Mozilla's Thunderbird email client has been turned into a new for-profit subsidiary, with Mozilla Corp giving the unnamed company with $3 million in start-up money.

The move is identical to the one made by the umbrella Mozilla Foundation in 2005 when it created Mozilla Corp to manage Firefox. "The new organisation doesn't have a name yet, so I'll call it MailCo here," said Mozilla CEO Mitchell Baker on her blog. "Technically, it will be a wholly owned subsidiary of the Mozilla Foundation, just like the Mozilla Corporation."

MailCo is the result of internal talks and public discussion about the future of Thunderbird that began in July. Then, Baker, who also chairs the Foundation, said that because Firefox was Mozilla Corp's first priority, it had to divest itself of Thunderbird. Among the options she outlined: Creating a new non-profit organisation similar to the Mozilla Foundation to focus on the email program; building a new subsidiary of the foundation just for Thunderbird; and releasing Thunderbird into the wild as a community-only project.

Scott MacGregor and David Bienvenu, the two Mozilla employees who headed Thunderbird development efforts, voted for the third option. Today, however, Mozilla chose the second.

Most Thunderbird users blasted Baker and Mozilla Corp for wanting to ditch the email program, which competes with Microsoft's Outlook and IBM's Notes, as well as with web-based email services such as Windows Live Mail, Yahoo Mail, and Google's Gmail.

The new company will focus on developing communications software based on the current Thunderbird product, its code base and its brand. The goal is to create a community of developers, similar to the one already in place for Firefox, that's dedicated to working on Thunderbird and associated products. "We can spark the same kind of excitement and energy level and innovation [as with Firefox] in the email/communications space," Baker said.

Among MailCo's out-the-gate goals, said Baker, are supporting existing Thunderbird users and creating "a better user experience for a range of internet communications" that will explore how email should work with other technologies such as RSS, instant messaging, VoIP, and SMS.