:Mozilla Thunderbird

Thunderbird is an e-mail, newsgroup, news feed, and instant messaging client with personal information manager (PIM) functionality, inbuilt since version 78.0 and previously available from the Lightning calendar extension. Additional features are available from extensions, which allow the addition of features through the installation of XPInstall modules (known as "XPI" or "zippy" installation) via the add-ons Web site that also features an update functionality to update the extensions.

Thunderbird supports a variety of themes for changing its overall look and feel. These packages of CSS and image files can be downloaded via the add-ons website at Mozilla Add-ons.{{cite web |title=Themes :: Add-ons for Thunderbird |url=https://addons.mozilla.org/en-US/thunderbird/themes/ |website=mozilla.org}}

With contributors all over the world, Thunderbird has been translated into more than 65 languages,{{cite web |title=Download a Thunderbird that SPEAKS YOUR LANGUAGE |url=https://www.mozilla.com/en-US/thunderbird/all.html |access-date=March 1, 2015 |website=mozilla.com}} although email addresses are currently limited to ASCII local parts.{{cite web |title=Mozilla Thunderbird – Reclaim Your Inbox |url=https://www.mozilla.com/en-US/thunderbird/all.html |access-date=November 13, 2013 |publisher=Mozilla.com}}{{Failed verification|reason=No mention of ASCII from this source|date=March 2021}} Thunderbird does not yet support SMTPUTF8 (RFC 6531) or Email Address Internationalization.

On 13 June 2022, it was announced that the Android app K-9 Mail had been taken over by MZLA Technologies Corporation, a subsidiary of the Mozilla Foundation. The plan was for K-9 Mail to be rebranded as Thunderbird for Android, including sync with Thunderbird on PC, integrating Thunderbird's automated account setup system, message filtering, and improvements to folders.{{Cite web |last=Axon |first=Samuel |date=2022-06-13 |title=Email client K-9 Mail will become Thunderbird for Android |url=https://arstechnica.com/gadgets/2022/06/email-client-k-9-mail-will-become-thunderbird-for-android/ |access-date=2022-06-14 |website=Ars Technica |language=en-us}}

On 30 October 2024, the first stable release of Thunderbird for Android (Thunderbird Mobile) was launched as version 8.0.{{Cite web |last=Ayhens-Madon |first=Philipp Kewisch, Monica |date=2024-10-30 |title=Thunderbird for Android 8.0 Takes Flight |url=https://blog.thunderbird.net/2024/10/thunderbird-for-android-8-0-takes-flight/ |access-date=2025-05-09 |website=The Thunderbird Blog |language=en-US}} On 6 May 2025, the stable version 10 and the beta of version 11 were released.{{Cite web |title=Releases · thunderbird/thunderbird-android |url=https://github.com/thunderbird/thunderbird-android/releases |access-date=2025-05-09 |website=GitHub |language=en}} Thunderbird for Android can be installed via Google Play and F-Droid, among others.{{Cite web |title=Thunderbird Mobile |url=https://www.thunderbird.net/en-US/mobile/ |access-date=2025-05-09 |website=Thunderbird |language=en}}

Thunderbird manages multiple email, newsgroup, and news feed accounts and supports multiple identities within accounts. Features such as quick search, saved search folders ("virtual folders"), advanced message filtering, message grouping, and tags help manage and find messages. On Linux-based systems, system mail (movemail) accounts were supported until version 91.0.{{cite web |url=https://www.thunderbird.net/en-US/thunderbird/91.0/releasenotes/#note-48 |title=Thunderbird 91.0 Release Notes |website=www.thunderbird.net |access-date=October 14, 2021}} Thunderbird provides basic support for system-specific new email notifications and can be extended with advanced notification support using an add-on.{{cite web |url=https://addons.mozilla.org/en-US/thunderbird/addon/gnotifier/ |title=GNotifier |website=addons.mozilla.org |access-date=July 21, 2017}}

Thunderbird incorporates a Bayesian spam filter, a whitelist based on the included address book, and can also understand classifications by server-based filters such as SpamAssassin.{{cite web |url=http://forums.mozillazine.org/viewtopic.php?t=367638&highlight=spamassassin |title=Mozillazine Forums |publisher=Forums.mozillazine.org |access-date=June 18, 2009}}

Thunderbird follows industry standards for email:

• POP. Basic email retrieval protocol.
• IMAP. Thunderbird has implemented many of the capabilities in IMAP, in addition to adding their own extensions and the de facto standards by Google and Apple.{{cite web |url=https://wiki.mozilla.org/MailNews:Supported_IMAP_extensions |title=MailNews:Supported IMAP extensions |website=mozilla.org}}
• LDAP address auto-completion.
• S/MIME: Inbuilt support for email encryption and signing using X.509 keys provided by a centralized certificate authority.
• OpenPGP: Inbuilt support for email encryption and signing since version 78.2.1,{{cite web|title=Thunderbird — Release Notes (78.2.1)|url=https://www.thunderbird.net/en-US/thunderbird/78.2.1/releasenotes/#note-0|access-date=2020-10-11|website=Thunderbird|language=en}}{{cite web|title=OpenPGP in Thunderbird 78|url=https://blog.thunderbird.net/2020/09/openpgp-in-thunderbird-78/|access-date=2020-10-11|website=The Thunderbird Blog|date=September 7, 2020 |language=en-US}} while older versions used extensions such as Enigmail.

