since 2017. Since then, the project can be reached under the domain . In addition, Thunderbird has also been converted to a new code base due to the innovations in Firefox (Quantum from November 2017). Until then, Thunderbird was based on the Gecko HTML rendering engine as the runtime environment . The user interface was written in XUL and JavaScript. The XPCOM code has been replaced by JavaScript.

Thanks to increasing donations, six additional developers were hired in January 2019. This means that a total of 14 full-time employees will work in the team in 2019. The Thunderbird developers and the enlarged team planned to make the Thunderbird program more stable, faster and easier to use and also to improve the integration of Gmail and the configurability of encryption .

In January 2020, Thunderbird got its own Mozilla company.


  • Michael Kolberg: Mozilla's Firefox, Thunderbird and Lightning: Internet, Mail and more . 1st edition. Markt & Technik, Munich 2009, ISBN 978-3-8272-4424-6 .
  • Thomas Reindlmeier: Thunderbird easy & understandable . Quadratur-Verlag, Osnabrück 2016, ISBN 978-3-945200-17-9 .
  • Rosa Riebl: Mozilla: Firefox, Thunderbird, SeaMonkey . 1st edition. C & L, Computer- und Literaturverlag, Böblingen 2010, ISBN 978-3-936546-52-1 .

Web links

Commons : Mozilla Thunderbird  - collection of images, videos and audio files

Individual evidence

  1. Thunderbird - Release Notes (78.1.1) - Thunderbird . (English, accessed on August 7, 2020).
  2. Firefox's addons are written in JavaScript. (No longer available online.) Rietta, archived from the original on August 4, 2009 ; Retrieved December 19, 2009 .
  3. Moritz Förster: 25 million users use the Thunderbird mail client. In: heise online. December 10, 2015, accessed on December 10, 2015 (German): "According to Mozilla's official statistics, the number of users exceeded 10 million in one day for the first time at the end of November."
  4. Kent James: Thunderbird Active Daily Inquiries Surpass 10 Million! In: The Mozilla Thunderbird Blog. December 9, 2015, accessed December 17, 2015 (American English): "So the best estimate of current active users is 25,000,000."
  5. Ryan Siper: Thunderbird, Enigmail and OpenPGP. In: The Mozilla Thunderbird Blog. October 8, 2019, Retrieved October 8, 2019 (American English).
  6. Jürgen Schmidt: Thunderbird integrates email encryption with OpenPGP. In: heise online. October 8, 2019, accessed October 8, 2019 .
  7. Thunderbird - Beta Notes (80.0beta). Retrieved on August 24, 2020 .
  9. Mozilla Wiki Thunderbird / Maildir. Retrieved December 27, 2019 .
  10. About Direct Messages. Retrieved August 22, 2020 (English).
  11. Instant Messaging and Chat | Thunderbird Help. Retrieved August 22, 2020 .
  12. Sebastian Grüner: Thunderbird gets a new UI and even more developers. February 2, 2020, accessed on February 2, 2020 : "Rewriting the address book, [...] integration of e-mail encryption [...] direct integration of the calendar function [...] support for OTR chats and [...] the matrix -Chat system [...] because Mozilla is switching to matrix "
  13. Thunderbird Portable. In: heise Download. Retrieved December 29, 2017 .
  14. heise online: Debian gives up the web browser Iceweasel and relies on Firefox again. Accessed November 20, 2018 (German).
  15. Postbox 3.0.10: Commercial Thunderbird offshoot with Retina support , on May 25, 2014.
  16. Stefan Beiersmann: Thunderbird: Mozilla withdraws from development .
  17. Daniel AJ Sokolov: Mozilla cuts support for Thunderbird. In: heise online. July 7, 2012, accessed August 27, 2020 .
  18. ^ Mitchell Baker: Thunderbird, the future, mozilla-central and comm-central. In: mozilla.governance mailing list. November 30, 2015, accessed December 10, 2015 .
  19. ^ Daniel Berger: Thunderbird: Mozilla would like to separate the mail client from Firefox. In: heise online. December 2, 2015, accessed December 10, 2015 .
  20. Detlef Borchers: p≡p developer: The crypto community needs the Thunderbird mail client. In: heise online. December 3, 2015, accessed December 10, 2015 .
  21. a b Daniel Berger: Thunderbird stays with Mozilla - and becomes independent. In: heise online. May 9, 2017. Retrieved June 24, 2017 .
  22. Philip Kewisch: Thunderbird's Future Home. In: The Mozilla Thunderbird Blog. Mozilla Foundation, May 9, 2017, accessed June 24, 2017 (American English).
  23. Simon Phipps: Finding a home for Thunderbird. (PDF) Mozilla Foundation, April 7, 2016, accessed June 24, 2017 .
  24. Sebastian Grüner: E-Mail Client: Thunderbird 60 brings new optics, quantum and web extensions - In: Golem. August 7, 2018, accessed December 21, 2018 .
  25. Axel Kannenberg: Thunderbird email client: hire developers, improve performance. In: heise online news. Heise Medien GmbH & Co. KG, January 3, 2019, accessed on March 5, 2019 .
  26. Sebastian Grüner: E-Mail Client: Thunderbird gets its own Mozilla company. In: January 29, 2020, accessed January 29, 2020 .