The only two paid developers working on the Thunderbird email client have quit Mozilla, just three weeks after Mozilla spun off Thunderbird to a new subsidiary.
Scott McGregor and David Bienvenu used blog posts last week to announce that their last day with Mozilla will be this Friday.
McGregor, who started the Thunderbird project in February 2003, said: "I plan to continue on, as a volunteer, with my role as a module owner for the Thunderbird project.
"I wish the Mozilla Corporation and the new Thunderbird Mail Corporation luck in their future endeavours," he added.
Bienvenu posted a similar message on his blog Friday.
Mozilla did not respond to questions and a request for comment on the departure of the two developers, who led the largely volunteer effort to create the Thunderbird email application.
In a blog posting of her own, Mozilla's CEO Mitchell Baker only alluded to losing McGregor and Bienvenu. As she retraced the decision to separate Thunderbird from the Firefox-centric work at Mozilla, she said: "Two things became clear. We had the team for developing... a standalone desktop email application. But we didn't have the complete set of people to address both that and the larger issues."
The second thing that became apparent, she said, was that Mozilla wouldn't be able to create the kind of email/communication software that was needed by users.
Last month, Baker announced the spinoff, dubbed "MailCo" until a permanent name can be found, would be a wholly-owned subsidiary of the non-profit Mozilla Foundation, just as is the for-profit Mozilla. The separation was the result of discussion within the latter, as well as public debate about Thunderbird's future that kicked off in July. Firefox, Baker said in July and repeated today, is Mozilla's first and overriding priority, which left Thunderbird a stepchild at best.
"Firefox was at the centre of a new wave of activity and a giant ecosystem," she said, referring to a period two years ago when Firefox share caught fire.
"Through this Mozilla acquired a stronger voice for openness, innovation and participation on the web." But not Thunderbird.
"Thunderbird is an excellent basis for thinking about these topics and improving internet and web-based communications as a whole. But this wasn't happening, Baker said. "We weren't seeing Thunderbird develop the kind of community or influence in the industry that Firefox has."
The split was also ordained by Mozilla's minimalistic approach to management, Baker claimed. To handle both Firefox and Thunderbird appropriately, the company would have needed to add another management layer.
"We have managers and management in the Mozilla Foundation and Corporation, but generally we have as little as possible to get the job done."
Thunderbird users who read McGregor and Bienvenu's notices were supportive and disappointed simultaneously. Some wanted to know more.
"Could you enable the verbose mode and tell us more about the reasons you and mscott are leaving MoCo despite the creation of a company dedicated to Thunderbird (aka 'MailCo')?" asked a user identified as LpSolit in a comment to Bienvenu's post. "Why so much mystery? All this generates is rumors... and that's probably not good."
Others saw a possible nightmare in the making. "The way I see it, Mozilla is spinning off Thunderbird and tossing them a safe amount of money," said Joel.
"They're safely removing all responsibility for the future of Thunderbird... and when MailCo flops they can shrug their shoulders and say market forces killed it."
McGregor and Bienvenu did not reply to email messages requesting comment and/or an interview.