Mozilla spun off its Thunderbird e-mail client into a new for-profit subsidiary on Monday and seeded the unnamed company with $US3 million in start-up money, the open-source developer announced.

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 organization 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 Corp."

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. The options she outlined included the following: creating a new nonprofit organization similar to the Mozilla Foundation to focus on the e-mail 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. However, Mozilla chose the second.

Most Thunderbird users criticized Baker and Mozilla for wanting to ditch the e-mail program, which competes with Microsoft's Outlook and IBM's Lotus Notes, as well as with Web-based e-mail 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 e-mail/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 e-mail should work with other technologies such as Real Simple Syndication, instant messaging, voice over IP and Short Messaging Service.

David Ascher, the former chief technology officer and vice president of engineering at ActiveState Software Inc., a Vancouver, British Columbia-based development tool maker, will lead the new company, said Baker in a statement. "David has been a respected member of the Mozilla community for many years, and we're excited that he is joining Mozilla to lead this important effort."

Ascher, also the director of the Python Software Foundation, has led Komodo, a Mozilla-backed, open-source development environment project. Less than two weeks ago, ActiveState debuted its Open Komodo Project, which will switch many of the company's already-free development tools to open-source.

Mozilla was set to announce the new venture Tuesday morning, but moved up the news several hours to Monday night when Yahoo Inc. said earlier in the day that it would acquire Zimbra Inc., a privately-held Web-based e-mail and collaboration provider, for $350 million.

It's unknown whether Mozilla's current in-house Thunderbird developers will continue with the new company. Baker hinted that they may not. In her blog, she explained that the $3 million in seed money for MailCo will "be spent mostly on building a small team of people who are passionate about e-mail and Internet communications."

Neither Thunderbird developer Scott MacGregor, who started the project in February 2003, or his co-worker, David Bienvenu, responded to a request for comment.