Email providers have increasingly adopted OAuth authentication in addition, or instead of, more traditional authentication methods, most notably by Gmail and Outlook. Thunderbird has full support for OAuth authentication and provides instructions for Outlook users transitioning from Outlook's now-deprecated "basic authentication".{{Cite web |title=Microsoft OAuth Authentication and Thunderbird in 2024 |url=https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202}}

Thunderbird provides mailbox format support using plugins, but this feature is not yet enabled due to related work in progress.{{cite web |url=https://bugzilla.mozilla.org/show_bug.cgi?id=402392 |title=402392 – Support other message storage formats. (prelude to pluggable mail stores) |website=mozilla.org |access-date=March 1, 2015}} The mailbox formats supported {{as of|2014|07|lc=y}} are:

• mbox – Unix mailbox format (one file holding many emails)
• maildir – known as maildir-lite (one file per email). {{as of|2019|08}} "there are still many bugs", so this is disabled by default.{{cite web |url=https://support.mozilla.org/en-US/kb/maildir-thunderbird |title=Maildir in Thunderbird |website=Thunderbird Help |publisher=Mozilla |access-date=August 30, 2019}}

Thunderbird also uses Mork and (since version 3) MozStorage (which is based on SQLite) for its internal database. Mork was due to be replaced with MozStorage in Thunderbird 3.0,{{cite web |url=https://wiki.mozilla.org/Thunderbird:Thunderbird3 |title=Thunderbird 3 Planning |date=August 10, 2009 |publisher=Wiki.mozilla.org |access-date=August 19, 2009}} but the 8.0 release still uses the Mork file format.

Since version 38, Thunderbird has integrated support for automatic linking of large files instead of attaching them directly to the mail message.

Thunderbird provides a wysiwyg editor for composing messages formatted with HTML (default). The delivery format auto-detect feature will send unformatted messages as plain text (controlled by a user preference). Certain special formatting like subscript, superscript and strikethrough is available from the Format menu. The Insert > HTML menu provides the ability to edit the HTML source code of the message. There is basic support for HTML template messages, which are stored in a dedicated templates folder for each account.

File:Tbird-Screen-15.18.0.jpg

Markdown support is provided through the Markdown Here Revival add-on.{{Cite web |date=2023-11-18 |title=Markdown Here Revival |url=https://addons.thunderbird.net/en-US/thunderbird/addon/markdown-here-revival/ |access-date=2024-05-24 |website=addons.thunderbird.net |language=en-US}}

Thunderbird provides security features such as TLS/SSL connections to IMAP and SMTP servers. It also offers inbuilt support for secure email with digital signing and message encryption through OpenPGP (using public and private keys) or S/MIME (using certificates). Any of these security features can take advantage of smartcards with the installation of additional extensions.

Other security features may be added through extensions. Up to version 68, the Enigmail extension was required for OpenPGP support (now inbuilt).

Optional security protections also include disabling loading of remote images within messages, enabling only specific media types (sanitizer), and disabling JavaScript.

The French military uses Thunderbird and contributes to its security features, which are claimed to match the requirements for NATO's closed messaging system.{{cite news |last=Marcel Michelson |date=December 10, 2009 |title=French Military Donated Code to Mozilla Thunderbird |agency=Reuters |url=https://www.pcmag.com/article2/0,2817,2356958,00.asp |access-date=April 24, 2011}}

As with any software, there may be limitations to the number and sizes of files and objects represented. For example, POP3 folders are subject to filesystem design limitations, such as maximum file sizes on filesystems that do not have large-file support, as well as possible limitations of long filenames, and other issues.{{cite web |title=Limits – Thunderbird |url=http://kb.mozillazine.org/Limits_-_Thunderbird#Folders_and_messages |access-date=March 8, 2015 |website=mozillazine.org}}

File:Thunderbird on Ubuntu.jpg{{Expand section|date=October 2023}}

While primarily used as an email client, Thunderbird is also a news aggregator, which is named News Feeds and Blogs in the application. It supports RSS and more recently added Atom as well.{{Cite web |title=How to Subscribe to News Feeds and Blogs {{!}} Thunderbird Help |url=https://support.mozilla.org/en-US/kb/how-subscribe-news-feeds-and-blogs |access-date=2023-10-22 |website=support.mozilla.org}}

