Lightning is available in 32-bit and 64-bit versions for Windows, OS X and Linux.
Version 0.9 was the last planned release for Thunderbird 2. A calendar was originally to be fully integrated into Thunderbird 3, but those plans were changed due to concerns with the product's maturity and level of support.[4][5] Lightning 1.0b2 is compatible with Thunderbird 3.1, Lightning 1.0b5 is compatible with Thunderbird 5 and 6, and Lightning 1.0b7 is compatible with Thunderbird 7.[6][7] Lightning 1.0 was released to the public on November 7, 2011. It was released alongside Thunderbird 8.0. Since then, every Thunderbird release has been accompanied by a compatible Lightning point release.
Sun Microsystems contributed significantly to the Lightning Project to provide users with an alternative free and open-source choice to Microsoft Office by combining OpenOffice.org and Thunderbird with the Lightning Extension.[8] In addition to general bug-fixing, Sun focused on calendar views, team/collaboration features and support for the Sun Java Calendar Server.[9]