Thunderbird is a mail/messaging application managed and developed by the Thunderbird community. These pages document Thunderbird and the MailNews backend which is also used in other projects such as Seamonkey and Postbox.
Thunderbird is built on the same technical platform as the Firefox web browser. Currently one of the most popular open source email clients, it is used by tens of millions of people around the world to bring together all their email accounts, chat, newsgroup and feed reading in a familiar high-productivity environment. (From early 2007 to early 2011 Thunderbird was developed by Mozilla Messaging, a subsidiary owned by Mozilla.)