The software has a chat client for instant messaging, supporting the IRC, XMPP, and (since version 102) Matrix protocols,{{Cite web |date=2022-06-29 |title=Thunderbird 102 Releases with Matrix Support and New Address Book |url=https://news.itsfoss.com/thunderbird-102-release/ |access-date=2023-10-22 |website=It's FOSS News |language=en}} and the Odnoklassniki network. In the past, it also had support for Twitter, Google Talk and Facebook Chat.{{cite web | url=https://www.ghacks.net/2012/09/28/make-thunderbird-the-chat-powerhouse-add-chat-protocols/ | title=Make Thunderbird the chat powerhouse: Add chat protocols - gHacks Tech News | date=September 28, 2012 }}

Thunderbird is also a newsreader for Usenet, using the NNTP protocol and supports NNTPS. Intended for reading use, it does not support NZB for binary downloading, nor does it have a search function for the newsgroups.{{Cite web |title=Thunderbird Review - Best Newsreaders Reviewed - UsenetReviewz.com |url=https://usenetreviewz.com/thunderbird-review/ |access-date=2023-10-22 |website=usenetreviewz.com |language=en}}

As of version 91, Thunderbird introduced a built-in PDF document reader, allowing users to open and view PDF attachments or files directly within the application without needing an external PDF viewer.{{Cite web |last=Sipes |first=Ryan |date=2021-08-12 |title=Thunderbird 91 Available Now |url=https://blog.thunderbird.net/2021/08/thunderbird-91-available-now/ |access-date=2023-10-22 |website=The Thunderbird Blog |language=en-US}}

File:Mozilla-thunderbird--dark-mode--emails-screen--without-tabs.png

Thunderbird runs on a variety of platforms. Releases available on the primary distribution site support the following operating systems:{{cite web |url=https://www.thunderbird.net/en-US/thunderbird/102.1.0/system-requirements/ |title=System Requirements 102.1.0|publisher=thunderbird.net |url-status=live |archive-url=https://web.archive.org/web/20220728230906/https://www.thunderbird.net/en-US/thunderbird/102.1.0/system-requirements/ |archive-date=July 28, 2022 |access-date=August 5, 2022}}

• Linux
• Windows
• macOS

Unofficial ports are available for:

• FreeBSD{{cite web |url=https://www.freshports.org/mail/thunderbird/ |title=mail/thunderbird |publisher=FreshPorts |access-date=August 18, 2012}}
• OpenBSD{{cite web |url=http://ports.su/mail/mozilla-thunderbird |title=thunderbird-31.4.0 – Mozilla e-mail, rss and usenet client |publisher=OpenBSD ports |access-date=March 1, 2015}}

Ports for older versions available for OS/2 (including ArcaOS and eComStation).{{cite web |url=https://os2news.warpstock.org/Warpzilla.html |title=Warpzilla – Mozilla for OS/2 |publisher=Os2news.warpstock.org |access-date=August 6, 2018 |quote=Firefox 52esr is the last version that will be ported to OS/2. |archive-url=https://web.archive.org/web/20180919085008/http://os2news.warpstock.org/Warpzilla.html |archive-date=September 19, 2018 |url-status=dead }}{{cite web |url=https://wiki.mozilla.org/Ports/os2 |title=Ports/os2 – MozillaWiki |publisher=Mozilla.org |access-date=November 13, 2013}}

The source code is freely available and can be compiled to be run on a variety of other architectures and operating systems.

In June 2022, the Thunderbird project announced that it would be collaborating with email client K-9 for Android to build a Thunderbird version for Android.{{Cite web |last=Evangelho |first=Jason |date=2022-06-13 |title=Revealed: Our Plans For Thunderbird On Android |url=https://blog.thunderbird.net/2022/06/revealed-thunderbird-on-android-plans-k9/ |access-date=2022-07-07 |website=The Thunderbird Blog |language=en-US}} To this end, K-9 lead developer Christian Ketterer joined the Thunderbird team in 2022. The plan was to transform K-9 Mail into Thunderbird on Android, including the respective name change and adoption of the Thunderbird branding. As soon as K-9 Mail had been brought into alignment with Thunderbird's feature set and visual appearance, this changeover would take place, according to Thunderbird's Jason Evangelho.

