In February 2017, Thunderbird packages were reintroduced into the Debian repositories, and on April 20, 2017, the Icedove package in Debian Stable was de-branded back to Thunderbird. Iceowl Iceowl was a calendar application distributed by the Debian project. It was based on Mozilla Sunbird, but was made entirely of free software. The Lightning calendar extension for Mozilla Thunderbird was rebranded as Iceowl Extension. Iceweasel History History and origin of name Mozilla Foundation owns the trademark "Firefox" and claims the right to deny the use of the name and other trademarks to unofficial builds. The Debian Free Software Guidelines are used by the Debian project to determine whether a license is a free license, which in turn is used to determine whether something can be included in Debian. As the logo did not meet these requirements, it could not be used by software which was to be included in Debian. This effect of the Mozilla trademark policy led to a long debate within the Debian Project in 2004 and 2005. During this debate, the name "Iceweasel" was coined to refer to rebranded versions of Firefox. The first known use of the name in this context is by Nathanael Nerode, in reply to Eric Dorland's suggestion of "Icerabbit". It was intended as a parody of "Firefox". "Iceweasel" was subsequently used as the example name for a rebranded Firefox in the Mozilla Trademark Policy, and became the most commonly used name for a hypothetical rebranded version of Firefox. By January 1, 2005, such strategic rebranding had come to be referred to as the "Iceweasel route". The term "ice weasel" appeared earlier in a line which Matt Groening fictionally attributed to Friedrich Nietzsche: "Love is a snowmobile racing across the tundra and then suddenly it flips over, pinning you underneath. At night, the ice weasels come." Debian was initially given permission to use the trademarks, and adopted the Firefox name. However, because the artwork in Firefox had a proprietary copyright license which was not compatible with the Debian Free Software Guidelines, the substituted logo had to remain. Trademark agreement revocation In February 2006, Mike Connor, representing the Mozilla Corporation, wrote to the Debian bug tracker and informed the project that Mozilla did not consider the way in which Debian was using the Firefox name to be acceptable. Connor confirmed that the Mozilla Corporation was revoking the previous agreement which allowed Debian to use the