In the 2022 Financial Report published on May 8th, 2023, Ryan Sipes (Product and Business Development Manager) mentions plans of hiring an iOS developer later that same year to start laying the foundation for Thunderbird on iOS.{{cite web|url=https://thunderbird.topicbox-usercontent.com/download/d9235ee6-1811-11e8-a2b4-c45ae5388869/G280ee443d9bfc8cb5bb0a386bdec6f10ff0d4b16/2022_Thunderbird_Financial_Report.pdf?accept=application%2Fpdf&access_token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJkOTIzNWVlNi0xODExLTExZTgtYTJiNC1jNDVhZTUzODg4NjkiLCJzdWIiOiJodHRwczovL3RodW5kZXJiaXJkLnRvcGljYm94LXVzZXJjb250ZW50LmNvbS9kb3dubG9hZC9kOTIzNWVlNi0xODExLTExZTgtYTJiNC1jNDVhZTUzODg4NjkvRzI4MGVlNDQzZDliZmM4Y2I1YmIwYTM4NmJkZWM2ZjEwZmYwZDRiMTYvMjAyMl9UaHVuZGVyYmlyZF9GaW5hbmNpYWxfUmVwb3J0LnBkZiIsImlhdCI6MTcxNzQzNzYwMH0.3tPaz9ys1sxxmpUVufTXxnhP4jIz8mLx69sRogszj4o|title=Thunderbird By The Numbers: Our 2022 Financial Report|author=Sipes, Ryan|date=8 May 2023|access-date=3 June 2024|website=Thunderbird.Topicbox.com}}

On 30 October 2024, the first stable release of Thunderbird for Android (Thunderbird Mobile) was launched as version 8.0. Thunderbird for Android can be installed via Google Play and F-Droid, among others.{{Cite web |title=Thunderbird Mobile |url=https://www.thunderbird.net/en-US/mobile/ |access-date=2025-05-09 |website=Thunderbird |language=en}} The Thunderbird team had planned in 2022 to maintain K-9 for one year after the release of Thunderbird Mobile, i.e. until roughly October 2025.{{Cite web |last=Evangelho |first=Jason |date=2022-06-13 |title=Frequently Asked Questions: Thunderbird Mobile and K-9 Mail |url=https://blog.thunderbird.net/2022/06/faq-thunderbird-mobile-and-k-9-mail/ |access-date=2025-05-09 |website=The Thunderbird Blog |language=en-US}}

On 6 May 2025, the stable version 10 of Thunderbird Mobile and the beta of version 11 were released.{{Cite web |title=Releases · thunderbird/thunderbird-android |url=https://github.com/thunderbird/thunderbird-android/releases |access-date=2025-05-09 |website=GitHub |language=en}}

{{Mozilla Thunderbird release compatibility}}

{{Thunderbird contrib release compatibility}}

File:Mozilla Thunderbird old logo.png

File:Mozilla Thunderbird logo.png

Originally launched as Minotaur shortly after Phoenix (the original name for Mozilla Firefox), the project failed to gain momentum. With the success of Firefox, however, demand increased for a mail client to go with it, and the work on Minotaur was revived under the new name of Thunderbird, and migrated to the new toolkit developed by the Firefox team.

File:Photo écran mozilla thunderbird grand.jpg

On December 7, 2004, version 1.0 was released, and received more than 500,000 downloads in its first three days of release, and 1,000,000 in ten days.{{cite web |date=December 10, 2004 |title=thunderbird breaks half a million downloads in three days |url=http://weblogs.mozillazine.org/asa/archives/007074.html |url-status=dead |archive-url=https://web.archive.org/web/20120211125215/http://weblogs.mozillazine.org/asa/archives/007074.html |archive-date=February 11, 2012 |access-date=February 9, 2013 |publisher=Asa Dotzler's Blog}}{{cite web |date=December 18, 2004 |title=thunderbird 1.0 reaches 1,000,000 downloads in just 10 days! |url=http://weblogs.mozillazine.org/asa/archives/007119.html |url-status=dead |archive-url=https://web.archive.org/web/20130708020638/http://weblogs.mozillazine.org/asa/archives/007119.html |archive-date=July 8, 2013 |access-date=February 9, 2013 |publisher=Asa Dotzler's Blog}}

Significant work on Thunderbird restarted with the announcement that from version 1.5 onward the main Mozilla suite would be designed around separate applications using this new toolkit. This contrasts with the previous all-in-one approach, allowing users to mix and match the Mozilla applications with alternatives. The original Mozilla Suite continues to be developed as SeaMonkey.

On December 23, 2004, Project Lightning was announced which tightly integrated calendar functionality (scheduling, tasks, etc.) into Thunderbird. Lightning supports the full range of calendar mechanisms and protocols supported by the Mozilla Calendar infrastructure, just as with modern (post-0.2) Sunbird.

On October 11, 2006, Qualcomm and the Mozilla Foundation announced that "future versions of Eudora will be based upon the same technology platform as the open source Mozilla Thunderbird email program."{{Cite press release |title=QUALCOMM Launches Project in Collaboration with Mozilla Foundation to Develop Open Source Version of Eudora Email Program |date=October 11, 2006 |publisher=Eudora.com |url=http://www.eudora.com/press/2006/eudora-mozilla_final_10.11.06.html |access-date=November 13, 2013 |archive-url=https://web.archive.org/web/20131001115204/http://www.eudora.com/press/2006/eudora-mozilla_final_10.11.06.html |archive-date=October 1, 2013 |url-status=dead}} The project was code-named Penelope.

In late 2006, Debian rebranded Thunderbird as Icedove due to trademark and copyright reasons. This was the second product to be rebranded.{{cite web |url=https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=354622 |title=Uses Mozilla Firefox trademark without permission – Debian Bug Tracker |website=Debian |access-date=September 18, 2010}}

On July 26, 2007, the Mozilla Foundation announced that Thunderbird would be developed by an independent organization, because the Mozilla Corporation (a subsidiary of the foundation) was focusing on Mozilla Firefox development.{{Cite news |url=https://www.informationweek.com/story/showArticle.jhtml?articleID=201201609 |title=Mozilla Gives Thunderbird E-Mail The Boot |last=Claburn |first=Thomas |date=July 27, 2007 |work=Internet section |access-date=July 31, 2007 |archive-date=December 9, 2007 |archive-url=https://web.archive.org/web/20071209003521/http://informationweek.com/story/showArticle.jhtml?articleID=201201609 |url-status=dead }}

On September 17, 2007, the Mozilla Foundation announced the funding of a new internet communications initiative with David Ascher of ActiveState. The purpose of this initiative was "to develop Internet communications software based on the Thunderbird product, code, and brand".{{Cite press release |title=Mozilla Launches Internet Mail and Communications Initiative |date=September 17, 2007 |publisher=Mozilla.com |url=https://www.mozilla.com/en-US/press/mozilla-2007-09-17.html |access-date=June 18, 2009}}

On February 19, 2008, Mozilla Messaging started operations as a subsidiary of the Mozilla Foundation responsible for the development of email and similar communications. Its initial focus was on the then upcoming version of Thunderbird 3. Alpha Preview releases of Thunderbird 3 were codenamed "Shredder".

File:Mozilla Thunderbird 5.0 Windows 7.png

On April 4, 2011, Mozilla Messaging was merged into the Mozilla Labs group of the Mozilla Foundation.{{cite web |url=https://arstechnica.com/open-source/news/2011/04/thunderbird-returns-to-nest-as-mozilla-messaging-rejoins-mozilla.ars |title=Thunderbird returns to nest as Mozilla Messaging rejoins Mozilla |last=Paul |first=Ryan |date=April 5, 2011 |publisher=Ars Technica |access-date=April 5, 2011}}

Following in the footsteps of Firefox, Thunderbird switched to a rapid release cycle in 2011.{{Cite web |title= Thunderbird Joins the Rapid Release Process, Introduces Shredder, Miramar and Earlybird - gHacks Tech News|date=June 17, 2011 |url=https://www.ghacks.net/2011/06/17/thunderbird-joins-the-rapid-release-process-introduces-shredder-miramar-and-earlybird/}} Version 4.0 was skipped so as to re-align Thunderbird with Firefox's version 5.0, both released in June 2011.{{Cite web |title=Thunderbird 5.0 - New Features and Changes - MozillaZine Knowledge Base |url=https://kb.mozillazine.org/Thunderbird_5.0_-_New_Features_and_Changes |access-date=2023-10-21 |website=kb.mozillazine.org}} By the end of the year it had reached version 9.0.{{Cite web |title=Thunderbird Release Notes |url=https://website-archive.mozilla.org/www.mozilla.org/thunderbird_releasenotes/en-us/thunderbird/9.0/releasenotes/?uri=/thunderbird/releasenotes/&locale=en-US&platform=linux-x86_64&version=9.0 |access-date=2023-10-21 |website=website-archive.mozilla.org}}

On July 6, 2012, a confidential memo from Jb Piacentino, the Thunderbird Managing Director at Mozilla, was leaked and published to TechCrunch.{{cite web |url=https://techcrunch.com/2012/07/06/so-thats-it-for-thunderbird/ |title=So, That's It For Thunderbird |last=Sarah Perez |date=July 6, 2012 |publisher=TechCrunch |access-date=August 18, 2012}} The memo indicated that Mozilla would be moving some of the team off the project and further development of new features would be left up to the community. The memo was slated for release on July 9, 2012. A subsequent article by the Executive Chair of Mozilla, Mitchell Baker, stated Mozilla's decision to make a transition of Thunderbird to a new release and governance model.{{cite web |date=July 6, 2012 |title=Thunderbird: Stability and Community Innovation |url=https://blog.lizardwrangler.com/2012/07/06/thunderbird-stability-and-community-innovation/ |access-date=August 18, 2012 |publisher=Mitchell's Blog}}{{cite web |title=Thunderbird/New Release and Governance Model |url=https://wiki.mozilla.org/Thunderbird/New_Release_and_Governance_Model |access-date=February 14, 2015 |publisher=MozillaWiki}} On July 6, 2012, Mozilla announced the company was dropping the priority of Thunderbird development because the continuous effort to extend Thunderbird's feature set was mostly fruitless. The new development model shifted to Mozilla offering only "Extended Support Releases", which deliver security and maintenance updates, while allowing the community to take over the development of new features.

On November 25, 2014, Kent James of the volunteer-led Thunderbird Council announced on the Thunderbird blog that active contributors to Thunderbird gathered at the Mozilla office in Toronto and discussed the future of the application. They decided that more staff were required working full-time on Thunderbird so that the Thunderbird Team could release a stable and reliable product and make progress on features that had been frequently requested by the community.{{cite web |url=https://blog.mozilla.org/thunderbird/2014/11/thunderbird-reorganizes-at-2014-toronto-summit/ |title=Thunderbird Reorganizes at 2014 Toronto Summit |date=November 25, 2014 |publisher=The Mozilla Thunderbird Blog |access-date=February 1, 2015}}

On December 1, 2015, Mozilla Executive Chair Mitchell Baker announced in a company-wide memo that Thunderbird development needed to be uncoupled from Firefox.{{cite web |last=Baker |first=Mitchell |title=Mozilla Governance: Thunderbird, the future, mozilla-central and comm-central |url=https://groups.google.com/forum/#!msg/mozilla.governance/kAyVlhfEcXg/Eqyx1X62BQAJ/ |access-date=January 2, 2016 |website=Google Groups, Mozilla Governance}} She referred to Thunderbird developers spending large efforts responding to changes to Mozilla technologies, while Firefox was paying a tax to support Thunderbird development. She also said that she does not believe Thunderbird has the potential for "industry-wide impact" that Firefox does.{{cite web |last=Lunden |first=Ingrid |title=Mozilla Wants To Split Off Its Thunderbird Email/Chat Client, Says Mitchell Baker Memo |url=https://techcrunch.com/2015/11/30/thunderbird-flies-away-from-mozilla/ |access-date=December 4, 2015 |website=TechCrunch|date=November 30, 2015 }} Mozilla remained interested in having a role in Thunderbird, but sought more assistance to help with development.{{cite web |url=https://blog.lizardwrangler.com/2015/12/03/thunderbird-update/ |title=Thunderbird Update {{!}} Mitchell's Blog |website=blog.lizardwrangler.com |access-date=October 13, 2016}} Therefore, at the same time, it was announced that Mozilla Foundation would provide at least a temporary legal and financial home for the Thunderbird project.{{cite web |last=Kent |first=James |title=Thunderbird Active Daily Inquiries Surpass 10 Million! |url=https://blog.mozilla.org/thunderbird/2015/12/thunderbird-active-daily-inquiries-surpass-10-million/ |access-date=January 2, 2016 |website=The Mozilla Thunderbird Blog|date=December 8, 2015 }}

File:Thunderbird Logo, 2018.svg

File:Thunderbird 2023 icon.png

On May 9, 2017, Philipp Kewisch announced that the Mozilla Foundation would continue to serve as the legal and fiscal home for the Thunderbird project, but that Thunderbird would migrate off Mozilla Corporation infrastructure, separating the operational aspects of the project.{{cite web |url=https://blog.mozilla.org/thunderbird/2017/05/thunderbirds-future-home/ |title=Thunderbird's Future Home |last=Kewisch |first=Philipp |website=The Mozilla Thunderbird Blog |date=May 9, 2017 |publisher=Mozilla |access-date=May 11, 2017}} Mozilla brought Thunderbird back in-house in an announcement on May 9, 2017, and continued to support its development.{{cite web |last=Kewisch |first=Philipp |title=Thunderbird's Future Home |url=https://blog.mozilla.org/thunderbird/2017/05/thunderbirds-future-home/ |access-date=May 29, 2019 |website=The Mozilla Thunderbird Blog |date=May 9, 2017 |publisher=Mozilla}}{{cite web |last=Lardinois |first=Frederic |title=Mozilla promises a faster, prettier Thunderbird with better Gmail support |url=https://techcrunch.com/2019/01/02/mozilla-promises-a-faster-prettier-thunderbird-with-better-gmail-support/ |access-date=May 29, 2019 |website=TechCrunch|date=January 2, 2019 }} The Thunderbird development team expanded by adding several new members and overhauled security and the user interface.{{cite web |last=Sipes |first=Ryan |title=Thunderbird in 2019 |url=https://blog.mozilla.org/thunderbird/2019/01/thunderbird-in-2019/ |access-date=May 29, 2019 |website=The Mozilla Thunderbird Blog |date=January 2, 2019 |publisher=Mozilla}}

The interim/beta versions Thunderbird 57 and 58, released in late 2017, began to make changes influenced by Firefox Quantum, including a new "Photon" user interface.{{Cite news |url=https://thenextweb.com/apps/2017/12/20/mozillas-thunderbird-email-client-isnt-dead-yet/ |title=Mozilla's Thunderbird email client isn't dead yet |last=Ghoshal |first=Abhimanyu |date=December 20, 2017 |work=The Next Web |access-date=December 26, 2017}}{{cite web |url=https://blog.mozilla.org/thunderbird/2017/12/new-thunderbird-releases-and-new-thunderbird-staff/ |title=New Thunderbird Releases and New Thunderbird Staff |website=The Mozilla Thunderbird Blog |date=December 19, 2017 |access-date=December 26, 2017}} Despite the removal in Firefox Quantum of support for XUL-based legacy add-ons in favor of WebExtensions, the stable/ESR release of Thunderbird 60 in mid-2018 continued to support them, although most would require updates, and it did not support WebExtensions except for Themes.{{cite web |url=https://wiki.mozilla.org/Thunderbird/Add-ons_Guide_57 |title=Thunderbird/Add-ons Guide 57 - MozillaWiki |website=wiki.mozilla.org |access-date=September 24, 2018}}{{cite web |url=https://www.thunderbird.net/en-US/thunderbird/60.0/releasenotes/ |title=Thunderbird — Release Notes (60.0) |website=Thunderbird |access-date=September 24, 2018}} In 2018, work was underway for planned support in Thunderbird 63 of WebExtensions and to continue to "somewhat" support legacy addons, according to Mozilla.{{cite web |url=https://wiki.mozilla.org/Thunderbird/Add-ons_Guide_63 |title=Thunderbird/Add-ons Guide 63 - MozillaWiki |website=wiki.mozilla.org |access-date=September 24, 2018}}

With the release of Thunderbird 68 in August 2019 it now only supports WebExtension addons.{{cite web |url=https://www.thunderbird.net/en-US/thunderbird/68.0/releasenotes/ |title=Thunderbird — Release Notes (68.0) |website=Thunderbird |access-date=December 8, 2019}} Legacy Addons can still be used if a special "legacy mode" is enabled, but even for this, the legacy Addon has to be converted.{{cite web |url=https://developer.thunderbird.net/add-ons/tb68 |title=Updating Legacy Extensions for Thunderbird 68 |website=developer.thunderbird.net |access-date=December 8, 2019}} Alongside the transition, OpenPGP support was integrated directly into Thunderbird as a standard feature, seeking to supplant the Enigmail extension.{{cite web|url=https://sequoia-pgp.org/blog/2021/04/08/202103-a-new-backend-for-thunderbird/|title = Sequoia: Super Powering End-to-End Email Encryption in Mozilla Thunderbird}} Mainly for licensing reasons, this is no longer based on GnuPG, but on the RNP library, which has more liberal licensing terms.{{cite web |url=https://mail.mozilla.org/pipermail/tb-planning/2019-December/007287.html |title=Thunderbird and OpenPGP - Why not GnuPG by default? |publisher=Mail.mozilla.org |date= |accessdate=2022-04-29 |archive-date=January 18, 2022 |archive-url=https://web.archive.org/web/20220118014845/https://mail.mozilla.org/pipermail/tb-planning/2019-December/007287.html |url-status=dead }}

On January 28, 2020, the Mozilla Foundation announced that the project would henceforth be operating from a new wholly owned subsidiary, MZLA Technologies Corporation, in order to explore offering products and services that were not previously possible and to collect revenue through partnerships and non-charitable donations.{{cite web |last=Cimpanu |first=Catalin |date=January 29, 2020 |title=Mozilla moves to monetize Thunderbird, transfers project to new subsidiary |url=https://www.zdnet.com/article/mozilla-moves-to-monetize-thunderbird-transfers-project-to-new-subsidiary/ |access-date=2022-02-27 |website=ZDNet |language=en}}{{cite web |title=Thunderbird's New Home |url=https://blog.thunderbird.net/2020/01/thunderbirds-new-home/ |access-date=January 28, 2020 |website=The Mozilla Thunderbird Blog|date=January 28, 2020 }}

As of version 78.7.1, Thunderbird will no longer allow installation of addons that use Legacy WebExtensions. Only MailExtensions are now compatible with Thunderbird.{{cite web|accessdate=2021-02-10|title=Update for Thunderbird 78|url=https://developer.thunderbird.net/add-ons/updating/tb78|website=developer.thunderbird.net}}{{cite web|accessdate=2021-02-10|title=Thunderbird 78.7.1 released with CardDAV improvements |url=https://www.ghacks.net/2021/02/07/thunderbird-78-7-1-released-with-carddav-improvements/|website=gHacks Tech News|date=February 7, 2021}} MailExtensions are WebExtensions but with "some added features specific to Thunderbird".{{cite web|accessdate=2021-02-10|title=Thunderbird add-on developer launches Kickstarter campaign to ensure continued compatibility |url=https://www.ghacks.net/2020/01/27/thunderbird-add-on-developer-launches-kickstarter-campaign-to-ensure-continued-compatibility/|website=gHacks Tech News|date=January 27, 2020}}

Thunderbird 91 features various UI improvements (including a new account setup workflow), Apple silicon support, CardDAV address book support, built-in import and export tools for Thunderbird profiles, the PDF.js PDF viewer, and the ability to encrypt emails to BCC recipients.{{cite web|last=Brinkmann|first=Martin|date=2021-08-13|title=Thunderbird 91 is available as a manual upgrade - gHacks Tech News|url=https://www.ghacks.net/2021/08/13/thunderbird-91-is-available-as-a-manual-upgrade/|access-date=2021-12-19|website=gHacks Technology News|language=en-US}}{{cite web|last=Brinkmann|first=Martin|date=2021-12-08|title=Thunderbird 91.4.0 Email Client has been released - gHacks Tech News|url=https://www.ghacks.net/2021/12/08/thunderbird-91-4-0-email-client-has-been-released/|url-status=live|archive-url=https://archive.today/20211219102023/https://www.ghacks.net/2021/12/08/thunderbird-91-4-0-email-client-has-been-released/|archive-date=December 19, 2021|access-date=2021-12-19|website=gHacks Technology News|language=en-US}}{{cite web|last=Nestor|first=Marius|date=2021-08-11|title=Mozilla Thunderbird 91 Released as a Massive Update with Numerous New Features and Improvements|url=https://9to5linux.com/mozilla-thunderbird-91-released-as-a-massive-update-with-numerous-new-features-and-improvements|url-status=live|archive-url=https://archive.today/20211219093202/https://9to5linux.com/mozilla-thunderbird-91-released-as-a-massive-update-with-numerous-new-features-and-improvements|archive-date=December 19, 2021|access-date=2021-12-19|website=9to5Linux|language=en-US}}{{cite web|last=Crume|first=Jacob|date=2021-08-12|title=Thunderbird 91 is a Major Upgrade That Could Help Reclaim its Position as the Default Linux Mail Client|url=https://news.itsfoss.com/thunderbird-91-release/|url-status=live|archive-url=https://archive.today/20211219094047/https://news.itsfoss.com/thunderbird-91-release/|archive-date=December 19, 2021|access-date=2021-12-19|website=It's FOSS News|language=en-US}}

On June 13, 2022, it was announced that the Mozilla Thunderbird team would take over development of the Android email client app K-9 Mail, with plans for it to eventually become a mobile version of Thunderbird with synchronisation support.

In November 2024, Thunderbird Mobile became available for download,{{cite web | url=https://www.howtogeek.com/thunderbird-mail-android-release/ | title=Thunderbird Mail for Android is Finally Out for Everyone | date=October 30, 2024 }} and in December 2024, iodéOS, an open source Android operating system, began including Thunderbird Mobile as the default email client for some 30+ devices.{{cite web | url=https://blog.iode.tech/get-ready-for-thunderbird-mobile/ | title=Get ready for the transition to Thunderbird mobile! | date=November 8, 2024 }}

Thunderbird development releases occur in three stages, called Beta, Earlybird, and Daily, which correspond to Firefox's Beta, Aurora, and Nightly stages. The release dates and Gecko versions are exactly the same as Firefox; for example, Firefox 7 and Thunderbird 7 were both released on September 27, 2011, and were both based on Gecko 7.0.

{{Timeline Mozilla Thunderbird}}

{{Reflist|colwidth=30em}}

{{commons category}}

• {{Official website}}

{{Email clients}}

{{Mozilla}}

{{FreeCollabManageSoftware}}

{{FOSS}}

{{Aggregators}}

{{IRC footer}}

{{Authority control}}

Category:2003 software

Category:Cross-platform free software

Category:Email client software for Linux

Category:Free email software

Category:Free multilingual software

Category:Free software programmed in C++

Category:Free Usenet clients

Category:Gecko-based software

Category:macOS email clients

Category:News aggregator software

Category:OS/2 software

Category:Portable software

Category:Software that uses SQLite

Category:Software that uses XUL

Category:Software using the Mozilla Public License

Category:Unix Internet software

Category:Windows email clients